No bass from one of my cornwalls

[asmosis]

trying to troubleshoot a problem with a Cornwall II speaker. There is no bass from one. I've tried testing the horn and the sub directly. The horn sounds just fine, but when I test the sub directly with the speaker wire there is sound, but no bass being produced. Is the subwoofer needing to be replaced, or is something else the matter? Thanks for any help.

T

[WMcD]

My guess is that you have a voice coil which is damaged and binding in the gap of the magnet structure.

I believe you can get to the front of the diaphragm of the bass unit by taking off the grill. Take the grills off both units.

Try pushing on the diaphragm with an open hand and move it about 1/8th of an inch with light pressure. My guess is that the "bad" one will feel jammed or gritty and the good one will move freely with a little spring to it. A good A - B test.

If you find binding, the driver will have to be replaced or reconed. We here usually refer to Bob Crites or 1-800-KLIPSCH for replacements.

Very often with speaker drivers, the voice coil fails electrically and there is no sound whatsoever. It tests bad (infinite Ohms with a multimeter).

But if it warps mechanically, sometimes because of long term overdriving and heating, the voice coil former (bobbin) warps and jams in the gap. High freqs still cause some small movement but the mechanical jam prevents the long excursions necessary for bass. The voice coil resistance still tests good with a multimeter (about 4 ohms for that unit).

I've read that sometimes a unit is dropped with some violence and this gets the precise ring of the gap to be displaced causing a similar binding problem.

Do you know anything about the history of the units? Part of troubleshooting is what happened just before the problem developed

Wm McD