[wushuliu]

I have the Audiocap Theta in my First Watt Burning Amp 3 right now, is it worth it to change to a ClarityCap MR?

Tony gee rates theta much lower than the mr. I love the mr. Like sonicap but muuuch better.

[Tyson]

Tony gee rates theta much lower than the mr. I love the mr. Like sonicap but muuuch better.

Agreed - I went from Sonicaps in my Serenity Acoustic Super 7's to the ClarityCap MRs.  Now that the MR's have broken in, it's true - tonally similar to the Sonicaps, but much more detail and soundstage info, and smoooooooth. 

But JonL was so positive about the AudioCap Theta in his review, I went with that in my amp.  Part of the problem is the amp uses 10uF for the cap size and some of these higher end caps just aren't made in that size.  Hence the question.....

[Tyson]

OK, I broke down and ordered the ClarityCap MR 10uF for the amp.  It would have just eaten away at me if I'd just stuck with the Audiocap Theta.  JonL recommends bypassing the Theta with Teflon, I'll give that a try too.

[wushuliu]

OK, I broke down and ordered the ClarityCap MR 10uF for the amp.  It would have just eaten away at me if I'd just stuck with the Audiocap Theta.  JonL recommends bypassing the Theta with Teflon, I'll give that a try too.

Let us know how it goes...

[Tyson]

Pulled the Audiocap Thetas from my BA3 and dropped in the Claritycap MR today.  Immediately there was better transparency and detail.  The Thetas are just a dull sounding cap, IMO.

[wushuliu]

Pulled the Audiocap Thetas from my BA3 and dropped in the Claritycap MR today.  Immediately there was better transparency and detail.  The Thetas are just a dull sounding cap, IMO.

I thought the same thing about the Dayton film & foil caps. Wonder if Audiocap makes those too...

[Nick77]

Pulled the Audiocap Thetas from my BA3 and dropped in the Claritycap MR today.  Immediately there was better transparency and detail.  The Thetas are just a dull sounding cap, IMO.

I installed a pair of MR's in my tube preamp with same results, their are nice caps.

[Tyson]

Good lord these ClarityCap MR's take forever to burn in....

[rajacat]

Good lord these ClarityCap MR's take forever to burn in....

Have you tried Jupiter HTs or the Jupiter copper foils in your BA3?

[OzarkTom]

 I had Dueland Alexaders in my Virtue amp, took 500 hours to break in.

The sound was horrible till then.

[Tyson]

Have you tried Jupiter HTs or the Jupiter copper foils in your BA3?

I need 10uf for my amp, Jupiter doesn't make a cap in that size with the 600v rating   And the copper foil 10uF is $500 each!!! :O 

[poseidonsvoice]

I need 10uf for my amp, Jupiter doesn't make a cap in that size with the 600v rating   And the copper foil 10uF is $500 each!!! :O

I thought I sent you the link below precisely to answer this question. Read up on low pass filter equations, specifically X(c) = 1/2*pi*f*c

Where X(c) is reactance, pi is the number 3.141569..., f=frequency and c=capacitance. Sengpielaudio has a calculator online.

http://www.diyaudio.com/forums/pass-labs/201281-burning-amp-ba-3b-balanced-51.html#post4712839

Given that the BA3 front end uses low voltage rails, you don't have to splurge on high voltage caps which are usually more expensive, and if you don't need an F3 at 0.3Hz which is damn near DC, why use 10 microfarads?

Try a few caps that are smaller and see what you think about the bass response. Or better yet, measure the low frequency response of your amp while you change the cap values. Usually choosing a cap that plays down to an octave below the lowest frequency desired should be enough I thought. Don't your Serenity's already have an active bass section?

Best,
Anand.

[Tyson]

I thought I sent you the link below precisely to answer this question. Read up on low pass filter equations, specifically X(c) = 1/2*pi*f*c

Where X(c) is reactance, pi is the number 3.141569..., f=frequency and c=capacitance. Sengpielaudio has a calculator online.

http://www.diyaudio.com/forums/pass-labs/201281-burning-amp-ba-3b-balanced-51.html#post4712839

Given that the BA3 front end uses low voltage rails, you don't have to splurge on high voltage caps which are usually more expensive, and if you don't need an F3 at 0.3Hz which is damn near DC, why use 10 microfarads?

Try a few caps that are smaller and see what you think about the bass response. Or better yet, measure the low frequency response of your amp while you change the cap values. Usually choosing a cap that plays down to an octave below the lowest frequency desired should be enough I thought. Don't your Serenity's already have an active bass section?

Best,
Anand.

Actually it only powers my midrange which goes down to about 200hz.  That actually gives me an idea that I want to try out - use the cap to reduce the bass of the amp to match the midrange so that the mid panels don't get a signal below 150 hz or so.  Just need to calculate what size cap will give me that with a flat 8 ohm speaker load...

[poseidonsvoice]

Actually it only powers my midrange which goes down to about 200hz.  That actually gives me an idea that I want to try out - use the cap to reduce the bass of the amp to match the midrange so that the mid panels don't get a signal below 150 hz or so.  Just need to calculate what size cap will give me that with a flat 8 ohm speaker load...

Going to my aforementioned link, you will note, that if you input 0.3Hz for frequency, 10uf for capacitance, then the X(c) reactance that Nelson Pass used was 53k ohms. Now that is your constant and you don't want to change that because that is a design parameter intrinsic to the amplifier design.

So for 150hz, assuming an X(c) of 53k ohms, you solve for capacitance, and you get 0.02 uf. The closest value typically is 0.022uf. If that makes you nervous, try 0.047uf which will allow even more low frequencies...65Hz to be exact.

Personally for full range speakers, I don't know why 0.3Hz is sought. I think 3 Hz would be plenty low and is nearly 2 octaves below 20Hz. But I bet this has to do with people over analyzing frequency response curves and wondering why the amplifier is starting to rolloff at >5Hz.

So theoretically, 1uf should be fine for a full range speaker. Besides, smaller capacitors are cheaper in cost, and can sound a bit more transparent in my book. It all comes down to the design.

Best,
Anand.

[Audiophile58]

A great cap that is in that high 12-12.5 range out of 14
And a Best buy is the Audyn True Copper capacitor it is large from Germany 1/2 thd price of Mundorf
Silver oil or silver gold oil  very similar to yhe Jupiter Copper , as good or better in my system , not quite as rich
And less then 1/2 the cost. At parts express. Check it out coupling caps especially.

[Tyson]

Going to my aforementioned link, you will note, that if you input 0.3Hz for frequency, 10uf for capacitance, then the X(c) reactance that Nelson Pass used was 53k ohms. Now that is your constant and you don't want to change that because that is a design parameter intrinsic to the amplifier design.

So for 150hz, assuming an X(c) of 53k ohms, you solve for capacitance, and you get 0.02 uf. The closest value typically is 0.022uf. If that makes you nervous, try 0.047uf which will allow even more low frequencies...65Hz to be exact.

Personally for full range speakers, I don't know why 0.3Hz is sought. I think 3 Hz would be plenty low and is nearly 2 octaves below 20Hz. But I bet this has to do with people over analyzing frequency response curves and wondering why the amplifier is starting to rolloff at >5Hz.

So theoretically, 1uf should be fine for a full range speaker. Besides, smaller capacitors are cheaper in cost, and can sound a bit more transparent in my book. It all comes down to the design.

Best,
Anand.

Oh right, because these are coupling caps and not output caps.  Sorry, brain fart.  So the input impedance of the Output Board is what I need.  Like you show, its probably 53,000 ohms but I should double check the values just to be sure. 

The calculator I use is http://www.carstereo.com/help/Articles.cfm?id=1 at the bottom - it's a little more flexible in that you can input any 2 values and it gives you the 3rd, regardless of position in the formula. 

[poseidonsvoice]

Oh right, because these are coupling caps and not output caps.  Sorry, brain fart.  So the input impedance of the Output Board is what I need.  Like you show, its probably 53,000 ohms but I should double check the values just to be sure. 

The calculator I use is http://www.carstereo.com/help/Articles.cfm?id=1 at the bottom - it's a little more flexible in that you can input any 2 values and it gives you the 3rd, regardless of position in the formula.

It's a bit more complicated. The 53K figure comes from not only resistances in series but in parallel as well, so without looking at a schematic, I don't know what values that he used to come up with that value. But I don't think I really need to know. We know that Pass likes a corner frequency of 0.3Hz as his low pass and he is recommending a 10uf cap for the BA-3 circuit. So from that you know the reactance already, without even looking at the BA-3 schematic or the output board schematic.

Best,
Anand.

[Tyson]

Found out the input impedance for the BA3 output boards is between 5k and 6k.  So I ordered up some .22 uF Jupiter Copper Foil Wax Paper caps and will be installing them when they arrive.  That should get the rolloff started at 150hz for my amp, which is perfect since my midrange panels only go down to 200hz or so.

[DaveC113]

Found out the input impedance for the BA3 output boards is between 5k and 6k.  So I ordered up some .22 uF Jupiter Copper Foil Wax Paper caps and will be installing them when they arrive.  That should get the rolloff started at 150hz for my amp, which is perfect since my midrange panels only go down to 200hz or so.

Usually calculations are for the F3, or -3 dB point, your slope would be 6 dB/oct, so the rolloff starts a half octave higher. Also, coupling and output caps are serving the same function, coupling is usually used if it's within the component. If it's coupling you know the impedance of the following stage, for output you have to assume low. 5-6k is pretty low.

I have the Jupiter copper caps in my preamp (output), amp (coupling) and midrange driver and tweeter (1st order xos). I like them a lot, very neutral and resolving with a touch of warmth/body...

[Tyson]

Usually calculations are for the F3, or -3 dB point, your slope would be 6 dB/oct, so the rolloff starts a half octave higher. Also, coupling and output caps are serving the same function, coupling is usually used if it's within the component. If it's coupling you know the impedance of the following stage, for output you have to assume low. 5-6k is pretty low.

I have the Jupiter copper caps in my preamp (output), amp (coupling) and midrange driver and tweeter (1st order xos). I like them a lot, very neutral and resolving with a touch of warmth/body...

Yes, starting the rolloff an octave earlier is exactly what I want.  The less bass my mid panels see, the better.  I have the servo bass woofers to go up to 200hz or so. 

I'm going to replace the Clarity Cap MR 10uF cap with the .22 uF Jupiter Caps.  That will also allow me to remove the .015 uF AuriT cap I have on the output of my preamp, which is currently rolling the bass off before it hits my BA3. So, I get to remove a small cap from the signal while at the same time replacing a large cap with a smaller cap of better quality.  Can't imagine I won't end up with better sound.  But I never count my chickens before they hatch.  Been wrong about too many things in the past