Friday night, the woofer in an old EV FM12-2a let go. I'm in the process of doing a postmortem and am looking to do an analysis of cause. What I do know so far is that it is the original EV 12'' speaker, something is rubbing on the magnet, and the voice coil is open. Cone is intact and still attached to the vc, and spyder is intact.
A couple questions, if you please.
I'm assuming I can have the speaker reconed - providing any parts are available for this dinosaur. Any recommendations? Places to stay away from?
As an alternative, I can replace the driver. I doubt seriously I can find specific part-number replacement. How would I go about determining what replacement driver (EV or aftermarket) would be appropriate?
Now, back to the postmortem - and cause.
Of course, everything is 30+ years old. I'm assuming these things just don't fail with age unless the spyder or cone become damaged or disconnected.
Do speakers give any indication of an impending voice coil failure? I'm guessing if it is heat related, the vc would begin to pull apart and start scraping the magnet.
I'm relatively sure heat was not the primary issue as we use it on a small stage at relatively low volume. The failure was within the first five or ten minutes of the beginning of the show.
Now, big mistakes have been made with the speaker over the years - feedback and pops from hot plugging various inputs with the channel open.
Now I did make some mistakes that night as well - significant popping when guitarist plugged and unplugged active DI with the channel open - series of five or so as he went through the process during setup.
After the first song, they were asking for more monitor volume - Django-type guitar with mic and pickup. I brought the volume up and immediate feedback - nothing horrible, but louder more than I expected. I cut all channels but the one with the pickup, and tried again, Same same. It seemed that if I breathed on the monitor volume it would go into immediate louder than expected feedback - and would stop as quickly - almost like an on-off switch. Finally all I got was a weak high signal and lots of hiss. Woofer was toasted at that point.
The amp processing the signal was a Crown XLS 202 - which worked fine with replacement speakers.
So - will a pop or series of pops cause the voice coil to open or start scraping the magnet? Could pops overheat the coil? (I don't think so) Could repeated feedback (one second max) overheat the coil or cause it to open?
Lots of questions - hope I have provided enough info.
Thanks in advance,
frank
edit first song instead of first set...
A couple questions, if you please.
I'm assuming I can have the speaker reconed - providing any parts are available for this dinosaur. Any recommendations? Places to stay away from?
As an alternative, I can replace the driver. I doubt seriously I can find specific part-number replacement. How would I go about determining what replacement driver (EV or aftermarket) would be appropriate?
Now, back to the postmortem - and cause.
Of course, everything is 30+ years old. I'm assuming these things just don't fail with age unless the spyder or cone become damaged or disconnected.
Do speakers give any indication of an impending voice coil failure? I'm guessing if it is heat related, the vc would begin to pull apart and start scraping the magnet.
I'm relatively sure heat was not the primary issue as we use it on a small stage at relatively low volume. The failure was within the first five or ten minutes of the beginning of the show.
Now, big mistakes have been made with the speaker over the years - feedback and pops from hot plugging various inputs with the channel open.
Now I did make some mistakes that night as well - significant popping when guitarist plugged and unplugged active DI with the channel open - series of five or so as he went through the process during setup.
After the first song, they were asking for more monitor volume - Django-type guitar with mic and pickup. I brought the volume up and immediate feedback - nothing horrible, but louder more than I expected. I cut all channels but the one with the pickup, and tried again, Same same. It seemed that if I breathed on the monitor volume it would go into immediate louder than expected feedback - and would stop as quickly - almost like an on-off switch. Finally all I got was a weak high signal and lots of hiss. Woofer was toasted at that point.
The amp processing the signal was a Crown XLS 202 - which worked fine with replacement speakers.
So - will a pop or series of pops cause the voice coil to open or start scraping the magnet? Could pops overheat the coil? (I don't think so) Could repeated feedback (one second max) overheat the coil or cause it to open?
Lots of questions - hope I have provided enough info.
Thanks in advance,
frank
edit first song instead of first set...
