Valab NOS DAC - subjective listening and modifications - Page 9

Bypass Caps

Pictures of the Obligatto .22uf bypass caps. I just tacked them on to the legs of the Kemet caps already in the dac. They are sounding very good but missing a little air but adding a refinement and 3D sound I wasn't getting with the stock caps. In my opinion the stock caps need to go or at least bypass them. Listening to the dac stock it has a bit of a raggedness when things get busy, the stock caps also sound thin giving the impression of a more recessed sound, with the Obligattos in place images are fuller/smoother and come from different levels of depth giving a 3D sounstage, the stage also seems to have moved a little more forward/closer which for me is a good thing. Now if I get the air back with break in I'll be a happy clam. Again, IMO the stock caps really need to go, higher quality caps will change the sound in positive ways, right now with minimal break in it's sounding like an entirely different dac. I think changing the coupling caps, or at least bypassing them will make a big difference, well worth experimenting with different caps.



By philltubes, shot with FE190/X750 at 2009-03-26

Not true. Same signal currents run through both. The geometry matters. The dielectric has a big effect as well.

I have been coaching Bill on these mods BTW.

Steve N.
Empirical Audio

Hi Steve, whats you're opinion with bypassing coupling caps and the problems of spectral overlap, in what way does overlap affect the sound?

What about output of Valab with like this: SoniCap 4.7uf (GEN-1, £11 a piece) bypassed with Blackgate PK series 0.22uf($1 each)..

Will that make an improvement? How do you guys think it will sound compared to stock??



I think I will settle for this on my stock Valab : Mundorf Mcap Supreme 4.70uf £20.07 ...... Is this something you guy's would accept. They are quite big so bypassing will be out of question. Is 4.7uf enough? Is this a good cap, yes it is below the silver edition, but I can't afford that.

Anyone ?!?!?

THANKS!!

K

No need to bypass the Sonicap, if you use the Blackgate as the main coupling cap then you cold bypass with a film cap. What cap to use, V-Cap or Sonicap, you have to try it and see, there are no concrete answers. 4.7 is ok but not a good idea to go smaller.

2x Mundorf Mcap Supreme 4.70uf ... what you think of these, tubes?

Hi Krisno,


I'm using Mcap Supreme's and find the top end a little smoother and cleaner sounding....also have some VTV pio .22uf on order for bypassing


Rich

But that's the only difference? just top end a little smoother? hmm... Have you tried anything else?

I think I have it solved... I will get soniccap 4.7uf 200VDC and bypass with soniccap GEN-2 0.22µF / 200VDC. It seems it is recommended and it will be cheaper than the mundorfs. But if you have almost no difference with mundorf supreme vs stock, then who knows hehe...

will i be able to fit the above mentioned soniccap's in the valab?

K

I guess I have to look at this closer. I agree about the dialectic. Bill's lucky to have you coaching him. Good call on the solid core.

What concerns me right now is the huge swing in discussion values of output caps. There's some that say 4.7uF should be enough. Other say go 33uF and higher. Today someone mentioned to me that Super E a pair of 33uF (which effectively gives you 66uF as I understand it) is ok.

In analog the size of the cap is quite important at output. I've never heard such swings even in the digital I"ve played with.

Krisno,

For me the added smoothness was worth the price of mundorfs, 55$ on sale from parts connection ...like tubes said there is no concrete answer for which type of caps to use

Z, I've been told by the MFR that the minimum value that should be used for the coupling cap is 4.7uf, anything lower will limit bass, at the top end you can go up to a 100uf cap. In the early Valab version they used a 50uf and now use a 10uf coupling cap. Don't know how you can such a large range, I guess as long as you have the minimum covered larger caps have no benefit?

Thanks Tubes. I guess this must be different in application because it doesn't work that way in analog. Too big and it slows the sound. There is usually a proper balance that allows the best reserve/headroom for bass along with a fast enough recycler so you have proper speed and attack.

I tried everything between 2.2uf and 100uf, the difference in bass was small, even 2.2uf (polypropylene) sounded fine.
For my taste these smaller polypropylenes like 2.2uf are a bit clinical, not very warm and I chose a standard 100uf/16V Black Gate, the sound is warmer then lower values like 10uf.
The sound is very smooth and warm but when I compare LP's with the CD version the CD is still brighter and the LP warmer.
I never found a small cap that really integrated, I also tried Obbligato.