Valab NOS DAC - subjective listening and modifications - Page 111

2x22uf was what I had at hand no other reason. But I was using the valab with a yaquin cd1 right up until I changed the caps in my 1st amp from silmic2 to Bg Fk. After they burnt in I realised the tube buffer was just getting in the way. The sound was balanced without it. I can play with pot size because I made the amps myself,so my call, but point taken. Def system dependancy has to be considered when moding the Teradaks. Lots of good stuff to chew on there guys, thanks!

I know, the VAlab probably has a much higher internal/output resistance than the Chameleon having roughly twice as much current capability, so you're probably hearing the better match with with either quite clearly.

I am thinking about getting me some output trannies for the Valab, know a guy who makes them with a nickel core yet I'll have to ensure that there is no DC on the output....


@Wood, no critisism it was just an attempt to illustrate that enough is enough....I also use odds and ends frequently.

a well designed steel tranny (well I hope you mean grain oriented silicon steel anyway, amorpous or not aside) can outperform a bad nickel core tranny any day so I wil not hold that against you ;-)

A good nickel core tranny however excels in the output of a DAC as its core is not that much at risk of saturating as elsewhere and the nickel content allows better coupling than with iron only.

i always bypassed the 47k resistors in my old valab, i wonder if that was a mistake. The input impedance on my headamp is 50k Ohm. Sounds pretty close to those 47k's. probably did not do myself any favors afterall. Wonder if i can replace the 47k resistors with 50k for a better match? (do they even make a 50k resistor?)

don't bother, the difference between 47 k and 50 k is too small to notice at this signal level (might be different with a phono cartridge)

If your head amp has 50 K I'd select a cap that is large enough not to limit the bass frequency and phase.
Most likely you'll end up using something like 6uF, a couple of pages ago Qusp showed the math on this.

BTW: if you ever were in need for a single voice to check all freq ranges of a cap, speaker or amp look no further than Greetje; YouTube - Greetje Bijma

After all it should all be about the music ;-)


Just connected a silver interlink as digital, and had a quick listen; the low end has good slam and drive , the total is quite involving musically yet the top is is still locked in without the amount of air and 3D soundstage I am looking for.
Only 50 hours burn in, so there is more to be had over time yet it seems that modding is unavoidable ;-)

Can't wait to chuck in some MIT and Mundorf caps, the Tx resistors and do the yellow wire mod, rip out the output filter and do the dir 9000 mod.

6UF huh? wow, someone from Sonic Craft told me 3.0 uf would be plenty and I just took his word for it. I guess that explains where my bass went, when I switched from 10uf tant's to 3uf Dynamicaps.

Sonic Craft are correct, the min recommended is 2.2uf for coupling. I Have 2uf in the input of my new amp project and thats plenty.

But my Valab needs more coupling value then 2.2uf. Pats works fine with 1uf, others need more. Downsteam gear is the factor here, and the fact this forum is about subjective listening also applies to cap values not just types.

Just do the math http://www.head-fi.org/forums/f7/val...ml#post6290509 and you'll know whether 1, 3 or more uF is 'nuff ;-)

I like to stay well above the capacitance that gets you quirky phase behaviour(hence my 6uF MIT caps at the time), there's always potential compatibility issues with other gear, but the main thing is to use a size that works for you in your setup.

just performed my first surgery on the valab deluxe, connected the yellow wire, removed the 5600pF output filter caps and bypassed the output coupling caps for a start.

It just sounded too promising to sit back and do the modding after 200 hours.......also found the source for the occasional scratchy noises, the yellow wire was scraping against one of the leads of the rectifying diodes.

First results with mods and 78 hours of burn in; more drive, more air and better detailed highs...High range is not yet what I am looking for, the upper midrange is still reluctant to let it rip but this thingy definitely has the makings of a truly good sound .....
Victoria Mullova trying to saw her way through a perfectly good violin on Paganini (philips) sounded just great, though she could have put some more resin on the bow ;-)

My all rime favourite; Mahler 2nd by Kubelik on Deutsche Grammophon (I know ancient recording but the best performance that I know) is getting there, but still a long way from hitting all the spots in the upper mid to ultrahighs.
EDIT; TX2575 are ordered and the Mundorf silver gold oils are in.....burn in continues but the parts needed for cardiac bypass surgery are laid out.

I have just started modding my Luxury 3.0 version and I have a question. Looking at the output circuitry of some of the older versions it appears to have 2 ferrite magnets per channel where my version has 1 ferrite magnet and one 24ish ohm resistor.

What is this 24 ohm resistor doing? Is it OK to just replace it with a wire? I am trying to do a "Bill Allen" star grounding mod and this resistor is causing me some confusion.

Thanks!

Think you are looking at an inductor in the disguise of a resistor, but anyway just connect the coupling cap directly to the I/V resistor and cut the circuit board conductor right after the IV resistor and connect the ground of the I/V resistor to your star ground. This way you have done two worthwile mods, star ground and cutting out the output filter