Can I destroy the Amp V4 with 24v power supply with 4 Ohms speakers?

DIY Products&Projects DIY Product Questions
1

The spec says:

  • 2x50W @ 4ohm load at 21V
  • 2x30W @ 8ohm load at 24V

I will use 4 ohms speakers load and wonder if the board would have a problem if I plug my 24 V DC power supply (?)
Or will the board limit the power to 50 W? Or deliver more than 50 W? Or, should I buy a 21 V power supply?

Thanks for your support

2

As far as I know there is a lot of debate on whether you can destroy speakers by over-powering them. In my opinion, this could happen if there is a huge mismatch between the output wattage and the speakers’ maximum wattage. However:

  • This may only happen if you pump up the volume to max. If we are talking about 2x50W I would rather worry for my eardrums, not the speakers.

  • When over-powered, speakers will distort and you will be aware that you leave the “comfort zone” of the speakers.

  • Except for short spikes, the amp cannot provide more power to the speakers than provided by the power supply. For example, if your 24V power supply can provide 4A of current, the amp cannot provide more than 100W to the speakers. Therefore, unless your power supply is really overdimensioned you should be on the safe side.

If I were in your shoes, I would not worry about this 21V vs. 24V thing. Rather, I would be happy to have a 24V power supply to have some reserves. I power my arylic 2.1 amp with the used power supply of a notebook (21V/4A) and I’m still angry that I could not find a 24V/4A one :wink:.

1 Like
3

Thanks for your interesting points :slight_smile:
It’s true that with a music source , there is a big difference between electronic theory and reality.
Computing the max RMS power for a class D amplifier doesn’t seem that simple also.
I couldn’t find clear articles on the way to compute it… and I struggle to understand if the announced power is RMS or music or other.
The key will be to filter the bass frequencies thanks to the Amp v4 dsp, in order to ensure that the speaker excursion (xMax) remains bellow its limits.

4

@EthanEsrah

I think the issue is a bit more complex, overloading increases the heating and harmonic distortion, which can put an extreme load on the coils of the speakers (practically the sine wave starts to distort in the direction of the square signal, which can damage in the speakers on fraction of the rated power). Lower supply voltage may limit the
output power.

5

The spec is measured with testing device in extreme condition. For example, input 1KHz 0dB sine wave signal with max volume. It’s used as a reference. And back to the normal condition, for A50 device, you could use 24V with 4Ohm load, but the device might enter protection mode in some condition with over current.

6

I would consider it an extreme load to operate under normal conditions (eg listening to music enriched with high-energy deep sounds (50-80Hz) at high volume - eg house party mode), especially if it is coupled with distortion (the sine wave is distorted into a square waveform). This also greatly increases heat production.