My little coupling-cap-test in a UL-70W-Amp

[Blitz]

Hi,

I just build a van der Veen UL-40 http://www.mennovanderveen.nl/images...uto-biasv2.jpg , but as Mono-Version with 4*El34 and with 7mA for the driver tube, no cap at the cthode resistor of the driver, with carbon / Z-foil-resistors, with the auto-bias-mod etcetc. (BTW in the phase splitter I used always Mundorf Supremes (0.1)

What I found was that the nature of the amp discloses differences of caps in an extreme way. I have just started the journey and would like to compare notes with you guys.

I have broke in the caps with playing real music for 7 days 24 hours non-stop, before I compare.

A. Mundorf Silver/oil:
A "nice" sounding cap. I used in in 0.47 ). And I mean "Nice"...so, it give a certain softness in texture, but the backround seems to be very black, the depth of the soundstage is definietly there. BUT...you have alwys the impression someone is standing on the brake and the attack and directness is not there yet. It is a bit like always a curtain is there. The last bit of air and sparkeling is missing. But...the vibrance of a tone is there. The bass has less control, is sometime simply too fat.

B. Mundorf Supreme:
Astonishing how clear and direct the amp can sound like. No comparison to the silver oil, the supremes are crystal clear. But...the sound as well a bit less musical, a big suprise is that the curtain is certainly removed, but that the depth of the soundstage has lost depth and that the vibrance of tones as well lost details. The nature of music is more difficult to follow. There is a signature of the cap which is crystal clear, but as well there is a loss in micro-details at the same time...strange. If you would not have hear them before you would not miss them...but now that I know that they are there...The Bass is very controlled. I used the 1200V 0.33uf version here which is as huge as the 0.47 silver in oil version.

C. Audionote Copper in Mylar / oil with silver lead outs:
They are in between currently. They are nearly as clear as the normal supremes, but have the musicality of the Mundorf silver oils. Nevertheless they introduce again a curtain...I will give theme another 7day / 24hours of burn on as these guys are really promising. They have maybe the largest richness / vibrance on tones sofar, and a micro-dynamic which is a pleasure. I am not yet sure if they are the kings in terms of imaging / depth of sounstage, but have at least the qualiy of the supremes without introducing anything artificial. They are faster that the silver in oils, currently they would be the coice, but if they do not improce, things would have the be improve to get the curtain out of the way.

Waiting to be tested:
- V-Caps 0.22uF/300V
- Maybe Mundorf Silver/Gold (not in Oil, Mundorf say clearly that the oil makes the caps slower in sound)
- Maybe Russian teflons, not sure if they are to big.

HAve you made similar experiences ? What have been your conclusions ? What is experience on the burn-in period on these caps ?

[analog_sa]

I only have experience with the SIO from your list. Took about 50hrs for break-in and they were very disappointing prior. Fully agree with calling them "nice" sounding. They are not particularly honest compared to a bypass but add a lot of pleasant effects, especially to the soundstage. As always the question is whether you are looking for a cap to add spice and musicallity or simply be transparent. IME none of the oil caps are transparent but some are really very pleasant. As sound reproduction at home is such an artificial endeavour anyway i have no objections to using flavours.

[Blitz]

Actually I want transparency, speed, vibrance / richness of tone, I want a cap to disappear.

[Yvesm]

Originally posted by Blitz
Actually I want transparency, speed, vibrance / richness of tone, I want a cap to disappear.

Use as few as you can !

http://www.dissident-audio.com/PP_6L6/Page.html

Yves

[ilimzn]

A comparison of the same capacitance values of various typea would improve the usefullness of this test - when the value changes, so does (at the minimum) the low end of the spectrum, regardless of cap type. As it stands now, the comparison has lots to say about materials the capacitors are made of, but little about the actual electrical values which determine the basic circuit operation - and these should stay the same so we can compare apples to apples...

[Blitz]

I think this is a bit to theoretical. In this amp a 0.47 means a -3db of 2.8hz. With 0.33uf it means a -3Db at 4.1 hz. If your speaker and your ears can her the difference of that change on values: Well than yours are better than mine.

[analog_sa]

Originally posted by Blitz
Actually I want transparency, speed, vibrance / richness of tone, I want a cap to disappear.

Not sure if these requirements are not a bit controversial. For transparency it's best to compare caps to a bypass if possible. I once had a system with no coupling caps: just transformers from MC levels to speakers and any coupling cap would stick out like the proverbial sore thumb. At the time i decided that the MIT RTX are as transparent as caps go but they will gladly reveal any ugliness if present. The have a long break in period and very dubious lead out wires which are best replaced. And they will not create a rich tone. The majority of boutique caps are tiny special effects boxes and i see nothing wrong will that. The poor music signal has often passed through lots of studio equipment of dubious transparency so a little help to restore musicality is just fine.

Forgot mentioning the Russian teflons. I appreciate what they do but really don't like them. People often call them neutral but to me they just sound cold and uninvolved, nothing like a wire bypass. Haven't tried V-caps out of fear it will be more of the same.