Pickup voltage measurements

[Rpschultz13]

Hi,

I'm designing a guitar tuner based on an ESP32 microcontroller. Trying to understand how much gain to apply, I seached around on the internet looking for different pickup type outputs... and really didn't find much. So I measured all the guitars I have access to on an Oscope. Maybe this will be useful to others here:



Definitely a large range, and I've read that some pickups are even 2-3v possibly. And I've also read some as low as 50mv.

 

[CR0SSBL4DE]

Yes. You can get differences as big as 40dB easily from a single coil low-output pickup to a high gain HB pickup. It's not only the pickup itself, but the height setup, the string gauge, the pick (plectrum) used, and definetly the player.

If you have enough resolution at your ADC, I would set the gain for the biggest signal you would expect, and then compensate the gain internally with an AGC. Maybe with a RC LPF at the input (removing higher harmonics you don't need for the tracking algorithm, and reducing the largest transients) you can consider it about 2Vpp. Or maybe someone is blasting a booster before the tuner and the input is the full excursion of a 9V powered pedal.

Keep in mind you don't play notes that hard when tuning. In fact, if you are not making a polyphonic tuner, the input will be 1 string at the time.