Valab NOS DAC - subjective listening and modifications - Page 109

yeah I guess the thing that really tipped me against the PRP is the fact i'm primarily using headphones and extremely revealing headphones at that (JH13 customs) and for me the PRP (plus VCAP OIMP and mundorf SIO with Lisa III as amp) were just a touch grainy and bright for this combination and I found myself turning up the bass knob to offset it, the JH13 have enough bass as it is, so this was not preferable. perhaps I didnt give them enough time, but i'm perfectly happy with the texas parts anyway as IEMs (even customs) can use any help they can get with the soundstage department. oh and for those who were asking I have built up a couple of the SSR01 Jung regs, will post some pics if you like. i'm not using them in the valab, but they may be of interest to you regardless, as IMO I think they would be a very good choice for replacing the fairly ordinary IC regs that come stock. i'm just waiting on another voltage reference before i'm finished, as I built these for fairly low voltage and the BOM I ordered was not stable down to below 5V so just need to change out a couple of R's and add some red LEDs for VR1

Hello all ~
Last week a friend send me 2 Russian pio caps to try for the digital input cap , while i was modding them i saw this Mundrof silver oil 0.47uf sitting at the power filter by-pass doing nothing ( i using outboard power supply ) so i couldn't resit and give it a go for the digital input cap , straight from the 1574 output to the input solder pad .
And the out come was just wonderful i never knew so much had been lost before . So i guess if anyone got some nice film cap hanging around might give it a try : )

I can imagine that not every cap will perform well in the digital input circuit.....Given that the signal carries/is a high frequency block pattern the cap does imho not need sound great in the analog path but it should be true to the signal.

those are the two options I have in mind, perhaps silver mica performs well there too...

Hi Everyone,

after almost one year of reading, collecting and choosing the right part. I have settled on a new variant of the valab v2.1

I want to share with you the "achievement" if so can be called to have improved drastically the performance and quality of this little box which does sound fantastic IMHO.

the pictures will count a thousand words each but just to put it black on white the mods are the following:

changed the noisy crappy transformer for an AMVECO 62041 (wonderful!!!)
changed all the digitial caps with sanyo caps
changed all the DACs caps with BG FK
changed the power caps with BG FK
changed the diodes at the bottom
changed the output resistors with AudioNote
changed the putput RCA with WBT-0210

recabled output wire to sochets with HGC silver wire.

I think now the only thing left is to change output caps but to be honest , I am very happy with the way its sound and the BG still have broke in.

so thank you very much to all the forum

Nice job there JJLucas76!!! Well done.

jjlucas76, very impressive, and that transformer you found fits a treat!

My experiance with BG is give it min 600 hrs, then your in for a treat.

I dont myself like those AN as IV, I suggest when things of relaxed in, to experiment some more there, then again if its ok its ok.

Superb job!!

well done, now the thing is screaming its need for decent coupling caps at you ;-)

Seeing your toroid reminds me of a 12V AC toroid (rated at 6Amps) I have in the unused filament heater PSU of my DAC tube stage....I'll give it a try and connect it (once my deluxe arrives) to see give the R-Core transformer a run for its money as I'll be reconnecting it to the yellow 12V wire anyway.

Really should make a list, so many things to do yet no DAC to tinker with yet....

Thank you all, your judgement on this project is very important to me.

I think positive on the recommendations received to change the output caps and try something else in place of the AN resistor to balance the quality of all components.

My eyes are going for the following but I am not sure on the value of the caps:

resistor : Charcroft Z-Foil Resistors for Audio 330R or 390R????


CAPS: Jupiter HT Beeswax Paper Capacitors μF 0.047 ??????


Thank you again and keep up with all your mods you are doing on the dac,...
...IT IS WORTH IT !! :-)

BTW with the new toroidal transformer from amveco there is no noise or vibration or overheating. I think it is the best transformer I have ever used. I got to know this company by disassembling my RSA HR-2 headphone amp and I thought that if Ray used it why not give a try myself. DIGIKEY is the place where to get it from.

LL

with 390 you run the risk of clipping , so I'd go for 330 Ohm.
0.047 uF is going to be too little capacitance and bass delivery will suffer as the cap is not large enough to let through low frequencies.

In my previous DAC I had 8uF as coupling cap, whereas smaller sized caps would do OK the phase linerarity suffered audibly (appearing to create a larger soundstage which invariably was falling through as hyped the better the recording was).
Not sure about the Jupiter caps either, there probably are better caps to be had for a similar budget but the final choice is also depending on the rest of the setup.

(I dislike caps in the signal path so much that I use a high pass filter without a cap for the tweeter of my two way speaker)

jjlucas76, optimum for the iv according to Teradak is 340r, normaly this is hard to find, so 330r, standard, is the one that is usualy used, but the Texas are made to your spec, so 340r is no prob.

If you are going to go for them I urge you to go straight to Texas components and email them, its the cheapest way, very nice people.

Much cheaper to go for the older type 100v Jupiter, check Michael Percy. Some consider the older type better, I haven't heard any types so can't comment but there you go.

Around 2uf is the min for me with output/input caps.

But any film type cap will blow away those stock caps.

You could also try Blackgate nx hq in super e cap conf, very cheap, Im playing with some at the moment as the output caps from my Valab.

Has anyone used the HiFace M2Tech with their VALAB DAC? What were the results? I have been reading lots of great things about this device and wonder how this improves the VALAB's already low jitter (with DIR9001 mod) response.

Concerning the BG NX HQ in the output stage...I used them, not in super e config, just one for each channel. They sound great. Recommended and a "real estate" and $$$ saver over comparable film caps.

Also...the distortion I was hearing was do to a bad power switch on my vintage tube amp. Once I disconnected it, the VALAB sounds awesome.