Marshall Line In Connector from DI box

[davnaim]

I recently bought a Behringer Ultra DI box (I know, insert comments here..). Here is how I'm plugging it in:

- Guitar to "in" on DI box.
- Balanced out of DI to desk
- "Link" out of DI in to Marshall JCM 900 In.

When I engage the "B" channel (dirty) on the Marshall, the distorted sound goes back through Line In jack in the head, through the DI and in to the desk. So, the sound I hear at the desk (which should be completely clean), is a mix of the clean sound and the distored sound coming back from the Marshall head. I checked with Behringer and they said the "In" and "Link" jacks are wired in parallel so the problem is definetely with the JCM 900.

Has anyone ever heard of such a thing before? Why is the head's output being sent back through the Input jack? Weird.

 

[Ed Dixon]

That's a new one. How close is the wiring from the DI box out from the Marshall? Any chance for interferance getting into the output line?

I have used that DI and many others with overdrive amps and never seen that case.

Ed

 

[davnaim]

the di box sits about 15 feet away from the marshall. it is a very odd situation. i've never seen anything like it before.