Film-Tech Forum ARCHIVE: Dead Subwoofer

This is topic Dead Subwoofer in forum Film Handlers' Forum at Film-Tech Forum ARCHIVE.

To visit this topic, use this URL:
https://ft-forum.com/ft/cgi-bin/ubb/ultimatebb.cgi?ubb=get_topic;f=1;t=011449

Posted by Chris Daigle (Member # 7347) on 05-16-2013, 04:25 PM:

I have a subwoofer in one of our small auditoriums that died on us this week...no sound coming out at all. The dolby processor and the amp both checked out OK. When we put a meter on the sub itself it was open, no resistance reading at all. Its a single 18" OAP brand sub which we've had for about 10 years. We just ordered a QSC replacement, but was wondering if this sub was repairable to keep on site as a spare. A quick inspection didn't look like the cone was ripped or that there was any visible damage, but I don't know enough about speakers or electronics to even know what to look for. Its probably not worth shipping out to fix as the cost to ship plus the potential repair is probably more than just buying a new unit (coupled with the fact that I have no idea if this brand is even worth salvaging). Any advice or do I just have a new 50lb paper weight on my hands?

Posted by Michael Harlow (Member # 1353) on 05-16-2013, 05:55 PM:

Hi There,
I generally always, if i have time, dismantle something, may be a wire has come loose, maybe just a faulty connector.
It is highly possible that the driver has failed, but for the sake of a quick look....
Michael.

Posted by Randy Stankey (Member # 64) on 05-16-2013, 08:15 PM:

If you put a meter across the speaker terminals and it read as an open circuit, the speaker is cooked.

There is a possibility that one of the wires inside the cabinet that leads from the terminal block to the speaker tabs has come loose. If you want to be sure of that, take the speaker out of the cabinet and test it directly.

However, my guess is that it's a 90% chance that the speaker is dead.

It is possible to get a speaker rebuilt. I don't know the cost. You might just be better off getting a new speaker. It all depends. Even if the cost of rebuilding the speaker is cheaper, you'll have to remove it from the cabinet, send it for repair and wait for it to be returned before putting it back into service. Buying a new speaker gets you back into operation a lot faster.

One question to ask yourself: Why did that speaker blow?

Speakers don't "just" die. Something causes them to fail.
It could be a bad amplifier. It could be that your sound system is out of adjustment. It could be that your speaker and your amplifier were not a good match. It's too hard to say without more information but, no matter the reason, if you don't find out what the problem is, you could end up replacing the new speaker, too.

Maybe the speaker just gave up the ghost. It is possible. Rare but possible.

If you don't figure out what the problem is before you replace that speaker, you could end up throwing good money after bad.

Posted by Gordon McLeod (Member # 33) on 05-17-2013, 03:55 PM:

before hooking a meeter make sure speaker is disconnected from the amp