Soon after buying my Breedlove acoustic guitar, I decided to buy a clip-on tuner. There are many clip-on tuners available at all price ranges, and they all basically work the same way. They pick up the vibration of the strings through the guitar body and neck, and display the current pitch in a way that shows you the current tuning.
I opted for a cheap tuner, the Intelli IMT500 . While it worked reasonably well, I noticed that the display would occasionally swing wildly to inaccurate values.
I also noticed that I could hear a slight buzzing sound when playing some notes on the guitar. At first I assumed this was an intonation issue, but after setting up the guitar and trying several types of strings, I ruled out intonation as a cause. Then it hit me: I removed the clip-on tuner, and the buzzing stopped.
If I shook the tuner a little in my hand, I could hear a slight rattling from inside the device. It struck me that this was the cause of the buzzing while I played. And I realized that this must also affect the accuracy of the tuner. If the tuner relies on vibrations to show the pitch, extra vibrations from the device itself would explain the wild swings I saw on the display.
This was easy to fix.
The tuner is held together with just two screws, and inside, the small circuit board is held in place with two more screws. There is some “play” where the edge of the board touches the housing, and that’s what causes the buzzing and extra vibrations. I grabbed a small bit of foam and cut it into bits that I wedged in between the circuit board and the housing. I reassembled the tuner, and that was that – no more buzzing, and much better tuning accuracy.