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Valab NOS DAC - subjective listening and modifications - Page 3

post #31 of 2010
Hi Tubes

OK i will put in the 33/16 tonight and see hows it goes .
post #32 of 2010
Quote:
Originally Posted by tubes View Post
Adriaan, have you tried any film caps?
Yes, I did, mainly on valve microphones including some exotic and expensive polypropylenes.
For me a well chosen straight Black Gate still is the best compromise, the higher capacity polypropylenes are either to big and still need a small film cap for clarity and the smaller models have a tendency to sound too analytical,
although I admit I only listened to a few of them.
The Valab 2009 plus Black Gate 10Mf/16V sounds very relaxed and balanced, a little bit to warm perhaps but very pleasantly so.
Violins sound very natural, piano (Take Five, Dave Brubeck), vibraharp (Modern Jazz Quartet, Pyramid) sound breathtaking, what more can you ask for $180 free shipping?
post #33 of 2010
Quote:
Originally Posted by adriaan243 View Post
- I tried the BG N but I did not like them, I prefer the standard BG's,
the sound is clean and quite warm, not overbright (I measured the frequency response: -0.5db 10khz and -1.2db 20khz)
That is very interesting that you only measured -1.2 dB at 20 kHz. Everything I’ve read indicates a 3 dB reduction at 20 kHz for NOS DACs due to the “sin(x)/x rolloff” phenomenon. I wonder why/how the Valab is different in that regard.

Did you happen to measure freq response before any mods?
post #34 of 2010
Quote:
Originally Posted by adam2434 View Post
That is very interesting that you only measured -1.2 dB at 20 kHz. Everything I’ve read indicates a 3 dB reduction at 20 kHz for NOS DACs due to the “sin(x)/x rolloff” phenomenon. I wonder why/how the Valab is different in that regard.

Did you happen to measure freq response before any mods?
A "normal" DAC I tested was ruler flat, I have no idea why the VALAB seems to be better, could it be the use of 8 DAC's?
I am quite sure the measurement was correct and to make certain I used this "normal" DAC as a reference.
A different output capacitor has no influence at all.
post #35 of 2010
I think that confirms the fact you can't go by measurements alone, I go by what my ears tell me.
post #36 of 2010

Oh Baby Thats Good!

Well I finally got around to doing the first Mod on the Cyro'd Control Dac.

First thing I did was put the C-Dac back in the system and took a serious listen to Mahler's 2nd Symphony. Understand this is one of my most difficult recording for me to enjoy with digital audio, a real litmus test. Well.... while it sounded good I have to admit I wouldn't want to listen to the whole piece. Mind you my Mod Dac churns through this piece all while toasting and buttering your bagel.

Off to the solder bench to put in the 220uf Blackgate NX. Removing the 8 screws on the front/back, the 3 screws holding down the Dac board & soldering in the new BG took me all of 10 minutes.

Picasa Web Albums - Bill - Valab Control

Check out all three pictures, captions at the bottom.

I left out 2 of the 3 Dac chip board mounting screws to allow outside air in the case. The Dac chips rest securely against the lower case with only one screw. I also drilled 3 holes on the top cover to let the hear out. One above the regulator and 2 above the main transformer. Heat flows out like a chimney.

Back in the system 30 minutes later, the C-Dac hit the road running. Exactly what I hoped would happen, nice drive and dynamic's. Right up there with the Mod Dac. This is a pretty drastic change to the Valab Dac ... in the right direction. I would highly recommend adding the 220uf Black Gate FK in this position. (Your milage may vary with other types/brands)

While Mahler with the C-Dac is still a bit raw for my taste the Valoomph is now there. What I am saying is the C-Dac lacks the ultimate relaxation that the Mod Dac oozes. Understand that these BG caps take 30 days to fully mature.

Next up are the coupling caps and I/V resistors.

Stay tuned.
post #37 of 2010

Heat

From the beginning I have used my 2009 Valab upside down and I have put thermal compound on the TDA1534's.
Upside down it dissipates heat much better, it only gets warm,never hot.
post #38 of 2010
Quote:
Originally Posted by Bill Allen View Post
Well I finally got around to doing the first Mod on the Cyro'd Control Dac.

First thing I did was put the C-Dac back in the system and took a serious listen to Mahler's 2nd Symphony. Understand this is one of my most difficult recording for me to enjoy with digital audio, a real litmus test. Well.... while it sounded good I have to admit I wouldn't want to listen to the whole piece. Mind you my Mod Dac churns through this piece all while toasting and buttering your bagel.
The only Mahler 2 I could find in my collection is Deutsche Grammophon/Abbado/Chicago Symphony/1977 analogue recording and the sound is excellent.
I am curious which version you were listening to.
post #39 of 2010
Quote:
Originally Posted by Bill Allen View Post
Well I finally got around to doing the first Mod on the Cyro'd Control Dac.

Off to the solder bench to put in the 220uf Blackgate NX. Removing the 8 screws on the front/back, the 3 screws holding down the Dac board & soldering in the new BG took me all of 10 minutes.
Stupid question perhaps: Why did you replace a 330uf Nichicon by a 220uf Black Gate FK?
post #40 of 2010
Deleted.
post #41 of 2010
not needed any more
post #42 of 2010
Adriaan, I think it was a 47uf Bill replaced with a 220uf.
post #43 of 2010

Mistake?

Quote:
Originally Posted by tubes View Post
Adriaan, I think it was a 47uf Bill replaced with a 220uf.
I think Bill made a mistake, on the board they call these capacitors 47uf, but I am quite sure Bill has the same capacitors I have on my 2009 Valab: LG330 C,
which means Nichicon LG 16Volt.
Maybe the Black Gate sounds better, but he picked a lower value.
post #44 of 2010
Did the super e last night ran the dac over night have listen just now and dont like it , so out the n33uf and put in the n 1uf in e setup sounded better now , i gonna let it run for some more hours ..
post #45 of 2010

Getting it Right!

Adriaan- Amazon.com: Gilbert Kaplan Mahler: Symphony No. 2 "Resurrection": Gustav Mahler, Gilbert Kaplan, John Hugh Thomas, London Symphony Orchestra, The Ardwin Singers, BBC Welsh Chorus, Cardiff Polyphonic Choir, The Dyfed Choir, Benita Valente, Maureen For
Mahlers 2nd is tough to listen to no matter who recorded it. This version gets to the heart of a 29 year old obsessed German composer in the throws of figuring out what life is all about. Most versions are prettifed, totally missing the point. All great music, pop to classic, must reflect the tone and temper of the time. Get this recording right and your system is "on song"!

You are correct these caps are 330uf.

http://www.nichicon.co.jp/english/pr...f/e-con_lg.pdf

I assumed the board was correct and never looked up the values. Kevin state they are 470uf Nippon caps on the Ebay add, I assumed that was a typo and they where 47uf. Humm. Well obviously the 47uf Blackgate FK's work fine in all the decoupling applications on the chipset board in my Mod Dac. I can tell you any bigger than 47uf 16v and the FK's would not fit on the board. (In the future I will install the original caps 8 chipset caps and see if anything changes.Plan is to salvage these caps for the C-Dac Chips)

The voltage for the chipsets is regulated down to 5V with the LM317T and futher reduced to 3.3 volts with two smaller surface mount regulators. Older Chipsets/Dac's ran on 5V while the newer Chipsets/Dac's on 3.3V. We are dealing with a mixed ship here. Point being, I can't imagine with this low of voltage/current they found the need for such high value decoupling caps. Maybe they had a surplus of them. Maybe these LG caps Kung Fu is weak requiring a larger value, who knows!

Fact is the 220uf Blackgate FK for decoupling the LM084CT regulator has just the right Kung Fu kick. The LM084 is set to output 7.8 volts directly to the Dac chips. This is the current that ultimately creates the analog output voltage and is very crucial. Simply sticking another one of those tiny OS-Can caps in this positions is a mistake. You need a big "fast" reservoir here. The nice thing is there is plenty of room to plug in bigger caps here.

Besides the Cryo Dip and 600 hours of break in, nothing was done to the C-Dac. Adding just this cap drastically changed the dynamic landscape of the Valab Dac. Putting a 1000uf BG FK maybe overkill at this postion... maybe not! However replacing the three 1000uf filter caps upstream with the 1000uf BG FK's will further the dynamic cause. These 4 caps plus the 8 on the Dac Chips are what create the overall drive of the analog output section. Careful filtering, matching and balancing of this power supply path is of the utmost concern. You want Kaplan's Mahler to sound right, then this is the path.

With a Dac as simple as the Valab everything matters. My next change to the Mod Dac will be hooking up a car battery in place of the AC power tranformer. Believe it or not every battery sounds different. I hear the best are the new fiberglass gell cells. Myself I really dislike the fact that that AC transformer is buzzing away on my finely tuned board. Maybe it's no big deal. Time will tell.

Sorry this is the version of Mahler's 2nd I actually own.
http://www.amazon.com/Mahler-Symphon.../dp/B00009Y30W
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