Hello all, hopefully this is in the right place.

I have a strange problem, well, it's strange to me but perhaps some of you understand what's going on.

When I record vocals into any mic, if the singer's headphones are within 5 feet of the mic (as they are when they are singing within a few inches from the mic) there is a doubling of the monitor signal to those headphones causing an echo effect.

Coming to the preamps, outboard, DAW and tape the signal is clean and perfect as is the monitoring of the signal to the engineer (Headphones from the same source and speakers located in another room). There is only a problem in the singer's headphones.

My setup:

Various LDC, SDC, Ribbon mics, to various preamps, input into RME Fireface 800 interface connected to Mac G5 running Logic Pro 7.1. Using ATH-M40fs Headphones and Dynaudio BM5A speakers for monitoring. The headphone monitored signal in all cases comes from the RME interface(Ch.9,10 headphone out) into a 4 channel stereo headphone amp, with 4 sets of ATH-M40fs headphones.

Here are some facts about the problem:

It occurs regardless of the instrument recorded(vocals, guitar, horns etc...) It occurs on ALL my mics, using ALL combinations of preamps (including using only the RME pres), as long as the headphones are within 5 feet of the recording mic.

Here's the kicker - it also only happens if I am using Logic to monitor the vocals. If I monitor using the interface only there is no problem. If I turn the monitor from of the interface unit off completely, and use Logic to monitor (still through the same interface outs) then the problem occurs.

So, as far as I can tell, a piece of software (Logic) is causing a signal doubling in headphones that are within 5 feet of the recording mic. As I said before, the same signal in the headphones (same kind, coming from the same source just a different channel on the headphone amp) and speakers that are over 5 feet away from the mic, is perfect.

This is NOT an issue of the headphones bleeding sound and causing a feedback loop when they are near the mic, as the problem does not occur when Logic is closed, and the recorded signal is perfect.

I am at a loss as to what is causing this problem and my singers are getting fed up with a strange echo in their ear! Any help would be greatly appreciated.

Thanks,

-M