How to Add a Panel-mount Gain Control to a C. B. Gitty Amp Board

How to Add a Panel-mount Gain Control to a C. B. Gitty Amp Board

Want to upgrade your next DIY amplifier with a gain control? Looking for greater control over your cigar box guitars tone?

In this post, you'll learn how to hack a  C. B. Gitty 2.5-watt amp circuit board and add a panel-mount gain control, giving you more command over your sound and style.

Why Use a Gain Control

You already know that the volume control determines how quiet or loud your amp sounds. 

The gain control is different. 

Installing a gain control allows you to adjust how clean or dirty the sound you get out of your amplifier is.

Think of it as a dial that governs how much of the signal goes from your cigar box guitar (CBG) to your amp board's volume control. 

The more signal you allow through the gain control (by turning it up), the hotter and dirtier your CBG's sound will be.

Conversely, the further you turn the gain control down, thereby decreasing the signal from your CBG, the cooler and quieter it will sound. 

Add a Gain Control in 3 Easy Steps

Adding a gain control to your C. B. Gitty amp board is a fairly simple task.

Here are the four steps it takes to upgrade your DIY amplifier:

  1. Pop the onboard trim potentiometer (pot) off the amp board
  2. Attach leads to a 10K linear-taper pot (gain control)
  3. Solder the other ends of the leads to the amp board.

It's as easy as that!

Watch the Video

In this video, Ben "Gitty" Baker and Glenn Watt walk you through exactly how to hack a C. B. Gitty amp board and add a gain control.

Parts Needed

Check out the short list of parts needed to upgrade your DIY amplifier:.

Tools Needed

As you can see below, you also need only a few tools for this project.

  • Wire strippers
  • Soldering iron and solder
  • Pliers (needle-nose or similar small-point pliers)

Step-by-Step Process

What follows are screenshots of the above video explaining in detail how to upgrade your C. B. Gitty amp board with a gain control.

Step 1: Remove onboard trim pot

With a pair of pliers or wire strippers, pull off the blue plastic trim pot from the amp board. 

Remove trim pot from amp board

Optional Steps:

After removing the blue, plastic trim pot there may remain a couple of the trim pot legs in the solder point locations. 

While it's not necessary to remove the legs, at C. B. Gitty we take these extra optional steps. 

Doing so makes room for us to insert the new leads into those solder points which makes for a solid, secure connections.

So if you're inclined, remove the trim pot legs by heating one end of each leg with your soldering iron until the solder flows.

While the solder is hot, use a pair of pliers on the other side of the amp board to pull the leg from the solder point.

Optional: Remove trim pot legs remaining in amp board

The next optional step is to re-apply some solder to those same installation points from which you just pulled those trim pot legs.

Optional: Re-apply solder to installation points

Step 2: Solder leads to gain control pot

Next, solder leads to the 10K gain control pot. 

With the back of the pot facing you, solder the lead designated as "negative" to the terminal on the far left (terminal #3).

Then, solder the lead designated as "positive" to the middle terminal (terminal #2.)

In these photos as in the video above, we use the black insulated wire as the "negative" and the red insulated wire as "positive."

Solder leads to gain control pot

Step 3: Solder leads to amp board

Now you can solder the free ends of the leads to the amp board. 

In the photo below, you can see which solder points are for the negative and positive leads. 

Identify gain control installation locations on amp board

On one side of the amp board, use the solder iron to heat a solder point until the solder flows, and insert the appropriate lead into that point.

Hold the wire there a moment or two, until the solder cools enough to harden.

Remember, don't blow on the solder to cool it. 

Cooling the solder too quickly can make for a poor solder joint. 

Just hold the inserted lead in place until the solder cools, which takes only a few seconds. 

Solder leads to amp board

And that, my friend, is it!

Your 3 easy steps away from modding your amp board to include a panel-mount gain control. 

For reference, below you can see the leads from the gain pot successfully soldered into the amp board. 

Finished gain control pot installation on amp board

Conclusion

Upgrading your DIY amplifier to include a gain control is simple. 

With a few parts and tools, you can use your C. B. Gitty amp board to control how clean or dirty your cigar box guitar sounds with one easily-hacked circuit. 

To review, here are the parts you'll need.

And here are the tools you need to get the job done.

  • Wire strippers
  • Soldering iron and solder
  • Pliers (needle-nose or similar small-point pliers)

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