Buzzing Basses

[Eric]

At church right now, we tend to have some issues with the bass, regardless of who is playing. There's always significant buzz if the bass volume is turned up very high, and sometimes the tone control can do it too. It really boxes us into a corner with volume and everything, as the buzz can be a real killer.

Does anyone have any general troubleshooting tips for this? The basses are not incredibly high-end, and I think the three are an Ibanez GSR something-or-other, Schecter, and Rogue (MF) 5-string. All of them but the Rogue have active electronics.

 

[t_ross33]

Sounds like a ground loop to me.

 

[Eric]

OK. I'm still figuring out the grounding thing, so what does that mean?

 

[marnold]

Since all the basses do that, it's time to look elsewhere. What amps are used? Are the guitars amped but the bass DI? Did you try a different cable? Also, P-bass pickups will cancel their own hum, but J-bass pickups won't unless you use both Js together. This is assuming that they are not noise-canceling pickups.

We have a problem with a ground loop in my church too. We've got a keyboard in the basement that is wired to the organ. Theoretically, the organist should be able to use the keyboard for piano/harpsichord sounds. Problem is, we get a nasty hum through the speakers for the organ if we do. The people who installed it years ago "solved" it by defeating the ground on the keyboard altogether which is not particularly smart. I also got one when we got an original PS3. It had a three-prong plug. We'd get hum through the T.V. Turned out that the cable line was not properly grounded.

Ground loops happen when electronics have more than one route to the ground. See Wikipedia for more details, the source of all things truthy.

 

[Eric]

I'm not sure of the pickup config for all of the basses, but I think at least one of them has a noise-canceling pickup.

They have all played through the same amp to date, which I suppose could be the problem. It's an old-ish Fender amp with two inputs, a 1 x something speaker (probably 12"), and this fuzzy, cream-colored exterior instead of tolex. The amp output is then taken and put through a DI box and run through the snake and into the mixer. In that way, the amp only serves as a head for the house and a monitor for the bassist. For power, the amp is plugged into a Furman power conditioner that serves all of the PA gear on stage (e.g. digital snake, power amps for monitors, etc.).

I don't know if 1) the buzz stops when they touch the strings or 2) if turning the bass angle changes the buzz (i.e. if it's electrical interference). My instinct is to say that 2 is a no, but I'm unsure of 1. I'll check in future weeks.

In writing this, I'm realizing that I don't have a ton of information, but I guess the first step is knowing what questions to ask and information to collect. Any other info I should gather for troubleshooting purposes?

 

[BigJD]

Check out EBTECH products. Inexpensive and work well.

http://www.ebtechaudio.com/

 

[marnold]

I'm not sure of the pickup config for all of the basses, but I think at least one of them is noise-canceling.

The low-end Ibanzes that I've seen have been P and J, which means that the P will be hum-canceling, but the J and the P/J combo will not be. To my ear, a ground fault sounds different than single-coil hum though.

They have all played through the same amp to date, which I suppose could be the problem. It's an old-ish Fender amp with two inputs, a 1 x something (probably 12), and this fuzzy, cream-colored exterior instead of tolex. The amp output is then taken and put through a cheap DI box and run through the snake and into the mixer. In that way, the amp only serves as a head for the house and a monitor for the bassist. The amp is plugged into a Furman power conditioner that serves all of the PA gear on stage (e.g. digital snake, power amps for monitors, etc.).

Try unplugging the DI line from the amp and see if the noise is there through the amp alone. That way you can eliminate the amp. Then just keep working your way up through the signal chain.

 

[Eric]

It may be entirely disparate problems too, with each bass having their own issue, but I feel like there's a common thread somewhere. I'll check on the bass amp thing.

 

[Brian Krashpad]

Is the buzz constant, versus intermittent?

If constant, sounds like ground loop or single-coil hum (what we'd call "60 cycle hum" with a guitar). As others smarter than I have already said.

Another cause can simply be low frequencies overloading the amp/speaker. But that wouldn't be constant, only when the low notes are hit.