[zzodhi]

Will do.

As we talked privately I spent the last 5 years chasing battery supply. At one point I had the lowest ESR SLA batteries in my home brew dac. One for each supply which worked out to three.

Seductively quiet, black as midnite. Just didn't have the drive. Reluctantly I pulled the batteries out and went to three separate supplies filtered as best as possible.

There's been endless discussions on this and the first reaction is to up the capacitance. This has rarely worked. It was recommended that Super cells or Super caps like those developed for electric cars may do the trick. I have never gotten my hands on any.

Really would love you to crack it.

 

[adam2434]

Completed the following mods tonight.

Caddock MK-132 IV resistors
Black Gate N 33 uF output caps
Mundorf ZN 0.1 uF bypass output caps

Got the parts from partsconnexion.com and had each set matched to 1%.

Wow, that was probably one of the most tedious things I've ever done! Drinkin' a beer to relax. Pinetop Perkins is playing right now, so it was a success from an execution standpoint. Have to say that for a first-timer, just having it work gives a sense of accomplishment and satisfaction. I've been wanting to learn how to solder and do component mods, crossover rebuilds, etc. - so this was a great learning experience.

Soldering to the existing leads was challenging. The exposed stock resistor leads were maybe 2 mm. Finessing and keeping the parts in place was a challenge and took a lot of lead manipulation to get it right. The Mundorfs just barely fit in the case. I have to think other component swaps or crossover work will be a breeze compared to this.

I'll reserve judgment on sound until after a couple days of burn-in.

Attached a couple pics. The "after" pic didn't turn out as good as I hoped, but you get the idea.

Thanks to all who provided input and guidance.

Adam

 

[PianoForte]

Quote:

Originally Posted by r8833 /img/forum/go_quote.gif My three sons all three dacs modded with rubycon ZA caps, 390ohm caddocks I/V and panasonic FM for power filtering DAC1 - Mundorf supreme 4.7 uf and .22uf Silver and oil bypass TeraDak - Obilgatto 4.7 and .22 Vacuum tube valley PIO Dac3 Obilgatto 4.7uf [/IMG] Rich

So, I guess Kevin, the manufacturer is the mother?

 

[r8833]

michael from teradak is the mother..kevin runs the adoption agency

 

[rhodes54]

@ PatOMalley: In the other (huge) topic of the Valab DAC you wrote that you changed the BYT52 diodes for Schottky 11DQ10. Is there a specific reason that you chose these type of diodes? As far as I could find they are not 'Fast Recovery' diodes and isn't this what you would like to have in a DAC?

I'm testing with 2x 6,8uF Mundorf Silver/Gold with 0,22 Mundorf Silver/Gold on the output stage right now. Directly after the swap the difference was huge. Still burning in though. So far so good.
I will post a more detailed description soon.

 

[PatOMalley]

rhodes54,

I had swapped them into my Cambridge 640p and it made a small improvement. I naievely used an assoretment of posaitive posts about them to justify it. I do think they made a small improvement in the DAC but I cannot now remember the nature of it. At any rate I perceived no negatives after the swap.

The more I think about it the more I remember all the power supply mods gave a bit of an increase in focus for each one.

But, like you, the output caps were a big change for the better.

 

[Pars]

Quote:

Originally Posted by rhodes54 /img/forum/go_quote.gif @ PatOMalley: In the other (huge) topic of the Valab DAC you wrote that you changed the BYT52 diodes for Schottky 11DQ10. Is there a specific reason that you chose these type of diodes? As far as I could find they are not 'Fast Recovery' diodes and isn't this what you would like to have in a DAC? <snip>

It's actually soft recovery that you are looking for. The idea is to suppress the switching transients of normal diodes, which create noise on the DC. Schottky diodes such as the 11DQ10, 31DQ10, etc. are ideal for this. The other commonly used diode type is known as a FRED, although ultrafast diodes are also used, but these will typically require snubbers to filter the noise out. See this post, as well as search here or diyaudio, etc. for more info:
http://www.head-fi.org/forums/616204-post22.html

 

[PatOMalley]

When I first fired up the VALAB I preferred the Toslink then got a small improvement with glass Toslink. The coax was dull sounding in comparison, at that time. Just plugged in my vbH D - 300 III HYBRID carbon type cable and I like it better. Softer with drama on the vdH coax vs clarity and dynamics on the glass Toslink.

So, maybe it took the whatever to burnin for the SP/DIF coax.

Has anyone does a few comparisons and/or what coax do you like?

 

[krisno]

Hi guys..

I have my 2009 Valab solderd up with Obbligato 4.7uf output caps. The sound is alot better, but really, the highs are a bit harsh. Some suggest a bypass.

1) Which will give the nicest treble(or best combo overall). Obbligato 4.7uf bypassed with Mundorf Supreme .22 OR Hificolletive's AmpOhm aluminium Paper in Oil .22uf ?? Price is the same. Will it help on the treble?

2) How many of you have bypassed the 47kohm resistors and solderd output lead's from the caps straight onto the RCA's?

Thanks in advance

Kris

.... QUESTION IS REALLY: How will a AmpOhm alu paper in oil .22uf bypass on my 4.7uf obbligato impact the sound ?? ?? anyone?

 

[Newk Yuler]

Why not an Obbligato .22uf bridge?

I'm curious about 'rolling' caps to see what happens (aside from the long burn-in times of each roll). I know many of the Valab owners here try different combinations that practically equates to rolling caps.

If caps are installed with intent to roll, is there a reason caps installed as a bridge can't be placed with solid copper mini alligator clips?

-Rand


Quote:

Originally Posted by krisno /img/forum/go_quote.gif Hi guys.. I have my 2009 Valab solderd up with Obbligato 4.7uf output caps. The sound is alot better, but really, the highs are a bit harsh. Some suggest a bypass. 1) Which will give the nicest treble(or best combo overall). Obbligato 4.7uf bypassed with Mundorf Supreme .22 OR Hificolletive's AmpOhm aluminium Paper in Oil .22uf ?? Price is the same. Will it help on the treble? 2) How many of you have bypassed the 47kohm resistors and solderd output lead's from the caps straight onto the RCA's? Thanks in advance Kris .... QUESTION IS REALLY: How will a AmpOhm alu paper in oil .22uf bypass on my 4.7uf obbligato impact the sound ?? ?? anyone?

 

[woolybugger]

Has anybody considered replacing the clock? I've been e-mailing w/somebody that does mods for a living and this was one of the initial suggestions he had outside of the power supply modifications. Just curious what others thought.

 

[dubai2000]

I am new to this forum and the Valab DAC, but after some modding I am getting the best digital sound I've ever had

.

To put this statement into perspective I should add that my setup consists of modded Khorns, a German preamp produced by FUNK, a Behringer DEQ 1496 and as power amp a modded TA2020 design.
Until recently my digital player was either a modded Philps CD104 or a Nakamichi CDP-2E (also modded according Lampizator). I am also familiar with Wadia and Einstein CDPs (though not in my rig) and the German DAC ADI-2 by RME.

All those pieces of equipment the Valab can easily compete with and surpass in lack of any digital fatigue (of course IMO and YMMV).

So what have I done to the DAC?

First two steps were replacing the stock resitors next to the output caps with 330R carbon resistors (nothing fancy - just something from a local electronic shop) and using 5µF Siemens MKV ( a kind of PIO) as output caps. Immediate result: more warmth - in stock form the unit sounded sterile.

Next step: adding 0.1µF Siemens KP to the small 8 smt caps next to the DAC chips. Result: more body to the tone - more 'colours'.

Now the Valab was a good unit - slightly better than my favourite so far: the Nakamichi (without tube output - for those family with the Lampizator's work).

But yesterday I received some more caps: I am not too fond of BG - only rarely do I find them musical and only in certain positions of various amps. Thus I did not follow the suggestions posted here regarding BGs

.

Anyway, my small envelope contained some Panasonic FM caps. I replaced the three 1000µF caps near the power transformer and the one 330µF next to the big heatsink with a 470µF FM. Additionally I bypassed the three 1000µFs with some small Wima MKP10 caps that just fitted under the board and the 470µF with a small Ero KP cap.

Finally I bypassed the MKVs with some K72 Russion Teflon caps (value 0.054 - I think).

Source for playback is an XP-based laptop, foobar 2000 with SRC and Ploytec USB Asio driver....I also configured the computer so that the USB output does not run through XP's mixer (no clue if that was necessary as I am using Asio anyway)

When I put one some very difficult recordings such as solo violin I encountered for the first time a sound devoid of any harshness. Believe me, I know the recording in question very well and listed to it in many different homes and shops but never had I experienced it in the way I do with the modded Valab. So thanks to all the posters who had given me ideas what to do to this DAC. To my ears it was worth the soldering and so far I am a happy camper....even though there might be even better ways to configure my laptop. But that is a field I still find puzzling.....

Thanks for your patience in reading all this....hope you find it useful.

Wolfram

 

[krisno]

How does bypassing output caps really work? Do you get all the sound of the 4.7uf obbligato's + the sound of for instance the ampohm .22uf which you use for bypassing??

OR does the .22 bypass change the whole overall sound so that the 'high's get replaced by the highs created by the Ampohm cap and only that??

As far as I understand bypass, it can create alot of problems, and in general you should use it to 'add' coloration/sound/space/treble, not to try to correct a too harsh treble which is allready there?? A bypass won't remove sound, just add?

What is correct answer??

Big thanks...

K

 

[rhodes54]

Here's an update of my Valab DAC.
I returned the 6,8 uF Mundorf Silver/Gold, which I had on loan, and bought 4,7uF Mundorf Silver/Gold in return. For now I bypassed them with 0,22 uF Mundorf Silver/Gold and 0,01uF MKP1837's to extend the top end a bit. As both the DAC and caps are getting burned in more and more I notice that I need the MKP1837's less every day. I guess soon there's no need for them anymore.
There is a small difference in sound noticable between the 6,8uF and 4,7uF Caps. The lower value seem to give slightly more details and reduced the bass a bit, making it less 'boomy'.

Comparing the orinal DAC with the Mundorf mod the soundstage has become HUGE. This is why I love the Mundorf Silver/Golds and Silver/Gold/Oils so much: They are the king of soundstage and are able to presents micro details I never heard before. There is by the way quite a difference in sound between the Mundorf M-Cap Supreme, Silver/Oil on one hand and the Silver/Gold, Silver/Gold/Oil on the other hand. The first ones are much warmer, less detailed and sound more analog than the Silver/Gold(Oils). These are quite analytical, neutral and open, which I love.

With only this caps mod it easily beats my heavy modded Benchmark DAC-1 (with Power Supply Upgrade, Tentlabs XO 2.2 clock, BB OPA 627 opamp upgrade, DC Servo Output and several bypass caps). Except for the bass, the benchmark is still the winner here. But I expect the bass to become better as soon as the other mods are done.

Right now the following mods are waiting:
- Power supply upgrade. A 30VA toroidial transformer will come in place of the humming original one. I know that 30VA is way too much but this way I am trying to reduce heat in the case.
- Caps Mod: The power supply will be updated according to Bill's mod: 3x 1000uF BG FK's, 1x 220uF BG FK and 8x 47uF BG FK's for decoupling of the DAC chips. 8 Sanyo Os-Cons SP (low ESR) 100uF/20V will replace the caps in the digital circuit.
- 4 Vishay 11DQ10 Schottky Diodes will replace the original ones on the board.
- The LT1084 will be replaced by the DEXA 7808 to reduce noise generated by the LT1084 (Attention: This requires rewiring of the DEXA as the pin-out is different).
- The 330R resistors of the I/V stage will be replaced by 340R 0,1% metal films for now. (might need to experiment more with different type of resistors)
- The Coax/Optical switch will we replaced by a relay so I can switch it from the front without extending the digital signal line all the way through the case.
- Last but not least I bought a nice Galaxy Maggiorato case at HIFI2000.it where the Valab will find its new home because the Caps & Transformer ain't gonna fit. Besides that I want to get rid of the cheapo look of the original Valab case. The Hifi2000 cases aren't expensive, have a good buildquality and look very nice.

 

[krisno]

Hificollective was all out of AmpOhm 0.22 Alu Paper in Oil. I could have gone for a .47 or something, but I went for the 0.22 AmpOhm paper in wax. Dunno if it will make much difference.

The wax is maybe the least 'spacious' of them all, but 0.22 might be more spacious than the 4.7uf obbligato. I was told the wax was a bit more musical. The NOS dac's has a rolloff anyways so I probably won't hear much highs even what cap I use. Maybe it will roll 'out' the sharpness in the DAC.

Interesting if your modded VALAB is better than your Benchmark. Is that running via USB also???

Don't mod it too much , little to gain, and alot of money?..!