Load power rating for testing 1kW amps?

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.

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?

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.