Bad tweeter?

[Guest eratosthenes]

I have a pair of AR-4x that I am working on restoring. I strongly suspect the one tweeter is bad. It exhibits as a 'sizzling' noise. Very annoying. The noise goes away if I apply pressure to the edge of the diaphragm. Is there any way to deal with this without replacement. I have already installed a new crossover cap. The old one was worn out and there was no sound to the tweeter at all. The control pot has been bypassed. I will be cleaning it and putting it back into play. The speaker appears to be approximately from 1972 (date on the drivers) and a #5 coil.

[Carlspeak]

>I have a pair of AR-4x that I am working on restoring. I

>strongly suspect the one tweeter is bad. It exhibits as a

>'sizzling' noise. Very annoying. The noise goes away if I

>apply pressure to the edge of the diaphragm. Is there any way

>to deal with this without replacement. I have already

>installed a new crossover cap. The old one was worn out and

>there was no sound to the tweeter at all. The control pot has

>been bypassed. I will be cleaning it and putting it back into

>play. The speaker appears to be approximately from 1972 (date

>on the drivers) and a #5 coil.

Sounds like a bad VC. Suggest you get 2 new ones from AB tech. I got one recently and it looks and works very well. Don't get just one. There is a significant difference in the efficiency between the new and old one.

Remember, it's all about the music

Carl

Carl's Custom Loudspeakers

[RoyC]

If the pot is completely by-passed, the crossover point has been lowered, and the tweeter is receiving much more current than originally intended. The 4x tweeter was crossed over rather low with only a series 20uf cap serving as the tweeter circuit.

If, as Carl suggests, the voice coil is bad, that by-passed pot probably contributed significantly to its demise.

If you are lucky, the buzz may go away when you restore the pot.

Roy

[Guest eratosthenes]

Thanks for all the info. I installed a fresh crossover cap and cleaned the adjustment pot before wiring it back into circuit. Unfortunately, the 'sizzle' is still coming from the tweeter. The sizzle goes away if I apply the lightest pressure to (any) side of the cone. I know any modification of the tweeter will change its characteristics, but I am willing to try anything to keep the tweeter going until I can find/afford a replacement.

[charger3834]

The tweeter is shot. I had a AR-4x tweeter fail in this way many years ago. It was a result of a clipping amp; there is nothing inherrently wrong with the design. The good news is that those tweeters are very affordable and available on ebay.

That driver was in fact a very good design. It was very wide in dispersion and it facilitated a 1200 Hz crossover. The entire system had very flat power response.