Reaper HP resonance cont'

I recently purchased a Reaper HP. I love the way it sounds, but now I'm noticing a strange resonance when I play an F note above the 12th fret. It's not the amp, as I tried several with the same guitar, and didn'tt hear it with them unless I hooked up to the Reaper. Any ideas for coping with this? No I don't want to give up F... :)

To clarify, This is exactly what is happening and what I've done.

Whenever I play an "F" note on the E, B & G strings (above the 12th fret), I get a piercing buzz-like resonance with the note. It only happens if I engage a dirt pedal.

I've used 4 different guitars (two Strats, a Jaguar, and an Epiphone Dot), 3 different dirt pedals, and 3 different amps with this speaker. It makes the noise with all of them.

I've only had it for a week or so, so maybe it's still breaking in?

Mike

If so, you might wanta get an RMA and get another one.