Pushing the limits of TDA1543 NOS DAC - Page 28 - diyAudio
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Old 19th February 2013, 12:07 PM   #271
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I just wanted to let you guys know that I have replaced the coupling caps, and moved to low-ohm input resistors (I am still experimenting, but I will probably settle on 1k - 1.5k).

The new caps were a very nice upgrade in its own right, the Nx series Black Gates are certainly a class above the ordinary N series.

Quite the opposite was true for the resistors - the change in the value itself has left the sound virtually unchanged (my initial impression of better detail was just a product of higher loudness). The type of resistor on the other hand has significant influence on the sound.
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Old 6th July 2013, 06:09 PM   #272
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hi im sorry to be reviving an old thread but i've so far built two of peter's latest designs on a veroboard. i think they're the best thing happened to 1543, btw. the problem i have though is when i try piggybacking 2 1543 together, the volume starts chocking out on heavy passages. if the music gets busy, the volume literally drops down, only to come back up when the things calm down. it's as if it's pulsating. do you think it's the circuit being extra sensitive to vref changes as the temperature increases on the piggyback setup? they're ofcourse ran at 8v, fed from lm317 reg and resistors are peter's values.
and i bolted a large to220 heatsink on top. besides the crippling issue, piggyback setup sounds a lot like 12 chip setup at 6v but slightly better at everything.
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Old 6th July 2013, 06:45 PM   #273
Hierfi is offline Hierfi  Canada
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I suspect the voltage output of the DAC's have risen considerably to the positive rail when you paralleled another DAC. I suspect clipping. You can reduce the 2k7's to something like half the value. Check out the quiescent voltage prior to paralleling the DAC's and measure the voltage after reducing the resistor.

Remember that the DAC's are current output devises with half the full scale current as the quiescent point. In other words it is (I x R) equal set point.

By the way, what are you using for the coupling transformer? What you are doing appeals to me as well.
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Old 6th July 2013, 08:57 PM   #274
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ih hierfi, i figured out that the pin 1 of the dac feeding the negative signal was disconnected, so in a way you were right. (excellent!)

but after repairing this i realize that indeed single chip solution sounds better, as peter stated. piggyback smears the sound- which i'm guessing is caused by phase distortion? also the frequency extension is better with single chip, most noticeable in the bass. right now i have altec 15356a and jensen je-10kb-c which i'm planning on connecting it in reverse for 1:4 out. you can see my build here. discrete output for single tda1543

Last edited by PreSapian; 6th July 2013 at 09:02 PM.
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Old 11th July 2013, 07:59 AM   #275
Piotr is offline Piotr  Poland
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Hi! Will TDA1543 work for one channel, mean without one's output pin resistor? I want to built dual mono dac of two dacs. The same question - will DIR9001 chips work with paralleled inputs with one spdif signal?
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Old 21st July 2013, 05:48 AM   #276
secanbj is online now secanbj  Sweden
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Hi

I finally dared to connect the power to test my take on the "pushed" TDA1543. As you see i took the sissy road and used PCB's, looked several times at Peters hard wiring but decided that i would not be able to fix that. This sounds so good, airy, vivid, smooth and powerful all at the same time. I am so happy

Now i just need to finnish and get the enclosure that it deserves

/Anders

PS sorry for the crappy picture quality DS

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Old 22nd August 2013, 01:41 PM   #277
Skorpio is offline Skorpio  Denmark
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Quote:
Originally Posted by Peter Daniel View Post

I decided not to use any coupling caps as sound purity was my main objective. Two of my listening associates actually preferred the caps and for their DACs I installed them.
Hi Peter,

As I understand, you are not connection anything to GND, but are going directly on the pins 9+10?

Ref: Picture in post #5

Last edited by Skorpio; 22nd August 2013 at 01:43 PM. Reason: Missing ref!
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Old 24th August 2013, 03:05 PM   #278
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Actually, the negative input from pic in post 5 is connected to circuit ground.

Anders, very nice work.
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Old 28th August 2013, 11:23 AM   #279
secanbj is online now secanbj  Sweden
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Thanks Peter!

Now when i know that my PCB's works i am thinking of testing better caps on the output. I know that you recommended V-Cap (very expensive...) Have you tried something in the middle, like Mundorf Silver Gold Oil?

/Anders
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Old 5th September 2013, 02:55 AM   #280
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I tried older Rel-Caps RTX and they founded fine too.
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