What's Wrong with 4343 Woofer?

[pyonc]

If his system is setup for Biamp, he should have just the Woofer leads coming out of the back of the system somewhere, right?

Unless the biamp switch has failed and completely removed the woofer out of the circuit somehow, can't he use a regular 1 1/2 volt battery (a single AAA, AA, C or D-cell) and, with a short piece of speaker wire, briefly connect the battery across the woofer leads and get a thump to verify the woofer is still useful??

I mean just the basic go - no go test?

Thanks. I just tested a regular AA battery, with both black and red leads on their ends.
I don't see the cone moving out or in as it used to do so before...

[pyonc]

He could use a battery Heather, I prefer an ohmmeter because it limits the current although a small battery isn't likely to do any harm. But a battery won't tell him if it's shorted or open (open being much more likely). I'd pull the woofer (4 screws IIRC) so that you can double check the remote possibility of a loosened connector. In any event methinks it's a toasted woofer

Yea, Paul. I'm just as sad as you're at the moment. All to blame myself. I'm going to pull out the woofer to check it by my own eyes, and report back.

[PaulB]

Yea, Paul. I'm just as sad as you're at the moment. All to blame myself. I'm going to pull out the woofer to check it by my own eyes, and report back.

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

[pyonc]

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

Thanks, Paul.
Please take a look at the pics of the troubled woofer.
To my eyes, I don't see anything wrong on the surface ...
The burnt voice coils are inside, right?

[PaulB]

Thanks, Paul.
Please take a look at the pics of the troubled woofer.
To my eyes, I don't see anything wrong on the surface ...
The burnt voice coils are inside, right?

Correct, the photos tell you nothing...

[JeffW]

So what amp did you have hooked to the woofer?

[pyonc]

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?

[JeffW]

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.

[pyonc]

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.

Thanks much for your kind explanation. I think I've paid a big price for trying this vintage X-over that I'm not so familiar with. I've had no issue with this Crown amp when I used it with JBL M552 or Ashly XR1001.

[JeffW]

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.

[John]

Hi, all,

Please give me your diagnosis and solution. And this is what happened:

I was trying to test vintage Crown VFX-2 crossover for 4343 this afternoon.
I hooked all the input and interconnect cables, only turning on the loss pass Xover switch, with the high-pass swtich off. When I did so, I heard some sort of strange
audible noise coming from the woofer (2231A) of the right speaker initially, and it disappeared. I didn't hear that from the left woofer.
When I did it the second time, I heard the same. Now the problem was since that happened, I could not hear any bass from that right woofer. What's wrong here? Any way to fix it by myself? Please help me out!!! At this point I just regret toying with this old Crown X-over, not knowing fully about its function...

When you say strange noise, was it more like a huge thump and then silence? Or did it sound like 60 cycle hum, kind of loud and then nothing? Does the cone have movement with no scraping?

[HCSGuy]

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?

[pyonc]

When you say strange noise, was it more like a huge thump and then silence? Or did it sound like 60 cycle hum, kind of loud and then nothing? Does the cone have movement with no scraping?

Thanks. It sounded more like the latter, but with that peculiar sound of something burning, then fizzling out, which was audible to me. When I heard it, I turned off the Loss Pass switch. When I turned it on, then I heard the same sound, and no more since then.

[pyonc]

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...

[Eaulive]

The definitive conclusion among the forum members here is its voice coil was burnt out...

I hate to say it but I agree