Martin D1 with DIY piezo pickups and a JFET preamp


This is a very simple project that I put off for a long time because I was too nervous to drill a hole in my acoustic guitar.

My main initiative was the fact that I record at home, in a non sound proof environment. I like using a microphone when recording acoustic guitars. I use them mainly for rhythm parts and the picking sound is what I’m after the most. The thing these recordings lack is a better sense of the guitar body sound. In order to get long ringing sustains I really need to push the preamp, thus picking up all sorts of unwanted ambient sounds. Adding a direct signal to that of the microphone can take care of that and a rich acoustic sound can be obtained.

I decided to use the piezo discs method easily found in many DIY sites. I went for two of them, both installed under the bridge with one roughly behind the bass E string and the other under the treble E string. The two outputs are then sent to a JFET transistor based pre amplifier (many such projects exist in the web – I went for a Tillman variety).

Lastly I added a ‘Tone’ knob which controls the balance between the two outputs. This, combined with the picking sounds picked by a microphone allows for very nice sounding acoustic recordings.

I must add that the ‘bass’ pickup gets a little woofy, which I intend to fix by adding a thin muffler between the microphone and the guitars’ body. I may replace one of the piezo discs with one under-the-bridge pickup at some point down the road. I’m very pleased with the ‘treble’ side though, and mixing the two properly works well even with the mentioned woofiness.

The video is very short. Just demonstrating the balance between the two piezos. I didn’t use a microphone at all on it, which I now regret as this would demosnstrate how well these sound combined with a condenser microphone.