Determining truth of 555 watt amplifier board

Click For Summary

Discussion Overview

The discussion centers around the power output specifications of a "555 watt" amplifier board, specifically analyzing the actual wattage the amplifier can deliver at different impedances and conditions. Participants explore theoretical calculations, practical limitations, and the implications of using multiple amplifier chips in parallel.

Discussion Character

  • Technical explanation
  • Debate/contested
  • Mathematical reasoning

Main Points Raised

  • One participant calculates that the amplifier delivers approximately 140 watts at 8 ohms with a power supply of ±36V, suggesting that the advertised 555 watts is misleading.
  • Another participant presents a theoretical maximum power calculation of 81 watts RMS at ±36V for an 8-ohm load, noting that real-world performance would be lower, around 50-60 watts.
  • A different participant discusses the total power dissipation when shorting the output, calculating it to be 1638 watts, which raises questions about the amplifier's design and safety.
  • One participant emphasizes the need to consider RMS voltage when calculating power, arguing that to achieve 140 watts RMS at 8 ohms, a higher supply voltage of ±47.3V is required.
  • Another participant questions the focus on 8-ohm impedance, suggesting that the output per chip aligns with the datasheet's specifications, indicating a potential misunderstanding of the amplifier's capabilities.

Areas of Agreement / Disagreement

Participants express differing views on the actual power output of the amplifier, with no consensus reached on the validity of the 555-watt claim. Multiple competing calculations and interpretations of the amplifier's specifications remain unresolved.

Contextual Notes

Participants reference theoretical calculations based on the amplifier's datasheet and discuss the implications of using multiple chips in parallel, but there are unresolved assumptions regarding the amplifier's design and real-world performance limitations.

Tesladude
Messages
168
Reaction score
1
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
 
Engineering news on Phys.org
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.
 

Similar threads

Need help with a 12 watt Audio amplifier
  • · Replies 13 ·
Replies
13
Views
7K
How do you read the ratings of a relay?
  • · Replies 4 ·
Replies
4
Views
4K
How Can I Safely Control an Electromagnet with a Microcontroller?
  • · Replies 7 ·
Replies
7
Views
15K