12x TDA1543 at 6V, output and Vref Resistor values

[mudihan]

If I want to parallel 12 TDA1543 and supply them with 6V, for the passive I/V stage, what would be the optimal values for AOL, AOR, and Vref? I choose 6V as compromise between 5V (too smooth and too soft) and 7-8V (slightly rough and need for heatsinks). I have searched, but the results always seem to concern 5v and 8v configurations.

[dddac]

12 in paralel? Good idea

Rload 68 Ohm
Rref 82

Results in maximum output (without clipping) of 0,6V eff

V Bias DC should be 2,5 Volt (checkpoint for you)

best regards
doede

dddac website

[xaudiox]

TDA1543 Calculator : http://www.diyhifi.org/forums/viewtopic.php?t=104

[dddac]

This calculator is pure Theory based on the datasheet minimum and maximum values specified and seems to have no relation to the real world I am afraid

My values are based on real measurement of currents and clipping points checked with a FFT analyzer....

On top of that checked several Bias points sound wise to tune this...

on 6 Volt the best midpoint is 2,5 Volt
on 8 Volt the best mid point is 3,85 Volt

which are completely different from the "calculator"

[dusr_123]

Hi Mudihan,

I think, It does't make sense run TDA1543 at 5V. The DAC isn't so good. At higher PS level 8 V and more the THD goes down. I use 9 V, but I use cooler, I have tested, that TDA1543 survive 9,2 V. I every case measure the THD level, don't rely on this calculator ...

[mudihan]

dusr_123: I do not plan to make a heatsink or use a fan for the set up. So the highest I could go is probably 6.5V.

dddac: Thanks. I have actually read a lot on your website. Do you think that output from the DAC(s) would be very low? I am asking since I only use a 25k ladder-type volume control before my power amp. Also, just out of curiosity, what would be the ideal resistor values if I were to use 7V?

xaudiox: Thanks. I had built a 8v 3xTDA1543 DAC before using that format, and it didn't work very well -- there were distortions. At that time, I had to change the values to make them work. So I think that those TDAs can not be pushed to their theoretical limits. There may be a few lucky ones and I will certainly order an extra set of resistors based on those calculations.

[dddac]

With 7 Volt, a good start would be:

Rref 90Ohm
Rload 100 Ohm
midpoint 3,3 volts

It seems your negative experience with 8 Volt, beside the cooling of course, is about wrong bias and load ?

Remember what values you actually used there ?

Sound tests proof for me also above 8 Volt sounds the best. But bias must be ok of course

Cooling is a point of course if you are not using sophisticated tools or fans

[Mario_JR]

Just to restore an old topic.

Midpoint is dc bias?
Should I measure it in Vref and ground?

Thanks!

Originally Posted by dddac

With 7 Volt, a good start would be:

Rref 90Ohm
Rload 100 Ohm
midpoint 3,3 volts

It seems your negative experience with 8 Volt, beside the cooling of course, is about wrong bias and load ?

Remember what values you actually used there ?

Sound tests proof for me also above 8 Volt sounds the best. But bias must be ok of course

Cooling is a point of course if you are not using sophisticated tools or fans

[dddac]

Originally Posted by Mario_JR

Just to restore an old topic.

Midpoint is dc bias?
Should I measure it in Vref and ground?

Thanks!

there is general riule like half....

I did some listening tests and my preference is:

Ub = 8V Vbias = 3,8V
UB = 6V Vbias = 2,5V

of course the load need to be such, that the dac is not clipping at 0dB
which can be easily measured with every soundcard and a fft program

[Mario_JR]

Im sorry for hijacking this thread.
Hey dddac.
But what are best values ( Rref, Rload and Bias) to 4 TDA1543 in 8.5V.
And for 8 and 12 TDA1543?

Thanks

Originally Posted by dddac

there is general riule like half....

I did some listening tests and my preference is:

Ub = 8V Vbias = 3,8V
UB = 6V Vbias = 2,5V

of course the load need to be such, that the dac is not clipping at 0dB
which can be easily measured with every soundcard and a fft program