Hi Dave,

 A great way to observe this is to use an additive synthesizer and dial up some tones by purposefully adding even or odd ordered harmonics and then recording some stabs. Record them clean so that the signal chain doesn't introduce any distortion.


 In the OPs case, now that he has mentioned the 6' guitar booth... it could also be comb filtering.

 I think it's still most likely that it's just too loud in there for that mic... it's hard to say if it's before or in the onboard preamp.  If it's before it could be saturation on the transformer. It could also be the ribbon getting over worked.

 It's reassuring to think that it still sounds fine with lower volume sources like singers and acoustic guitar.


 At this point I'd suggest pulling the amp out of the small room and trying the mic out in a larger space.


 BTW, what was the other mic that seems to work ok? The sm57? Or the SE2200?


 best regards,
mike


 

The ribbon is new so wouldst expect it to need that. Maybe i should be contacting the manufacturer.

I didn't expect the rear hatch on my new car to leak, either, but it did.


All of these inexpensive ribbons are made on the cheap in Shanghai and are famous for their high rate of manufacturing defects, ribbon tension being #1 on the list. I've read many accounts of people having to re-tension ribbons on brand-new Chinese ribbon microphones (as well as tighten screws and reassemble basket components that were left rattling around inside after manufacture).  


Michael Joly, who's quite the expert on such things, says that 30 to 50 percent of new Chinese ribbons are improperly tensioned. And guess what? One symptom of an improperly tensioned ribbon can be asymmetrical waveforms.


Good luck contacting the manufacturer. Hope you speak Chinese! :)