CD Mod- Avoid opamps after TDA1543?

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I have Philips CD614 cd-player with TDA1543 dac... Unfortunately signals that came to it are already oversampled, but this is not my goal... So question: is it posible avoid output opamp stage with help of Doede Douma idea for increasing power.
Doede Douma TDA1543 DAC part

Thank You in advance!

Attachment: shematic of the same part on my CD-614

edit: My idea is using only one TDA1543, not eight.


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If I wasn't clear...

Yes, you can use a simple resistor for the I/V as done by Doede.

Just remove from the cdp the two LM833, the caps 2660 and 2661, the resistors 3660 and 3661.

You thus have access to the tda1543 output pins (pin 2 of the opamps). From pin 2 to gnd, add a 2.2K (or 2.7K) resistor, in parallel with a 1500pf cap (on each channel obviously). Then add a 0.47uf cap in between pin2 and the output to block DC offset. You're done.
bezobraznia said:
Thank You for reply, I'll do that, but what You mean "especially one of the M50432 decoder"? Be more specific please? Talk to me in "pins and farrads" if it's posible :)
Thank You in advance!

Best reggards!

My suggestion was to optimize the positions of the decoupling capacitors (and possibly to replace them with something better - for example tantalum caps) around all ICs...

It's desired to have the decoup. caps as close to IC pins as possible and for the decoupling currents to travel by the shortest part of the ground plane...

Simply, you have to put one "leg" of the cap as close as possible to the IC's supply pin and the other as close as possible to the IC's ground pin...

I've uploaded an example bellow. As seen on the CD604 diagram C2573 and C2583 should be put as close as possible to the M50432 ground pin (73 or 32). You should do this with all decoup. caps...

They are both also bypassed with a small ceramic SMD cap (which is rather difficult to move - so you might leave them be :dead: ).


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I've also attached a picture of my (un)tidy work to help you visualize the problem...

Also, if you look at the SM, you'll see some cheapscate-ing - for example the decoup. cap for the one of the optical processors has been left out in the final production (it's in the Sm, but not on the PCB itself! :xeye: )

Hope this helps,



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Thank You,

SoNic_real_one said:
I have replaced LM833 with NJM2068 and the results where amazing... and the filter is intact, not like in the case of jumping over the opamps.NJM2068

I was replaced all of them a time ago with OPA2604 and OPA2134 The sound was great, but with changes above I'm not even get to the opamps... thank You anyway :)

dddac said:

be carefull on your advice. the 270R value is based on 8x TDA1543 in parallel... just to make sure :angel:

if you use 1 TDA1543 2k2 is fine, but then Rref (pin 7) should be like 1k5 ....

Thank You Doede, I've put two 1K and Vref also 1K .
edit: I'm using for VA+ standart 5.25V from CD Player
For 8 of TDA1543 I have Your DDDAC as You remember :)
Unfortunately I'm not assemble yet...

But, Doede I was thinking using Your receiver CS8412 and XO Tent Clock from Your project DDDAC1543 for The same topology DAC, but with TDA1541A. I have several of them even S1 version... And I have CD player with TDA1541A - Sound great compare to the other player with TDA1543. Is it posible and what i have to do? Is there need using XO Tent and how?
Thank You in advance!
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