Buzz in PA system

jasrahl · #1 01-26-2009, 01:51 PM

I am not the bass player I play guitar and do sound. With that said we have an issue that the bass causes a buzz in the PA system and I am trying to figure out how to get rid of it. Once you start playing it isnt noticable. We have tried a couple of different bass guitars and it doesnt seem to matter we still have a buzz through the PA. The sound board is a good 50 ft from the bass. I have a direct box that I used for my guitar at one point but that doesnt seem to help. Is there a particular direct box that is for a bass? It seems to be worse when he turns up the drive on the bass but when he turns it down it doesnt sound as good.

Thanks!

JKT · #2 01-26-2009, 01:58 PM

Let's see, you've so far swapped out basses and used a direct box. How were you doing it before? Line out of the amp?

How did you patch the DI? just the bass or at the amp? Did the DI have a groundlift switch on it?

What exactly do you mean by the "drive"? Is this an effect in the bass signal chain or are you referring to a line level output control on the amp?

Need more and clearer info

JKT

jasrahl · #3 01-26-2009, 02:05 PM

We have tried both directly into the jack which goes to the board and going through an amp. Through the amp is noticably worse.

DI always inbetween the bass and what ever we hooked it up through whether direct to PA or into the amp. Does have a ground lift switch which made a little difference. The lift made it go from flat out wont work to annoying.

The drive is how are bass player would put it. On the bass itself he would talk about his drive knob. I emailed him to clarify what exactly he means. He may mean gain.

jasrahl · #4 01-27-2009, 09:04 AM

The bass player says its his drive knob on his bass. If he is calling it by the wrong name then how should he look going into the PA. Should it go from his bass into an amp and then into PA? (this caused the most buzz) OR should I just have him plug directly into the jack that goes into the board? Where does the DI box sit? Would a preamp help or does the amp act as that? Thanks for the input!

Jehos · #5 01-27-2009, 02:36 PM

Is he using Jazz basses or anything else with single-coil pickups? Is he soloing one pickup? That problem would carry across basses if both had single-coil pickups.

Fresh batteries in the basses?

Did you try moving everything over to a different channel on your mixer?

I'm really surprised the ground lift made the signal stop working. That to me indicates a problem with the DI.

To troubleshoot I'd take a known-good DI (make sure it works correctly with some other instrument), plug the bass into it and it into the board. See if that works. If it doesn't, switch the DI to a different channel until you find one that works. If none work, try a different bass or a guitar. If that doesn't help your DI is crap. If the different bass or guitar helps, it's the bass. If you get it working with the original bass, add components back into the bass signal chain until you find the problem.

Also, send your bass player over here for some education. "Drive" knob on the bass? ***?

EBBassMan · #6 01-27-2009, 10:21 PM

Sounds like it might be a problem in the DI box.

JimmyM · #7 01-27-2009, 11:29 PM

Drive, people, drive!

Overdrive is noisy when you're not playing. He needs some sort of noise gate or he needs to turn down the volume unless he's playing. Noise is inherent in overdrive and there's nothing you can do with it except gate it out.

jasrahl · #8 01-28-2009, 06:13 AM

The DI being bad wouldnt surprise me. I looked up noise gate pedals and that would make sense. Should I get both? What is a recomended noise gate pedal? I saw a few.

Jehos · #9 01-28-2009, 08:33 AM

You need to isolate the problem before buying anything to try to fix it.

EBBassMan · #10 01-28-2009, 09:47 AM

Quote:

Originally Posted by JimmyM

Drive, people, drive!

Overdrive is noisy when you're not playing. He needs some sort of noise gate or he needs to turn down the volume unless he's playing. Noise is inherent in overdrive and there's nothing you can do with it except gate it out.

He's saying the "drive" knob is on the bass itself. I don't know of any basses that have OD built into the on board preamp. Is it a treble boost maybe??

OP switched out basses, amps, went direct with different basses through the DI. If you've tried different cables, different basses, different channels on the board, different channels on the snake the next step would be the DI I would think. I would try to borrow another DI next to see if that's the problem. Don't go buying anything until you know what the problem is.

jasrahl · #11 01-28-2009, 12:05 PM

Thanks. His bass is a passive. The DI is cheap. We got a new mixer and it did it with the old and the new.

I have been reading the forums and I am going to pick up a countryman or a radial JDI.

I have not done the very obvious and just walked the bass to the board to see what happens which is a "duh" but sometimes when it is right in front of your face you miss it.

My bass player just admitted that the "drive" is what he calls it. He has no label on the bass. I will definetly point him to this forum.

Where should the DI sit? Between the bass and the amp, the amp and the wall jack?

JimmyM · #12 01-28-2009, 01:11 PM

Hmmm, he calls a knob on his bass the drive knob? Yeah, he's more than likely using wrong terminology. Now that I understand, I agree not to start throwing money at it yet. Isolate the buzz to one component by process of elimination, THEN throw money at it

Jehos · #13 01-28-2009, 01:34 PM

Do you know what kind of bass he's using? We can probably tell you what the controls do and appropriate settings to eliminate buzz.

ac1710 · #14 01-28-2009, 01:58 PM

My first thought is that youve got unbalanced cables some where in the set up.
But then again if your going into a DI box before the PA you shouldn't get the buzz that unbalanced cables often create.

Look at the set up. Try different combinations until you identify what is causing the buzz, then replace/fix it.
For example see if there is a buzz if the bass is coming through an amp only...
Chances are there something that isn't connected right in the chain. So look at it systematically...

GregShadoan · #15 01-28-2009, 02:43 PM

It could also be an AC ground loop issue. It is highly recommended that the stage get power from the same AC mains as the sound, and is isolated from any other AC usage, such as lighting.

JKT · #16 01-29-2009, 01:26 PM

I can't remember, did anybody suggest groundlifting at the amp AC yet?

JKT

EBBassMan · #17 01-29-2009, 02:11 PM

Quote:

Originally Posted by JKT

I can't remember, did anybody suggest groundlifting at the amp AC yet?

JKT

Not a good idea, especially if your bassist uses a microphone for anything. I can get quite, um.... shocking

JPaulGeddy · #18 01-29-2009, 08:22 PM

Wonder if he has his 'drive' knob down really far and cranking the gain elsewhere down the chain to compensate?

JKT · #19 01-30-2009, 09:56 AM

Quote:

Originally Posted by EBBassMan

Not a good idea, especially if your bassist uses a microphone for anything. I can get quite, um.... shocking

yeah, there is that possibility but easily tested for before laying your wet lips on the mic

Plus, if the noise is amp ground-loop in origin you can often have the sound system ground switched to prevent any accidental zapping.

JKT

Alaska Bass · #20 01-31-2009, 03:02 AM

Quote:

Originally Posted by JKT

I can't remember, did anybody suggest groundlifting at the amp AC yet?

JKT

NNNNNNOOOOOOOOO! Don't ever tell anyone to do that again, please. There are WAY to many products to deal with ground issues without eliminating the AC ground of ANY equipment to ever recommend something like that.