TS808 clone burns marshall's celeston speaker?

[mugan]

Hi, i'll tell a strange thing that has happend to me today.

A friend of mine was trying my ts808 clone in a chain like this:

epiphone les paul classic - ts808 - boss hyper metal - marshal combo 100w valve state.

After playing for 3 hours and half the amplifier muted down. So i removed the panel behind the speaker discovering it was very very hot! I placed a fan over it and after a hour of rest it worked again, with a little loss of sound quality. The amplifier was 4 years old.

Did someone had the same experience? I'm afraid that there's something wrong with my stompbox (even if it sounds great   ).

[RDV]

That's amp troubles my friend.

RDV

[R.G.]

You say "the speaker". Is this the only speaker attached to that 100W amp? Is the amp able to put 100W into 8 ohms? If so, is the speaker able to handle 100W without melting down?

You may have simply overpowered the speaker.

If the amp can put 100W into a single speaker AND the speaker can handle 100W, I would instead suspect that there's something wrong with your amp. The amp could be oscillating, or have a DC offset that is frying the speaker.

There is no reason in what you say to suspect that the effect caused this until the stuff mentioned above get excluded.

[mugan]

thank you for answering so quickly!

R.G., the amp is a marshal combo never modified, it's 100 w (a think it's the maximum power handled by the speaker).

But... using 2 distortions plus a little of gain may be too much, right?

[petemoore]

First thing I'd do is figure whether it's in the speaker or the amp.
 Do you have another speaker or amp to test with?

[Ed G.]

If that amp was cranked and the pedals' output was also cranked it could send the solid state power amp into clipping. When solid state power amps clip, it's real easy to damage speakers.

[brett]

Sorry to hear of your misfortune.

If so, is the speaker able to handle 100W without melting down?

I don't know much about amps and speakers, but I think that you need to be careful about different waveforms.  With a sine wave, the amp might clip the tops of the signal at 100W, while a square wave might sound fine at the same wattage because it has smaller peak voltages (0.7 of sine peaks).  Also, with any electro-mechanmical device like a speaker, the transients of a sine wave are going to be easier to follow than the craziness of a clipped waveform.

[Ed G.]

Did a little more research and I still really think that what happened was the output volume was cranked on one or both of those pedals, which clipped that Marshall's solid state power amp, sending DC directly into the speakers. This doesn't happen with tube amps, btw. I found this on the JBL web site:

"When an  amplifier receives an input signal capable of driving it beyond its power rating, the result is clipping. This means that the negative and positive peaks of the amplifier's output signal are "clipped" off. The amplifier may also clip in an asymmetrical fashion, meaning that the positive side of the signal is clipped more than the negative (or vice versa). When subjected to an asymmetrical clipped waveform, one end of the loudspeaker's voice coil is "on average" spending more time outside of the gap (corresponding to the direction that is clipped) than the other. The end of the coil that is spending more time outside of the gap has poor heat transfer to the magnet structure. As a result, it overheats and burns. "

So if you take apart your speaker and find that your voice coil is burnt at one end, that is likely what happened.

[mugan]

OK, i'll check the coil, thank you for helping.

[petemoore]

Hard to say without being there..I'd check the speaker sound before tearing open to see the coil...unless you're certain the speaker is bad.