Bass Amp Buzz, Certain Notes

  • Thread starter Thread starter MetroCenter
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MetroCenter

MetroCenter

Pint o' Guinness, please.
I have a new bass amp (Ampeg BA-110), which I bought 2-3 weeks ago. It buzzes very bad on certain notes (low A through C). I've tried positioning the amp in different ways, but nothing seems to help.

Has anybody else had this problem? I obviously want to return the amp if it is faulty, but not if it is ok.

So I've been brainstorming and have come up with the following ideas for testing the amp:

  • I'll try plugging the bass guitar into something else (my guitar amp or directly into the mixer), to see if the buzz is coming from the bass itself or something nearby.
  • I'll take the amp outside for testing, to eliminate the possibility of resonance coming from the room or something in it.
  • I'll try playing sine waves (from my signal generator) through the amp input, to see if I still get a buzz.
  • I'll also try playing sine waves through the amp's cd input, to bypass the preamp.

Do these tests make sense? Any other ideas?
 
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Try bringing it back to where you purchased it and ask them what the problem is.
 
Good simple answer, thanks.

I'll try my tests tonight, and if the results point to the amp itself, I will bring it back to the store.
 
How have you got this eq'd? Ampeg stuff is generally good quality, but this is a budget / practice amp are you asking too much from it?
Try a flat eq - and gradually build the volume.
 
Thanks for the advice. I did try different eq settings, always buzzed on the problem notes. And it always buzzed no matter how quiet I made it: higher volume just made the buzz louder.

Of course, I don't expect this small, inexpensive ($180) 35-watt amp to provide high-end nuanced sound. But buzz-free sound on all notes at low volume -- that's a pretty minimal test to fail. Heck, my crappy computer speakers can reproduce 120 Hz without buzz, so really I don't think I'm asking too much.

So last night, I performed my tests as planned.
  • Plugged the amp into well-grounded GFCI outlet, outside the house. Still buzzed. (This eliminated room resonance and grounding issues as possible causes).
  • Swept a pure sine wave through the amp, it buzzed from 110 Hz to 130 Hz. (This eliminates the bass guitar as a possible cause of buzz).
  • Tried the CD input, same thing. (This bypasses the preamp, and thus eliminates the preamp as the source of the buzz).

So either the power amp, the speaker or the cabinet itself is causing the buzz.

(I can't get over the fact that the issue is centered on 120 Hz, double the frequency of AC wall power. Is that just a big coincidence? Or could it be that the power amp is not properly isolated from the AC frequency?)

I think I'm overthinking all this. Since I just bought the amp a few weeks ago, I'm going to return it to the store and have them take a look at it. If they can't fix it, I'll exchange it for something else (maybe an Acoustic model).
 
MetroCenter said:
[*]Swept a pure sine wave through the amp, it buzzed from 110 Hz to 130 Hz. (This eliminates the bass guitar as a possible cause of buzz).

So either the power amp, the speaker or the cabinet itself is causing the buzz.
Click to expand...

Well done on eliminating the other possible causes. It does sound as though there is something faulty with the combo, maybe something as simple as a loose screw or bolt and 120Hz might happen to be the resonant frequency that sets it off. A chat with the retailer sounds in order.
 
Problem solved, returned the amp for a new one of same make/model. Yes, I was overthinking it, seeing how I was within the 30-day return period. The store gave me no hassle at all.

As far as the new amp: I made sure the box was sealed and had never been opened, and then I tested it carefully in-store, at volume 6, playing each note one-at-a-time. No buzz at all. I'm confident this is a good one.

Even at less than $200, this was still hard-earned money, so I'm glad I didn't just "deal with it". We consumers need to do our part to keep quality high, by returning products when they don't meet our expectations.
 
MetroCenter said:
Problem solved, returned the amp for a new one of same make/model. Yes, I was overthinking it, seeing how I was within the 30-day return period. The store gave me no hassle at all.

As far as the new amp: I made sure the box was sealed and had never been opened, and then I tested it carefully in-store, at volume 6, playing each note one-at-a-time. No buzz at all. I'm confident this is a good one.

Even at less than $200, this was still hard-earned money, so I'm glad I didn't just "deal with it". We consumers need to do our part to keep quality high, by returning products when they don't meet our expectations.
Click to expand...
It's amazing the quality amps they have now at low prices. I just got a Fender 25R amp for someones birthday and it rocks. Retail only $85.
 
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