Help with Dbx 166xl compressor

[MosuraNZ]

I recently purchased a DBX 166xl rack compressor. Im very happy with it but am in need of a little help. Im getting a nice smooth tone generally, but when I engage my fuzz pedal I get a horrible squeel/whistle.
I have the compressor/gate going through the effect loop of my Genz Benz GBE600. I run my pedal board through the front of my head this order fuzz>sansamp>chorus>delay. Everything works well other than this.
Can anyone shed any light on why im getting this horrible noise? Any help would be greatly appreciated!

 

[4Mal]

Umm microphonic feed back perhaps ? knock the volume boost down in the chain somewhere ...

 

[agedhorse]

Umm microphonic feed back perhaps ? knock the volume boost down in the chain somewhere ...

That would be my guess too. A couple of things working here... the fuzz pedal is going to add a lot of gain (in additiona to noise) and if you are compressing heavy, there will be a lot of gain when the compressor is below the threashold. The combination of the two can cause acoustic feedback when the pickups are picking up the acoustic vibrations. I bet if you tap the bass body, it's loud.