by Beate Ritzert » Fri Feb 24, 2017 6:04 pm
The condensor microphone is probably a great idea to record the true acoustic sound of the guitar.
Two disadvantages come to mind: sensitivity to feedback. Long ago i tried something similar with a violin - horrible in that respect, but otherwise great sound). The 2nd disadvantage: the clip cannot be safely attached to most metal tailpieces.
A while ago i built a solid body guitar with a spruce body using a low impedance pickup. A modified tele neck pickup mounted in the 90°-scale position typical of musicman basses.
Even on the solid body with the strat bridge i achieve a surprisingly acoustic sound.
And that's not surprising: a Low-Z-magnetic pickup has a much smoother and wider response than any piezo, especially when it has a small aperture (i.e. is a single coil or a stacked humbucker).
Some experimentation has to be done with the position of the pickup: only the positions close to the bridge will catch the full range of harmonics of a string. On the other hand there is some danger of weak fundamentals. The 90% position appears to be a reasonable compromise between these contradicting requirement.
Back to the pickup itself: i have been using 500 windings of really thick wire. It can drive the microphone input of a mixing console but it is still powerful enough to drive a guitar amp. A preamp with a gain of 20 dB should bring its output into the range of high impedance pickups - but that is not really necessary. Due to the low impedance of the pickup the volume pot can also have a small impedance - 2.5 kOhms! - which will not affect tone when the volume is decreased.
I can only recommend to experiment in that direction. The only disadvantage of such pickup system is that it requires the use of a pickguard.
Ken Parker apparently uses a similar approach on his archtops, and he whites that he avoids piezos because of their sonic disadvantages.
Another idea which i am still thinking about: if the main criterium for the sound of an archtop bridge is its weight, it might be possible to make a hollow bridge, give it a bone saddle with a piezo wire underneath, squeeze a 3.5 mm stereo jack in the treble side and a "Till-Jfet-preamp (a JFET with two resistors...)" in the bridge body, and chances are good that the acoustical tone is affected hardly or not at all. All the rest - volume, tone, power supply - is put into an external breakout box.
What Do You think? (I am considering to design such a bridge for my problem child archtop as soon as i am sure that i finally succeeded. Which will require quite a few months of observation)