Determining truth of 555 watt amplifier board

AI Thread Summary
The discussion centers on the actual power output of a "555 watt" amplifier board, with calculations suggesting it delivers approximately 140 watts at 8 ohms and 36V, rather than the advertised 555 watts. Theoretical calculations indicate a maximum power of around 81 watts RMS, with real-world output likely lower, between 50 to 60 watts. The users debate the implications of shorting the output and the internal resistance of the ICs when configured in parallel, which affects total power calculations. The consensus highlights that achieving 140 watts RMS would require a higher power supply voltage than what is currently provided. Overall, the claims of 555 watts appear to be misleading based on the technical analysis presented.
Tesladude
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Determining truth of "555 watt" amplifier board

My math is showing that this amplifier is not 555watts but 140watts at 8 ohm at +-36v and 555 watts when shorting the output with ground. What do you guys think?

amplifier board:
http://www.ebay.com/itm/High-power-7x-TDA7293-IC-in-Parallel-555W-Mono-Power-Amplifier-Board-Assembled-/121245748119?pt=US_Home_Audio_Amplifiers_Preamps&hash=item1c3acf4b97

IC datasheet:
http://www.st.com/web/en/resource/technical/document/datasheet/CD00001887.pdf
 
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The power is always directly proportional to the voltage.
So for +/-36V at 8 ohm we can get theoretical
P_max = 36^2/(2*8) = 81W RMS power. Of course in real life the power will be much lower in range of a 50W ...60W

And if you shot the output, the power dissipated in the amp will be equal to:

Ptot = 36V * 7*6.5A = 1638W (234 per TDA).
 
What do you get with all of them in parralel?

I found the internal resistense of the ic at max power, found what it is all at parralel and added the 8ohms and used v=ir and iv=w and got bout 140
 
Tesladude said:
What do you get with all of them in parralel?
Current, you increase output current capability.
Tesladude said:
I found the internal resistense of the ic at max power, found what it is all at parralel and added the 8ohms and used v=ir and iv=w and got bout 140
But this is wrong. This 140 has nothing to do with RMS power (continuous power).
To get 140W of a RMS power at 8 ohm you need √(8 * 140) = 33.47V but this is RMS voltage.
The peak voltage is 1.41 times larger. So your power supply voltage must be larger than +/-47.3V
 
Ok thanks, I think thatsall I need for now, thanks.
 
Why are you fixated on 8 ohms impedance?

555W from 7 chips is about 80W per chip. That is consistent with P0, in table 2.3 of the datasheet.
 

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