Wierd "woofing" sound from amp?

japetus

japetus

Moderator
I got back from recording earlier and we ran into a problem that I have never encountered. We were using a JCM800 2203 through a JCM cab with g12-65's. I was not playing that loud at all, maybe 2 on the volume, when the cab started making this "woofing" sound, almost like the speakers were bottoming out. I turned it all off, and switched heads to see if the speakers were messed up, and everything was fine. I then plugged the 2203 into a Rivera 4x12, once again not loud at all and there was that woof woof sound again.

I decided to replace all the tubes to see if it helped...nope. It doesn't seem like it's losing power at all, volume is not going up or down but there is just that WAY bassy overtone sound. Anyone have any ideas? Thanks.
 
you changed the preamp and power tubes? that is a weird problem and it sounds like it devolped and wasn't already there.?
 
Okay update, I decided to really get headfirst into this problem, so I plugged it in to get a sound clip of the sound and...it's not doing it anymore. I played it for 3 hours straight, nothing. So, so wierd. If it does it again, I will make a sound clip....
 
Does it do it all the time or only when you play specific things? Any chance of getting a clip / video?

I’ve had something similar to a woofing type sound twice. First was when the power tubes were going out in an amp and it was a constant, but I see you mentioned changing the power tubes.

Second time was with a 5150, d standard tuning, and oddly enough partly muting the strings and striking the 4th and 5th string open. It would start off sounding normal but all the sudden the low end would just take off and woof / rumble regardless of volume. Fix was tweaking the low / resonance settings on the amp slightly and then tightening down the back panel of the cab and the terrible sound went away. I’m pretty sure the back panel of the cab was loose and rattling
 
Inearthed":3chv3gzn said:
Does it do it all the time or only when you play specific things? Any chance of getting a clip / video?

I’ve had something similar to a woofing type sound twice. First was when the power tubes were going out in an amp and it was a constant, but I see you mentioned changing the power tubes.

Second time was with a 5150, d standard tuning, and oddly enough partly muting the strings and striking the 4th and 5th string open. It would start off sounding normal but all the sudden the low end would just take off and woof / rumble regardless of volume. Fix was tweaking the low / resonance settings on the amp slightly and then tightening down the back panel of the cab and the terrible sound went away. I’m pretty sure the back panel of the cab was loose and rattling
Click to expand...

This was the first time I had ever heard it happen, and I have been playing this amp on and off for over 15 years. Just so, so wierd. It wasn't like a resonance cab woof, I know what you are talking about as far as that. If it does it again, I will record it but...frankly I hope it doesn't. I almost wonder if something crazy was going on with my power, but the other amp worked fine.... :scared:
 
i am going to say to tighten the screws. could be flex from the back of the cab from not being tight on with the center stud. also tighten the speakers to the cab.

i had that happen once.

the worst that can come from my advice is five minutes of time wasted.
 
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