TDA1543 supply cap size!?

[fedde]

Another post from a steamy hot Holland

I did some experiments again with my Nonoz II DAC yesterday. I suspected that the supply was oscillating, as the sound was sometimes tiring. Turning the DAC off/on for a short moment restored the original & fine sound. I guessed that it was the 8V supply on the TDA1543 that gave the problems. I use an 7808 followed by an 100 uF BG FK. I hoped that the Black gate would provide sufficient HF decoupling, but it seems it didn't.

I tried an ordinary Rubycon 22 uF 50 V instead of the 100 uF, and the sound drastically changed. The sound is extremely smooth, but also slower and less defined. This cap definitely needs a smaller one in parallel, though it seems a more stable solution so far.

Now my question:
I am wondering what would be the ideal size of a supply cap for the TDA1543? Are there any rules of dumb for that !?
Would a 4.7 uF cap be sufficient ? I have also seen schematics with 20 uF or even 470 uF.

Thanks in advance,

Fedde

 

[Werner]

FWIW, I'm doing a prototype TDA1543 DAC now. Power supply is a 317 as current source into a TL431 regulator set for 5V. Then 220uF Rubycon ZA 10 mm from the DAC, and a 10uF + 100nF X7R SMD pair smack under the DAC chip between ground and VDD pins.

I would not call it tiring. Sound moves between mostly-brilliant and plain-boring,
being in brilliant mode for 70% of the time.

DAC not finished, now just running directly from the IV resistors (and 1nF filter cap and 22uF coupling cap) into a 100kOhms preamp.

Oh, the CS8412, of course, has its SMD decoupling caps and VCO filter cap directly soldered to the IC pins. The 8412's pin layout is so inviting that I keep wondering why not everyone is doing this.

 

[Guido Tent]

Another post from a steamy hot Holland

I did some experiments again with my Nonoz II DAC yesterday. I suspected that the supply was oscillating, as the sound was sometimes tiring. Turning the DAC off/on for a short moment restored the original & fine sound. I guessed that it was the 8V supply on the TDA1543 that gave the problems. I use an 7808 followed by an 100 uF BG FK. I hoped that the Black gate would provide sufficient HF decoupling, but it seems it didn't.

I tried an ordinary Rubycon 22 uF 50 V instead of the 100 uF, and the sound drastically changed. The sound is extremely smooth, but also slower and less defined. This cap definitely needs a smaller one in parallel, though it seems a more stable solution so far.

Now my question:
I am wondering what would be the ideal size of a supply cap for the TDA1543? Are there any rules of dumb for that !?
Would a 4.7 uF cap be sufficient ? I have also seen schematics with 20 uF or even 470 uF.

Thanks in advance,

Fedde

Fedde

I am not fond of the LM78 series. The output noise depends on the DC load ........Besides that they just do not sound right.

The differences in sound are fully due to the different capacitors.

I suggest you measure on the output noise, if you have equipment available doing so.

Can I challenge you in starting to make a shunt reg ?

I propose a 2 transistor current source using LEDs as references, and a shunt eventually based on a Vbe multiplier (the better ones). Inspiration can be found here

http://www.hagtech.com/pdf/vbe.pdf

When doing a shunt the right way, you can end up with some 10's of nF across the chip, that is all....

And yes, it IS hot - I propose to lower your supply voltage, less dissipation