Quiet Bass, Buzz/Hum from PreAmp/Processor

[davidk_528]

I've searched this forum and not found anything like the problem I'm having. I would greatly appreciate any help you could offer.
The set up:

• G&L L-2000 (active) Bass<O

Pre/Processing Rack (6 space Gator Rolling Rack):<O</O

• Furman AR-15 Voltage Regulator
• Korg DTR-2000 Tuner<O
• Demeter VTBP-201S Preamp<O</O
• dbx 160A Compressor<O</O

Power Amp: (4 space Gator Rolling Rack)

• Crest CA9<O

Cabinet:<O</O

• Bergantino HT322<O

Problem:<O</O
My setup emits a mid-range buzz or hum. It sounds like single coil pickups under fluorescent lights. The noise:<O

• Gets worse as I get closer to my pre-amp rig, but is audible (when not playing) no matter where I stand.<O
• Is present at the same level whether my hands are on the strings or not.<O
• Can be exaggerated or minimized by turning my body in a different direction, but is always there.
• Is present in passive, active and active w/ high-end boost modes. Going from passive to active to active w/ high-end boost makes the noise louder, but it's clearly present even in passive mode.
• <OIs present at my rehearsal studio and at every gig I play so local power is not the issue.

The bass is shielded and grounded. Two reputable techs have done continuity checks on the electronics and the bass checks out OK. Also, I've played the bass through other rigs and the bass was dead quiet, so clearly the bass is not the problem.<O</O

I’ve installed all the rack components with double vinyl washers (between the rack and the component back and the screw and the component front).

I've checked the cables and they're all good. I'm using good quality connector cables and they're separated from the power cords as well as possible.

I've tried to isolate the problem but can't find a single source. Turning up the volume on the compressor makes the noise louder, so the noise is being introduced at or before the compressor.

<OFrankly I'm stumped – can you offer any advice on this, please?<O</O

Thanks in advance,
David<O

 

[perucci]

Maybe a "ground loop"? A couple of things to try:

• Look at how you connect the power on everything - try to keep power-cords short, and all connected to a central point.
• Get/borrow an "issolation transformer" (like an EbTech 'Hum Eliminator') - if you do have a ground-loop, you may be able to interrupt the loop by placing the issolation transformer at the right link in your chain (experiment).

Note: This is really more of an "amp" or "effects" topic than a "setup" topic since you've ruled-out your bass.

 

[KPO2000]

I have a similar problem with my CA9+F2B preamp setup. In my case, I think the magnetic field generated by the CA9 is being picked up by the F2B. I separated the two by putting them in different roadcases and I try to put my CA9 on it's side next to the cab when possible.

Try seeing taking the preamp out the rack and separating the distance from the CA9 and seeing if that reduces the hum.

I love my CA9, but this problem and the weight are a hassle.

 

[Bass-only]

First - try a different bass.

I've had 5-6 L2K's over the years and most had some level of "buzz" or "hum". I don't know if it's because the pickups are so high output, but I've almost always ran into the same problem with L2K's.

I would think it was my amp or an electrical issue - then I'd plug in one of my Stingrays instead and it would be dead quiet.