Valab Dac-First Impressions - Page 50

filter noise

Right Phill,

I have been reading about noise trimming. Again, if you have better coupling caps you should have less noise? No, yes, who knows? I know that many shun the ferrite; if anything that should go but the Cambridge 640p has them input. This stuff is voodoo.

But removing them will present a different load to the DACs so shouldn't the output resistors go higher to 600ohms?

It's wild to read back on the build history of this DAC. We are the pilot group! I wonder if Kevin watches this thread.

Yahh, that's true and we set multiple links on other qualified forums in Europe to our discussion, hope it spreads even more out because this little thing is really well done!
Pat, a question - even if it's an off topic here - is it easy to remove the shell of the Denon 103 cartridge without damaging to the cantilever? I got the link of Thomas Schick from Germany with the instructions but dunno if it's full of risks?
Thanks,
Ciao from Rome,
Hist.

risky business

There is risk.
Remember to rock the body up and off, back up, using the front area as if there was hinge there. You want to make sure the body rocks up and away from the cantilever. -go slow- is the best advice. Move the body a little bit, have a look at where it is going. It will become apparent. Make a wrong move, though ...

You can do it.

Valab 2009 Circuit Board Pictures

My friend Tony received his 2009 Valab Dac last Thursday. He reports it beat his current Dac right out of the gate. He initially had pops and clicks but they quit around 60 hours. He is rolling through 100 hours with no change in sound. I asked him to report back at the 180 hour mark.

My new Dac's are still stuck in customs in Los Angeles.

Here are pictures of the 2009 Circuit Board from Tony. Thanks Tony!

Attachment 13633

Notice how short the analog signal patch is now, this should "really" improve the sound. The I/V resistors are located right next to the mica coupling caps. The I/V's are the blue resistors, swapping them out with 400 ohm Caddock USF340 should sharpen things up a bit. Not to mention soldering in a nice pair of Jupiter coupling caps. All good things to those who wait!

Attachment 13634

Notice how the ouput/dac chip board is cutout in the center. This allows the board to float so 3 screws can hold the Dac Chips against the case for cooling. Tony reports the Dac is only warm to the touch.......... Cool!

I hope so, i've been waiting a month to get mine... /sigh

who can keep up?

The analog path _is_ short. You have to wonder how good can it get?


There is a blue cap along the DACs. Is that for trimming as well? What value is it? And can you tell what the value of the surface mounted resistors are in the analog output neighborhood?

I can not figure out how a 47k(I followed them, they are in the path, the trace goes under the board), 390, and a series of 2 caps at 526ohms add up to 590.

EDIT: Ha. I think I got it.
There are 3 22R in paralle making 7.5, then a variable 194 resistor then out to two 390 resistors. So 7.5 + 194 + 390 = 591.50. Damn.

Having all this junk in the analog output area does make it easier to figure out vs the older boards. Hard to believe they can tighten that board anymore.

Here are the pictures that show the resistors:

Pat,

when I finally get the new Dac board in my I hand I will try and sort out what is really going on with this simple circuit.

The old circuit board was a work in progress which made it hard to follow the logic.

I just checked EMS tracking and it looks my Dac's have cleared customs. Maybe tomorrow.

Thanks for all your effort Pat, Phill, Bill and all others try to make this DAC sounds better.

I have my 2009 version and burning in from 21 Jan til now non stop. I make some changes, replaced 3 powering/ filtering caps from Rubycon 1000uf/35V to BG's FK 1000uf/16V, LM 317T to LT 317A, 2 resistors (100r/ 5210r) next to the LT 317A to Holco, 2 340r resistors to Holco lying under the output metal caps, but thinking this will be change to Holco 390r because I measures the original value should be 390r. Does anyone know the RMG resistor is sound better than Holco? I would give a try with RMG in the two output 390r resistors later this week.
http://picasaweb.google.com/dannie01...80484620478626

BiG caps

dannie01,

The Blackgates are big. Nice way to fit.
Notice a difference?

Tubes set me on this DAC - is it up for sale yet? I'm tempted to pick one up pretty soon if it is!

Bill are we talking night and day difference between these dacs(I have the late Dec 2008 version)or are the differences subtle?Regards,Paul from the Prescott area remember me??

Hi Pat,

Tha's the way I now use to place the BG but I can tell you the headroom of the Valab is really tight and I can't even close the lid that with only thin cables pass over the transformer, so I let the lid open and I will rewire the cable from both sides of the transformer and the heatshink.

It's too early to say how the Valab sound with the BG FK since there are only about 100hrs for the burn in. But for the soung sig I can hear a powerful in mid to lower bass than the Rubycon but a bit less in highs, I don't know if this is a matter of the different value resistor of the output stage I changed. I will try out to put the RMG 390r to replace the Holco 340r to see if there are any changes.