# Running receiver with no load - safe?



## grn1969c10 (Sep 18, 2008)

So far, I have connected the REW output directly to the sub or used the multichannel input for the sub on the back of the receiver. Both of these methods bypass the crossover used by the receiver. Someone suggested in another thread that the REW input could be connected to an AUX IN on the receiver and the mains disconnected to allow the sub to be isolated for measurement with the crossover rolloff.

I was under the impression that running a stereo amp with no load could possibly damage the unit! Is it safe to crank it up with no front speakers? My tx-ds575 is old, but I don't want to bury it yet by doing anything dumb.


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## Anthony (Oct 5, 2006)

Amps are only strained when they have a load. An open condition is like an infinite resistor to them. All voltage, no current.

I don't even have a center channel hooked up to the fifth channel in my amp, it's open all the time. And many people like me use a receiver as a preamp and just don't use the amplifier channels on it. They are still fine. So no worries there.

The method you described is perfect for testing the effects of the crossover on the sub. You can make sure the point and the slope are what you thought they were (and later confirm that the mix with the mains is proper as well by testing the whole system).

Good luck and welcome to the Shack.


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## brucek (Apr 11, 2006)

> Amps are only strained when they have a load. An open condition is like an infinite resistor to them. All voltage, no current.


Yeah, solid state amps are fine without a load.

The trepidation people have about this was born in the tube amp days, where the no load condition was a real no-no. The output transformers on the tube amplifiers required a low impedance load. Without it, the transformer could easily overheat and melt the windings.

brucek


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## grn1969c10 (Sep 18, 2008)

Thanks a lot for the info. I'm sure that feeling of trepidation resulted from my dad fussing at me 25 years ago as I attempted to ruin all of his gear. (In the name of science, of course!)
My front door is open in anticipation of the big brown trucks arrival. With a wider assortment of cables and adapters, I should have a bit of fun with REW this weekend!


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