Tips, Techniques, Examples about my favorite musical instrument, the Twelve-String Guitar.

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Monday, January 29, 2007

Losing the Whomp

I'm not liking the Jecklin array much lately. The LKSM-12 is tuned to down a minor third and this puts the 5th course at about 91 hertz; this happens to be the same as the sound hole is tuned and for close mic'ing, which I do with omni mics in the Jecklin array, the 'whomp' of the A course bothers me. The spectrum shot above shows 2 of the whomps (circled). Look how much louder they are!

This seems to only happen on the LKSM-12, maybe because the combo of a 91 hertz sound hole is a bad match with tuning down a minor third, which puts the whomp at a critical spot (the open 5th course). One of the standing waves in the studio is at about 90 hertz, and this doesn't help matters. On a guitar tuned to concert pitch this whomp would occur around the first few frets of the lowest tuned course. That would be nicer and if I played a 6 string tuned to concert I would probably be very happy with the Jecklin array.

I know the room could use more treatment, but for now I relocated the recording position a bit to make sure I'm not where the 90 hertz is peaking. However, the Whomp remains; only action left is to move the mics away from the sound hole.

Here the mics are positioned inside spider holders about 18 inches apart. Finding a good place to point them took the best part of yesterday. One constraint for my situation is that the mics have to be as close as possible to the sound source, the guitar. There is too much ambient noise in the neighborhood and the house, and even with a large studio and some room treatment, ambient sound and 'room presence' needs to be avoided. After some recording tests I tried putting an ear stopper in one ear and telling myself, "I am a microphone", gradually scanning the surface of the guitar a few inches away with my un-stopped ear.

Here is the current position: the near mic in the above picture is about 3.5 inches, or 9 cm, above the 8th fret. This mic on the fretboard side of the sound hole was the most susceptible to sound hole whomp, so I located it furthest away from the sound hole. The capsule of the fret-side microphone capsule is about 25 cm. from the center of the sound hole. The far mic in the above picture, which is on the player's right, is about 7 inches, or 18 cm, above the saddle, and the mic capsule is about 18 cm. from the center of the sound hole. These positions don't seem to be critical within several centimeters, because I do tend to adjust the guitar position sometimes.

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