HELP: Do I Have a Blown Speaker?

[Soporific]

So I bought a JVM410C about a month ago and I've taken it to a rehearsal space a couple times now and I noticed today after a little while that when I hit a muted E power chord and let it ring that there was a buzz coming out of the back of the amp. It seemed to be coming out of the right side if you were facing the front of the combo. I talked to the guy at the local music dealership that sold it to me and he basically said, well if you turn it up to high you could have... Duh. So I asked him how much volume was too much because I thought these things were really supposed to sing at high volumes and he just said, what do you think sounds good. So I said LOUD! Anyhow, he was useless and basically just gave me the number to the local Marshall tech.

To continue, it almost sounds like I'm rattling the screen in the back or something like that, but I do believe that I also was pushing the speakers too hard at some point(s). How much volume is too much volume on these things? The first time I was loud with it I had the master at 2-3 o'clock and the volume at Noon. The second time I had the volume at 10 and the master about Noon. I like to hit the strings hard and heavily muted, but I don't think I've actually ever blown a speaker on other amps I've had. I also don't believe it's a tube as it sounds like a mechanical buzz. Sorry this is long, I'm just frustrated and unsure of how to proceed to figure out if this really an issue or just me being paranoid.

Thanks to anyone who responds.

~S

(cross posting this on jvmforum)

[Southbay Ampworks]

What Celestions are in the amp? Need a speaker name, power rating, ohm rating, etc.

[chaz]

Get the facts first. That said, I've had tubes rattle that bad that I thought it was the speaker. Not saying that's what it is, just that it's a possibility. Then you might test the speaker with another amp or have a friend touch and dampen the tubes while you recreate it to see if it's the cause.

[Soporific]

Southbay Ampworks:

The amp has a Celestion Heritage, and Celestion Vintage (both 75W I believe), I looked extensively online before and couldn't find the rating. I suggested 75W to the guy who sold it to me today and he agreed it "probably" was... I'm not sure of the Ohms I would think 8, wired parallel to get the individual sound of the speakers.

chaz:

I doubt I'll find a friend to touch a glowing tube. That said, it's my understanding that touching a speaker wire connected to an amp can cause a shock while holding a guitar. Does that basically hold true for anything in the back of an amp; not counting internal wiring? I wanted to touch the grill, back panel, etc. while I did this today but was concerned about giving myself a nice charge. A Princeton Reverb I had that was ungrounded (then fixed) used to give me buzzes when it felt so inclined so I'm a little paranoid.

Thank you both.

~S

[Southbay Ampworks]

At this point you need to have the amp & speakers checked separately by a qualified tech. Hope it's still under warranty. Good luck!

[Soporific]

At this point you need to have the amp & speakers checked separately by a qualified tech. Hope it's still under warranty. Good luck!

It should be, 5 year warranty on it.

Thanks again.

~S

[B-Rad]

That sounds almost exactly what happened to a speaker I had in my amp. I only really noticed it at low volumes because the rattling was drowned out at higher volumes. I pulled the speaker out and noticed that there was a scratching sound when I pushed the cone in and out. I guess this is what they call 'coil rub'. Basically, either the voice coil or the basket or something was warped from over-use and the voice coil was actually rubbing up against the magnet, causing the sound. Even though the noise was barely noticable, it would have eventually led to the death of the speaker if the coil had worn through.