Originally Posted by lonestarwings
when I play a measurement sweep above about 80 db or so, I get a weird doubling of the tone from about 1200-2000 hz. It sounds like a loud lower harmonic almost as loud as the fundamental.
I was wondering if this sound could be an indication of a damaged midrange?
Rather than a sweep tone, use a fixed frequency sine wave. To do so, turn on REW's Generator tool. Select sine wave. Set the frequency near the problem area, say 1500 Hz. Set the volume low on the AVR, and activate the sine wave.
The tone should be free of distortion at low levels. If not, fix that first.
Gradually advance the loudness. At some point you will hear the added harmonics appear. Leave the volume so you can hear the distortion. Gently touch the cone of the midrange driver. If the harmonics stop or change, you have found the problem driver. If not, move your finger around the driver to see if you find anyplace that changes the sound. If nothing happens, try the tweeter. This is more delicate so be extra careful.
If you do confirm that slight diaphragmatic deformation induced by calibrated fingerwerkin alters the distortion, it means the driver is rubbing something, usually the voicecoil former vs the magnet. New driver is indicated. Been there, fixed that.
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