| cusanus |
Hello a question for those who's built one.
I've followed Ryohei Kusunoki's design pretty closely. I've used 6 TDA1543 instead of 4 in parallel, and changed i/v conversion resistor to 400ohms and Rref at 240 ohms according to TDA1543calc utility floating around, driving with 8.5V supply.
Sound comes out. but there is something fishy going on.
I thought I've wired the blasted thing properly but DC voltage of left and right channel are different. the utility suggests 4.55V, but I get 4.25V on one channel and 4.7 on the other.
The mismatch is far too great in my mind to brush off as a chip to chip performance variation. And too small to be a failure of one of the chip's output.
A question for those of you out there who's played around with this chip. Has anyone experienced this behavior?
-Cusa |
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| ErikdeBest |
Hi Cusanus
I can't be of much help, but anyway want to suggest something. What is the tolerance of the resistors you're using? The differences you're mentioning are within a 10% marge, way too much for 1% resistors, but normal for some unmatched NOS carbon types.
Erik |
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| cusanus |
Hello Erik
I am using holco 's (1%) measured them as well. So this probably isn't it.
Thanks for the interest however.
-Cusa |
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| ErikdeBest |
Hi Cusanus
Well, than I don't know. I see that at Fedde's Nonoz III
DAC he is using a variable resistor, but this one has other function.
Erik |
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| Andypairo |
Try with one chip and the appropriate resistors and see if the mismatch is still there.
Did you cool the chips?
Cheers
Andrea |
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| cusanus |
Andrea,
Yes, that would have been my next course of action but I put the chips on a heat sink with a LOT of thermal compound. Just couldn't motivate myself to clean the mess up, pull out each chip and change resistors.
Guess I have to get my hands dirty.
-Cusa |
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