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1982 Belle tweeters


lkahn

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Allright guys, here's a puzzle. The tweeter on one of my old Belles wasn't working. I checked out the binding posts and all the connections on the crossover. I took one lead off each of the woofer and squawker so I could hear when and if the tweeter began working. I figured that I'd reverse the leads on the CROSSOVER side of the tweeter (not the tweeter side of the binding posts; don't ask me why I thought this might help) Of course, once I had disconnected the red/red to the red post, and connected the red/black lead to the red post, the tweeter began playing perfectly. This is with either the red/red hanging in the air and nothing attached to the black lead, or the red/red attached to the black. HUH? I'm attributing it to tunneling. It sounds good but I'm wondering if it's an unstable load to the amp, or if the tweeter is out of phase. What do you think? Thanks. LK.

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It sounds it is coincidence that reversing the wires makes it work. What happens if you put them back into phase? Does it still work? I suspect it will. If so, there is a faulty connection somewhere. Either a broken wire in the tweeter wiring, or something on the crossover that you bumped into and made work temporarily.

I don't know why any driver plays with only one wire connected.

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I'm not sure at all what is going on. It is tough to tell without a schematic and also knowing where the wires are going. The schematic may not descibe some "sneak" circuits.

Obiously, the tweeter is good and stopped working while connected to the crossover.

Is there some chance there is a tweeter protection device which opened up permanently? My very limited understanding of the devices is that usually heal, after a while, so this may not make sense. It might, though, account for the good tweeter not working while connected in an orthodox arrangement.

Disconnecting wires at the crossover side of the barrier strip could have caused a sitution where one side of the tweeter is still connected to a real ground back before the tweeter network. Also, if this is a third order tweeter crossover, and a ground point is lifted, then it would be possible to create a circuit through the first cap, down the center inductor, and to what would otherwise be a ground on the output to the tweeter. Complicated to explain. I'd love to be there to help.

Bob G. had pointed out the danger of disconnecting drivers when there is a second order circuit (like you've done with the mid and woofer). With the resistance of the driver removed, a second order circuit forms a series resonant circuit which at some frequency, forms a short circuit, or nealy so to the amp. So be careful.

Please let us know the model of the crossover. Is is an AB? Someone should be able to post a schematic. Then you can dope out the circuit and what is going wrong.

Best,

Gil

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