Speakers turning into Lights?

[Ayliffe]

Hey everyone!
Right to the point here:

Whenever i get feedback, the top two speakers of my 610 light up. Literally.

I run a pretty hot setup, with a lot of gain, and a noise suppressor that doesn't seem to want to work. This is kinda scary, i'm starting to think they're gonna set ablaze or something.

Signal path goes like this:

Warwick Thumb BO (Only used passive), Whammy 4, Musket, Porkloin, VTbass, Boss Noise Suppressor into a Peavey Mark VI from the 80's (i think) into an Ampeg 610 HLF

It only seems to happen when the Musket starts to really get pissed off.

Any ideas what this is, how to fix it, or if it's a big deal or not?

Thanks in advance guys

[D1on]

There's a light bulb in line with the tweeter that acts as a fuse. not unusual

[Bardley]

That's probably a small light bulb that is sometimes used to protect high freq drivers (the horn). It lights up to protect the horn, like a fuse.

[Bardley]

Beat me to it.

[billfitzmaurice]

Originally Posted by Ayliffe

I run a pretty hot setup, with a lot of gain, and a noise suppressor that doesn't seem to want to work. This is kinda scary, i'm starting to think they're gonna set ablaze or something.

The light indicates that you're stressing the crossover and tweeter. Intermittent flashing and even a low level glow is OK, but a sustained bright glow can indicate you're on the verge of toasting the lamp, crossover or tweeter, or all of them.

It only seems to happen when the Musket starts to really get pissed off.

Then don't use it!

[jlepre]

What they said. Not uncommon, but pretty disturbing, it you've never seen it before.

[Ayliffe]

Ok Awesome! Thanks guys.

[fenderhutz]

Turn down the tweeter. Ampeg amps have a lightbulb for the tweeter circuit (much like a car headlight bulb). You are about to blow it.

Turn down the attenuator on the tweeter, a good bit.

It only happened to me when using a gain/distortion pedal. I had to almost turn the tweeter off.

[Bob Lee (QSC)]

It's a simple and reasonably clever way to protect loudspeaker drivers.

The resistance of a light bulb filament changes a lot with temperature. At room temperature the resistance is very low, and if you push the loudspeaker hard the increased current will heat up the filament, maybe to the point where it glows, and the resistance increases. That will resist current and thus help protect the voice coil(s).

When the signal decreases, the filament quickly cools back down, and its resistance goes back down, too.