My Classic 30 makes a weird "pounding" sound when I play sometimes. It sounds like, well...pounding! It's pretty loud, so it definately needs to be fixed. It this a tube or speaker problem?
Gibson Vintage Mahogany LP
Line 6 Echo Park
Peavey Classic 30
Seagull Entourage Mini Jumbo
Vox V847A Wahwah pedal
I think your input jack maybe is a bit loose..
Squier Standard Telecaster.
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Maybe it's your neighbor pounding on the wall every time you crank it up.