[LosNir]

I'd go with Nichicon MUSE / FW 2200uF (x3 / x4 / x5 Per Channel) or 6800uF (x1 / x2 Per channel) or a single 10,000uF per channel, OR, Panasonic FM 2200uF (x3 / x4 / x5 Per Channel).
 
This is what I'm using (Panasonic FM 2200uF x3 Per Channel):
 

 

[marcelnl]

Quote:

What frequnecy could that be? Under 30hz?

well that would totally depend on the input impedance of your amplifier....there are formula's out there but you;d need to find out the amps input resistance first. Most transistor designs lie around 47kOhm whereas a tube amp lies in the 220-470kOhm range.
2.2uF would be cutting it close imho....phase shifts do occur way before your teh lower end gets cut off in a sonically meaningful way.

 

[donpoon]

Quote:

Thank you so much for your suggestion.  Seems like it's not as bad as I thought.  I have ordered ten TDA1543 from Taiwan.  Will have to wait for the shipment. 

Just received the TDA1543's.  Replaced all 8 from the board.  Now the distortion is gone.  However, I only hear sound from the Right Channel.  The Right Channel sound fine though.  Do I just keep swapping the TDA1543 until I hear the left as well or do you think there is still problem some where else?

 

[Wood]

I think there is a problem with a dodgy RCA connector. Also make sure the TDA1543 pins dont bend when you put them in the sockets.

 

[donpoon]

Quote:

I think there is a problem with a dodgy RCA connector. Also make sure the TDA1543 pins dont bend when you put them in the sockets.

 
Now it works!  It happened to be  a bad connection of one TDA1543.  I loosen the heat sink of the TDA1543's and rock it a bit until both channel works.  It's now back to normal.  Thank you so much for trouble shooting the problem with me.  Now I've been messing around with the Valab, I would soon join the experts and start modding it one day.

 

[Wood]

Oh thats great news!!

 

[Dynobot]

Just curious.
 
Valab Dac owners, what other Dacs have you compared the Valab too? 
 
What other Dacs do you own?
 
I myself own a couple, one re-clock version and one pre re-clock version.  Over the past couple of years I have tried a lot of Dacs in the $300-$1600 price range, most went back or were sold but the Valab is a keeper for sure.  Curious about others impressions vs. other Dacs.
 
I have compared the Valab to these Dacs:
 
Apogee Mini
Lavry DA10
Matrix Mini
TC Konnekt 8
RME Fireface
M-Audio ProFire 610
Audio GD Ref 5
Audio GD Ref 7
Mdht Havana

 

[marcelnl]

think it would interest more people to know what the results of the comparisons were than only knowing to which DAC the VALAB was compared to....
 

 

[Dynobot]

Quote:

think it would interest more people to know what the results of the comparisons were than only knowing to which DAC the VALAB was compared to....
 

Very Good Point!
 
Would you care to give an example?
 

 

[marcelnl]

I never made a good comparison so I'll leave that bit of proza to you....
The only thing I can say about the Valab is that it is very musical and invlving, has good pace and slam, enough punch in the lower freq and a nice top end expecially when modded
My former dac was a gold crowned Maratz, heavily modded, and it outperformed about every DAC in the 80ies and 90ies, my valab comes close in some respects and not close enough yet in others.
 

 

[donpoon]

My Valab(Late 2008 version) has been working fine with my Head-Direct EF-1.
 
I just got a Class-D amplifier (amp6-basic assembled) to drive a pair of Infinity P163.  It sounds great when I use the headphone jack of my notebook as source.  However, when I connect it to my Valab, I got a much higher noise-floor.
 
I believe all I have to do is to modify the input of my amp6-basic to match the output of the Valab.  Would adding a 50k potentiometer (volume control) help in this case?

 

[marcelnl]

If you have assembled the amp yourself you should know (or be able to find out) the input impedance pretty easily. I imagine it will be close to 47k, so I doubt that the elevated noise floor is an impedance mismatch, I vote for a ground loop somewhere between the Valab and your amp.

 

[MikoLayer]

 
[size=medium]

Looks like the thread is all but dead, have you guys moved onto something better in your lives? 

 
Anyway, I am still battling the grave problem I had described a few months back, The truth is, I once again had stashed it away for a few months. Here I am looking at it again, as puzzled as ever. 
I get about 3.20v drop between the ground and positive ends of the left output cap (which is working), whereas it is zero in the malfunctioning right channel. The I/V resistors incur 3.20v drop on both channels respectively, so I figure the problem is somewhere between the output caps and the I/V resistors. Just to be sure, I have confirmed yet again that there is nothing wrong with either RCA output (have swapped the connections and either output would play fine as long as it is connected to the left output cap).
 
Now, I have no idea where exactly the output caps are connected to; a schematic would help if there is a such thing available somewhere out there. Who was it again that helps you with troubleshooting over email, Kevin?  
​

[/size]

 
 
Quote:

hello gang, been away from head-fi for a while, had other things happening in life.

wonder if you guys made any breakthroughs during my absence?

I basically had to set it aside and wasn't able to work on it for a couple of months.

Just a few minutes ago, I finally unscrewed the board from the bottom plate, and immediately noticed there were exactly three spots were traces were cut.

When I say 'cut', I mean literally cut as if it was done intentionally with an exacto knife. There isn't anything that comes to mind that might have caused such precise cuts when I didn't even separate the board from the case up until now.

Could this be a part of the original design / abrupt design changes that were meant to be there? If not, i guess my best bet is getting a hold of some conductive pen tomorrow.

Let me try to take some pics with my phone

Here it is


Now that I think about it, I think the mods went in this order

Output caps -> DIR9001 -> Resistors / Input caps

It was after the output caps mod that I lost the one of the channels (but wasn't aware, as the outputs were shorted and I was hearing dual mono from there on

). Must have been the easiest mod, can't imagine something going wrong there. I was gonna ask if a failed DIR9001 mod could mute one of the channels, but I guess it was happening before I mucked with DIR9001.

 
 

 

[marcelnl]

the output caps are connected to the output of all 8 dacs, to which the I/V resistor is connected too (and to ground).
Not knowing what mods you did and in what order I;d say that a loose I/V resistor, a dodgy soldering joint or loosened circuit board pad or something like that is far more likely to make you loose a channel.
 
Schematics are out there, not sure what version you have but the general output is the same, DAC output paralleled into the I/V resistor to the Capacitor and then some riffraff analog filter and attemt to fixate output resistance (just unsolder all of that)....what equipment do you have available/are you comfortable working with (scope, multimeter etc)?
 

 

[MikoLayer]

well in my laziness I just quoted one of my random old posts. Now I do know in which order we did the mods and when exactly this happened: just after the output cap modding. 
 
I doubt it's a loose I/V resistor, seeing how I see identical voltage drop across the resistor on either side. Probably should check the soldering joints on the DACs, or get a hold of some TDA1543s and replace them if they can be had cheap enough.
 
I have a DMM and a decent soldering station, but not an oscilloscope or anything like that. I have contacted Kevin through the valab's ebay homepage, got a response saying he can fix it at the cost of replacement material and one way shipping to his place. When I sent him another reply asking if he could help me with troubleshooting instead, he stopped communicating
 
Oh, and thanks for trying to help me out, I wasn't expecting people would care any more