troubleshooting a speaker

[rockyh]

Hi,
Our band has a monitor that somehow became quieter than the rest. I was checking it with a test tone CD and it was able to reproduce most frequencies ok, except 4K. It was almost silent at this frequency. It could reproduce 6k and 8k, but not 4k. I found this odd. It is a monitor with a 12" cone and 1" throat driver and passive x-over. Would this be a bad driver or did the x-over get messed up somehow?
Thanks

[rone]

It could be the tweeter is connected in the wrong polarity - switch the leads + for - and see if it fixes the problem. Be careful with test signals, you can fry most tweeters quite easily, even pro ones.

It is conceivable that some sort of physical damage or degradation of a crossover capacitor could have caused the problem, but more likely it is a wiring thing.

[davidld]

Swap the high frequency driver with the unit that currently works leaving the crossover in the unit that currently doesnt work. Then determine which unit doesnt work. If the high frequency driver and everything works in the 2nd unit and the 1st unit still has problems you will know its a crossover component in the 1st unit. Otherwise the high frequency driver is bad, and needs replacement.
If the crossover turns out to be bad in the first unit I'm betting the cap in series with the tweeter on the first unit is messed up. That repair is simple and inexpensive.
Since 4K is out of the range of a 12-inch woofer, its either the tweet itself or the crossover parts leading to the tweet.

> Hi,
> Our band has a monitor that somehow became
> quieter than the rest. I was checking it
> with a test tone CD and it was able to
> reproduce most frequencies ok, except 4K. It
> was almost silent at this frequency. It
> could reproduce 6k and 8k, but not 4k. I
> found this odd. It is a monitor with a
> 12" cone and 1" throat driver and
> passive x-over. Would this be a bad driver
> or did the x-over get messed up somehow?
> Thanks

[philip]

I believe the tweeter capacitor has changed values and may be nearing a total failure. It is an easy fix, not to much money.

> Hi,
> Our band has a monitor that somehow became
> quieter than the rest. I was checking it
> with a test tone CD and it was able to
> reproduce most frequencies ok, except 4K. It
> was almost silent at this frequency. It
> could reproduce 6k and 8k, but not 4k. I
> found this odd. It is a monitor with a
> 12" cone and 1" throat driver and
> passive x-over. Would this be a bad driver
> or did the x-over get messed up somehow?
> Thanks