Determining truth of 555 watt amplifier board

[Tesladude]

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

 

[Jony130]

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).

 

[Tesladude]

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

 

[Jony130]

What do you get with all of them in parralel?

Current, you increase output current capability.

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

 

[Tesladude]

Ok thanks, I think thatsall I need for now, thanks.

 

[AlephZero]

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.