On-board preamp?

[Mike McLane]

I recently saw a vid where an inexpensive piezo under saddle pup was placed under a Tele bridge plate with great success. No need for those expensive replacement saddles. I was wondering if anybody has interest in adding piezo to electric guitar or bass AND IF SO, might there be interest in developing a small on-board preamp to drive it. I have used the EMG PA2 in the past which will give a low-Z 20dB boost and is tiny tiny. Could something like that be replicated with a thru hole design and be kept sufficiently small (like 1/8 watt resistors, etc)? The switch and pot would go off-board.

 

[Feral Feline]

Or go the largest-sized SMD and it would still be very small.

Could be a fun experiment.

 

[Mike McLane]

I found this on the internet:

This pcb layout appears to be to scale and designed around 1/4 watt resistors, etc (forgive the ghost images to either side). In talking to some of the experienced members of the forum I'm surprised as to how cheaply PCB's can be made in small qty if you know the right vendors. Even more, how little additional it costs to have them populated with SMD parts. Going SMD may be the smart way to go sans the 500K pot and switch which would go off-board (500K push/pull).

 

[Mike McLane]

Maybe the question I should be asking is whether or not the piezo requires an on-board preamp. Is there enough signal strength to run a "naked" piezo pup thru a standard guitar cable to a pedalboard mounted preamp? Anybody have any info on the output levels of piezo undersaddle pups?

 

[Passinwind]

Maybe the question I should be asking is whether or not the piezo requires an on-board preamp. Is there enough signal strength to run a "naked" piezo pup thru a standard guitar cable to a pedalboard mounted preamp? Anybody have any info on the output levels of piezo undersaddle pups?

The signal level typically isn't a problem, but the loading effects of the cable definitely can be IME. And not just high and/or low end rolloff, but cable microphonics, which used to drive me nuts with my upright.

I've done my own boards for a couple of J201 based buffer/preamps, one based on the so-called Tillman circuit and one on an open source version of the Borbely Follower. They both work pretty well and even the through hole versions would fit easily in most onboard applications. I have a project coming up soon that merits a revisit of this topic, more than happy to share whatever I come up with.

 

[Mike McLane]

I'd be interested as to what else might be out there.

 

[Passinwind]

I'd be interested as to what else might be out there.

Here's one: https://www.zachpoff.com/resources/alex-rice-piezo-preamplifier/

OSHpark board share here: https://oshpark.com/shared_projects/unq7nAAX

 

[Mike McLane]

The PA2 schematic calls for 4/ea - 49.9K resistors & 1/ea 499K resistor. I see that those values exist, but Tayda doesn't carry 'em. Will the world end if they are 50K and 500K respectively????

 

[Passinwind]

The PA2 schematic calls for 4/ea - 49.9K resistors & 1/ea 499K resistor. I see that those values exist, but Tayda doesn't carry 'em. Will the world end if they are 50K and 500K respectively????

 

[Mike McLane]

That bad, huh?

 

[Feral Feline]

Basically the equivalent of the History Eraser Button... the jolly candy-like button...