Solid State Combo Amp going BZZZZBOOMSLAHGHG

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AlecBeretz

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This is a recording website... but i figured I'd pick your brains before i go make another user account for an amp repair website or something.

I've got a Fender Frontman 212r. two 12 inch speakers, 100 watts. Solid state.

Anyway, when driving this thing to hell at high volumes one day, something gave out. When i crank the volume, it makes the speakers sound like they've been blown out. heavy distortion. ALSO, the little LED on it that tells you what channel you're on flickered, as if its power was getting interrupted with the vibrations of the loud amp.\

I started diagnosing the problem by putting it on the clean channel. Same problem. I took out all the bass EQ and it STOPPED, mostly. The speakers sounded clear as day, so I FIGURED it wasn't a speaker problem (unless speakers are built to have bass parts and treble parts... but i don't think so) it sounds like a digital distortion anyway, or a wiring problem, rather than a speaker problem. Its not a gradual distortion like you'd get if you were driving an amp too hard

I then bypassed the preamp and it still did it. I rattled the amp to see if there was a short and it buzzed and hissed at me. So i THINK something in the power amp section of the amp gave out.

Has anyone else encountered this? Why do you think is happening? Has anyone fixed it, or know how much it would cost? My issue is i payed $230 for this amp. if it costs close to that to repair i don't really want to bother since i would loose all resale value. Thanks!
 
You should take it to a tech for an estimate. Then decide if you want to trash it. Not easy to diagnose even with all the details you provided...
 
try to use another speaker.... I wonder if the speaker has gotten off center and shorts the output when at higher volumes. just guessing.

you need a good speaker to crank it up with...

if your going to throw it away anyway.... , <edit>.... I removed a comment of troubleshooting in case you arent familiar with repairs.>...

It might have a safety/circuit for shorts.
I used to have a power amp do that and it was a short that seemed to happen intermittently at the speakers.

as I understand it often the scratchy noises and crap we hear is the speaker has lost its "center" and the wires are actually rubbing on the magnet and being amplified as SSCSCSCCSCSZZZZZZSSSSTTTTTCHCHHHHCHHHCZZZZ

the removal of the bass means you arent making the speaker extend as far.....worth a shot! wht the help..! its already fuzz fried

Try some other speakers....



This is a decent article...
http://www.ehow.com/how_7767894_repair-short-speaker.html
Check internal loudspeaker wiring
1
Use a screwdriver to remove the largest driver on the loudspeakers. This will provide the easiest access to the internal wiring of the speaker.

2
Visually examine the wiring that runs from the each speaker to the crossover circuit board located inside each speaker. Short circuits can occur at any point inside the loudspeaker, but, most frequently, will be found on the connections of the individual drivers.

3
Check each driver in the loudspeakers for melted voice coils by pushing in on the speaker cone and listening for a rough or grinding sound. A driver with those characteristics is blown out and may be causing a short. Replace the driver with a comparable unit.
 
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The Frontman 212 is a pretty low-budget amp, for a 212. Fender's attempt to compete with Line 6 and similar, IMO. If it is not speakers causing the problem, you may find repairing it is not worth the money- most shops charge a bench fee of around $75- if you can get it repaired for that, or $100 at most, it may be worth the repair, but they sell for $300, new- so if it's gonna cost more than that, I'd just remove the amp and use it as a cab with a better amp. Not dissing your amp, or you- we all buy what we can afford and what works for us.

You can test the speakers by hooking up your home audio system to them- if that plays clean, the problem is not your speakers (yeah, I know this seems obvious, but just in case you missed it...)
 
bass makes the speakers move more, as Coolcat pointed out so even if a speaker has a problem, turning the bass off might make it seem like the problem went away.

However, generally a speaker problem won't make noise when you shake the amp.

My guess is that you've got a fractured solder joint in there and when you have the bass up, it vibrates the amp causing that joint to vibrate enough to make noise.
If you were a good enough amateur tech to fix this yourself, it's the kind of thing you would have already fixed so it'll have to go to a tech. Possibly an easy fix for a decent amp guy.

Whether it's worth it or not is your call but unfixed the amp is worth nothing so NOT fixing it isn't gonna do anything good for resale value either.
But one of those doesn't have a LOT of resale value regardless so this might be a time to get a better amp.
 
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