BillFitzmaurice.info

Is there a way to accurately test a used amp with out hooking it up to speakers to
make sure you are not getting a piece of junk?

An RMS voltmeter and a test tone generator for solid state amps, but not on tube amps. Most tube amps require an output load. Plus, this will not tell you if the amp has any noise in the chain.

You can make a dummy load from these.

http://search.digikey.com/scripts/DkSea ... T200-25-ND

http://media.digikey.com/photos/Hunting ... 200-25.JPG

Set two in parrallel and adjust them to equal 13 ohms each and they will give you a 400 watt 6.5 ohm static dummy load for under 50 bucks. I would highly recommend you mount to a heavy wooden base and use no paint. Mounting to any type of metal would require some sort of heavy duty high heat insulators like ceramic standoffs etc.

With a high current dummy load you can use SMAART or another RTA type program that has the coherency capabilities. You simply compare the noise signal sent through the amp to the original noise signal generated by SMAART.(of course it will be necessary to pad the amps output reading with a series resistor or perhaps go through a D box that accepts speaker level signals. Thats what I generally use. My old DOD direct boxes work well for this.

You will immediately see if there's any difference in output between channels or non linearity's that exist when the amp in outputting the signal!

Thanks, that is what I was looking for
R