Ever plug in a new, electric cigar box guitar build only to find it’s making a humming noise?
That small noise can be maddening.
After the time and care it took to build your cigar box guitar (CBG), and closely following the instructions on how to install the pickup, hearing that dreaded hum after you plug in your new build is discouraging, to say the least.
To help you overcome this confounding issue, in this article you’ll learn 10 easy ways to identify the source of the hum and how to eliminate it.
Pickup Hum Is Maddening
Electrifying your CBG or other homemade instrument build can be a very rewarding experience.
Being able to plug into an amp not only gives you more volume, but it opens the door to a huge range of effects that otherwise would not be available.
And it is a proven fact that a pickup in a CBG makes it easier to sell – being able to plug in and rock out evokes images of Eddie Van Halen and Slash and is sure to get any would-be rocker’s blood pumping.
In an ideal situation, electrifying your build is as simple as gluing in a piezo (or mounting in a magnetic pickup), wiring it to a jack, and bingo... you finish the build, plug it into an amp and it sounds great.
Sometimes, that is exactly what happens.
Those are the good times.
Unfortunately, sometimes the sound isn’t so good.
Instead, you finish your build, plug it into your amp, and… hummmmmmmmmmmmm – the dreaded 60-cycle hum.
"But wait," you say, "the last build I did was just like this, and it didn’t hum!"
Or you think, “This harness I bought from C. B. Gitty must be no good! That shyster!”
Fortunately there are some things you can do to minimize (and hopefully eliminate) hum and buzz in your guitar.
The exact causes of hum and buzz in electric guitar pickup circuits can be a very arcane and involved subject.
I don’t claim to know everything about it, and there are plenty of other builders out there who may disagree with what I’m about to say, or who would offer their own tips.
That’s fine. More power to them.
My goal is just to give some pointers to people who want to know what to do.
We have built hundreds of electrified CBGs in the C. B. Gitty workshop, and these are some of the methods that have worked for us.
Walk Away Today Knowing 10 Tricks To Stop Your Electric CBG From Humming
1. Pre-test your equipment
Get in the habit of testing your harness before it is installed in the box.
For piezo harnesses, you can plug it into your amp and tap on the piezo or hold it against another instrument’s sound board with your fingers.
While holding the piezo in place against the soundboard, give the instrument a strum and you should hear sound through your amp.
If the harness has a volume pot, test its full range by fully twisting the knob in both directions.
Also test magnetic pickups.
Before installing, plug the pickup harness into an amplifier.
Hold the pickup over an already-strung-up guitar and strum the strings.
Make certain the volume control works, as described above.
Whether a piezo or magnetic pickup harness, there should be a minimal amount of humming when tested.
Strangely, sometimes a pickup harness will have no hum when tested, but will hum once installed.
Which leads us to...
2. Test your pickup circuit before finishing the instrument/sealing the box
Note: Most of the following tips and tricks are a lot easier if the guitar hasn’t already been sealed.
Get in the habit of testing your electronics before finishing the instrument.
Even if it isn’t strung up yet, you should be able to tap over where a piezo pickup is installed and hear sound through the amp.
For magnetic pickups it’s a little trickier if the instrument isn’t strung up yet.
But with a little dexterity and another guitar you can still effectively test your pickup.
Plug your new build into the amp, then quickly strum the second guitar and hold its strings over the pickup in your new build, and you should hear sound through the amp.
3. Avoid creating wire coils
Any time a conductor (like the wire leads in your pickup circuit) is coiled, wacky things can happen.
The coil can act like an antenna, making the circuit more susceptible to outside interference from electric motors, fluorescent lights, etc.
While it is tempting to wrap any excess wire lengths inside the instrument up into tight, little coils, fight the urge and find other ways to deal with the loose wires.
For instance, as an alternative to coiling wire you can use a dab of hot glue to secure the loose wires to the inside of the box.
Now, let's say you haven't any coiled wire in your build but there's still a hum when plugged in.
Other than the wires, potentiometers (pots) used as volume and tone controls can sometimes be the issue.
4. Pots are hum-prone
Adding a volume pot to a pickup circuit is a common cause of hum and buzz.
Make sure that you ground to the back of the pot’s metal casing as in the photo above.
This is a simple step we take with all of our pickup harnesses that include pots at C. B. Gitty.
5. Look around
Pickups exposed to electromagnetic noise will hum and buzz loud enough to make you tear your hair out. Look around for items that may be producing electromagnetic stuff.
Are there fluorescent lights right overhead? Or is there anything else that might be producing electromagnetic noise?
If so, move to a less electrically busy place and trying again. You might find the hum is reduced.
6. Check your power source
Your amp and its power source might be the cause of the buzz.
AC (wall) power is inherently noisy and its 60 hertz frequency (60 Hz in the US, 50 Hz elsewhere) can come through your amp as the “60-cycle hum”.
If there are fluorescent lights or electric motors plugged into the same circuit as your amp, their electromagnetic noise can manifest itself through the speaker.
Try plugging into different circuits in your house or workshop, and see if the noise reduces.
7. Ground to the strings
If touching the metal shaft part of your output jack with your finger greatly reduces the amount of hum you are getting, then you definitely have a grounding problem.
One common way to address this is to run a wire from the ground leg of your pickup circuit in such a way that it connects to your strings.
This is a lot easier to do if you have a metal tailpiece… just run a discrete wire to the tailpiece, and once it’s strung up you should find that the hum is greatly reduced.
If you don’t have a metal tailpiece but do have a metal saddle, you can run a lead to that.
If you don’t have either of these, you’ll have to get creative in finding a way to add your strings to the ground circuit – it really can help.
8. Move stuff around
If none of the above things help, you should consider moving the components in your build around, if possible.
As I said above, the whole topic of hum and buzz can be pretty arcane topic.
Sometimes the same harness will hum in one build and not in another.
Why? Heck if I know. But moving things around can sometimes help.
9. Bad components?
It is always possible that bad components are to blame.
At C. B. Gitty we pre-test every harness we make before it ships out, and we don’t ship out any that have hum problems.
But if you bought your pickup from somewhere else or made your own harness, it’s possible that a wiring fault (look for a single hair of wire going from hot to ground!), bad solder joint, or bad component is to blame.
Check your connections carefully and try swapping things out to see if you can isolate the cause.
10. Replace it and try it in another build
If nothing else works, all you can really do is give up and try another harness.
If you’re an optimist, save the hummer for another build.
*Bonus Tip: Check for grounded AC outlets
Here is a tip from master cigar box guitar builder John Nickel of Nickel Cigar Box Guitars:
“I always make sure the wall outlet is grounded first. You probably own a power strip with a ground light on it (if not, they are cheap).
Once you know you have a grounded outlet, it’s always the guitar.
Seems like a minor thing, but I had the home studio rewired last year … because of this.
My build shop (where I test my cbgs) was grounded but when I brought my guitars home to record, I found out that certain rooms in my house were not.”
And that wraps up 10 surefire ways to eliminate hum and buzz in your cigar box guitars.
Here’s what we’ve learned:
- Pre-test your pickup harness
- Test the pickup after installation but before sealing the box
- Don’t coil your wires
- Ground the pots
- Keep your eyes peeled for sources of electromagnetic noise
- Check your power source
- Ground to the strings via bridge or tailpiece
- Move the pickup around
- Bad components can happen
- Replace a humming pickup if necessary
And the Bonus Tip: Check for grounded outlets
I hope that these tips will help you work through issues of hum and buzz in your builds.
If you have other tips that have worked for you, let us know and we’ll add to the list! Reach out to us at firstname.lastname@example.org.
Happy hum-free building!
Ben "Gitty" Baker