Valab NOS DAC - subjective listening and modifications - Page 104

oh ok, so you just want to do the 1 voltage? thats easier then and 7.4 should be fine. I used 7.75

my plan is to use battery power where sound would benefit most.
If the voltage is impacting the soundstage the nominal voltage of 7.4 might be a tad low for extended listening at best quality.....
Those babies appear to have a slightly higher voltage when fully charged, to drop to the nominal voltage after a small discharge to maintain that voltage for long period until almost empty.

we'll see, could always use a 11V lipo with a voltage regulator....

when I said big money i was specifically refering to 150$-200$ Optima Red Top Batteries

that would be Le Monstre material :-)
one of the best sounding non tube Amps IMHO, measly 8W/ch but you can spot weld with the PSU.

indeed you could......

though depending on the reg you use you might want to allow for a larger voltage drop than that

ah well but the AT version of the LM 317 would only require something like 1 Volt to work with (off the top of my head)

Regulated PSU design is not really my thing, so far I've mostly used full wave double phase tube rectification for HT in tube amps using several RCL stages and unregulated AC for the heaters.
My work on the PSU in my DAC mainly consisted from upgrading components and upping and bypassing the Capacitance of buffers present so I am happy for any input when the time comes ....fingers crossed Air China does not crash with my DAC on board;-) then burn in and then the games can start.

yeah sure, IC based regs you would get away with it; but while the 317 is OK, if you gonna upgrade the power supply I would definitely choose something different otherwise it will be the bottleneck. I know bugger-all about tubes, so yo got me there. was interested in tube buffer (DIY not ebay kit) for my dac for a while, never got around to it because i'll just build a tube amp if I want that. I would rather have the dac be as high resolition/low distortion as possible and add any extra flavor afterwards. that way I can choose if/when its in the signal path. in general i'm definitely a discrete SS guy, but I do like transformer coupling with some of the newer lower distortion units from lundahl

yeah you are right there, 317 is no current beast.....and I's rather do without any unncessary chips feeding the precious source signal.

My belief is that tubes do/should not add any flavour, anyone looking for that should buy a DSP imho ;-)
I am looking for the most natural sound, getting as close as possible to the 'live' experience, which for me works best following the less is more path.....so a 6V6 tube amp delivering a whopping 0.8 watt/ch using a 12SN7 gain stage fed by a 600VA tranny rectified by 6x4 in a fullwave double phase setup, lots of hardware and definitely not the greenest of amps, but as little in the signal path as possible :-)

Think I'll end up with something like a nickel core transformer coupled digital path, we'll see....

Ok i finally made some intensive tests with the Duelund CAST PIO.

Those really are incredible caps, maybe not perfect but damn near.

The improvements are very easy to hear on the Valab when i used it on my main system but with my second system in my office the Duelund are clearly overkill, it's better than other caps but not enough to justify the price.

I think the modded Valab with Duelund caps could be a giant killer but unfortunately in my main system the balance of the "stock" ModWright Transporter was much better so it was difficult to compare.
I use some RCA VT231 output tubes on the ModWright, they are more warm than neutral and match my taste very well.
My main system :
Horning Agathon Ultimate (the best speakers i heard so far, on the paper they can't sound right but in the real world...wow).
ModWright KWA150 amp (bettered tons of things i tried from Halcro, Vitus, Pass...)
ModWright Transporter modded with Texas resistors
Acrolink S10000 speaker cables and Harmonic Tech Photon interconnects.

My office system :
MHI Evidence speakers with TBI subwoofer (both are just great too)
Stello HP100 / S100 combo
Audience Au24 cables

I ended putting the Duelund in the MW Transporter : i could not be more happy with my system.
The modded Valab went back in my office, i put the ModWright caps i removed from my Transporter there and the result is very very good too. The ModWright caps should be considered seriously, compared to the Duelund it's just a bit more closed, a bit less refined and the bass is less extended (well only if you have a system that goes really low) BUT overall the performances are just great and the price is great too.
I also have tried some Clarity caps : very good but the ModWright caps are better, more spatial, resolving and still not bright.

duelund silver CAST in valab...overkill??....

nah.....

really??.....

did someone ever try a servo to overcome the output DC with success?
Never heard anyone say that it worked better than a cap, but it might be a lead.

I only have the copper version

I just put a 'burnt in' cap across the LM334 thats provides the 2.2v ref voltage on my Valab, I used a sanyo oscon SP 270uf, definite improvement in noise floor, sounds more fluid richer, vibrant IMO!

Hang on............... just noticed I get hiss at max volume with the cap there damn!

you should choose a small value film capo for this 0.1uf,