What might be causing my bass to buzz through a PA?

[rob_d]

The last couple gigs I've played there has been a bit of a hum or buzz when I play my bass. It doesn't occur when I'm not playing or when I'm muting the strings, only when I'm actually playing notes. I don't get this buzz when I set up my equipment at home..only through a PA. In one instance the sound was going from the DI on my amp head, and in one case the guy was putting me through a direct box which leads me to believe the source is in the bass. I'm going to change my batteries this week, but usually when my batteries start to go my bass just pretty much stops functioning..but maybe this is an early sign, who knows.

FWIW I use a Euphonic Audio Iamp 600 and play a Modulus Quantum.

Thanks in advance.

 

[bassplayertom77]

Sounds like you need new batteries. Try that first before you do anything drastic. My Cirrus didn't always act the same when the batteries went out, so hopefully that's it.

 

[BassDeluxe]

The reason why you only hear it throught the PA is because the PA amplifies the higher frequencies more than your amp. I'm in the same situation (before and after a battery change): loud hum unless I tough the strings or any metal part on the bass.

I used to have the bass and treble knobs on my bass on "full" (because the knobs for some reason don't have a catching "middle position", so I thought they just "cut" frequencies instead of amplifying if >12:00 and cutting if <12:00 as normal with active basses) but I found the hum is reduced if I adjust treble and bass to "neutal" on the bass.

Oh well there seems to be few forum posts about this topic, strange, I would have expected more people having this problem... maybe we're missing something?

 

[bassman1185]

Sounds like a grounding issue. Most basses act like that to some degree. I wouldn't worry too much about it unless it gets really loud.

 

[Austicoatk]

Bassman1185's probably right--you probably have a ground loop going on: http://www.audioholics.com/tweaks/c.../ground-loops-eliminating-system-hum-and-buzz:

When two or more devices are connected to a common ground through different paths, ground path noise, or a ground loop can occur.

If you amp has a ground-lift switch, that will help, but not all amps do. If you play with through a DI, it might also have a ground-lift switch. Flourescent lights can also interfere. course, the aforementioned site has a caveat (and we're talking cable TV here, not bass stuff, buy anyway ...):

Ground lifting in unbalanced connections works effectively only when both pieces of equipment are properly grounded to same point. In some cases the humming problem may become worse if a ground lift is used. Thus, this so called "fix" should be employed with extreme caution and usually only as a temporary solution.