[Roger A. Modjeski]

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.

[bdp24]

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!

[Roger A. Modjeski]

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.

[bdp24]

   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!

[Roger A. Modjeski]

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.

[Freo-1]

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.


 

[Roger A. Modjeski]

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.


 

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.

[Freo-1]

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.   

[kenkirk]

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

[Roger A. Modjeski]

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.

[Freo-1]

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. 

Having said all that, I'm still partial to Mundorf caps, and PRP resistors.  Great sounding combination.

[Roger A. Modjeski]

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.

[rajacat]

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.
To say that caps never make an audio difference is a gross overstatement, IMO.  At some point you have to trust your ears.

[Freo-1]

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 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.
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.   

[Roger A. Modjeski]

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.

[corndog71]

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.

[rajacat]

There are those over on the AVS forum who say that all amps sound the same.   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.

[Roger A. Modjeski]

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. 

[Roger A. Modjeski]

There are those over on the AVS forum who say that all amps sound the same.   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?

[rajacat]

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.