Acoustic Bass Preamp Replacement

Written By: Juan Chavez

Difficulty

Moderate

Steps

Time Required

1 - 2 hours

Introduction

This guide will help you replace the preamp for your acoustic bass. This guide can also be applied to other guitars because of the similar process.

For this process, make sure to purchase a preamp kit that will fit your bass or guitar.

Cut the zip tie holding the excess length of wires in place. This is located inside the bass.
The zip tie is most likely right under the bridge of the bass.
This will allow you to disassemble all parts the wires will connect to later on in the repair.

Look for the tuner/equalizer/preamp and carefully remove each screw using a Phillips screwdriver.
Once screws are removed, look for the endpin jack and remove it.
In the first image, the part had already fallen off. Refer to the second image if you have trouble finding the endpin jack.

Place the tuner over the area you removed the previous one from.
Scratch a line around the opening to the area of the bottom portion of the tuner.
Refer to the second image for a visual reference.
Ensure the scratched guideline is made to the parameter of the parts behind the face of the tuner.

Using a metal file, file up and down, following the outline.
Continue this, going around the outline until the desired opening is made.
This will most likely take quite a bit of time. If you have access to a small jab saw or similar power tool it will speed up the process.
Do this step ideally in a well-ventilated area as the wood shaving are small, and inhalation can cause harm or injury. Wear protective gear like a face mask, and goggles/eye protection to prevent injury or pain.

Get your output platform and measure, with a ruler, the perimeter of the parts under the face with the screw holes.
The second and third images show the underside of the part, measuring around the internals.
Once you measure each side, jot them down for Step 9.

Use a pencil and paper to outline the measurements jotted down.
Cut the shape out using a pair of scissors.
Place the paper over the opening on the guitar and trace the perimeter of the paper.

Insert the file into the opening and file up until you reach the outline you traced.
Then follow the outline until the opening is completely cut out.
Do this step ideally in a well-ventilated area as the wood shaving are small, and you may inhale them.

Place the preamp into the opening and screw into place with your power drill.
A power drill and four screws are required in this step. This will allow you to create a hole to screw in the screws or just directly screw in the screw without drilling holes.

Using your power drill and the other four screws, drill the screws into the output platform openings.

Get your pickup stick and insert it into the hole in the bridge.
Look into the guitar for the end of the pick-up stick and pull it until it reaches the preamp box.
Plug in the pickup stick jack into the box, as seen in the fourth image.

Look for the preamp inside the bass. You will find a wire showed in the first image.
Stretch your arm into the bass to reach the output platform and find where you will need to plug the wire into.
Ensure the wire plugs in the right way and is firmly plugged in.

Use a zip tie to secure the extra length of wire inside the bass.
This step is not required but will help disguise wires and keep them tucked inside the bass.