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How to Dimension a Power Supply for an Audio Amplifier ? (discuss.tchncs.de)

submitted 1 year ago by [email protected] to c/[email protected]

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Hi,

I recently bought a few pre-made amplifier modules for an 8-channel amplifier project (for a sound installation).

The amp is based on the TDA7294 chip and is rated 85W nominal. Now I'm looking for a power supply, but I'm a bit lost (this isn't really my strongest field, to put it mildly).

Do I just need to add up the output power, 8*85W = 680W, or could I get away with using something smaller, like a 300W or 300VA?

Also, the seller said that you need to use CV power supplies, CC won't work and kill the circuit. Does that mean a switching supply can't be used?

It looks like the module has a rectifier and smoothing caps integrated, so I could potentially just use a transformer, right?

Best, N

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[–] [email protected] 3 points 1 year ago (1 children)

There will be loss in the process so you should go a little above. You also need to account for the efficiency curve of your power supply: is it best efficient at 80% load? 90% load? Can it handle 120% momentarily in case of a spike?

CV power supplies are the standard: constant voltage. It outputs say 12V, and trips when overcurrent. A CC supply would limit current to say, 20A. It does so by dynamically adjusting the voltage output to match that target. That's a lot less common and usually used for battery charging or testing/troubleshooting. So, I guess, don't plug it on a battery charger.

It should come with specs as to what input it can take. Follow the recommendations. If it says DC give it DC unless you're absolutely sure of the circuit in there. The presence of a rectifier and caps doesn't tell you much given it's an amplifier, it could be part of the amp circuit for the MOSFETs and not its power supply.

[–] [email protected] 1 points 1 year ago

Well, it says to use a toroidal transformer between 12V to 32V output, and looking at pictures of other people who bought it, it seems to work on AC directly, so I have high confidence that that's what it is.