Valab NOS DAC - subjective listening and modifications - Page 117

well my thinking is what can it hurt? if the blackgates are faster, it will be like the stock ones are not even there anyhow, i dont see how they are gonna ruin or even affect anything, but maybe i am wrong

my personal favorite for bypassing film caps are styroflex, or in case you use MKT some MKP . The beauty is that these caps do not need to be "signal grade" and a cheaper NOS film cap can work wonders already.

listen and learn, it may be true in one application but not in the other.....

just give it a try with both options, worst case you'll have to put them back in...

.

I appreciate your remembering me but I already picked up on your info from the Chameleon DAC thread and your web page in your sig. I didn't know the steel was more linear, though. That's good to know and a good reason to decide to go that route. Thanks for setting the example.

On a side note, things are going a bit strange with Cinemag. My initial contact was with David Green (vice president). He gave me a per unit quote, asked about making with channel mounts, and asked for an address with shipping information so he could get a total. After I replied he never got back with the invoice. That was back at the 1st of the month. Did you have to pay first? I've written twice asking if everything is straight. I'm beginning to wonder if the transformers are being made.

EDIT, Feb 22. Heard from David Green by email today after 22 days of silence. He said they're making a small run of the CMOB-2S within a week or so. Apparently they wait until they have enough interest to set up for certain models.

EDIT, Feb 24. Received a Paypal invoice for payment on two transformers from Cinemag and promptly paid for them. Two pieces (22.10 USD ea) and shipping (10) totaling 54.20. Now more waiting.

I think I found the problem!

I got my replacement TDA1543 and put that back in. Still had HUGE amounts of distortion as before though....

After some VERY close looking about I found that the center leg of my LM334 current source was broken. Was very hard to see.

Ordered another one up so hopefully that will sort me out!

It is amazing. I am generally a very careful (OK anal) guy. I have so far managed to rip the legs off one of my TDA1543 DAC's, broke a leg of off my LM334 AND blew the fuse (piece of wire laying on the table).

AND I was REALLY TRYING to be careful!

Appreciate the help from everyone.

skibum

questions.... if you remove the stock transformer on the valab, you see a picture that indicates two output coils, is one of those for the dacs and the other for the chipsets? which one is which?

also is it true that the stock transformer puts out 2 * 13.2 volts, did i read that right?

i still have not done my dir 9001 mod, i can not even see the pins, i gotta get some magnifier thing

Looks like the regulars have all moved on to the Chameleon thread since they're concentrating virtually all new mod efforts on that DAC.

http://www.head-fi.org/forums/f7/cha...ations-465039/

I'm still very happy to have jumped into Valab modifications when I did with a March 09 version. That short lived revision fit my need perfectly and later revisions with the clocks were something I absolutely didn't want. My little high resolution system with the modded Valab is running anytime I'm home and currently has well over 5000 hours on it. (I have a hardwired hour counter on my music server.) I wonder if it's burned in yet...

Promise this'll be my last novice question.
I've got AmpHom 4.7s and Mundorf Supremes 0.47uf by-passing the existing caps.
I'm happy with the result, the balance is there - may need something for the
top end, but that can wait.
I'm at the point where I need to remove the exisiting caps, supplied with the
DAC. How do I do this? Earlier people said it's best to cut the legs - but how?
Do they make pliers that small or will a sharp stanley knife do it?
Thanks
BG

Problem - related to DAC board ?

Hello,

When I turn my Version 3.0 on it has huge amounts of distortion. The output volume will not change when I increase/decrease the volume from my Squeezbox. After about 2-7 minutes the volume slowly goes down and then the distortion disappears and then the output sounds gorgeous.

After playing around for HOURS I found that if I attach the DAC board with the 3 screws to the chassy the distortion never goes away. When I remove the three screws the above happens.

Once the output sounds good if I press down on the DAC board the distortion comes back! So I assumed that one of the connections to the board was faulty.

I replaced the inductor and resoldered all the connections and it made no change....

When I vary the output voltage by adjusting the blue variable resistor that seems to reduce the time that it takes for the distortion to disappear.

But no matter what I do when I turn the power off for 5 minutes and turn it back on the distortion is always there. If I attach the DAC board to the chassy with the 3 screws the distortion never goes away. If I detach the DAC board from the chassy it eventually sounds good.

HELP!!!

???


Thanks

A quick update....
The back (or front) didn't come off as easily as I thought, so abandoned the idea of taking the board out of the chassis.
Tried "sawing" the legs off existing caps with stanley knife. Didn't work.
Got out my trusty Dramel, but found I had no cutting discs.
One pair of kitchen scissors - holding firmly by handle and applying pressure
nearer the tip - ping - they came off.
Have my array of 47uf and .47uf going straight to rcas.
Sounds much cleaner - although I need to tidy up the caps as they won't fit under the cover any more and they look like the result of terrorist rookie school homework.
As a first foray into the diy hi-fi, I think it's worked out quite well.
BG