There is a definite 58 hertz major resonance in the room, and a smaller one at 71 hertz and another at about 91 hertz; despite many broad band traps in the corners they are still there. I think that removing these completely will require many more panels of mineral wool and 703. But for now the best I can do for recording is to find a spot where they aren't prominent, and this I did.
Above, you can see the 58 hertz resonance, and the echos at 10, 20, 30, and 40 milliseconds that reinforce it. However, in this recording position, the peak is low and the other resonances at 71 and 91 hertz, which are more in the 12-string guitar's range, are very subdued.
I'm still working on the tremolo piece - it's finished, but I'm having to work to get the tremolo smooth - it's almost like a magician's illusion. While getting the illusion perfected I've been playing around with Freight Train Blues by Elizabeth Cotten. I think the acoustics make the guitar sound better both while I'm playing, and after on the recording. Here are the SoundClick links to 'Freight Train - 12-string instrumental'
lo-fi URL hi-fi URL
Update: Freight Train was recorded with a Taylor LKSM-12 tuned down one note with medium weight Elixir strings. It was recorded into a Jecklin Array comprised of 2-Oktava MC-012 microphones with matched omni capsules.
