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Buzz Coming through amp - I'm running out of options

R

RDR RKR

Jun 12, 2010
9
0
San Francisco East Bay
#1
Here we go with another "buzz" question, but I'm at a loss.

I've got a buzz that comes through my amp when I'm at my rehearsal studio. I've been practicing at the same place for 8 years and the buzz seems to have started about 6-9 months ago and has recently become unbearable. It happens with different basses and different amp heads and different cables. When I rotate my body holding the bass I can find a narrow position where it becomes silent but I can't stay in that one position when I play. It only does it (by "it" I mean unacceptably loud) at my studio, not at home or at gigs. I called EMG and they recommended I replace my all my pickups on all of my basses - what a surprise!

I should mention is doesn't sound like low and deep like a 60hz ground hum but rather a higher pitched thin buzz, like a bee caught in my speaker cabs.

I play though an Eden WT405 amp, SWR Workingman's 4x10cabs and Fender Jazz, Yamaha and Schecter basses; some with active EQ, some without, but all pro quality gear. Any suggestions?
 
#3
Here's the usual barrage of questions:

1. What kind of pickups are you using? (brand and type)
2. Have you tried plugging your amp into the same AC outlet as your guitar player?
3. Does this buzzing occur at gigs or at home or anyplace other than the rehearsal studio?
4. Are any of the lights in your rehearsal studio on dimmers?
5. Have you tried a different bass or different amp for comparison?
6. Does lifting the ground on the amp have any affect on the buzz?
7. What kind of instrument cables are you using?
 
#4
1) My Schecter has EMG HZ passive pups with active preamp. My Fender Jazz has stock passive J pickups and my Yamaha has active soap bar style pickups, also stock.
2)Tried all the different outlets in the rehearsal space. Even physuically moved my whole rig next to the guitar amp.
3)Little to no noticeable buzz at home and at gigs. Just at the rehearsal space
4) No light on dimmers.
5) I've tried all three basses mentioned above and two amp heads, my Eden WT405 and my GK RB800. I should note that with my Fender, the buzz only occurs if I have one or both volume controls at less than max. If both are at max, no buzz.
6) Neither my GK nor my Eden has a ground lift switch. (In truth my Eden has one but for the DI output only)
7) I only use genuine Monster instrument and speakers cables throughout. 14 gauge instrument and 12 gauge speaker.
 
#5
RDR RKR said:
I should note that with my Fender, the buzz only occurs if I have one or both volume controls at less than max. If both are at max, no buzz.
Click to expand...

well thats age old stuff right there. single coils will buzz. when you have both pickups full it cancels as one is reverse wound.

no idea whats up with your other basses, but this is the case for the fender. id just get used to it if you like the sound of the bass.
 
#6
If it only happens in the rehearsal space then that is where the problem is. It can't possibly be with your basses or amps otherwise it would happen everywhere, and it's extremely unlikely that all of your equipment would have developed faults that produce the same symptoms whatever configuration you use them in. Trust me on this I have many years experience in troubleshooting techniques and the only constant is the rehearsal space.

It sounds to me as if something changed in the rehearsal space, and that something produces more electro-magnetic radiation. When your jazz has both pickups on it's effectively cancelling out the hum so that points to some sort of electro-magnetic interference as does being able to find a small position where the interference doesn't happen.

Quizzing the rehearsal space owners about any work done in the last few months would be the next step
 
#10
Time to start dropping breakers in the panel as a troubleshooting method. You may have to get the site owner involved beforehand.

"Recently become unbearable" suggests something progressively deteriorating and emanating RF -- or throwing RF onto the AC line and then the building wiring acts as a transmission antenna. I second Hdracer's thought concerning fluorescent ballast. It doesn't necessarily have to be in the same room or even nearby. It's possible for noise to get injected onto one phase of the 220 and then appear on every wire in the house connected to that same phase, which would create a REALLY big broadcast antenna. Remember, we're not talking injection via the power into the amp's AC input, we're talking about injection into the amp's input, with the house wiring acting as a broadcast antenna for the noise that's modulating the AC waveform, and your BG and cord together acting as the receiving antenna.

Another thing you can try is unplugging (not just shutting off) everything you can get to, then plugging in only your amp. It's a stretch, but it could be something as simple as a misbehaving wall wart, or an amp that draws idle current even with its power switch off.
 
#12
ok, so it looks like the only two basses of mine that do it are the two that have active preamps. One has EMH HZ passive pickups with a Schecter stock preamp. My current thinking is the active basses when plugged in are creating some kind of antenna and receiving the buzz. you think shielding the cavities would work or do I need to switch to passive basses or take the preamp out of my two that have it?
 
#13
RDR RKR said:
ok, so it looks like the only two basses of mine that do it are the two that have active preamps. One has EMH HZ passive pickups with a Schecter stock preamp. My current thinking is the active basses when plugged in are creating some kind of antenna and receiving the buzz. you think shielding the cavities would work or do I need to switch to passive basses or take the preamp out of my two that have it?
Click to expand...

shield all the cavities, pick up cavities too it should solve the issue
 

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