Easy DIY Pre-Amp: Makes Piezo-Equipped Cigar Box Guitars Sound Better

Easy DIY Pre-Amp: Makes Piezo-Equipped Cigar Box Guitars Sound Better

Reduced feedback. Deeper bass response. And no more "quack!"

I was complaining about certain tonal problems with piezo pickups when the idea for this standalone pre-amp came to me. It's deceptively simple... a $17 acoustic guitar pre-amp with a hacked input becomes a great EQ and signal boost. And it's all housed in a cigar box!

Hear the Demo

First of all, here's how it sounds...

I built this prototype in less than one hour. 

Here's how to do it:

Parts Needed

Pre-amp parts

  1. C. B. Gitty Pre-Amp Unit Model EQ-7545R ($16.49)*
  2. 1/4" guitar jack ($6.99/3 pack)
  3. Empty cigar box that is deep enough to house the pre-amp. These boxes are a good example.
  4. 9-volt battery

(*Note: a piezo rod pickup is included with the pre-amp. We'll need this!)

Tools Needed

  1. Wire stripper/cutter
  2. Soldering Iron and solder
  3. Coping saw, scroll saw or Dremel rotary tool.
  4. Small #1 Phillips head screwdriver

Here's a quick overview of the process. We'll get into detail with photos after the video.

Step 1 

Cut a 3.5-inch x 1.5-inch hole in the box to fit the pre-amp. 

You can use a coping saw, carpenters knife or a Dremel rotary tool with a cutting disk.

Hole for pre-amp cut into cigar box

Step 2 

Drill two 3/8-inch holes in the box, one for each guitar jack needed.

Drilling holes for pre-amp jacks

Step 3

Take the rod piezo out of the pre-amp packaging. Using wire cutters, cut off the rod piezo pickup from its wire. Cut closest to the pickup, leaving the longest length of wire possible.

Cutting lead off of rod piezo

Step 4 

Pull back the ground wire sheath to expose the lead wire. Strip off 1/4-inch of the lead wires insulation.

Strip insulation from wire

Step 5 

Solder the ground sleeve wires to the ground prong (the inner, circular portion of the jack). Solder the lead wire to the other prong (the lead prong) of the jack. This is now our hacked pickup wire and will become the input jack.

Solder piezo lead to jack

Step 6 

Insert the 1/8-inch plug of the hacked pickup wire into the receptacle of the pre-amp unit.

Insert plug into pre-amp

Step 7 

Install both guitar jacks to the cigar box. I recommend positioning the hacked wire (Input) on the right side of the layout and the the black plastic jack (Output) on the left side. Also insert the 9-volt battery at this time.

Organize pre-amp wires inside cigar box

Step 8 

Mark your input and output jacks accordingly. I used a woodburning pen. You could use paint or any other method. (Remember, this pre-amp in the photos is a prototype. My next one will have a cooler layout, better graphics, a carrying handle and feet!)

Finished cigar box pre-amp

Bonus: Add a Hidden Guitar Pick Caddy! 

If there's extra room in the box, you can glue an Altoids tin to the bottom for a place to store your guitar picks. I simply used a hot glue gun to attach the bottom of the tin to the inside bottom of the box.

Altoid tin guitar pick case inside cigar box pre-amp

Additional Notes

  • Unplug the guitar cables when not in use or it will drain your 9-volt battery.
  • Dialing-in the right tones is an art. Each instrument is different. The pre-amp is there to sculpt the tones ... and to also give signal boost to low-output piezos.
  • If the guitar sounds too distorted, try dialing back the volume on the pre-amp and increasing the volume on the amp/PA system.
  • If you sell cigar box guitars with piezo pickups, these pre-amps could be a great way to make additional income. Get fancy with them and give them a product name.

Have fun with this! And when you're done making your pre-amp, share it with C. B. Gitty so they can feature your work on cbgitty.com!

Must Reads

Learn more about how rod piezos will improve the sound of your cigar box guitars with the following must-read articles:

THE BEST ACOUSTIC TONE: Piezo Rod Pickup & Pre-Amp in a Neck-Through Cigar Box Guitar

What's A Rod Piezo & Why Use One In Your Cigar Box Guitar?

Improved Stand Alone Pre-Amp Hack - Use tiny craft store box

20th May 2019 Shane Speal

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