Noise From Tech 21 SansAmp Bass DI

[mrnasty]

I've used a Tech 21 SansAmp Bass DI for several years and its one of my favorite pieces of equipment. I always use a Tech 21 power supply and a good quality, noise-canceling power conditioner.

Here is my situation: When I use the SansAmp with just my rig, everything sounds fine. But when I hook my rig up through the sound system (which is rare), I get feedback when I turn on the SansAmp; it disappears when I turn it off. This happens when I run a line out from the SansAmp or a run a line out from my bass head (a solid state Ampeg SVT).

One sound engineer, who is also a bass player, told me this is common with this pedal, so I don't use it in my signal chain during our "big gigs," which I hate because it adds so much to my sound.

I've heard that using a 9-volt battery instead of the power adapter might solve this problem. I'll try this solution the next time my band plays, but I have an outdoor gig coming up this weekend where I am in the opening act, so our sound check is limited.

Has anyone else had a similar problem with a SansAmp and how did you solve it?

[Darkglass]

It sounds like a ground loop to me (since you are having the same problem with two different DI systems) Ground loops ocurr when you have 2 ground paths with different impedances, and therefore, they have different potencial difference (one is lifted above 0V compared to the other one)
I am taking a wild guess here anyways, but Did you try with the Ground Lift switch? This cuts the ground of the DI signal, leaving only one path to ground and therefore there's no differences of voltage in the ground.

Greetings

Doug.