Condenser/SM58 bass problems

[Jack Green]

I have a Sontronics STC-2 Condenser mic, and a normal SM58. I've been recording demo's mostly with my acoustic guitar and classical guitar initally with the SM58, because my Condenser was picking up loud interferences in the background. My SM58 didn't so I used that, and the quality was quite acceptable, but thats not the problem. The problem is when I played either my acoustic or classical, certain notes, or one note in particular (A at 440hz) were naturally more bassy than the other notes, including other bass notes.
Eventually those loud interferences were taken care of and I decided to use the condenser was sounded alot better in quality which was great, but the exact same problem with the bass note/s was with the condender as well.

Now I doubt that it's a problem with my guitars because the fact that two guitars have the exact same problem at the same time just doesn't seem that likely. What I do think is possibly my positioning of where I'm playing from or in what position the mic's are recording. Basically, I'm sitting down on a short stool and the Condenser/SM58 is positioned at my guitar level in front of me.

For extra info, I'm using an Mbox 2, and I course know about phantom power with the condender mic

I hope that someone can help me out on this, otherwise thanks for your regard.

[TOM@METRO]

One type of correction for this would be to get a Carnegie Hall Frequency Chart and duck the frequency of the offending note with a parametric eq with steep Q. Resonate frequencies in un-tuned rooms are common.

[albee1952]

First thing I would try is changing the position of the mic in relation to the guitar. Next thing would be to change the position in the room(supporting what TOM said). You might also try the lo-cut filter on the STC-2