Valab NOS DAC - subjective listening and modifications - Page 101

Good point.

It's a long story but the coax out of my device finds its source out of the optical out on the back of the MacMini. OK, jitternauts attack.
Yes, it is not ideal but it is what I am working with as the manufacturer of the device employs me (for testing purposes) and it is part of a much larger Automation system with a built-in music server, etc...

So, I don't know if I would install another LL1572 at the source end, but certainly something to consider such as using it inside a USB to coax device.

can you explain then what the benefit would be in that situation? what are you protecting from jitter in the case of a transformer at both ends; the coax cable? if you have a transformer inside the dac to convert to 75R (or 110R, whatever the termination resistors are) then thats that dealt with.

oh and yeah I knew something was up ;D

I see your point. No argument here.

Thank you for the complement. I try very hard to make sure every component is as nicely placed as it can. Of course, I have more real estate as I have used BG's instead of film caps for the output caps. In fact, I believe I am the only one who has used BG's in that location.

The transformer is certainly highly recommended. I will know more after this evening's listening session while I play with my kids before they go to bed.

BTW, where has Bill Allen gone? Moved on to another project? You seem to be the only one hanging on since the beginning. In fact, I just realized you are the guy who started all this.

yes this is my preamp, the 0.1uf caps are in the path of the input signal, do not look at V1 and V2, they are in the phono section, look at V3 and C6 coming off of R19

Ah yes the one on the 250k pot, perhaps that accounts for the high impedance.

Fair question, all I know is I tried a pulse at both ends and it sounded more balanced, but.... I will try at just the dac end again. Hope its not necessary for 2 because I want to try that Lundahl, and there not very cheap. Trouble is I've got caps burning in all over the place so will wait.

Can anyone tell me, is the luxury version worth the price difference? Has anyone compared the two? Anyone tried Valab toslink cable? Thanks in advance

i've heard both, i'd say it's worth the small difference. But if i was buying new right now, i'd be looking into the Chameleon Dac.

Does anyone know where I can get 340R TX2575 resistors online?

edit:never mind..... i found em

I put my order in for Chameleon combo tonight, what are the plans to mod this dac? It already has an input transformer right? Is the digital input chip superior to the old dir9001, what about the usb input chip? I don't know much about these new parts.

I plan to drop a couple ~3.3 UF Mundorf Silver in Oil's in there with some of those nice TX resistors, and maybe bypass output with sonicap plat's, down the road.

Id love to hear that combo MikeW, nice.

Similair combo recomended by Steve Nugent, on an Audiophile thread recommends 3.3uf V-Cap oils bypassed with .22uf Sonicap Platinums.

I will prob go for something similair, but first I will try blackgate nxhiq in super e configuration, for the hell of it, as I am very impressed with my recent bg fk upgrade to my amp.

But first I want to investigate the impedance balance in my system, qusp and errnst, have got me thinking there might be a prob here. I see that pat is getting good results from just 1uf caps, I cant get the same result, I need at least 3uf or I get rolloff, the sound thins out in the mids, despite the fact I am using a Yaguin, buffer, which helps a lot, but is not a cure.

Im going to start by switching my 50k pot with 100k, Dact type, in my amp.

If I can get the impedance right, if there is a prob, then lower value caps=lower price, and should sound better anyway.

someone cares to share a source for the TX2575 ?

I'm afraid I'll be needing some soon and can't find them anywhere (pref a source from the EU).

(just pulled the trigger on the lux version Valab and am in the process of gathering my mod components)

I've been following this thread for a while now, guess I'll be posting some more soon.

for sure mikeW go for it, sound like a nice combo, though in all honesty I would probably just leave the sonicaps out and stick with the SIO. the SIO are an incredibly fast and pure sounding caps, with that awesome Mundorf magic soundstage and effortless detail. I see no reason to add more caps for the sake of it. even in the case of VCAP OIMP they are not as fast as the teflons being a poly caps rather than foil, so can use the bypass, my experiences with SIO are they work better without a bypass. but go right ahead I can almost guarantee you will stick with the mundorf. they do take a little to hit full stride though so give them some time.

the new spdif reciever is a very good chip, same as in my mux in the buffalo32 and many top dacs, not much to improve on there IMO. what USB chip they using in there? there really isnt that much to choose from with USB->spdif chips of decent quality

look forward to your results.

wood, not sure what output impedance you are getting with the valab, but with a general calc I use (in excel) for figuring out cap sizes to avoid rolloff/intermodulation using 1uf and a 50K pot I get this

F = 1/(2 * pi * C * R)
F = 1/(2 * pi * 0.000003300 * 25000)
F = 1/(2 * pi * 0.08)
F = 1/(0.52)
F = 1.93 Hz

ENTER AMP INPUT IMP IN K =50
ENTER CAPS in uF =1
CORNER FREQ =3.183098865
PHASE DISTORTION UP TO IN HZ =31.83098865< SHOULD BE BELOW 20

FORMULA
PI =3.14159265
CAPS FORMULA0.000001
INPUT IMP FORMULA50000
WORKING0.05
WORKING0.314159265
WORKING3.183098865

and for 100K


ENTER AMP INPUT IMP IN K =100
ENTER CAPS in uF =1
CORNER FREQ =1.591549433
PHASE DISTORTION UP TO IN HZ =15.91549433< SHOULD BE BELOW 20

F = 1.93 Hz
PI =3.14159265
CAPS FORMULA0.000001
INPUT IMP FORMULA100000
WORKING0.1
WORKING0.62831853
WORKING1.591549433

so with 100K you're safe, but its always better to use lower pot if possible, so there's a trade off there, lower pots tend to be more linear.

cheers