What can cause a blown speaker?

[emilio]

Hey guys, I got a job at a bar recently and I've experienced a couple of problems lately.

First problem was a blown speaker in an amplified baffle. We connected a mic into a mixer then to the speaker. Worked fine one night, the next, it was clipping so we lowered the gain until it clipped slightly and had the faders at 0 and the level in the baffles at unity. Eventually one of the speakers blew and the baffles were only at half the full power they put out.

Second problem that we encountered was a tube amp who's power tubes wouldn't light up, but the preamp tubes and all of the lights on the amp did. Checked all fuses and they were fine.

The third problem was last night when an amplifier at volume 6 started smell like something was burning. We powered it down and it worked fine for about half a minute until it smelt the same and eventually no sound came from the amp. Checked the speaker and its ohm reading went from "8" to 1.2.

My question is: is there something wrong with the wiring of the bar, are we very unlucky, or are we just stupid?

[zzmoore]

Re: What can cause a blown speaker?

Fixing things via The Internet is fraught with difficulty.......
I doubt the bars Mains Wiring is causing this.
Typically the only "thing" that blows a speaker is too much power. Do you know the history.? If not, who knows what abuse they may have suffered in the past.....just waiting for you to come along.
8 to 1.2. That is an odd reading.....Can you pull at least One Wire form the speaker and measure again.?
Sounds like you need a decent sound guy to check out the PA in said bar.

Many amps use different feeds for the heaters. It is not uncommon for the power tubes and preamp tubes to be on different power supplies.
I just worked on a Genz Benz with that same problem. If you cannot pull the chassis and check it out, you may need a tech. Sounds like you guys have A LOT of issues to deal with.
Good Luck and be careful.