ONBOARD EQ, BUFFER, AND especially boost circuits for guitar have seen plenty of action over the years, and several popular models are available from EMG, Seymour Duncan (the Pickup Booster or Firestorm), Wald, Walker, CAE, and Alembic (the still-kicking and easy-to-install Stratoblaster). There was a time when lots of guitars came with onboard effects like fuzz or phaser (Gretsch Chet Atkins Super Axe, anyone?). An extreme recent example is Matt Bellamy of Muse building a Korg Kaoss pad into his guitar. I am not suggesting you build your entire pedalboard into your guitar, but if you have a favorite booster, distortion, or even reverb pedal, it might be cool to have it as a little onboard secret weapon.
Back in the day there were popular books by Craig Anderton, Electronic Projects for Musicians and Do-It-Yourself Projects for Guitarists. The latter encouraged intrepid guitarists to take the soldering gun into their own hands and start building some of their own electronics. There are also a couple of popular FET and op-amp buffer circuits online, but you can just as easily buy one preassembled and save your skills for the installation.
The main reason you may want a buffer in your guitar is that the lower impedance output from the guitar will be less susceptible to high-end loss from cable and pedal capacitance and give you a more consistent tone. Jerry Garcia was known for the unity-gain buffer preamp in his guitar. If you have the option, some buffers work best with a 25k volume control.
From there you can step it up and add a boost circuit. Recently I was asked to build an Xotic EP Booster into a guitar. Onboard boosters can be a great way to raise your level for a solo or get more gain out of your amp’s front end. It can also help you match levels if you’re switching between, say, a high-output humbucker guitar and a loweroutput single-coil model.
If you’re on the go and don’t want to hassle with pedals, you can build many effects right into your guitar. I have a customer who brings a travel guitar on trips. He likes the convenience but hates the dry tone in his headphones. I installed the circuit of a greatsounding Neunaber Technology Wet Reverb pedal into his travel guitar, making for a much more enjoyable listening experience.
A few considerations when planning your install: The big challenge is usually real estate. Some circuits have potentiometers soldered directly to the circuit board. If you are in luck you can find a way to keep the pots on the board and mount that as-is to the guitar. More likely you will have to remove the pots from the board and remotely wire them back up, same with switches. To consolidate, consider using push/pull pots to add switches and concentric controls for more knobs. Is there space for a battery? If not, you’ll need to rout for a battery cavity. If you can’t fit a battery in your guitar you can build an external battery box that can go on the floor, your strap, or the back of the guitar. You can even buy these boxes premade from B-Band, Highlander, and EMG.
If you are looking for a jumping- off point, stompthatbox.com/byo.html has compiled a large group of links that can help you through your project.
Gary Brawer runs Stringed Instrument Repair in San Francisco. His many clients include Joe Satriani, Metallica, and Neal Schon.