Load power rating for testing 1kW amps?

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My understanding is that most of the tests don’t run on max power and those that drive the amp to the max power output do it for a relatively short time, so I believe don’t need a 1kW resistor to analyze a 1kW amp. What is the workable load power rating for testing amps up to say 1kW? I have the QA401 if it matters.

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Take a look here, https://quantasylum.com/blogs/news/basics-power-amps the QA40x does chirp measurements that last a few milliseconds. If you use “pulse withstanding” resistors you can put in more power than their power rating for a short time and still stay within their safe operating limits.

Don’t make the mistake I did: set-up for a chirp measurement and play a 1kHz continuous tone instead :face_with_peeking_eye:

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I read that article and it wasn’t immediately clear to me how to translate those calcs to basic load resistors like those from Parts Express. I suspect if I use 4x100W 4Ohm resistors to build a 4Ohm load it will work for a 1Kw amp measurements, but can I use smaller resistors? Is pulse withstanding something that’s usually specd?

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I think that would work but is probably overkill - I think you could get away with one of these for short pulses.

I cannot find the energy rating for these types (assuming the standard aluminium heatsink resistors) but a similar type is the Ohmite 280 it can handle 10x the rating for 5 seconds (see datasheet Res 280 | Ohmite Mfg Co). So 100W resistor is rated for 1kW for 5 seconds.

This is a list of Ohmite’s surge energy (pulse withstanding) resistors High Energy Resistors - Pulse Withstanding & Anti-Surge Resistors | Ohmite Mfg Co you can play the game for what’s in-stock and price and probably get a compact and low cost solution.