I have been occupying my few spare moments building acoustic guitars. Over the past two years I have built three from scratch, first one, then two more simultaneously. With the most recent build, I thought about adding a pickup and output jack without including a pre-amp. The pickups I thought about using were disk shaped piezo elements that would be glued in strategic locations to the sound board. I read that sometimes the output from those elements is sufficient to not require a preamp. At the time I opted not to do so. I completed the build as an acoustic only guitar. Both of the recent guitars sounded good but one was a little more muted than the other. Perhaps due to the tone wood or the construction, perhaps due to the Martin OM style tight waist design or perhaps both. I thought that if I was going to convert one of the three into an acoustic-electric guitar, this would be a good candidate.
Step 1: The Pre-amp and Tools
I ordered a Cherub G-Tone GT-6 which included an under the saddle piezo pickup, preamp with 3-band equalizer, reverb, delay and tuner. The cost was about $36. I had some apprehension about it being fairly inexpensive and made in China, but I rationalized that fear by thinking if it failed after being installed, the acoustic guitar always works. The installation required that I cut two holes into the side of my guitar, one for the preamp and one for the output jack/battery holder. This caused some dismay as I pondered my decision and reviewed online information and youtube videos about installation of this device. I delayed the installation as much as I could by finding small related tasks to help procrastinate actual cutting on the guitar. I made card board templates to test the fit. I connected the device, leaving it hanging from the guitar to test its function. I pondered the surface on which to mount the preamp. I thought about how to recover from problems I might encounter. Finally I decided to dive in.
Tools you may need:
Rotaty tool (like a Dremel or B&D) and thin abrasive disk
hack saw blade
small phillips head screw driver
1/16" drill bit
Step 2: Fitting the Pickup
The piezo element is connected to a small cable so I needed to drill a hole at the end of the saddle trench to the inside of the guitar. The element fits underneath the saddle and is about 1-2mm thick, so that means the height of the saddle needs to be reduced or the trench it rests in needed to be deeper. The bone saddle on my guitar was already pretty short. I was afraid that making it much shorter would cause it to tilt too much in the trench and throw off the intonation. So I made the trench deeper. First I used a rotary tool with a small burr ball end bit and some washers as spacers to remove small, even amount of wood from the trench bottom. I was worried about removing too much so after a few passes I switched to a different tool. I used the non-business end of a small round file to scrape wood. After a few trial fits of the piezo and saddle and many scrapes I had the depth I wanted. I also filed a concave surface on the bottom of the saddle with that same file to help it fit to the tubular shaped piezo.
Step 3: Cutting the Holes
Next I covered the areas where the holes were to be cut with masking tape and used the card board templates I made to trace the shape of the hole. Using my rotary tool again with a thin, flat abrasive disk I cut as much of the hole as possible. I finished with a hacksaw blade and careful, light sawing strokes. Test fitting the preamp and battery holder I found I needed more clearance in some areas, so I used a small file and sandpaper. The hole for the preamp needed to extened out slightly in the corners to provide clearance for the screws that hold the retainer to the preamp body. Care should be taken not to overdo the battery holder clearance because the mounting screws need some wood for attachment. I marked and predrilled undersized pilot holes for these screws.
Step 4: Connecting the Wires and Mounting the Components
Before attaching the preamp and battery holder to the guitar body, I connected all the wiring, through the holes. The screws were turned in snuggly and it was ready to test. I left the guitar strings attached with the bridge pins during this process. Be sure to pull the string ends up to the bottom of the bridge area before turning the tuners to tighten.
Step 5: The Final Results
I found that the pickup and preamp with my Roland Cube amplifier was pretty sensitive. I kept the volume knob set fairly low. I’m still experimenting with the equalizer, reverb and delay settings, but I am pleased so far with the results.
without elec. - recorded with Audacity on Dell laptop using built in mic.
with elec. - recorded with Audacity on Dell laptop sing built in mic.
guitar connected to Roland Cube 15XL amp
G-Tone settings: EQ - low, medium, high set mid scale
Volume - low
Reverb - low/medium
elacc playing - another variation recorded with mobile phone voice recorder
EQ - set low/medium
useful youtube vids ....but mixed French and English: