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Other Stuff => Archived Manufacturer Circles => Music Reference => Topic started by: Roger A. Modjeski on 24 Jun 2014, 06:19 pm

Title: Favorite Coupling Cap Brands and Types
Post by: Roger A. Modjeski on 24 Jun 2014, 06:19 pm
I would like to hear your recommendations. After I get a few I will start a poll.

If you know the price of your favorite 0.1 uf 600 V (or similar) coupling cap please state as prices vary widely.
Title: Re: Favorite Coupling Cap Brands and Types
Post by: corndog71 on 24 Jun 2014, 08:03 pm
My current production favorite is the Clarity Cap MR series.  0.1uF 630V $29.94

This may not apply but lately I've been enjoying Russian millitary K42Y-2 caps.  They are slightly warmer in overall tone than the MR caps but seem to have the same level of resolution.  I haven't done extensive testing but at around a $1 each (0.1uF 630V) they are a serious bargain. 
Title: Re: Favorite Coupling Cap Brands and Types
Post by: Mike B. on 24 Jun 2014, 09:25 pm
If you have the time, here is a cap comparison. They recommend the cheap Vishay MKP series caps for bypass. I use them and think they are nice.

 http://www.humblehomemadehifi.com/Cap.html
Title: Re: Favorite Coupling Cap Brands and Types
Post by: DaveC113 on 24 Jun 2014, 09:53 pm
Check out the new Jupiter copper foil caps. Not sure on pricing, but would guess in the neighborhood of $50 each.
Title: Re: Favorite Coupling Cap Brands and Types
Post by: jtwrace on 24 Jun 2014, 10:01 pm
Roger


I thought you were not into boutique caps though? 
Title: Re: Favorite Coupling Cap Brands and Types
Post by: Roger A. Modjeski on 24 Jun 2014, 10:07 pm
Roger


I thought you were not into boutique caps though?

You are correct, I am not into boutique caps but some customers require them.
Title: Re: Favorite Coupling Cap Brands and Types
Post by: jtwrace on 24 Jun 2014, 10:12 pm
You are correct, I am not into boutique caps but some customers require them.

 :o   You had me really nervous there for a few minutes.  Whew. 


BTW-Have you ever had your amps measured on an Audio Precision (http://www.ap.com/products/2700) or dScope (http://www.prismsound.com/test_measure/products_subs/dscope/dscope_home.php)?  If so, where can I see them? 
Title: Re: Favorite Coupling Cap Brands and Types
Post by: Roger A. Modjeski on 25 Jun 2014, 12:10 am
:o   You had me really nervous there for a few minutes.  Whew. 


BTW-Have you ever had your amps measured on an Audio Precision (http://www.ap.com/products/2700) or dScope (http://www.prismsound.com/test_measure/products_subs/dscope/dscope_home.php)?  If so, where can I see them?

I have run some amplifier and audio transformer tests on the audio precision. However I prefer the Sound Technology distortion analyzer as it lets me manually look at the things I want to see. I admit it would be nice to have a AP to make some curves when the amp is done. If anyone sees one for a good price let me know. The most basic one would be fine. I don't need the digital stuff.

I am not familiar with the other ones but I will look into them.
Title: Re: Favorite Coupling Cap Brands and Types
Post by: Jon L on 25 Jun 2014, 03:58 am
Check out the new Jupiter copper foil caps. Not sure on pricing, but would guess in the neighborhood of $50 each.

Jupiter Copper Foil at 0.1 uF/600V is $55 at Parts Connexion, but 0.22 uF/600V is only $5 more at $60, which is likely the sweet spot. 
Excellent capacitor  :thumb:
Title: Re: Favorite Coupling Cap Brands and Types
Post by: steve f on 25 Jun 2014, 04:39 am
Please supply fancy caps only as an option.  I'm interested in purchasing well designed reliable products. Overpriced boutique parts prevent many people from enjoying products because they raise the price of admission and do nothing for performance. Audio is one of those places where a Timex can be equal to or better than a Rolex.
Title: Re: Favorite Coupling Cap Brands and Types
Post by: BobM on 25 Jun 2014, 12:33 pm
The new Jupiter copper's are truly special. Every bit as good as the lofty Duelands but at a much more affordable price. A real winner.

I always liked basic Sonicap's as well for their price/performance ratio, but they don't have the magic of the Jupiters.

Of course there are expensive teflons (V-Cap, Sonicap Platinums) which also are great for a bypass. For an inexpensive teflon you can try the Russians, but even though they are very transparent they do have a bit of forward hardness to them that the better teflons don't have.
Title: Re: Favorite Coupling Cap Brands and Types
Post by: Roger A. Modjeski on 25 Jun 2014, 03:31 pm
Please supply fancy caps only as an option.  I'm interested in purchasing well designed reliable products. Overpriced boutique parts prevent many people from enjoying products because they raise the price of admission and do nothing for performance. Audio is one of those places where a Timex can be equal to or better than a Rolex.

Thank you Steve. I agree and I will always use good reliable parts. The Boutique capacitor market has gotten out of hand in price, reliability and fantastic claims.

Here is an technical argument against them for anyone to use.

1. Since a coupling cap has no signal voltage across it the dielectric absorption makes no difference at all. Low DA is the main claim of sonics.
2. Since a coupling cap conducts virtually no current (typically 1-10 microamps) its series resistance (ESR) and series inductance is of no consequence.
3. As long as there is no DC leakage the materials of the capacitor are of no consequence. We could say the materials are immaterial.
4. I have seen too many Boutique capacitors fail. I presume this is due to the lack experience in small new companies making them.

I recently met some one who loves Duelund cast caps. However he says they fail in about a year. He uses them as coupling caps in a 300B amplifier. These might be the most egregious of the business at $185 for a 0.1/630 volt.  http://www.partsconnexion.com/capacitor_film_duelund_pio_electonic.html

I recently replaced two silver caps with the logo SK where the S was over the K. I cannot find the maker of these caps. They were in the JADIS JA-200 and had shorted. Does anyone know this brand?
Title: Re: Favorite Coupling Cap Brands and Types
Post by: DaveC113 on 25 Jun 2014, 03:57 pm

I recently met some one who loves Duelund cast caps. However he says they fail in about a year. He uses them as coupling caps in a 300B amplifier. These might be the most egregious of the business at $185 for a 0.1/630 volt.  http://www.partsconnexion.com/capacitor_film_duelund_pio_electonic.html


Umm, you should check out the price of Duelund silver caps  :o    Fwiw, I agree with you about the ridiculous prices. Jupiter's caps are very reasonable in comparison.

I'd like to hear your thoughts on the Jupiter caps after trying them vs some decent MKP or whatever coupling caps you generally use. I would bet you will change your mind about "boutique caps".  :wink:
Title: Re: Favorite Coupling Cap Brands and Types
Post by: corndog71 on 25 Jun 2014, 04:52 pm
Thank you Steve. I agree and I will always use good reliable parts. The Boutique capacitor market has gotten out of hand in price, reliability and fantastic claims.

Here is an technical argument against them for anyone to use.

1. Since a coupling cap has no signal voltage across it the dielectric absorption makes no difference at all. Low DA is the main claim of sonics.
2. Since a coupling cap conducts virtually no current (typically 1-10 microamps) its series resistance (ESR) and series inductance is of no consequence.
3. As long as there is no DC leakage the materials of the capacitor are of no consequence. We could say the materials are immaterial.
4. I have seen too many Boutique capacitors fail. I presume this is due to the lack experience in small new companies making them.

I recently met some one who loves Duelund cast caps. However he says they fail in about a year. He uses them as coupling caps in a 300B amplifier. These might be the most egregious of the business at $185 for a 0.1/630 volt.  http://www.partsconnexion.com/capacitor_film_duelund_pio_electonic.html

I recently replaced two silver caps with the logo SK where the S was over the K. I cannot find the maker of these caps. They were in the JADIS JA-200 and had shorted. Does anyone know this brand?

Clarity Cap's MR series are based on the premise that "mechanical resonances within a capacitor have a measurable effect on output sound quality." "...the result of which is a capacitor which virtually eliminates internal sonic resonance." 

I don't know.  It makes sense to me that almost every part can have an effect on the output of an audio device.  But I suppose that's my bias showing.  I can concede I'm possibly a victim of placebo effect.  But mechanical resonances are real and measurable.  It's been claimed by some that there are phenomenon that are being perceived by lots of people that we simply haven't figured out how to measure or quantify yet.  Do you guys believe that's possible?
Title: Re: Favorite Coupling Cap Brands and Types
Post by: corndog71 on 25 Jun 2014, 05:49 pm
A few years ago Danny Richie over in the GR Research circle created an experiment that anyone could test out.  On an inexpensive pair of speakers Danny installed 2 separate crossover boards and made them instantly switchable.  The parts for one crossover were generic parts and the other crossover was made with so-called "boutique" parts of higher quality construction.  Both crossovers have identical measurements and identical measured output from the speaker.  Yet they sound different.  I think he still has them available.

At the very least here's the thread.

http://www.audiocircle.com/index.php?topic=87808.0 (http://www.audiocircle.com/index.php?topic=87808.0)
Title: Re: Favorite Coupling Cap Brands and Types
Post by: Speedskater on 25 Jun 2014, 08:06 pm
..............................................
 The parts for one crossover were generic parts and the other crossover was made with so-called "boutique" parts of higher quality construction.  Both crossovers have identical measurements and identical measured output from the speaker.  Yet they sound different.  I think he still has them available.
....................................... .....
It takes big expensive machines to make capacitors of the highest quality construction. "boutique" capacitors (unless custom manufactured by a major manufacturer) are seldom of the highest quality construction.
Title: Re: Favorite Coupling Cap Brands and Types
Post by: corndog71 on 25 Jun 2014, 08:17 pm
It takes big expensive machines to make capacitors of the highest quality construction. "boutique" capacitors (unless custom manufactured by a major manufacturer) are seldom of the highest quality construction.

I guess what is meant by "boutique" parts would be those that aren't cranked out on an industrial scale and have as little effect on the audio signal as possible.  It's not so much that better parts make the sound better so much as mass-produced parts or parts made to meet a spec. have a negative effect on the sound despite meeting their electrical obligations.

I may have lost some respect at this time but so be it.  Hearing differences in components is what got me into this hobby.  I'm always willing to concede that I'm fooling myself.  But I repeat tests and ask other's opinions without expectation or at least as little as possible in order to reduce bias as much as possible. 
Title: Re: Favorite Coupling Cap Brands and Types
Post by: Roger A. Modjeski on 26 Jun 2014, 03:40 pm
A few years ago Danny Richie over in the GR Research circle created an experiment that anyone could test out.  On an inexpensive pair of speakers Danny installed 2 separate crossover boards and made them instantly switchable.  The parts for one crossover were generic parts and the other crossover was made with so-called "boutique" parts of higher quality construction.  Both crossovers have identical measurements and identical measured output from the speaker.  Yet they sound different.  I think he still has them available.

At the very least here's the thread.

http://www.audiocircle.com/index.php?topic=87808.0 (http://www.audiocircle.com/index.php?topic=87808.0)

As I have said many many times. A crossover is one place where caps can make a difference and I do believe anyone who says so.  The problem I see is that audio enthusiasts have taken this to apply to all capacitor applications. Coupling caps in an amplifier are not doing the same thing. They have virtually no current going through them and no voltage drop across them.

The boutique capacitor thing has gone viral. It may never end. Very few designers are willing speak out against it. We have a lot of capacitors being made by companies who have little experience.  The equipment and the materials to make them is very inexpensive. You could start a Boutique cap company in your garage for $10,000 and make $100 caps that have $1 in materials. Snake oil has a long and sordid history.

I ask this question: If resistors made a big difference, and they do, who is going to make Boutique resistors and who is going to put them in? They are much harder to make than capacitors and require far more expensive equipment and difficult processes. Resistors do have some problems not discussed such as drift with temperature, drift with time and voltage coefficient (change in resistance with voltage causing distortion).

In the ESL amps we use a $25 Caddock resistor in the feedback network because it has the lowest voltage coefficient available. There are 4 of these in the amp. They are beautiful with gold plated leads. They are non-inductive. This resistor swings 5000 volts of signal across it and that resistor alone is a major contributor to making the amplifier low distortion. Using a standard resistor would increase the distortion measurably. Of course I could blindly apply this discovery to every resistor in the amps and double the price of this amplifier. I could put them where their exceptional qualities would make no difference. There are some resistors that have no voltage across them and their value can change 100% and not make any difference in how the amp works. There are other resistors that have so little voltage across them that these qualities are vanishingly small. In the OTL-1 the DC considerations are larger than in most amps so I want resistors that won't drift over time so I use the mil-spec Vishays. They cost only ten cents vs 3 cents for common MF resistors. There are about 50 of them. The $25 Caddpcks would make no difference where they are swinging 0-15 volts vs 5,000 volts. They would make a $6,000 difference in the price of this amp. [/b][/b][/b]

In all our amps we use precision metal film resistors with low temp and voltage coefficients. In the OTL-1 we are using all Dale/Vishay mil-spec resistors in the signal path. I know this makes a difference, so this is where I spend the money. Botique caps to the back of the room. :nono:

If you could buy these resistors would you be willing to find the values of 50-100 resistors in your amp and replace them? At what cost? Capacitors are easy to read, they stand out, the new ones are very pretty and usually there are only 4 in a stereo power amp.

We worked on an RM-10 where the coupling caps were replaced by the owner. He thought it sounded great. It came in for another problem which we fixed. When testing the amp on the bench I noticed one channel had high distortion and less than half power. I found one capacitor had been connected to the wrong terminal and one output tube was not being driven at all. The push-pull amp had become single ended in that channel. At very low power the problem was not noticeable but that channel clipped at 3 watts vs 35 watts for the good channel.

I have an additional theory about upgrades. The Audio Enthusiast will spend the most money on the thing that is easiest to replace. Cables, power cords, fuses are easy to upgrade and have little or no risk of harming the equipment.

If I thought Botique caps made my amps sound better why wouldn't I use them. Do you think I do all this work to make a great sounding amp and overlook something like caps?
Title: Re: Favorite Coupling Cap Brands and Types
Post by: Roger A. Modjeski on 26 Jun 2014, 03:47 pm
It takes big expensive machines to make capacitors of the highest quality construction. "boutique" capacitors (unless custom manufactured by a major manufacturer) are seldom of the highest quality construction.

The machines that wind boutique caps are the same sort of machines that make the industrial ones. They are not big or expensive. The winder is about the size of a sewing machine. I visited Bass Lim's RELIABLE CAPACITOR factory and learned a lot about making caps from him personally. Caps are wound from strips of material that come off big rolls and go on a mandrel. That is the only machine that is involved. That's why you can start making caps for a few thousand $$. What specifically do you know about making capacitors that you would like to share here?

The point I am making is that virtually anyone with decent manual dexterity and a little money can start making caps in their garage, and sadly they are doing just that. With no experience in reliability they are causing a lot of problems. BTW crossover caps are the easiest to make as they have no DC voltage across them. It's virtually impossible for them to short. The boutique caps I have seen fail have several hundred volts across them (yet well less than their rating) and when they fail they take out tubes. When they leak (electrically) they cause bias to rise and run away.
Title: Re: Favorite Coupling Cap Brands and Types
Post by: corndog71 on 26 Jun 2014, 04:32 pm
Coupling caps in an amplifier are not doing the same thing. They have virtually no current going through them and no voltage drop across them.

If I thought Botique caps made my amps sound better why wouldn't I use them. Do you think I do all this work to make a great sounding amp and overlook something like caps?

Does the audio signal pass through a coupling cap? 

Why do I hear changes in sound quality between different caps?
Title: Re: Favorite Coupling Cap Brands and Types
Post by: Roger A. Modjeski on 26 Jun 2014, 05:08 pm
Does the audio signal pass through a coupling cap? 

Why do I hear changes in sound quality between different caps?

The first is a good question, the second I cannot answer.  "Does the audio signal pass through a coupling cap?"  Pass through to me means there is a current. In a crossover there is certainly a substantial current that can be several amperes. Indeed things like ESR make a big difference. Dielectric absorption (DA) also makes a difference as the low frequencies are absolutely pumping the dielectric material up and down with many volts. The louder you play the speaker, the lower the impedance, the larger the effects. Yes a big bass transient leave behind a "ghost voltage"in the tweeter series cap due to DA. Lets not have that. I advise people to change caps in their crossoves without reservation. However, I go further to encourage them to save that money and get and electronic crossover (where the caps pass no current) and go direct to their drivers. Crossovers overboard!  8).

Of course, changing the caps is easier. How many are willing to take that big step and make a big difference in their systems. The point about multi-amping is that you can choose specific amps for their specific job. I just hooked the OTL-1 to my horribly inefficient (less than 80 dB/watt) ESL speaker. By design that amp only sees 100 Hz up and a 500 watt transistor amp of no distinction plays 100 Hz down. Even with that inefficient ESL I can play plenty loud. With a conventional speaker of that low efficiency playing full range I would be running out of power in the bass region. 

I recall the whole boutique cap thing started in crossovers and with that I totally agree. Damn the 10 cent electrolytics with their high ESR and loss of capacitance over time. They are usually 10-20% accurate in value so the crossover points and slopes can vary widely. Bypass them but that won't fix the DA problem because the bypass is to small, but it will help the ESR.

Having said all that in my honest opinion as one who does understand how electrons get about in a system, there is virtually no current (a few microamps) at best and no voltage (the cap has little or no reactance at audio frequencies) that the audio signal does not pass through the anymore than it passes through a wire. (I am not inviting a discussion of hook up wire in an amp :nono: :nono: :nono:)

Are you saying that coupling caps in an amp make as big a difference in your hearing as crossover caps?

The best analogy I can think of right now is that high octane gas vs low octane gas will make a big difference in a high compression engine. It will make less difference in a low compression engine and will make no difference, in my experience, in starting a fire.  :D
Title: Re: Favorite Coupling Cap Brands and Types
Post by: BobM on 26 Jun 2014, 05:33 pm
How about adding a smaller, quicker bypass cap to those large value electrolytics in the power section of an amp or preamp or CD player or whatever? IYO is there any benefit to that?

Title: Re: Favorite Coupling Cap Brands and Types
Post by: corndog71 on 26 Jun 2014, 06:31 pm
Let me give an example.

I have a Bottlehead Sex SET headphone amplifier.  http://bottlehead.com/s-e-x-2-1-specs/ (http://bottlehead.com/s-e-x-2-1-specs/)

There are two cap positions in particular where changing caps made audible differences.  The tubes are 6DN7.  There's an interstage cap (0.1uF 630V) and output coupling cap (1uF 630V).  In the original kit an inexpensive poly cap is used for interstage and a Solen for output cap.

(http://i576.photobucket.com/albums/ss207/corndog642/Bottlehead%20Sex%20Amp/IMG_1844.jpg)

At some point I replaced those caps with ERSE brand caps.  I really didn't hear much if any difference.  For the record I have AKG 702 headphones.

(http://i576.photobucket.com/albums/ss207/corndog642/Bottlehead%20Sex%20Amp/IMG_2330.jpg)

At some point I added the Constant Current Source upgrade that Bottlehead sells.  It's a little circuit board; one for each channel.  That made a significant improvement to the sound.

Later, when I had some money to burn I picked up a pair of Clarity Cap ESA and MR series for the output caps.  I also had a pair of 0.47uF V-Caps from another project.  I tried various combinations of interstage and coupling caps and each time the sound changed.  Sometimes for the better but more often for the worse.  With each combination I played and listened for hundreds of hours.

(http://i576.photobucket.com/albums/ss207/corndog642/Bottlehead%20Sex%20Amp/5f3c6b5c.jpg)

(http://i576.photobucket.com/albums/ss207/corndog642/Bottlehead%20Sex%20Amp/0aa7725c.jpg)

With the V-caps in the interstage position and the Clarity ESA in the coupling cap position.  I got a nice, detailed yet warm on the top sound.  More detail and clarity over the original and ERSE caps.  Swapping the ESA cap for the MR cap was a revelation!  Everything became more detailed.  Separation of instruments and voices became more defined.  Details emerged that had been muted or obscured.  But over time I found it too revealing!  My ears would get fatigued after about 30-45 minutes of listening.  I loved the resolution I was getting but hated the fatigue.  I was disappointed because in my tube preamp the MR caps remained highly resolving yet never fatiguing.

I ended up switching back to the ESA output caps and the warmth returned and I could listen once again with no fatigue.

Recently I acquired a bunch of Russian military caps in various values.  Most of them are paper in oil types sealed in glass with metal outer bodies.  A couple are large teflon caps. (0.1uF 630V)

I hooked up the teflon FT-3 caps as interstage caps and a pair of PIO K42y-2 output caps.  After running them for a while I gave them a listen and now feel they have better resolution than the ESA caps especially in the treble region yet retain the overall warmth that keeps my ears from getting fatigued.
Title: Re: Favorite Coupling Cap Brands and Types
Post by: Roger A. Modjeski on 26 Jun 2014, 10:40 pm
It is interesting to hear that some boutique caps made it worse some made it better. All in all I guess you ended up spending as much or more on the caps than the original Bottlehead amp. I know the V- caps are very expensive, especially in the large sizes. I bought some for customer at his request. As I said, I don't mind doing it, I don't feel its the best use of money when other more important things can be done in a system.

As to what you heard. The 1 uF output coupling cap is conducting current so that is the one that should make the most difference. The difference in current is more than ten thousand to one vs the interstage cap. The output coupling cap is driving a load of a few thousand ohms, the interstage cap is driving something like 470,000 ohms and at lower 15 times lower signal level (15 is the mu of tube).

I also think the output coupling cap should be a lot bigger. If you are driving a 3000 ohm transformer the -3 dB down point is 53 Hz with 1 uF. This should be a problem, however 32 ohm phones move the -3 point down by 4 to 1 is the inductance of the output transformer is sufficient. Has anyone measured that? I clicked on specs but couldn't find any.

I never use less than 33 uF in my rather similar 6EM7 parafeed amp.  Why is that cap so small? These are the things that I think need attention.
Here is a nice calculator for that sort of thing. http://www.sengpielaudio.com/calculator-XLC.htm

I am not surprised to hear the current source mod made a big difference. That is a major circuit change. In my mind it has much more influence over the sound than a cap change. A current source unloads the input triode reduces distortion and raises gain. Did you notice the gain change?

If you had a variety of output transformers and chokes to try you would hear bigger differences and it's not about the materials. Magnequest promoted some unusual expensive iron some time ago, where is it now? Seems everyone making parts has become a self appointed materials expert.

However who wants to fool around with changing transformers, though yours are pretty easy to get to.  Do you know the primary and choke inductance values. They had better be large. Why dont people fool with transformers more than capacitors. The have a bigger chance of making a difference. I will propose that a tranformerm is too difficult and varied to specify. You have to express the impedance ratios, the input inductance, the leakage inductance, the copper loss, the iron loss, the Low frequency saturation point. A cap is easy to specify, capacity and voltage, done.  :) The rest is going on and on about exotic materials, winding techniques, leads, yada, yada , yada.

How about changing the 6DN7 to a 6EM7 which has the same pinout but  lower output impedance. You would have to change the cathode resistors but little else I imagine. The output impedance is 750 vs 2000 ohms, almost 3 times lower. That will make a big difference.

I am simply stating that there are bigger things to do that fooling with caps, however, for some reason fooling with caps has become very popular perhaps only one step below tube rolling. I think it is obvious in any hobby that people change the things that are easiest to change, while leaving the more difficult yet more important things alone.

I could make you some iron that would blow the socks off the Bottlehead stuff. Look at the pricing of the kit. Break it down by the parts you know the cost of and you will see that the two output chokes and two output transformers can only cost about $25- $50 each. If you have $250 to spend on a Vcap how about the same for a transformer or audio choke?

How about replacing that $2 volume control with a Noble or Alps.

I really don't understand how more resolution caused listener fatigue. I find the more detail I get the more I can turn down the volume and that certainly reduces fatigue. Of course the good recording sound better and the bad recordings sound worse. So go play the bad ones in the car.  :wink:
Title: Re: Favorite Coupling Cap Brands and Types
Post by: corndog71 on 27 Jun 2014, 04:29 am
Thanks, Roger.  I have homework now as there are many points in your post to respond to. I'll have to do some research.  I also rode a bike 8.5 miles after work!
Title: Re: Favorite Coupling Cap Brands and Types
Post by: neobop on 27 Jun 2014, 12:00 pm
The first is a good question, the second I cannot answer.  "Does the audio signal pass through a coupling cap?"  Pass through to me means there is a current. In a crossover there is certainly a substantial current that can be several amperes. Indeed things like ESR make a big difference. Dielectric absorption (DA) also makes a difference as the low frequencies are absolutely pumping the dielectric material up and down with many volts. The louder you play the speaker, the lower the impedance, the larger the effects. Yes a big bass transient leave behind a "ghost voltage"in the tweeter series cap due to DA. Lets not have that. I advise people to change caps in their crossoves without reservation. However, I go further to encourage them to save that money and get and electronic crossover (where the caps pass no current) and go direct to their drivers. Crossovers overboard!  8).

Of course, changing the caps is easier. How many are willing to take that big step and make a big difference in their systems. The point about multi-amping is that you can choose specific amps for their specific job. I just hooked the OTL-1 to my horribly inefficient (less than 80 dB/watt) ESL speaker. By design that amp only sees 100 Hz up and a 500 watt transistor amp of no distinction plays 100 Hz down. Even with that inefficient ESL I can play plenty loud. With a conventional speaker of that low efficiency playing full range I would be running out of power in the bass region. 

I recall the whole boutique cap thing started in crossovers and with that I totally agree. Damn the 10 cent electrolytics with their high ESR and loss of capacitance over time. They are usually 10-20% accurate in value so the crossover points and slopes can vary widely. Bypass them but that won't fix the DA problem because the bypass is to small, but it will help the ESR.

Having said all that in my honest opinion as one who does understand how electrons get about in a system, there is virtually no current (a few microamps) at best and no voltage (the cap has little or no reactance at audio frequencies) that the audio signal does not pass through the anymore than it passes through a wire. (I am not inviting a discussion of hook up wire in an amp :nono: :nono: :nono:)

Are you saying that coupling caps in an amp make as big a difference in your hearing as crossover caps?

The best analogy I can think of right now is that high octane gas vs low octane gas will make a big difference in a high compression engine. It will make less difference in a low compression engine and will make no difference, in my experience, in starting a fire.  :D

Looking at different amps/preamps and gestalt on the net, it seems like you're a minority of 1.  I'm not an EE or a circuit designer and certainly don't understand every possible movement of electrons, but it seems virtually everyone else hears significant differences using technically superior coupling caps.

What's the function of a coupling cap, to block DC ?   Then it's very much like a speaker crossover cap only not in the middle of the audio band.  It might not matter if very little current goes through it, it's still in the signal path.   I was told by an EE that every part in a circuit is in the signal path, whether it's in series or a shunt capacitor.  True?  Why do high end preamps have no tone controls, even ones that can be switched out?  I was told that even having the wires connected whether the circuit can be switched out or not, would degrade the sound.  Do your preamps have tone controls?  If not maybe it's for a different reason?

A speaker crossover might do more than divide frequencies, and slopes on different drivers aren't necessarily the same.  There might be impedance compensation and/or amplitude response correction.  I don't how common zobels or series notch filters are, but they certainly exist and their exclusion might degrade performance of an individual driver without them.  Crossover design is aided by computer these days and such things as phase performance between drivers is complex.  In a general way it might be beneficial to lose the crossover and bi-amp or tri-amp, but that depends on the speaker.

At the top of this thread you asked for suggestions for those looking for better quality coupling caps:
http://tubelab.com/designs/tubelab-se/manual/capacitors/

http://diy.ecpaudio.com/p/some-notes-on-coupling-capacitors.html

http://www.diyaudio.com/forums/tubes-valves/82502-best-coupling-cap-under-20-a.html

http://www.high-endaudio.com/Modifications.html

http://www.gearslutz.com/board/geekslutz-forum/434325-what-best-musical-sounding-capacitors-use-recap-pro-audio-gear-2.html 
Title: Re: Favorite Coupling Cap Brands and Types
Post by: DaveC113 on 27 Jun 2014, 01:42 pm
Looking at different amps/preamps and gestalt on the net, it seems like you're a minority of 1.  I'm not an EE or a circuit designer and certainly don't understand every possible movement of electrons, but it seems virtually everyone else hears significant differences using technically superior coupling caps.



Eh, check the diyaudio tube amp forum. LOTS of very talented tube designers seem to have hearing impediments.  :icon_twisted:

Sorry, I couldn't resist, just a joke...  :lol:
Title: Re: Favorite Coupling Cap Brands and Types
Post by: corndog71 on 27 Jun 2014, 04:33 pm
It is interesting to hear that some boutique caps made it worse some made it better. All in all I guess you ended up spending as much or more on the caps than the original Bottlehead amp. I know the V- caps are very expensive, especially in the large sizes. I bought some for customer at his request. As I said, I don't mind doing it, I don't feel its the best use of money when other more important things can be done in a system.

As to what you heard. The 1 uF output coupling cap is conducting current so that is the one that should make the most difference. The difference in current is more than ten thousand to one vs the interstage cap. The output coupling cap is driving a load of a few thousand ohms, the interstage cap is driving something like 470,000 ohms and at lower 15 times lower signal level (15 is the mu of tube).

I also think the output coupling cap should be a lot bigger. If you are driving a 3000 ohm transformer the -3 dB down point is 53 Hz with 1 uF. This should be a problem, however 32 ohm phones move the -3 point down by 4 to 1 is the inductance of the output transformer is sufficient. Has anyone measured that? I clicked on specs but couldn't find any.

I never use less than 33 uF in my rather similar 6EM7 parafeed amp.  Why is that cap so small? These are the things that I think need attention.
Here is a nice calculator for that sort of thing. http://www.sengpielaudio.com/calculator-XLC.htm

I am not surprised to hear the current source mod made a big difference. That is a major circuit change. In my mind it has much more influence over the sound than a cap change. A current source unloads the input triode reduces distortion and raises gain. Did you notice the gain change?

If you had a variety of output transformers and chokes to try you would hear bigger differences and it's not about the materials. Magnequest promoted some unusual expensive iron some time ago, where is it now? Seems everyone making parts has become a self appointed materials expert.

However who wants to fool around with changing transformers, though yours are pretty easy to get to.  Do you know the primary and choke inductance values. They had better be large. Why dont people fool with transformers more than capacitors. The have a bigger chance of making a difference. I will propose that a tranformerm is too difficult and varied to specify. You have to express the impedance ratios, the input inductance, the leakage inductance, the copper loss, the iron loss, the Low frequency saturation point. A cap is easy to specify, capacity and voltage, done.  :) The rest is going on and on about exotic materials, winding techniques, leads, yada, yada , yada.

How about changing the 6DN7 to a 6EM7 which has the same pinout but  lower output impedance. You would have to change the cathode resistors but little else I imagine. The output impedance is 750 vs 2000 ohms, almost 3 times lower. That will make a big difference.

I am simply stating that there are bigger things to do that fooling with caps, however, for some reason fooling with caps has become very popular perhaps only one step below tube rolling. I think it is obvious in any hobby that people change the things that are easiest to change, while leaving the more difficult yet more important things alone.

I could make you some iron that would blow the socks off the Bottlehead stuff. Look at the pricing of the kit. Break it down by the parts you know the cost of and you will see that the two output chokes and two output transformers can only cost about $25- $50 each. If you have $250 to spend on a Vcap how about the same for a transformer or audio choke?

How about replacing that $2 volume control with a Noble or Alps.

I really don't understand how more resolution caused listener fatigue. I find the more detail I get the more I can turn down the volume and that certainly reduces fatigue. Of course the good recording sound better and the bad recordings sound worse. So go play the bad ones in the car.  :wink:

I bought the V-caps out of curiosity.  I probably wouldn't spend that much on them again although I do think they sound excellent.

I don't have the current version of the the Sex amp which is version 2.1.  Mine is the previous 2.0 version.  Mine has off the shelf chokes and ouput transformers that have since become discontinued.  I believe the choke is 30mH and the OT is 8K.  The newer version has custom-made iron.  Bottlehead does offer their version 2.1 iron as an upgrade.  They don't post the values so I can't comment on that.  Magnequest still offers upgraded sets as well and uses Nickel as the special metal to increase the price.  According to the bottlehead guys the more nickel the better the sound.  I think they wrote some more about it but I can't seem to find it.
I was planning on getting the upgraded bottlehead iron as it's only $200.  If you can make better iron then I would certainly be interested.   :bounce:
They supplied 1uF for the outputs but also recommended 2uF as an option; especially with the upgraded iron.

Switching to 6EM7 sounds like fun too.  The bottlehead guys did tinker a bit with the 6EM7 tubes and posted the needed changes although I haven't heard of anyone actually doing it.  The whole point of the kit was that it was flexible enough to try various circuits/ tubes.

The current source did improve the amp considerably.  I do recall a bump in gain.

I do think you're right about why people mess with caps.  They are easy to figure out the values needed and swap out.  As a seemingly never-ending novice to this stuff I can personally confirm this.  :wink:  The bottlehead gear is designed for guys who want to put the puzzle together but don't necessarily want to figure out the details behind each piece. 

I've considered upgrading the volume knob but usually I just max it out as I have a separate preamp connected upstream.  The sex amp only has one input whereas my preamp has two. 

Yeah, the MR caps being too revealing really threw me.  It did sound fantastic but at the same time irritating after a while.  I have the MR caps in my preamp and don't get the same effect.  It's weird.  Maybe I need a Shakti stone or ultrasonic filter.   :lol:
Title: Re: Favorite Coupling Cap Brands and Types
Post by: rpf on 27 Jun 2014, 05:17 pm
Okay, I'll jump into this morass. And hopefully won't get attacked too badly.    :lol:

Yes, for those of us with no technical knowledge, or even soldering skills, having caps changed is an easy, relatively inexpensive, path to a potentially significant upgrade.

I've had caps changed on a bunch of equipment as follows and usually found an easily noticeable difference. And, no, I'm not prone to a prolonged placebo effect.

Changed the output coupling caps in a pair of Dodd Mono 50s from the stock Sonicap Is to Sonicap Platinum teflons. The latter had more detail but were lacking in warmth and had an overly smooth, "slippery" quality to them that I hated: preferred the less expensive originals. Changed them out again for Rel AudioCap PCUs (copper foil) and was very happy: more resolution, warmth and tonal accuracy across the board.

Changed the output coupling caps on a MHDT Havana DAC from the stock proprietary ones to Jupiter HTs. Heard a very large increase in resolution, dynamics, soundstaging dimensions and tonal accuracy. Changed the input caps and an interstage coupling cap from the stock ones to Jensen copper foil caps and think I heard a slight improvement in tonality. The latter were not worth the difference.

Changed the output coupling caps on an Eastern Electric Minimax DAC from stock to Jupiter HTs. Large increase, as above in the Havana. Changed some other (interstage coupling?) caps to Rel PCUs and heard no difference.

Changed the output coupling caps on an Eastern Electric DAC Plus from stock to VH Audio OIMP and heard a more relaxed, less digital presentation in the highs, and a bit more warmth to the sound.

Changed the output coupling caps on a Rogue Cronus Magnum from the stock un-labelled low cost Mundorfs to Mundorf Evo Silver/Gold/Oil and heard a slight increase in detail and a larger increase in refinement.

My takeaway is that the type/brand of output coupling caps used have a significant effect on the sound: other caps not so much.

All of the before and after values were identical except for the output caps on the Havana which were 10% higher in value after the change. 
Title: Re: Favorite Coupling Cap Brands and Types
Post by: Speedskater on 27 Jun 2014, 05:35 pm
Boutique capacitor manufacturing:

(http://www.audiocircle.com/image.php?id=101543)

Mainline capacitor manufacturing:

(http://www.audiocircle.com/image.php?id=101544)

Title: Re: Favorite Coupling Cap Brands and Types
Post by: Roger A. Modjeski on 27 Jun 2014, 06:13 pm
It takes big expensive machines to make capacitors of the highest quality construction. "boutique" capacitors (unless custom manufactured by a major manufacturer) are seldom of the highest quality construction.

I agree about the unreliability of Boutique caps. Thanks for the pictures of the machines. The machine in the bottom picture is quite something and cost big $$$. Do you have a link to the company that made it?

In any art there is the combination of the machine and person using it. There is a lovely book "In Marconi's Footsteps" where the author reproduced the early commercial radio equipment made by the Marconi company circa Titanic. In the book he has lovely color pics of the wood and brass radio sets (before tubes) that he made with a hand drill and a hand jig saw. I was impressed to see such beautiful work done with the most basic, non precision tools.

In the early days I made some very good transformers on a very crude winder I made my self. Futterman made his power transformers on a lathe. Bass Lim at RelCaps made capacitors on equipment he made himself. His company's claim to fame was that he could make 1% capacitors consistently. While 1% caps are nice to make RIAA EQ stages accurate, they make no difference in coupling where the value is larger than the lowest frequency. I bought all my 1% RIAA caps for the RM-5 from him. His main customers were telecommunications companies making very accurate, repeatable filters where 1% caps are necessary. He further told me that the big makers (Sprague, ITT, Mallory, etc) would also sell me 1% caps but they would do it by winding a big lot, measuring each one and selling me the ones that were within 1%, the rest they could sell in their regular 10 % line. Out of perhaps 7,000 rel-caps I bought from him over the years only 1 has failed open. None have ever shorted.

Bass also taught me about self-healing capacitors. Metalized film caps will heal from a short all by themselves. This is not true of film and foil capacitors. Silver, tinfoil, oil and paper and copper caps are not self-healing. The caps in the Jadis were not self healing. Once shorted they stay shorted.

There is a lot to know about capacitors. This is just the tip of the iceberg.
Title: Re: Favorite Coupling Cap Brands and Types
Post by: BobM on 27 Jun 2014, 06:33 pm
Roger - I think this question may have inadvertantly gotten lost in the recent large posts, so I will ask again.

How about adding a smaller, quicker bypass cap to those large value electrolytics in the power section of an amp or preamp or CD player or whatever? IYO is there any benefit to that?
Title: Re: Favorite Coupling Cap Brands and Types
Post by: Roger A. Modjeski on 27 Jun 2014, 06:43 pm
I bought the V-caps out of curiosity.  I probably wouldn't spend that much on them again although I do think they sound excellent.

I don't have the current version of the the Sex amp which is version 2.1.  Mine is the previous 2.0 version.  Mine has off the shelf chokes and ouput transformers that have since become discontinued.  I believe the choke is 30mH and the OT is 8K.  The newer version has custom-made iron.  Bottlehead does offer their version 2.1 iron as an upgrade.  They don't post the values so I can't comment on that.  Magnequest still offers upgraded sets as well and uses Nickel as the special metal to increase the price.  According to the bottlehead guys the more nickel the better the sound.  I think they wrote some more about it but I can't seem to find it.
I was planning on getting the upgraded bottlehead iron as it's only $200.  If you can make better iron then I would certainly be interested.   :bounce:
They supplied 1uF for the outputs but also recommended 2uF as an option; especially with the upgraded iron.

Switching to 6EM7 sounds like fun too.  The bottlehead guys did tinker a bit with the 6EM7 tubes and posted the needed changes although I haven't heard of anyone actually doing it.  The whole point of the kit was that it was flexible enough to try various circuits/ tubes.

The current source did improve the amp considerably.  I do recall a bump in gain.

I do think you're right about why people mess with caps.  They are easy to figure out the values needed and swap out.  As a seemingly never-ending novice to this stuff I can personally confirm this.  :wink:  The bottlehead gear is designed for guys who want to put the puzzle together but don't necessarily want to figure out the details behind each piece. 

I've considered upgrading the volume knob but usually I just max it out as I have a separate preamp connected upstream.  The sex amp only has one input whereas my preamp has two. 

Yeah, the MR caps being too revealing really threw me.  It did sound fantastic but at the same time irritating after a while.  I have the MR caps in my preamp and don't get the same effect.  It's weird.  Maybe I need a Shakti stone or ultrasonic filter.   :lol:

I read about your Bottlehead amp last night. I have been watching Bottlehead for years and noted their line has expanded significantly. I noticed the $199 upgrade for the transformers and chokes. It would be nice for them to give some comparative specs. I note that Doc is more of a story teller than a numbers guy. I hardly see any numbers for the equipment.

On the transformers: They clearly admit using a line matching transformer (available everywhere for $5 to $9) as the output transformer. I have measured these and they start to fall off around 5 KHz and are down several dB at 20KHz  They are indeed attractive as they are a common off the shelf item used in every distributed sound system. When the principal came over the PA system in your school you were listening to him through these transformers. There is one on each speaker and the taps on it allowed the system to play each speaker at a different volume as required. The taps are literally labeled in watts. The input is 25 or 70.0 volts constant level. The installer chooses a power tap to get the appropriate volume for that room, hallway, auditorium or cafeteria speaker. Since they are intended for PA the bandwidth is limited. The windings are not interleaved and they are made in the simplest way. They are just fine for what they are intended. From a price point of view he is clever to use them. I was on to them at about the same time. Their bandwidth is load dependent and they do work much better at 32 ohms than 8.  At 32 ohms at headphone levels they are actually pretty good if properly applied.

A 2 uF coupling cap would help the bottom end for an 8 ohm load but the 1 uF is probably acceptable but not ideal at 32 ohms. The only way to know is to make a few simple measurements or just make the cap bigger and listen to the bass.

I know this suggestion is beyond what some may want to do but for a few hundred  $$ one can buy a scope, generator and AC voltmeter used on eBay and make many of the important measurements such as gain and frequency response.  A distortion analyzer can be had for $200 these days. That includes the generator and voltmeter. Anyone wanting to set up a bench should let me know here and I will make some recommendations. There is so much really good used test equipment available these days as America has given up manufacturing. You can set up a bench for less than the cost of a couple of Boutique caps.

In my classes in SF and Berkeley we will be using test equipment so we can combine measurements and listening tests. Measurements can go a long way into explaining and modifying the sound of an amplifier. However there are some things that appear to defy measurement and have to be determined by listening. I do both, however I want to know that when I hear great bass its not because the response is bumped up. Myself and my fellow designers generally want to make sure something measures reasonably before bothering to haul it into the listening room.
Title: Re: Favorite Coupling Cap Brands and Types
Post by: Roger A. Modjeski on 27 Jun 2014, 07:01 pm
Roger - I think this question may have inadvertantly gotten lost in the recent large posts, so I will ask again.

How about adding a smaller, quicker bypass cap to those large value electrolytics in the power section of an amp or preamp or CD player or whatever? IYO is there any benefit to that?

What is a "quicker bypass cap"? Caps don't have speed, though I know that language is prevalent in the audio community. However I can translate audiospeak into techspeak. On its face the idea makes sense. The big cap does the low frequencies but is not so good at the high so we put in parallel a little film cap that is good at the high end. Unfortunately, and no one talks about this, it makes things worse. Perhaps they should do the experiment I will describe below.

In 1978 I made a simple experiment to test this. I took a 22 uF electrolytic and a variety of smaller caps (0.01 to 1 uF) and put them in parallel as is suggested everywhere. Then I put them across the output of a square wave generator. The combination rang like hell at the top of the audio band. In the power section, as you inquire, this could easily bump up the response at high frequencies or cause other problems because we want the cap to be a short. Without the bypass there was no ringing and the capacitor did its job properly. Given this discovery I stopped using bypass caps very early in my career.

In most electrolytics the point where the cap starts to give up its ability to be a short is typically above the audio band at 50-100 KHz. Adding the bypass cap actually pushes this point down into the audio band where we don't want it.
Title: Re: Favorite Coupling Cap Brands and Types
Post by: steve f on 27 Jun 2014, 09:04 pm
Roger, that's one of the reasons I enjoy the Music Reference forum. I learn something almost every time I visit.  Quite a few years ago, I picked up a PS Audio II amp. It was known for being among the first amps to bypass a bunch of caps with various film types.  Being curious, young, foolish, and probably voiding the warranty, I removed some of the bypass caps to try them in a couple of other circuits. I did notice that the other circuits did not sound better, but after removal, the PS did. I didn't understand why. Now I do. Thank you.
Title: Re: Favorite Coupling Cap Brands and Types
Post by: GMuffley on 30 Jun 2014, 02:08 pm
I have been DIYing tube equipment since 1976 and the availability of better passive components, resistors and capacitors, has been a boon to the hobbyist. Changing coupling capacitors can yield significant and audible changes to the reproduced sound--good and bad.  I have a large assortment of boutique caps that I have tried over the years and my "go to" cap for years has been the Rel-Cap polystyrene; it seems to work in many different amps and preamps and it is a high performance component.  It has temperature limitations compared to polypropylene, but I simply keep it away from high heat sources.  I haven't tried the most expensive V-Caps, but I have not hopped on the teflon band wagon.  Tried the paper and oils as well, but htey didn't give me the results I was looking for.
Title: Re: Favorite Coupling Cap Brands and Types
Post by: DaveC113 on 30 Jun 2014, 02:26 pm
How about adding a smaller, quicker bypass cap to those large value electrolytics in the power section of an amp or preamp or CD player or whatever? IYO is there any benefit to that?



On this one, I have settled with unbypassed Clarity TC caps rather than use any electrolytics at all. They are expensive and large, but the results have been worth it imo.
Title: Re: Favorite Coupling Cap Brands and Types
Post by: corndog71 on 30 Jun 2014, 04:46 pm
On this one, I have settled with unbypassed Clarity TC caps rather than use any electrolytics at all. They are expensive and large, but the results have been worth it imo.

I agree that they are worth it.  And Clarity does say these are self-healing.
Title: Re: Favorite Coupling Cap Brands and Types
Post by: paul79 on 30 Jun 2014, 05:18 pm
IME, a good polypropylene film & foil cap works well bypassing power supply electrolytics.
Title: Re: Favorite Coupling Cap Brands and Types
Post by: Freo-1 on 30 Jun 2014, 09:44 pm
Mundorf Silver/Gold are my favorites.  Great coupling caps.
Title: Re: Favorite Coupling Cap Brands and Types
Post by: Roger A. Modjeski on 3 Jul 2014, 02:25 pm
Roger, that's one of the reasons I enjoy the Music Reference forum. I learn something almost every time I visit.  Quite a few years ago, I picked up a PS Audio II amp. It was known for being among the first amps to bypass a bunch of caps with various film types.  Being curious, young, foolish, and probably voiding the warranty, I removed some of the bypass caps to try them in a couple of other circuits. I did notice that the other circuits did not sound better, but after removal, the PS did. I didn't understand why. Now I do. Thank you.

Thanks for trying things and reporting on your results... As the commercials say "your results may vary". I think we can see from all this that capacitor rolling is a personal thing. I will continue to use what I feel is good and not raise the prices of my equipment with Boutique caps. I will still put them in on request.

Title: Re: Favorite Coupling Cap Brands and Types
Post by: bdp24 on 4 Jul 2014, 11:07 am
Thank you Steve. I agree and I will always use good reliable parts. The Boutique capacitor market has gotten out of hand in price, reliability and fantastic claims.

Here is an technical argument against them for anyone to use.

1. Since a coupling cap has no signal voltage across it the dielectric absorption makes no difference at all. Low DA is the main claim of sonics.
2. Since a coupling cap conducts virtually no current (typically 1-10 microamps) its series resistance (ESR) and series inductance is of no consequence.
3. As long as there is no DC leakage the materials of the capacitor are of no consequence. We could say the materials are immaterial.
4. I have seen too many Boutique capacitors fail. I presume this is due to the lack experience in small new companies making them.

I recently met some one who loves Duelund cast caps. However he says they fail in about a year. He uses them as coupling caps in a 300B amplifier. These might be the most egregious of the business at $185 for a 0.1/630 volt.  http://www.partsconnexion.com/capacitor_film_duelund_pio_electonic.html

I recently replaced two silver caps with the logo SK where the S was over the K. I cannot find the maker of these caps. They were in the JADIS JA-200 and had shorted. Does anyone know this brand?
Roger, give Tom at Brooks Berdan Ltd. in Monrovia a call. Brooks was (R.I.P.) a Jadis dealer, and Tom was his Tech (he is now Sheila Berdan's Tech. Say, is the shop still a Music Reference dealer?). I often saw Tom with a Jadis amp upside down in front of him at his workbench. Hmmm. Never saw Tom repairing a Music Reference amp!
Title: Re: Favorite Coupling Cap Brands and Types
Post by: Roger A. Modjeski on 4 Jul 2014, 08:00 pm
I speak with Tom often. He has told me that there have been some problems with Jadis, the Defy 7 especially. The JA-200 that I worked on was nicely built but could only put our a few watts at 20 KHz. Not good for a 200 watt amp. At low frequencies it was fine but above about 8 KHz the amp was slewing like crazy due to the driver's lack of current. At 5 KHz the amp was down to about half power. This I believe is intentional in their designs. Trumpet music will suffer due to this!

Although I still speak with the folks at Brooks Berdan, give talks there, and supply them with amps on request they do not promote the amp though they like it. The problem is simple. They have a rather wealthy clientele. When someone wants a tube amp they would rather sell them a $30,000-$50,000 amp than a $6,500 amp. Rather simple math isn't it. You are only going to sell the guy one amp so it might as well be an expensive one.

Since I am not really interested in making the audio jewelry so popular these days we are selling mostly direct and keeping the price down. We hope that some listeners can appreciate that. I think I will put up a post for those who want to discuss the topic of current pricing in the market these days.
Title: Re: Favorite Coupling Cap Brands and Types
Post by: bdp24 on 5 Jul 2014, 04:50 am
   Yep, Brooks recommended MR amps to his more sophisticated/experienced customers, and I never saw a used one for sale in the store. Lots of ARC's, though (probably traded in on Jadis'!). Tom shared with me his ARC power amp horror stories (a lot involving that company's habit of placing 8 power tubes on a circuit board, a melt-down waiting to happen). The Jadis output at high frequencies explains why subjective reviewers often describe them as sounding "burnished" (like that's a good adjective for an amp). Brooks had one solid state amp he also recommended to the same type of customer, the BEL 1001.
   It was at one of your appearances at BB, Ltd. that I met you, Roger. I asked you about using the then-brand new RM10 with the original Quads. You advised me to instead get the RM9, but the next time I saw you, you said you had reconsidered, and the 10 WAS the better choice. But when I told you I had a pair of Quad II amps, you said why not just use them? I was impressed!
Title: Re: Favorite Coupling Cap Brands and Types
Post by: Roger A. Modjeski on 7 Jul 2014, 02:58 am
Thanks for the kind reply. Of all my dealers I was closest to Brooks. I knew him before he had his own store. Tom is a great tech and his stories about ARC are true.  Everyone suffers when ARC breaks, which it does all too often. Power tubes should never be on circuit boards, too much heat for any kind of PCB lifetime.
Title: Re: Favorite Coupling Cap Brands and Types
Post by: Freo-1 on 7 Jul 2014, 09:01 pm
Thanks for the kind reply. Of all my dealers I was closest to Brooks. I knew him before he had his own store. Tom is a great tech and his stories about ARC are true.  Everyone suffers when ARC breaks, which it does all too often. Power tubes should never be on circuit boards, too much heat for any kind of PCB lifetime.

Well said!  I had a ARC D115II that was an absolute pain to maintain.   Lots of problems.

Speaking of caps, I have Mundorf  Silver/Gold caps in these, and the amps sound fantastic!  They put out 110 watts each into a 4 ohm tap pentode.  I used to think pentode was not able to provide superior sonics.  This amp proved me wrong.  Sounds way better than any tube amps I've owned to date.  The Mundorfs are a big part of that sound.


 (http://www.audiocircle.com/image.php?id=102022)
Title: Re: Favorite Coupling Cap Brands and Types
Post by: Roger A. Modjeski on 7 Jul 2014, 09:18 pm
Well said!  I had a ARC D115II that was an absolute pain to maintain.   Lots of problems.

Speaking of caps, I have Mundorf  Silver/Gold caps in these, and the amps sound fantastic!  They put out 110 watts each into a 4 ohm tap pentode.  I used to think pentode was not able to provide superior sonics.  This amp proved me wrong.  Sounds way better than any tube amps I've owned to date.  The Mundorfs are a big part of that sound.


 (http://www.audiocircle.com/image.php?id=102022)

Nice job on the amps. I wish more people could build their own. I will be teaching those who can attend in the SF Bay Area this winter.

It is a thrilling experience to be listening to your own creation. This is how the hobby started in the 1950s when there wasn't so much built equipment available. People wrote articles, shared ideas, magazines published articles by people who knew what they were doing.

Now we have so many product choices and so much misinformation surrounding them. Like any industry that reaches monetary visibility others will come to the party. Like most late comers they may not be dedicated to the work as much as getting the money out of peoples pockets. What do they actually contribute to the industry?

I would hope you are more proud of your work than in selecting Mundorf caps. How about putting some other caps in one amp and put them on an instant A/B switch. That is what I do to decide if a difference is worth it or if there is a difference at all.
Title: Re: Favorite Coupling Cap Brands and Types
Post by: Freo-1 on 7 Jul 2014, 09:34 pm
Thanks.  My buddy did all of the hard work.  I helped with the circuit implementation, and some with working out the bugs.  The 1625 is a basically a 6L6 on steroids.  It can handle up to 700 volts on the plate.  This one has about 525 volts on the plates, and a separate 300 volt screen supply.  The input tubes are 12SN7.  All signal resistors are 1 watt PRP types.

The one real issue was resolving an oscillation problem.  I found the answer on the DIY website.  Miles Prower had suggested a snubber circuit on the plate cap that was installed to correct the problem.  The iron is all from Heyboer, who IMHO, makes the best "bang for the buck" iron in the business.   It also has NOS sockets from the late 40's.   This amp will likely outlive me. 

I got the DIY bug back in the 90's, when I bought a pair of Dyna MK IV's at a yard sale, and bought and installed a rebuild kit for it.  I was shocked at just how much improvement that inexpensive rebuild kit made.  From there, was hooked on tubes for good.

I have a solid state setup for general family use, but serious listening is with tubes.   :thumb:
Title: Re: Favorite Coupling Cap Brands and Types
Post by: kenkirk on 9 Jul 2014, 12:29 pm
This might be interesting reading for those wanting to "play" with caps.  :)

I would be interested in what Roger or other EE's think of the article. It seems pretty spot on to me.

Ken

http://sound.westhost.com/articles/capacitors.htm
Title: Re: Favorite Coupling Cap Brands and Types
Post by: Roger A. Modjeski on 11 Jul 2014, 05:13 am
This might be interesting reading for those wanting to "play" with caps.  :)

I would be interested in what Roger or other EE's think of the article. It seems pretty spot on to me.

Ken

http://sound.westhost.com/articles/capacitors.htm

Thank you Ken..I really really like this guy. I hope to I meet him someday. Unlike the specious claims of premium cap, everything he says is technically true. It's a long read but I got his message early on and I will quote the end. One thing you can count on ... if anyone wants to sell you 'special' capacitors, designed to replace 'inferior' types (such as polyester, PET, Mylar®, etc.), then you know that there is a problem. These vendors are cashing in on the audio snake-oil bandwagon. :)
Title: Re: Favorite Coupling Cap Brands and Types
Post by: Freo-1 on 11 Jul 2014, 01:20 pm
Thank you Ken..I really really like this guy. I hope to I meet him someday. Unlike the specious claims of premium cap, everything he says is TRUE. It's a long read but I got his message early on and I will quote the end. One thing you can count on ... if anyone wants to sell you 'special' capacitors, designed to replace 'inferior' types (such as polyester, PET, Mylar®, etc.), then you know that there is a problem. These vendors are cashing in on the audio snake-oil bandwagon. :)

Have a real world story about this:

There is thread on AC about ATC SCM-19 speakers that wound up in quarantine, due to one or two folks getting a bit insulting.  One of the members who is involved with speaker design recommended that the sound of the SCM-19 could be improved by changing out the crossover parts.  My buddy (who made the 1625 amps shown above) has upgraded hundreds of speakers over the years, and said he would be happy to upgrade the SCM-19's.  So, I dropped them off to have him do the work.  He rang be back a few days later, and stated that the SCM-19's sounded so good, he saw no need to "upgrade the components".  He further said they were perhaps the best monitors he has ever heard (and he has more experience than I in these matters). The lesson learned was that while good quality parts help, there is point where it just becomes hype, and disconnected from reality.  In the case of the SCM-19, the super linear driver and excellent tweeter was the upgrade.  :lol:

Having said all that, I'm still partial to Mundorf caps, and PRP resistors.  Great sounding combination.
Title: Re: Favorite Coupling Cap Brands and Types
Post by: Roger A. Modjeski on 11 Jul 2014, 01:53 pm
Back in 1979 when we released the RM-1 at Beveridge, TAS got the first review unit. John Fermin at Beveridge was very fond of Harry P. and visa versa. That unit had Sprague mylar caps. At the time polypropylene caps were just coming on and hard to find. They were the great new thing. Once we got the polyprops in John sent HP another preamp with the new caps. BTW there are a lot of interstage compling caps in an RM-1 although none of them is output as that is DC coupled. After listening to both Harry preferred the Mylar version. So we had to offer a mod back to mylar.
Title: Re: Favorite Coupling Cap Brands and Types
Post by: rajacat on 11 Jul 2014, 02:34 pm
In the Cheap and Cheerful HiFi circle, specificfully the TPA3110 andTPS3116 thread, upgrades in caps are generally considered necessary to draw the best sound out of the amps. http://www.audiocircle.com/index.php?topic=122011.msg1342664;boardseen#new
So the predominant view here is that they're all wasting their time and have defective hearing? Or all of them just deluded and hearing the placebo effect? There's also many over on diyaudio who are also deluded and weak minded. :roll:
To say that caps never make an audio difference is a gross overstatement, IMO.  At some point you have to trust your ears.
Title: Re: Favorite Coupling Cap Brands and Types
Post by: Freo-1 on 11 Jul 2014, 02:41 pm
In the Cheap and Cheerful HiFi circle, specificfully the TPA3110 andTPS3116 thread, upgrades in caps are generally considered necessary to draw the best sound out of the amps. http://www.audiocircle.com/index.php?topic=122011.msg1342664;boardseen#new (http://www.audiocircle.com/index.php?topic=122011.msg1342664;boardseen#new)
So is the predominant view here is that they're all wasting their time and have defective hearing? Or all of them just deluded and hearing the placebo effect? There's also many over on diyaudio who are also deluded and weak minded. :roll:
To say that caps never make an audio difference is a gross overstatement, IMO.  At some point you have to trust your ears.

I don't think anyone is saying "all caps sound the same" per se.  I think the point is that a lot of the qualities associated with caps are overblown.  Circuit design has MUCH more to do with the overall sound. 

Overblown or not, I still love my Mundorfs.   8)
Title: Re: Favorite Coupling Cap Brands and Types
Post by: Roger A. Modjeski on 11 Jul 2014, 04:44 pm
Does the audio signal pass through a coupling cap? 

Why do I hear changes in sound quality between different caps?

1. It passes though in the same way as a wire, though I expect some disagreement on this.

2. Perhaps because you want to.

This is really easy to find out if there are differences and what they are. Take a double pole double throw (6 lug switch) or relay and connect it so you can switch one speaker from one channel to the other. Drive both channels simultaneously. Mono the signal using 20K resistors so the right and left channels don't fight each other. This is common practice in mono-ing a signal. If you don't use resistors you may get a lot of distortion from your preamp. If your preamp has a mono switch use that.

Be sure your amps don't mind being unloaded, most are just fine as long as the input stays constant which it will.

Prove to yourself that your two identical channels sound identical. If they don't you have to work on them till they do. Invite a friend whose ears you respect to join you. He gets the easy part, listening.

Now change whatever caps you want in one of the channels. Listen again. What do you hear?

This is the easiest experiment I can imagine. Get a heavy switch at any electronics or hardware store. A good one is 10 amps with a 1 inch x 3/4 inch body. You can get ones with screw or solder terminals, you can put it in a box with connectors or wires of your choice.

I really encourage you to do this. This is a much better experiment than what is commonly done using acoustical memory with time between changes. Go back and forth a lot at first when you hear something new, check it. Eventually you might leave the switch in one position for a long time. The benefit of the switch is that you can go back and forth anytime without having to get out the soldering iron.

Compare the time it takes to make this little device compared to the time it takes to change caps.

Title: Re: Favorite Coupling Cap Brands and Types
Post by: corndog71 on 11 Jul 2014, 07:18 pm
I have a new tube preamp which has a balance knob.  Say I wanted to compare the output caps of this preamp.  Would it be ok for me to simply use the stock cap on one side, a different cap on the other side and run a mono signal to both inputs?  Then I could switch between channels using the balance knob.
Title: Re: Favorite Coupling Cap Brands and Types
Post by: rajacat on 11 Jul 2014, 07:24 pm
There are those over on the AVS forum who say that all amps sound the same. :lol:  You might as well go with the cheapest amp because the only important spec. is the power output. Pro amps like the iNuke are the favorite over there. Many also claim that tubes just add distortion so SS is the only way to go.
Title: Re: Favorite Coupling Cap Brands and Types
Post by: Roger A. Modjeski on 11 Jul 2014, 11:47 pm
I have a new tube preamp which has a balance knob.  Say I wanted to compare the output caps of this preamp.  Would it be ok for me to simply use the stock cap on one side, a different cap on the other side and run a mono signal to both inputs?  Then I could switch between channels using the balance knob.


How do you plan to hook up the outputs of the preamp? If you are going into two separate speakers put them close together (touching). I have done a similar experiment with two speakers touching but I always found that I could hear too much difference that was caused by differences in the speakers and their placement. It is best to have just one speaker.

If you are wiling to make a resistive Y connector and sum the left and right preamp outputs into one power amp and one speaker that would be much better.

Be very sure before you make the modification that the two channels sound the same. 
Title: Re: Favorite Coupling Cap Brands and Types
Post by: Roger A. Modjeski on 11 Jul 2014, 11:52 pm
There are those over on the AVS forum who say that all amps sound the same. :lol:  You might as well go with the cheapest amp because the only important spec. is the power output. Pro amps like the iNuke are the favorite over there. Many also claim that tubes just add distortion so SS is the only way to go.

Could you please provide a link?
Title: Re: Favorite Coupling Cap Brands and Types
Post by: rajacat on 12 Jul 2014, 12:14 am
I can't provide a specific link without devoting more time than I want. However, at least in this thread, http://www.avsforum.com/forum/155-diy-speakers-subs/1291022-hey-guys-we-need-little-rallying-here.html, there have been many posts that imply that amps aren't that important as long as they have enough power. Definitely, the very inexpensive iNuke is a favorite there. $150 gets you 2 x 300 Watts into 4 Ohms. http://www.behringer.com/EN/Products/NU1000.aspx.

I'm not saying I agree with this, to my thinking an extreme position, but it's a highly prevalent opinion among those in the home theater crowd. They tend to think that the speaker is by far the most important component.
Title: Re: Favorite Coupling Cap Brands and Types
Post by: bladesmith on 12 Jul 2014, 12:28 am
There are those over on the AVS forum who say that all amps sound the same. :lol:  You might as well go with the cheapest amp because the only important spec. is the power output. Pro amps like the iNuke are the favorite over there. Many also claim that tubes just add distortion so SS is the only way to go.


X2....
Title: Re: Favorite Coupling Cap Brands and Types
Post by: Roger A. Modjeski on 12 Jul 2014, 02:17 am
I can't provide a specific link without devoting more time than I want. However, at least in this thread, http://www.avsforum.com/forum/155-diy-speakers-subs/1291022-hey-guys-we-need-little-rallying-here.html, there have been many posts that imply that amps aren't that important as long as they have enough power. Definitely, the very inexpensive iNuke is a favorite there. $150 gets you 2 x 300 Watts into 4 Ohms. http://www.behringer.com/EN/Products/NU1000.aspx.

I'm not saying I agree with this, to my thinking an extreme position, but it's a highly prevalent opinion among those in the home theater crowd. They tend to think that the speaker is by far the most important component.

Thanks that's all I needed to get started. This is a forum I have never seen. I will study it.

I have played with some of these inexpensive high power amps and some of them put our their rated power and some just plain lie. I had a Pyramid amp that was supposed to be 200 watts and it as 40. http://www.sonicelectronix.com/item_30279_Pyramid-ZPA150.html?utm_source=google&utm_medium=cpc&utm_campaign=sc&scpid=2&scid=scsho3605219&gclid=Cj0KEQjwlv6dBRDC7rGfrvidmJgBEiQAjd3hMD9t8hd_h7HC7iAuD2XSf-SaxUNL6M3ivr

But that is not the main problem. These high power amps have very little tolerance for difficult loads due to the aggressive short circuit (over current) protection. They cant drive electrostatics to any appreciable level before the limiter cut in. They do fine with resistive loads.

The iNuke amp is a class D. I have no idea how it is protected.
Title: Re: Favorite Coupling Cap Brands and Types
Post by: Freo-1 on 12 Jul 2014, 12:54 pm
I can't provide a specific link without devoting more time than I want. However, at least in this thread, http://www.avsforum.com/forum/155-diy-speakers-subs/1291022-hey-guys-we-need-little-rallying-here.html (http://www.avsforum.com/forum/155-diy-speakers-subs/1291022-hey-guys-we-need-little-rallying-here.html), there have been many posts that imply that amps aren't that important as long as they have enough power. Definitely, the very inexpensive iNuke is a favorite there. $150 gets you 2 x 300 Watts into 4 Ohms. http://www.behringer.com/EN/Products/NU1000.aspx (http://www.behringer.com/EN/Products/NU1000.aspx).

I'm not saying I agree with this, to my thinking an extreme position, but it's a highly prevalent opinion among those in the home theater crowd. They tend to think that the speaker is by far the most important component.

I tend to agree that the speakers by far are the most important component in getting good sound.  Having said that, its not possible to get the best sound from the speakers without quality electronics supplying the signal.  The AVS guys are more concerned about movies than music, so to some extent, their agenda is not the same as folks who are after the highest quality stereo reproduction.  I don't think they are as obsessive about music as we are.  :lol:


Case in point:  For a vacation home, I've got a basic setup that uses a Yamaha RX-A1030 receiver with a pair of T + A Criteron 160 floor standing speakers.  They are all Dynaudio drivers (with 2 10" LF drivers in each cabinet).  The speakers are so good, they sound great with the basic Yamaha.  Can hardly wait to hook up the good electronics consistently to them.

  (http://www.audiocircle.com/image.php?id=102176)
 
Title: Re: Favorite Coupling Cap Brands and Types
Post by: bdp24 on 13 Jul 2014, 09:05 am
I can't provide a specific link without devoting more time than I want. However, at least in this thread, http://www.avsforum.com/forum/155-diy-speakers-subs/1291022-hey-guys-we-need-little-rallying-here.html, there have been many posts that imply that amps aren't that important as long as they have enough power. Definitely, the very inexpensive iNuke is a favorite there. $150 gets you 2 x 300 Watts into 4 Ohms. http://www.behringer.com/EN/Products/NU1000.aspx.

I'm not saying I agree with this, to my thinking an extreme position, but it's a highly prevalent opinion among those in the home theater crowd. They tend to think that the speaker is by far the most important component.

The DIY Subwoofer guys use Pro Sound Amps (Crown etc.). For subs they're fine (assuming high damping factor), except for the fan noise.
Title: Re: Favorite Coupling Cap Brands and Types
Post by: Roger A. Modjeski on 13 Jul 2014, 05:00 pm
The DIY Subwoofer guys use Pro Sound Amps (Crown etc.). For subs they're fine (assuming high damping factor), except for the fan noise.

I agree that some these pro sound amps are great for subs and I recommend them in my Resistance Loaded Sub system for ESLs. There are some that do not have fans which is preferable. Note that these new small, high powered amps with fans (now that a fan is cheaper than a big heatsink the manufacturers have moved more toward fans) do not always put out their stated power and may have severly sensitive load line limiting causing clipping into a difficult load. A woofer generates a lot of back EMF which will cause amps with fewer output transistors to limit.

As an alternative I suggest buying a good quality used amp on eBay. There are many. I have several available for my system.
Title: Re: Favorite Coupling Cap Brands and Types
Post by: bdp24 on 14 Jul 2014, 12:44 pm
Older, fairly high-powered SS amps from the 80's, like JGH's favorite the Eagle 2A by Electron Kinetics, can be had for $300-400 on AudioGon and eBay. Whatever you do, do NOT buy, or even hook-up to your subs, the Adcom 555. They're notorious for their leaky power supply capacitors, and will fry a driver in an instant. If not today, tomorrow.
Title: Re: Favorite Coupling Cap Brands and Types
Post by: Roger A. Modjeski on 14 Jul 2014, 04:05 pm
Of course any older amp should be checked out by a technician or the new owner on a speaker of low value.

One can very safely use a 1 or 2 amp fast blow fuse in series with the woofer to test the amp and I advise you leave it there. Although the fuse has a little resistance it will not harm the sound of your sub. If you play the woofer loud you might need a larger fuse. The power rating of the woofer will help you figure the maximum fuse by the formula

Watts= fuse current squared x speaker impedance. Here are a few examples for an eight ohm speaker.

Use a 1 amp fuse for a 10 watt speaker, 2 amps for 32 watts, 3 amps for 76 watts. Work your way up and blow a few to see where you need to be.   Since most subs are high powered 1 amp is a bit low to start. The fuse will actually blow at about 1.5 times its rating, which actually doubles the power but the time is short.

Fusing for amplifier faults is actually easier than using a fuse to limit signal power. Most amps put out DC when they fail and that will blow the fuse quickly. I usually end up with a 2 or 3 amp fast fuse. You can get a nice in-line fuse holder with heavy wires from most electronic or auto parts stores.
Title: Re: Favorite Coupling Cap Brands and Types
Post by: poseidonsvoice on 15 Jul 2014, 04:10 pm
I suppose it is tempting, if the only tool you have is a hammer, to treat everything as if it were a nail.

by Abraham Maslow, The Psychology of Science, 1966.

http://positive-feedback.com/Issue74/duelund.htm

:duh:

Best,
Anand.
Title: Re: Favorite Coupling Cap Brands and Types
Post by: Roger A. Modjeski on 15 Jul 2014, 05:53 pm
I suppose it is tempting, if the only tool you have is a hammer, to treat everything as if it were a nail.

by Abraham Maslow, The Psychology of Science, 1966.

http://positive-feedback.com/Issue74/duelund.htm

:duh:

Best,
Anand.

That PF article is really long and a lot of money and effort went into it $ 18,621 to be exact. The autoformers were $6,219. What the actual improvement is, who knows.

It is interesting that they compared the weight of the original autoformer to the Duelund which is much heavier due to the casting compound and case. What is important is what is in inside. Some measurements of the two transformers would be interesting.

In reading this article I learned something new, I had not known that silver will migrate over an insulator over time and degrade that insulator.
Here is the my post concerning that and what I learned from the Bell Telephone article.  http://www.audiocircle.com/index.php?topic=127381.0
Title: Re: Favorite Coupling Cap Brands and Types
Post by: BobRex on 15 Jul 2014, 08:15 pm
Considering the dollar value of that "upgrade", I would think the next step would be to compare the change to fully active bi-amp with an external xover.  That should be a plug and play exchange with just minor tweaking.
Title: Re: Favorite Coupling Cap Brands and Types
Post by: Freo-1 on 15 Jul 2014, 08:28 pm
Considering the dollar value of that "upgrade", I would think the next step would be to compare the change to fully active bi-amp with an external xover.  That should be a plug and play exchange with just minor tweaking.

That just opens up another entire can of worms with the parts, design, etc. of the active crossover.  Once one dives into these rabbit holes, it gets hard to climb out of them.  :lol:
Title: Re: Favorite Coupling Cap Brands and Types
Post by: steve f on 15 Jul 2014, 08:57 pm
Wow. I just breezed through the article. I can't imagine why anyone would want to spend that kind of money to build a passive crossover. Two quality amps like Music Reference and an active crossover just makes a lot more sense. I don't know why audiophiles are so hung up on passive crossovers.
Title: Re: Favorite Coupling Cap Brands and Types
Post by: Roger A. Modjeski on 15 Jul 2014, 09:17 pm
Wow. I just breezed through the article. I can't imagine why anyone would want to spend that kind of money to build a passive crossover. Two quality amps like Music Reference and an active crossover just makes a lot more sense. I don't know why audiophiles are so hung up on passive crossovers.

Considering the dollar value of that "upgrade", I would think the next step would be to compare the change to fully active bi-amp with an external xover.  That should be a plug and play exchange with just minor tweaking.

I agree that an active crossover is a far better solution and requires less money and less effort, though a different kind of effort. My take on it is that people dont really understand active crossovers. The main concern I hear is that they fear the electronics in the crossover will add coloration, that they will not be as good as a neutral line amp. What people don't understand is that the electronics in a crossover are more neutral than a line amp as they usually have no gain at all.

It is well established that speaker crossover components have serious drawbacks by their nature. Coils have resistance which reduces woofer damping. If they are wound on iron they have hysteresis and saturation problems. Capacitors have dialectical absorption and ESR problems. All these problems are eliminated by the electronic crossover.

A further advantage of electronic crossovers is that they have level controls for the individual drivers which allow one to tune the system to his room and preferences. I trim my levels at will just a bit for different recordings. If something is too bright I turn down the tweeter. If I want more bass I turn up the woofer. Inter-modulation distortion is almost eliminated and one can now choose amplifiers for their characteristics to please the individual drivers. The woofer amp should have high damping and more power than the tweeter amp which can now be something single ended if that is desired. Single ended amps have certain virtues in the mid range and highs. They are generally not preferable for woofers.

I think the main reason is laziness. It is easier to replace a few crossover parts than buy and wire up a bi-amp system. However in the case of the PF article over $18,000 and considerable effort was expended for a less than perfect solution.

I would love to hear from others who modify speaker crossovers what keeps them from going to active crossovers.
Title: Re: Favorite Coupling Cap Brands and Types
Post by: Freo-1 on 15 Jul 2014, 10:50 pm
I agree that an active crossover is a far better solution and requires less money and less effort, though a different kind of effort. My take on it is that people dont really understand active crossovers. The main concern I hear is that they fear the electronics in the crossover will add coloration, that they will not be as good as a neutral line amp. What people don't understand is that the electronics in a crossover are more neutral than a line amp as they usually have no gain at all.

It is well established that speaker crossover components have serious drawbacks by their nature. Coils have resistance which reduces woofer damping. If they are wound on iron they have hysteresis and saturation problems. Capacitors have dialectical absorption and ESR problems. All these problems are eliminated by the electronic crossover.

A further advantage of electronic crossovers is that they have level controls for the individual drivers which allow one to tune the system to his room and preferences. I trim my levels at will just a bit for different recordings. If something is too bright I turn down the tweeter. If I want more bass I turn up the woofer. Inter-modulation distortion is almost eliminated and one can now choose amplifiers for their characteristics to please the individual drivers. The woofer amp should have high damping and more power than the tweeter amp which can now be something single ended if that is desired. Single ended amps have certain virtues in the mid range and highs. They are generally not preferable for woofers.

I think the main reason is laziness. It is easier to replace a few crossover parts than buy and wire up a bi-amp system. However in the case of the PF article over $18,000 and considerable effort was expended for a less than perfect solution.

I would love to hear from others who modify speaker crossovers what keeps them from going to active crossovers.


OK.  In theory, active crossovers make a lot of sense.  Speakers such as those by Meridian and ATC have active powered models, and are widely recognized as some of the best sounding speakers available.  So, it makes me wonder:  Why is it speaker companies do not offer a active crossover to go with their speakers?

I am interested in making a quality two way crossover (at 80 Hz) for my tube setup.  I would then have a lower powered tube amp  made for the HF to go with the ATC SCM 19 speakers. There really isn't many available on the commercial market.  The only one I can think of that is reasonably priced is this one:

http://www.hsuresearch.com/products/high-end-crossover.html (http://www.hsuresearch.com/products/high-end-crossover.html)

Guess I should look for a good schematic for a tube crossover.
Title: Re: Favorite Coupling Cap Brands and Types
Post by: Roger A. Modjeski on 15 Jul 2014, 11:03 pm
OK.  In theory, active crossovers make a lot of sense.  Speakers such as those by Meridian and ATC have active powered models, and are widely recognized as some of the best sounding speakers available.  So, it makes me wonder:  Why is it speaker companies do not offer a active crossover to go with their speakers?

I am interested in making a quality two way crossover (at 80 Hz) for my tube setup.  I would then have a lower powered tube amp  made for the HF to go with the ATC SCM 19 speakers. There really isn't many available on the commercial market.  The only one I can think of that is reasonably priced is this one:

http://www.hsuresearch.com/products/high-end-crossover.html (http://www.hsuresearch.com/products/high-end-crossover.html)

Guess I should look for a good schematic for a tube crossover.

I have the RM-3 which is a good SS crossover capable of slopes up to 24 dB/octave, any alignment as the crossover components are on plug in cards. The high pass is all discrete push pull transistor and the low pass is IC.

If you are sold on tube crossovers you should check our Marchand Electronics. His crossover is modular and you can buy just the boards or kits for less. It is a good unit, I have worked on one.

For simple 6 dB per octave you can just put caps and resistors at the input jacks of the amps.

A tube active crossover is easy to build. You just need a few cathode followers and appropriate filter components.

As to your question: Speaker companies are not electronics companies. They really don't know much about active circuits, they live in a passive world. If one approached me I would be happy to make what they needed.
Title: Re: Favorite Coupling Cap Brands and Types
Post by: Freo-1 on 15 Jul 2014, 11:06 pm
I have the RM-3 which is a good SS crossover capable of slopes up to 24 dB/octave, any alignment as the crossover components are on plug in cards. The high pass is all discrete push pull transistor and the low pass is IC.

If you are sold on tube crossovers you should check our Marchand Electronics. His crossover is modular and you can buy just the boards or kits for less. It is a good unit, I have worked on one.

For simple 6 dB per octave you can just put caps and resistors at the input jacks of the amps.

A tube active crossover is easy to build. You just need a few cathode followers and appropriate filter components.

As to your question: Speaker companies are not electronics companies. They really don't know much about active circuits, they live in a passive world. If one approached me I would be happy to make what they needed.

I'm not necessarily hard over on a tube vs SS crossover.  Wouldn't a second order crossover be in order for the SCM-19?
Title: Re: Favorite Coupling Cap Brands and Types
Post by: bdp24 on 16 Jul 2014, 01:19 am
A 1st order passive high-pass filter with active low-pass for subs has long been the way for Electrostatic owners, especially Quads. With a lot of subs now being active, it's easier than ever. It's bi-amping without having to buy an amp or separate x/o, if the ones built into the sub are good enough. For a steeper high-pass, the Marchand tube x/o's have a great reputation amongst finicky :lol: enthusiasts. Harvey Rosenberg used them with his Quads and horns. When I was using a Bedini 25/25 on my Quads I had Tom at Brooks Berdan's place install a cap and resistor (I think it was both, though it may have been only a resistor) filter on the backside of it's RCA input jacks, and ran subs with the active section of the Dahlquist bi-amping unit (John didn't call it a cross-over)---2nd order to the sub amp. That route avoided the extra cable and connections going through the Dahlquist to the Bedini would necessitate. Tom just took the amp's input impedance and the x/o frequency I requested, and calculated the values required. It's great to have a tech in the neighborhood! I'm about to do the same with my RM200, but without the Dahlquist in the system (the current subs are powered and have their own adjustable---2nd or 4th order, 40Hz to 240Hz---low-pass filters).
Title: Re: Favorite Coupling Cap Brands and Types
Post by: BobRex on 16 Jul 2014, 12:51 pm
For simple 6 dB per octave you can just put caps and resistors at the input jacks of the amps.

I think I know the answer to this, but just for confirmation:

Suppose I wanted to put the highpass (6 dB) on one of the outputs of the pre-amp, instead of inside the amp.  Do I need to consider the characteristics of the interconnect as part of the calculation, or is that just noise.  Also, since the pre outputs are just a parallel circuit, will the change in the aggregate load at low freqs affect the other output?
Title: Re: Favorite Coupling Cap Brands and Types
Post by: Roger A. Modjeski on 16 Jul 2014, 02:41 pm
I think I know the answer to this, but just for confirmation:

Suppose I wanted to put the highpass (6 dB) on one of the outputs of the pre-amp, instead of inside the amp.  Do I need to consider the characteristics of the interconnect as part of the calculation, or is that just noise.  Also, since the pre outputs are just a parallel circuit, will the change in the aggregate load at low freqs affect the other output?

The high pass is the easiest to do. Cable capacitance is no more an issue with or without the high pass. You need to know the output impedance of your preamp and input input impedance of your power amp, the latter will probably dominate when they are added together.

Here is a good calculator I have recommended before. http://www.sengpielaudio.com/calculator-XLC.htm

I worked out a typical example for you. If the preamp output impedance is 1 Kohm and the power amp input is 47 K add those together and put 48K into the calculator. For 80 Hz crossover the series cap is 0.414 uF. As you can see the output impedance doesn't matter much adding 1 k to 47 K wont change the answer appreciably. If you don't know the output impedance of your preamp you can likely ignore it as it should be small compared to the input impedance of your power amp.

The cap value is not critical. The closest standard value it .039 and even .047 would not be bad as the roll-off is so gradual. The main advantage of doing this is to relieve the amp and main speaker from having to play deep bass which robs power and causes intermodulation. I would go for the smaller cap and help the speaker/amp more. Using a 0.033 uF would be a good choice.

The cap goes in series with the hot lead either at the output of the preamp or input of the power amp. The power amp input is preferred.

This is a really simple but very valuable thing to do. A big improvement for little cost and effort. There are many things like this we can do to improve our systems without buying into some pricey, doubtful modification that we read about in the magazines.
Title: Re: Favorite Coupling Cap Brands and Types
Post by: bdp24 on 17 Jul 2014, 02:51 am
I just looked, and found my receipt for the caps Tom installed in my amp, one on each channels input jack; 00.0033 MFD +/-10% 200V Siderealkap (matched). With an input impedance of 50K Ohms, does the frequency end up around 80-100Hz? I think that's what I was shooting for.
Title: Re: Favorite Coupling Cap Brands and Types
Post by: tubegroove on 17 Jul 2014, 07:09 am
The high pass is the easiest to do. Cable capacitance is no more an issue with or without the high pass. You need to know the output impedance of your preamp and input input impedance of your power amp, the latter will probably dominate when they are added together.

Here is a good calculator I have recommended before. http://www.sengpielaudio.com/calculator-XLC.htm

I worked out a typical example for you. If the preamp output impedance is 1 Kohm and the power amp input is 47 K add those together and put 48K into the calculator. For 80 Hz crossover the series cap is 0.414 uF. As you can see the output impedance doesn't matter much adding 1 k to 47 K wont change the answer appreciably. If you don't know the output impedance of your preamp you can likely ignore it as it should be small compared to the input impedance of your power amp.
...............
Once one has the data on hand of the pre amp and amp respective impedances and the freq response of the main speaker, how does one practically decide the high pass crossover point (80Hz in your example)?  Is it typically the-3dB point of the main speaker's low end of the freq response?  Should it be somewhat higher than the -3dB point thereby creating some overlap between the main speaker's bottom end of the freq response and where the intended sub woofer kicks in?  Whats good practice to come up with the crossover point? Or does it not matter so long as its within the sub woofers crossover range?
Thanks
Title: Re: Favorite Coupling Cap Brands and Types
Post by: sfox7076 on 17 Jul 2014, 02:38 pm
Someone should get Dennis Murphy in here.  He is the crossover guy for Salk and his own speaker line.
Title: Re: Favorite Coupling Cap Brands and Types
Post by: Roger A. Modjeski on 17 Jul 2014, 04:09 pm
I just looked, and found my receipt for the caps Tom installed in my amp, one on each channels input jack; 00.0033 MFD +/-10% 200V Siderealkap (matched). With an input impedance of 50K Ohms, does the frequency end up around 80-100Hz? I think that's what I was shooting for.

Someone missed a zero there. 0.0033 and 50K form a corner at 965 Hz. However if the cap is actually 0.033 then the pole is at 96 Hz which is fine.

numbers, numbers, numbers.... :(  This is why I teach electronic numbers in $$$. People pay attention to $$ because they have as real a value as electronic numbers have to  me.
Title: Re: Favorite Coupling Cap Brands and Types
Post by: bdp24 on 18 Jul 2014, 01:52 pm
Yeah, I assumed that number had the accidental zero. I'm going to open the amp (I still have it, but it's been in a box for years. Toobs rule!) and look at the cap to make sure.
Title: Re: Favorite Coupling Cap Brands and Types
Post by: Roger A. Modjeski on 20 Jul 2014, 08:51 pm
Once one has the data on hand of the pre amp and amp respective impedances and the freq response of the main speaker, how does one practically decide the high pass crossover point (80Hz in your example)?  Is it typically the-3dB point of the main speaker's low end of the freq response?  Should it be somewhat higher than the -3dB point thereby creating some overlap between the main speaker's bottom end of the freq response and where the intended sub woofer kicks in?  Whats good practice to come up with the crossover point? Or does it not matter so long as its within the sub woofers crossover range?
Thanks

Since I don't want male vocals coming out of the sub I chose 100 Hz and 24 dB/octave. If your slope is not that steep on the sub you have to choose a lower crossover point.

I would not go to the -3 dB of the main speaker, try to stay half an octave above that especially if there is a peak before the fall as there often is. There are lots of trade-offs to explore. Experiment if you can. If your satellites don't go low then you have to go higher with the Sub. If they go low and you have amp power go lower in the crossover. Listen to each speaker separately.

In my ESL system and with QUADS I recommend 100 Hz, 24 dB octave in both directions.