12x TDA1543 at 6V, output and Vref Resistor values - diyAudio
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Old 25th February 2009, 09:42 AM   #1
mudihan is offline mudihan  United States
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Default 12x TDA1543 at 6V, output and Vref Resistor values

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.
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Old 26th February 2009, 02:13 PM   #2
dddac is offline dddac  Germany
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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)

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doede

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Old 26th February 2009, 03:29 PM   #3
xaudiox is offline xaudiox  Philippines
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TDA1543 Calculator : http://www.diyhifi.org/forums/viewtopic.php?t=104

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Old 26th February 2009, 04:23 PM   #4
dddac is offline dddac  Germany
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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"
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Old 26th February 2009, 10:44 PM   #5
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Default why ?

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 ...
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Old 27th February 2009, 03:01 AM   #6
mudihan is offline mudihan  United States
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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.
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Old 27th February 2009, 04:52 PM   #7
dddac is offline dddac  Germany
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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
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Old 15th March 2011, 11:59 PM   #8
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Just to restore an old topic.

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

Thanks!
Quote:
Originally Posted by dddac View Post
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
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Old 19th March 2011, 08:18 AM   #9
dddac is offline dddac  Germany
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Quote:
Originally Posted by Mario_JR View Post
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
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Old 23rd March 2011, 10:33 PM   #10
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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

Quote:
Originally Posted by dddac View Post
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
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