Updated 1st December 2019 Updated 10 May 2018 Updated 1 June 2018 December 2019. Time moves on and the PF5102 has been discontinued by On-Semiconductor and is nearly unobtainium. It looks like the J111/J112/J113 are the only TO-92 JFETS suitable for our purposes. We are currently sampling the J113. Some Piezo Preamps will be shipped… Read More »
Updated – see below for information on improving the design to lower the output impedance. We have had enquiries about adding volume and tone controls to the Unbalanced Piezo Preamp (available in the shop here). The PCB was not designed for the addition of these controls, so this article represents something of a hack. Here’s… Read More »
Update: Modules are available in the shop here now. I finally decided to retire the Altoids Piezo Preamp Kit and Altoids Piezo DI kit projects from the shop; I received good feedback from customers – but not enough people bought them. Fully built and tested Altoids Piezo Preamps are available from the shop here. The… Read More »
Phantom Piezo Preamp Modules are available from the shop here. Sometimes, back-of-the-envelope calculations do not tell the whole story (and neither do simulations). This article is a follow-up to the original article Phantom Piezo Preamp and addresses some errors and misconceptions that have arisen. The Phantom piezo preamp module (available in the shop here) has… Read More »
I was asked to comment on whether the Phantom Piezo Preamp (available in the shop here) is suitable for connecting to a balanced piezo transducer as covered by Chrisitan Liljedahl here. The short answers is yes, absolutely – the Phantom Piezo Preamp has balanced input and output and effectively you connect a single or double… Read More »
I had an enquiry (which which puzzled me slightly) about using LED’s to protect the input of the Phantom Piezo Preamp (available to buy in the shop here). However it was noted that if a piezo transducer is dropped onto a hard surface, the voltage spike generated could be high enough to damage downstream electronics.… Read More »
Update: Please see also Phantom Piezo Preamp revisited Update: Phantom Piezo Preamp modules are available for purchase in the shop here. A few years ago, Alex Rice put a design up on the internet for a phantom-powered JFET piezo preamp. Here’s the schematic of the original design as reported by Zach Poff: So far so… Read More »
I’ve had some interest in and feedback for my Altoids Piezo DI box and I have revised the design sufficiently to warrant a new post. The new design has the following changes from the previous version: 1/4″ jacks on input and output Low-voltage monitor (TC54) on the battery supply Higher voltage zener (33V) Increase R7… Read More »
Update: Fully built and tested Altoids Piezo Preamps are available for sale in the shop here. I’ve been taking my Altoids piezo DI box to open mic nights and have had some interest and feedback. People seem to like the concept but are less impressed with the balanced output and phantom power – which is… Read More »
There is an update to this article here. As I mentioned in my post on the vagaries of phantom power, I have been looking at designs for a compact self-contained box to connect an upright bass to the PA. The bass pick-up in question is a piezo jobbie integrated into the bridge like the Fishman… Read More »