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Valab NOS DAC - subjective listening and modifications

Mar 25, 2009 at 1:22 AM Post #106 of 2,013
In a lot of cases a larger value will help with delivering a better bottom end.
The only issue is with a larger cap, especially the Blackgates, you are going to run out of room to fit the bypass cap and close the lid as well.

You really do want to bypass that Electrolytic. I have used Blackgates at output but bypassing with a foil really opens things up, adds speed and dynamics. A .22uF cap will cut into the midrange nicely. The bottom will be delivered by the Electros. You can even add a higher value of .01uF to add air to the top. If you can fit a Teflon cap [they are large] in that spot you will get some sparkle and a lot more air on top.

But like Bill says, you gotta fool around with caps when bypassing. Like making soup. Gotta try different things till you find what you like. Usually you stumble upon it.

Quote:

Originally Posted by krisno /img/forum/go_quote.gif
Since noone answerd me I just orderd 2 x (CAP-9324) - 33uF 16V Black Gate N Type...... was this a big mistake?? Is the 4.7uf the one I should have got?? honestly guys, was this a waste??

Are they 'ok' for replacing those Titanium tantalums? I don't know what the heck are those output cap's. But by putting in those black gates will i remove the 'tubiness' of the DAC?

Bill.... you think all types works well? Well the guy said use soniccap + v-cap.

K


 
Mar 25, 2009 at 9:22 AM Post #107 of 2,013
I want to try that V-cap 4.7uf and sonicap platinums .22uf .. These will be big, so they have to be installed outside or in a different casing. BUT, I really don't know if the Valab is worth that kinda expensive output caps. its $200 the above mentioned stuff!

That PSU on the 2009 edition really is annoying me though. Humming like hell.

Do you have a link to the film you think I should bypass the 33uf with??

But last question, would a standard 10uf blackgate had been a better(and cheaper) choice than 33uf 16v Blackgate Non-polar?

I am afraid the warmth of the dac will be gone with blackgate vs titanium's.. aren't the titaniums 'film' or are they electrolytics?
 
Mar 25, 2009 at 6:46 PM Post #108 of 2,013
Krisno,

I don't think anyone on this forum is going to jump out on a limb and say what cap you should use. Truth be told the stock Russian KR53-14, tantulum or whatever there made out of, sounds quite good. I recommend you practice bypassing this cap first, you will be surprised by the results. Only with experience will you get meaningful results for "your" audio system.

Don't fret over your choice of the Blackgate 33uf's, they will work fine and will most likely sound warmer that than the Russians. However be prepared or a very long break-in time when using Black Gates. You have to have patience if you are going to start modding your gear.

I finished converting my Valab Dac to battery power and external mounting of the large Jupiter Caps last night. This may prove interesting to you.
 
Mar 25, 2009 at 7:03 PM Post #109 of 2,013
When you bypass something, what does actually happen? If I bypass those russian's with the black gates, do I get the sound of both? ...

by bypassing I just solder the legs of the blackgates onto the legs of the russian?

I saw some DIY'ers used teh 1543 chips and many used blackgate output caps.

The thing is that I have this x-can V2 headphone amp, and with this 2009 dac, it really is sharp and harsh in treble! I am not sure if is the amp or the DAC.

Maybe the black gates would fix this? Tubers are supposed be smooth, but I really find them sharper than solidstate. I also got this Burson HA100 discrete headphone amp, will try that on the 2009 dac before soldering on the blackgates.

using akg k 701 headphones btw..

K
 
Mar 25, 2009 at 7:21 PM Post #110 of 2,013
Quote:

Originally Posted by krisno /img/forum/go_quote.gif
The thing is that I have this x-can V2 headphone amp, and with this 2009 dac, it really is sharp and harsh in treble! I am not sure if is the amp or the DAC.


Hmmm, my experience with the Valab and other NOS DACs is the opposite of harsh treble. I find them to have a very laid back high end, to the point of missing some detail/sparkle.

Have you listened to the amp and phones with other sources without experiencing the harsh treble?
 
Mar 25, 2009 at 7:56 PM Post #111 of 2,013
I finished a major remodel of my Mod Dac last night and now its looks quite presentable. I found a nice little 5"X 3" metal box at Michaels craft store that was perfect for storing the large Jupiter Caps. I also added a DC power jack for supplying battery power to the Valab Dac.

274-1582 Coaxial DC Power Jack
274-1569 DC Power Plug (I make my own battery cables from solid 18 gauge wire)
278-1223 45 ft of Solid Core 18 Gauge Wire, in 3 colors.


Check this link for all the details. Scroll to the end for the DC Jack & Cap case mod. Captions at the bottom of page.

Picasa Web Albums - Bill - Valab DAC Mod
 
Mar 25, 2009 at 8:31 PM Post #113 of 2,013
According to the MFR. you can use up to a 100uf coupling cap, the larger the value cap the more bass will pass through. A 33uf cap is fine, just try it and see if you like it.

I tacked some .22uf Obligato film caps (Thanks Pat) onto the legs of the 10uf Kemet caps in my Teradak. Immediate results in the refinement department, smoother richer sound but less transparant and detailed so far. Hopefully with some break in it will open up.
 
Mar 25, 2009 at 11:12 PM Post #116 of 2,013
Z- the Obligatto's are a metalized poly film caps made by Brian Cherry in Hong Kong and are quite good for the price. There are now a premium version and a film/oil version.
Obbligato Copper Caps | Diy HiFi Supply

Gary you have a valid point on relocating the Jacks but in this situation you have to run the ground wires up toI will solder the wires directly to the Jupiter Caps with a pair of Silver Eichmann Bullet Plugs only on the Preamp end. Plan is to use the new single crystal silver wire from VH Audio.

VH Audio - Wire and Cable

For now I rewired the DAC back to its original configuration with the ferrite blocker filters and 47K idle resistors back in the circuit path. To be honest it's a bit thinner sounding, Humm? When I rewire with the VH Audio Wire I will once again eliminate these parts.
 
Mar 25, 2009 at 11:45 PM Post #117 of 2,013
Bill. Ground wires should have less effect on the signal than signal wires. Anyway, just one person's opinion. I'm just cautious to keep the concept. In these dacs and in chip amps some of big breakthroughs were in infinitesimal signal paths. Once we start elongating them back to old analog ways I think we lose what makes them sound exceptional.

Well unfortunately all the BG 10uF 50V N caps are now sold out at the source I told you about so I'm stuck looking for an equal or superior alternative that's both economical and fits the case.
 
Mar 26, 2009 at 12:01 AM Post #118 of 2,013
See that white thing?
dac_board_back.jpg


It is Bud Purvine's Litz wire attachment to the RCA ground and it adds a bit of focus in this application.

Quote:

Originally Posted by zzodhi /img/forum/go_quote.gif
Bill. Ground wires should have less effect on the signal than signal wires. Anyway, just one person's opinion. I'm just cautious to keep the concept. In these dacs and in chip amps some of big breakthroughs were in infinitesimal signal paths. Once we start elongating them back to old analog ways I think we lose what makes them sound exceptional.

Well unfortunately all the BG 10uF 50V N caps are now sold out at the source I told you about so I'm stuck looking for an equal or superior alternative that's both economical and fits the case.


 
Mar 26, 2009 at 3:16 PM Post #119 of 2,013
In Bill's link to the Obbligato's - what about this small 22uF film cap as an output cap replacement, without using a bypass cap? Seems like it would fit in the case.
Obbligato Film Cap 22uF 35v | Diy HiFi Supply

A general question about film caps:
What's the construction/performance differences between the large can film caps and the small rectangular film caps like what's in the link above or caps like Wima MKP4 types?

I have noticed that the large can film caps generally are rated for higher voltages.
 
Mar 26, 2009 at 4:12 PM Post #120 of 2,013
adam2434,

I do not think there is one answer to the performance question. Yuo have materials for dielectric that make a difference. Teflon, Paper in oil, bees wax. You have copper leads, tinned copper leads, steel leads. You have cans that will go to ground that need to be covered or kept away from other components.

And there is a bit of touchy feely to changing caps for taste.

A good thing is to get a few cheap caps like the Russian PIOs and Teflons and have a go at chaing them in and out to get and idea. More than a text answer you need "your own" hands-on experience to get real guidance.
 
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