There won't be anything visible... If the other fella is going to bring an ohmmeter to verify, that will give you your final answer. There may be someone out there that can rewind a voice coil, you guys would know better than I. I've successfully rewound solenoids, same principal but not fun
So what amp did you have hooked to the woofer?
Thanks for asking, JeffW. It's Crown DC300A, which I've used for bass in the bi-amp mode.
And the Crown x-over is VFX-2 (attaced pic). When I hooked them up, I turned off the Hi Pass Hz off, only with the Low Pass Hz on, with x-over at x10, and 3.5 initially.
Do you have any clue if this amp might be the cause, along with the x-over?
I guess it could be either. If, for some reason, the X-over is passing a DC voltage to the amp, the Crown Amp will amplify that DC signal. On the other hand, the amp could have a DC voltage on its own. Again, a volt-ohm meter is priceless when using these things.
When Mark comes over with the multimeter, turn the gain knobs on the front of the amp all the way down. Disconnect any speaker leads and the x-over. Power up the amp with no input signal. Put the volt meter on "DC Volts" and connect it to the speaker terminals, one side at a time. It should read a few millivolts, hopefully less than 10~15mv.
If it passes that, go to the next step. If it fails, the amp probably needs service. I wouldn't want to see more than 25mV, but you can download the DC300A Service Manual Here
If it passed, then with the volt meter leads still attached, increase the gain knob and see what the amp does. It might go up a little, but should still be in the millivolt DC range.
Next hook the X-over up, turn it on, and see if that makes the DC at the speaker terminals increase. Start with low gain on the amp and go up.
What you want in all cases is for the DC voltage on the speaker terminals to remain very low. If you get more than maybe .1 volts with the gain all the way up, I'd say there is a problem in the x-over or amp.
Your speaker is likely fried. It looks like JBL kits are still available.
If you're comfortable with the amp, then just check the DC level on the output of the X-over first. I would expect it to be very low, but one of the features of some of the Crown Amps (and I think the DC300A was one of them) was the ability to amplify DC voltages. This is why they found service in industrial applications such as motor drives. If the x-over has introduced a DC voltage to the input of the amp, then the amp will faithfully amplify that voltage. And speaker voice coils absolutely hate any significant DC voltage.
Have you tested the woofer now that it is out of the enclosure? Battery test may help now that the switch is out of the way. If you smell the woofer behind the cone, does it stink? I used to work at Circuit City and we would take unsellable open box speakers over to the car stereo room and hook to the demo board's 12V power supply to render them truly unsellable. It was always accompanied by that pungent "Burnt electronics" smell - you know the one?
Yea, I took it out, and did the battery test. No movement of the cone either in or out, just like it used to. Actually I failed to smell the woofer even after all this happened yesterday afternoon, as I was not sure of the cause. A moment ago, I tried to smell the woofer behind the cond, and smelt some slight stink. The definitive conclusion among the forum members here is its voice coil was burnt out...
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