Gallien Krueger MB150S speaker Buzz

valloti · #1 01-30-2013, 04:02 PM

Hi There, finaly i got to buy a gk MB150S for a really cheap price. Sounds amazing with my DB and also with my fretless, very natural sound and loud! But it has a small buzz when i play specially the E string from G down to E. I'm pretty sure it's from the speaker, but it's just like new. I think it could be a tiny hole where the air is scaping and producing this small vibrations.
What do you think? What could i do without spending a lot of money?
Thanks a lot!

Slowgypsy · #2 01-30-2013, 04:06 PM

If you can find that small hole in the speaker... you could glue another piece of thin paper over it. That's inexpensive. If that's really the cause. Another cheap thing to try is snug up every screw you can find with a Philips screwdriver. If this is an older unit there's a good chance screws have loosened up a bit.

I've had the same combo for many years. It's been used a lot and it's still going strong. Built to last!

GrowlerBox · #3 01-30-2013, 04:08 PM

Also try turning down the bass control and/or inserting a high-pass filter (e.g. fdeck's HPF-Pre) between your pickup and the amp input.

valloti · #4 01-31-2013, 03:39 AM

The high pass filter helps a lot but looses bass bottom, i also tryed to tighten the speaker screws and somehow got better, not 100% but better, i guess i will have to really tight them strong!
Thanks guys!

robgrow · #5 01-31-2013, 04:53 AM

Which series of the MB150 do you have? The current Series III uses a welded aluminum case, however the older models have a cabinet that is fastened together with screws and gasket material. The new welded cabinets are usually very trouble free, but the older amps can develop buzzes when the fasteners get loose or threads get stripped. Also the power transformer is located in the back of the speaker cabinet on the older amps, and they have been known to get loose and cause buzzes. You can try tightening the four screws in the back that secure the transformer, if you have one those models. Of course the problem could be with the speaker itself. One common problem with older MB150 speakers is the foam surround starts to break down.

valloti · #6 01-31-2013, 05:26 AM

I have the series III, i just squeezed the screws again but no change. I removed the speaker to see if there was something inside causing the noise but everything was in order. It is indeed weird, the speaker is brand new, now traces of use or scratches, holes, etc, everything is tight, but still there's this small buss on the three lower notes of the upright. It sounds like an air thing and not a malfunction on the cone it self. I don't know.
Any ideas?
Thanks a lot anyway people!

GrowlerBox · #7 01-31-2013, 11:41 AM

Quote:

Originally Posted by valloti

The high pass filter helps a lot but looses bass bottom

If this helps, you may simply be asking too much of a single speaker.

valloti · #8 01-31-2013, 12:32 PM

I thought about that but it's happening at not very high volumes, the input knob at 11 o'clock and the output at 1 o'clock. I guess i will just take it to a GK guy (if i find one here in Berlin)
Thanks!

fdeck · #9 01-31-2013, 07:12 PM

Here are a couple things to try.

I once took my amp apart, to fix a buzz, and discovered that the problem was my input cable.

The next thing to try, you have to be extremely careful not to damage your hearing. Put your ear close to the amp and try to figure out exactly where the buzz is coming from. This might help you chase an air leak. The MB150 has a couple of large screw holes in the sides. Do those holes have screws in them, or are they open? You can cover holes with tape.

When you removed the speaker, did it have a good gasket?

Finally, it could be something in your room that's buzzing. There's a cabinet in my living room that I have to stay away from because it buzzes.

BHBassman · #10 02-01-2013, 05:30 PM

Try the GK with an extension spk.
Shut off the combo spk. & see if the buzz is still there.
Mine sounds so much better with the ext. paired.

Badong · #11 02-02-2013, 09:44 AM

Quote:

Originally Posted by BHBassman

Try the GK with an extension spk.
Shut off the combo spk. & see if the buzz is still there.
Mine sounds so much better with the ext. paired.

This is a really good diagnostic. I thought something was wrong with the speaker on my MBS but it turned out I was just overloading the input by using too much pre-gain.

tombowlus · #12 02-03-2013, 12:45 PM

You are not setting an iPhone on top of the amp by any chance, are you? I recently discovered that my iPhone 4s was the source of an "electronic noise" that I was hearing whenever I played through my buddy's MB115 combo.

clodhopper · #13 02-06-2013, 07:31 AM

I had a similar issue after my MB150S was serviced. I took the amp head off and found some holes into the speaker cabinet which looked like they were once filled but were now open. I stuck blu-tak (as we call it in the UK - putty used to stick posters on walls) over the holes and reassembled. That fixed it the buzz.