Speaker pop causing feedback?

JJT247 · #1 12-17-2011, 05:52 PM

Hello, I purchased the mesa boogie powerhouse 2x12 new and by accident my friend pulled out the cable while the amp was on.
There was a pop noise in the speaker.
After that, I was noticing bad feedback. Could that have caused the feedback or am i just getting paranoid? If not, what can cause bad feedback on this amp?

**B-string** · #2 12-17-2011, 06:07 PM

What amp head are you using to drive the cab?

JJT247 · #3 12-17-2011, 06:12 PM

Orange Terror bass 500 watts

JJT247 · #4 12-17-2011, 06:21 PM

The only thing the i physically want to know is if the speaker pop i heard can cause feedback in the amp

**B-string** · #5 12-17-2011, 06:22 PM

Maybe just coincidence? You do have a preamp tube in there (12AX7) and feedback is common to a failed preamp tube.

**B-string** · #6 12-17-2011, 06:23 PM

Quote:

Originally Posted by JJT247

The only thing the i physically want to know is if the speaker pop i heard can cause feedback in the amp

Not likely with a SS output amp, if it was tube output yes.

JJT247 · #7 12-17-2011, 06:28 PM

This is a new amp just picked up from the store - could the preamp literally be not working?

**B-string** · #8 12-17-2011, 06:39 PM

Quote:

Originally Posted by JJT247

This is a new amp just picked up from the store - could the preamp literally be not working?

New production tubes are not up to the build quality of the stuff 40 years ago. They are getting better, but early failure is not uncommon and that is where warranty covers you.

JJT247 · #9 12-17-2011, 06:55 PM

That really sucks, I guess il have to return it

**B-string** · #10 12-17-2011, 07:35 PM

Take it in for warranty service if you liked the sound of it. It is a problem that can happen with ANY new amp that uses tubes. Not a constant occurring problem, but you got the "luck" of the draw.

onosson · #11 12-17-2011, 07:50 PM

Quote:

Originally Posted by B-string

Not likely with a SS output amp, if it was tube output yes.

I had an Eden WT400 which has a 12AX7 tube in the preamp and solid state power stage. The first gig I used it on, I was getting serious feedback problems in between playing, I had to turn the volume on my bass to zero every time we stopped a song. I changed the tube, and the problem was completely fixed. Not sure how that relates to "speaker pop", but you should check the tube I would think.

billfitzmaurice · #12 12-17-2011, 08:38 PM

Quote:

Originally Posted by JJT247

The only thing the i physically want to know is if the speaker pop i heard can cause feedback in the amp

It could have damaged the output stage of the amp by shorting the output when the jack was pulled. Eliminating this potential is one reason why Speakons should be used.

**B-string** · #13 12-17-2011, 09:06 PM

Quote:

Originally Posted by billfitzmaurice

It could have damaged the output stage of the amp by shorting the output when the jack was pulled. Eliminating this potential is one reason why Speakons should be used.

Class D should be tolerant of short term faults. Is it possible maybe to self oscillate with a switch mode output? Class D is too new for my training.

billfitzmaurice · #14 12-17-2011, 09:08 PM

Quote:

Originally Posted by B-string

Class D should be tolerant of short term faults.

I'd expect so, but you never know. The OP started having problems after the incident, and I don't believe in coincidence.

craig.p · #15 12-18-2011, 04:26 AM

First thing I'd do would be to toss that speaker cable your friend tripped over. There could be internal damage that's not visible to you, enough to have caused its impedance (not just resistance but also reactance) to have changed in a way that's causing the amp's output to operate "off spec."