V-dac modifications - Page 8

Ok. But what capacitor i should replace with Panasonic? C22 or C27?

Could you consult me about few more questions.

I decided to replace signal path capacitors.

For C147, C151, C51, C47 i found only 3300pF 63V polypropylene capacitors.
1. Is it crytical to have 3900pF or i can use 3300pF?
2. 63V - is ok or should be more?

3. Polypropylene capacitors are the best for C3, C4. But 47uF polypropylene is very big. So i will use ELNA Silmic II and i should setup it with right polarity. How can i find where + and - is? Or better to use Nichicon Bipolar.

Thanks in advance

Power supply replacement = no big deal

My results do not support this. I bought a big ol' power supply with 3 amps continuous, 13V, and the VDAC doesn't sound any better. I can barely tell a difference. Of course, I WANTED to hear a difference, but the honest truth is, I didn't.

This is the supply that I bought:
Samlex America RPS1203 3 Amp Regulated Linear DC 12 Volt Power Supply

Any comments are welcome. Thanks,
Hukk

Is this safe?
People here are saying, "it's OK to remove the output caps of the VDAC as long as your preamp has input caps, because the preamp's input caps will prevent your speakers from getting DC" --
but, what if your preamp's volume control is BEFORE the preamp's input caps? Won't this send a ton of voltage to your preamp's volume knob, basically frying it?
Hukk

Hi,
for those in EU, who are going to buy and modify a MF V-DAC:

my V-DAC is for sale: http://www.head-fi.org/forums/f43/fs...ac-mod-465535/

And for others, who already have a modified V-DAC:
I have also a browndog adapter with 2xBB OPA 627 on board for sale, which can be placed in a IC7 socket.
Never used and brandnew.If anyone is interested please send a PM.

Thanks.

Upgrade

Has anyone tried 2 AD797's on a browndog adapter in IC7?

Hello,

I modified my V-DAC using OPA4277, OPA2134, adding some Rubycon 1000uF and OSCON 100uF capacitors. I used also more powerfull supply-1000mA. It was wastly improvement reg. bass quality, details and transients. However entering this forum, I hoped to find schematic of V-DAC, but only some photos was available. Any of you have any idea where this schematic can be found?

Hi I did some reverse engineering and have full schematic of this DAC. But without most of the values, as I did not need them. Schematic is little bit messy as I did not clean it up but again it was not necessary for my needs. I was just redesigning output stage (not only changing op-amps, but also caps and resistors) and supplying it with high quality shunt regulated power supply. There are some stuff left and I am waiting for few parts from farnell now to continue. If the results will be satisfying I will post them here. I will be also tuning USB receiver part as the implementation in V-DAC is really crappy. Beside this V-DAC is really cool device.

Edited by barmanekm - 5/25/10 at 5:56am

I want to mod my V Dac so that it sounds colder and more detail because i´m having a tube pre. My pre sounds very warm somethime  too warm for me. Thats why i want a cold source to make balance......any suggest ?  

Try OPA627BP in second stage (you need browndog adapter), and maybe LME49740 on first one. I am actually running 2xOPA1612 on first stage and LME49860 on second, but I am aiming to neutral and transparent sound. Analog stage in my V-DAC is powered by two independent SuperTeddyRegs at +/-17V. It was best improvement. Much, much better than changing opamps and caps. Now changing opamps gives much more differences and it is easier to find a differences. Sound is very smooth, transparent, full of details and with well defined bass. Lack of bass control and sometimes screaming highs was main drawbacks of V-DAC for me. Now it is a better source than NAD545. When going for cold sound and trying very detailed output opamps (like mentioned OPA627BP) be careful. With low power quality (unfortunately this is the case for V-DAC. Use heavy decoupling after switching DC converters or better use separate ultra low noise regs) these opamps may sound screaming, and make you tired very fast. Power, power, clean power for analog stage - this is the best mod for V-DAC. Now I am wondering how I was able to listen to it before....

Edited by barmanekm - 6/7/10 at 4:35pm

HI All,

 

On the subject of power supply, I have used a QED Positron (originally designed for use as an upgrade for the QED Digit DAC).  The is rated at 15v DC - the Digit "required" 12V.

The tranformation in sound was immediately obvious, power authority and dynamics. It shows how poor the original supply is!!

I suppose these can still be found secondhand and should be very expensive (at least until folk realise what they can do for the V-DAC)

 

Regards,

Jim

Hi All,

The last paragraph should read "very inexpensive" apologies,

Jim

Hi there,

 

I'm new here and I'm interested in upgrading my V-DAC.

 

Would it be helpfull to replace all the condensors for instance with Wima folie c's?

Not adjusting the values of components but just replacing them of those with a better quality?

 

Thx,

 

Jordi