[tubes]

Thanks Kooka but you lost me at the end when you said remove the small russian cap, do you mean remove one of the input caps that goes between the Coax RCA and pin1 of the transformer and does it matter which one of the 2 input caps you remove. Thanks.

 

[Kooka]

Quote:

Originally Posted by tubes /img/forum/go_quote.gif Thanks Kooka but you lost me at the end when you said remove the small russian cap, do you mean remove one of the input caps that goes between the Coax RCA and pin1 of the transformer and does it matter which one of the 2 input caps you remove. Thanks.

No, I mean like this:
Pin 1 to RCA coax +, in between you put a cap (I will use one of the 2 small 0.01uF russian ones removed from the board).
Pin 2 goes to RCA -
Pin 3 goes to the board in the place where you removed the small russian cap.
Pin 4 goes to ground (same place where ground goes without the transformer.
It's like in the picture (but in this picture there is no cap between RCA + and transformer, because he's sure he has no AC coming from his source), and after removing the 100R (you see 101 marked) smd resistor under the board, you put a 57R resistor where you see the oval.
Hope this helps.

 

[highendman]

Kooka, I noticed the 100R input resistor also. I thought it was perhaps an attempt to get an approximate impedance match with the existing circuit -- the RCA jack is probably about 90ohm, plus all the board tracings and input switch may make it's effective impedance about 100 ohms. It's very possible, that with the original circuit, the best match is 100ohm.

 

[Pars]

You really should use 75-ohm mini coax such as RG-179 for the connection from the transformer to the board instead of that long yellow wire in the picture (holy 75-ohm fail, batman!). Also, the resistor (100 ohm) that you are replacing is in parallel with whatever the input impedance of the next device is, so 75 ohm may not be the proper value to be putting here. If the impedance of the following device is really high, then the resistor will dominate, so 75 ohms would be OK. Of course the RCA jack is also not 75 ohm, but IMHO you should do what you can to try to make things as close as possible.

 

[highendman]

Pars,

In the 3.0 version, only a short run of wire (about 1.5-2 inches) is needed from the input transformer to the input resistor. I have the transformer output ground, grounded where the input jack was grounded and run a short run of wire to the input resistor (exactly like Pat's).

You feel that a better way to do this would be with mini coax (in my case it would have to be 110ohm coax) to both sides of the resistor, and NOT ground it at the jack?

Thanks.

I'm wracking my brain how I could have lost slam on my last batch of mods. I assumed macro dynamics would be much better. I'm assuming and hoping it's simply a matter of break-in. My 47uF BG FK caps replace the surface mount caps on the DACs, but because the hover over the board, there is impedance in the leads. Could that be it? It wouldn't be the 3A shottkys?

 

[Pars]

A short wire should be fine; coax that short is difficult to work with.

 

[tubes]

Kooka, I'm assuming that if I put the cap in line with the transformer both input caps can be replaced with jumpers? Of course I would use one of the input caps with the transformer.

 

[Kooka]

Quote:

Originally Posted by tubes /img/forum/go_quote.gif Kooka, I'm assuming that if I put the cap in line with the transformer both input caps can be replaced with jumpers? Of course I would use one of the input caps with the transformer.

Yes, I would say yes.

 

[djembeplay]

Hey everyone. My Valab DAC just failed

. This is the newest 2009 model. It has hardly been used. I've always had it plugged into a surge protector with a high quality power cord. It always had plenty of ventilation as well.

There is still a signal, but it is accompanied by a loud scratchy hiss that intermittently turns on and off. This happens regardless of what input or source is used... it's definitely a malfunction in the DAC and not my source or amp.

Has anyone else has a similar occurrence or know what might be the problem? How is Valab customer service?

 

[Wood]

This problem has been mentioned before sometimes in this forum, the solution seem to be to leave it on for a few days. It will eventualy clear up. I dont know what the cause is. But I would suggest give it some time and if no joy, contact the supplier. They will exchange/repair or give a refund.

 

[djembeplay]

Thanks for the info, Wood. That's good news - so maybe I don't have to lose my DAC.

Any idea what causes this? Is there any danger to my amp in this condition, or is it just signal level distortion?

 

[Wood]

My guess is, and its just a guess, is its the TDA1543's settling in.

 

[Wood]

Nobody has reported any damage to amps, ever in this forum!

 

[skibum]

Just bought the new "luxury" version and I am a bit confused about the new additional 33.8688 MHz "re-clock" circuit that is on this version. What is this new circuit doing? I am also confused as to what the 12.000 MHz clock does?

Doesn't the DIR9001 have it's own clock (SCKO frequency) that can be set by the state of pins 13 & 14? What's the 12.000 MHz clock for then?

Will the DIR9001 mod of connecting pins 13 & 14 to 3.3 Volts still work for this version?

Sorry, probably very basic questions...

Still working out the schematic but planning my first audio mod!

Thanks,

Scott

 

[MikeW]

the 12 mhz clock is for USB only, the 33 Mhz reclocker is for SPDIF input. Yes the DIR9001 has it's own reclocker. I have no idea if it's disabled or not when using the outboard reclockers.

I started having a problem in my modded 2.1 dac recently, a low "hum" in the right channel. I checked all my connections and tried swapping out capacitors. Eventually I swaped out my PRP Resistor in that channel for a el-cheapo radio shack resistor and the problem was solved. I put the PRP back in for now, and have some more Takman and PRP resistors on order. Does anyone know why a Resistor can cause this low hum? how does a resistor "go bad"? Did I overheat it at some point? just bad luck?