Going Through a Phase

It hadn't occurred to me until I came across this site that if you wired two piezos in parallel, say to reduce the impedance, that they would likely be out of phase when place on the instrument. So I set out to build a new pickup with two piezo benders on top of each other. The results unfortunately were mediocre.

First, I soldered together two piezo benders in parallel and then stuck them to each other using Elmer's post-it adhesive. I used this material because it is sticky, cheap and I had read that some use it to attach piezo pickups to the surface of instruments, as it supposedly attenuates the signal, thus reducing clipping and noise.


Then I dipped the whole think in Plasti-Dip and added some stylish yellow heat-shrink tubing.


I recorded some very sloppy playing on an Epiphone steel-string guitar using the new pickup, the basswood piezo pickup described in this post and then my Audio Technica Pro 37 microphone.

New Pickup

Basswood Pickup

Pro 37

The basswood pickup, which I thought sounded very good on a nylon string guitar, sounded mid-rangy here. The new pickup sounds better, although muffled and also mid-rangy. There are many variables that could be causing this: the benders themselves, the adhesive, etc. It's beyond me. I've contacted the author of the site that I link to above, but have heard nothing back about his pickup.

Heart-Shaped Box

 

Singing into the sound hole of my ukulele, with a piezo taped to the body and plugged into the Sonuus G2M (see my last post), inspired me to make a piezo resonator box.  I was hoping that this would allow me to use the Sonuus G2M as a MIDI controller for a variety of instruments without pickups.

I bought a heart-shaped chipboard box at a craft store for $0.69.  I cut a sound hole in the top and a 5/8" hole in one of the sides so that it would sit on a microphone stand.  It split a little on the side while I was cutting, so I reinforced it with packing tape.  I glued a piezo to the inside back and wired it to a 1/8" mono jack on the side opposite the hole for the microphone stand. 

The results so far are underwhelming, with very erratic reproduction.  I'm guessing this is a result of the chipboard. Along with a cheap piezo, one can't hope for very accurate transduction of sound pressure, to vibration, to voltage to MIDI.  Maybe the erratic reproduction can be used for interesting effects though.

I made few samples, simultaneously recording in Cubase the MIDI signal from the Sonuus G2M and an audio signal through a Audio Technica Pro-37 placed by the box, pointed at the instrument.  For the MIDI signal, I chose similar VST instruments from Steinberg's Halion 1. 

Cheap Tin Whistle

• Whistle by itself
• VST whistle
• Both

Hohner Weekender Harmonica

• Harmonica by itself
• VST harmonica
• Both

Ukulele

• Ukulele by itself
• VST "Velo" guitar
• Both

Out of Controls

In the year and a half since I last posted, I haven't made any new piezo pickups. But, I have found new applications for them. Piano tuning, at least for Concert A, while the children are running around screaming, was one. Creating odd MIDI controllers is now another.

I recently bought a Sonuus G2M guitar-to-MIDI converter for about $99. It's as good as advertised, with low latency and accurate note and pitch bend detection. I was curious how it would work with one of my piezos instead of a guitar pickup, however, and am weirdly excited about the results.

First, I input into the G2M one of my large Plasti-dipped piezos that I had taped to an inexpensive ukulele. The MIDI reproduction was less than spectacular, maybe because of the high register of the ukulele. The G2M manual states that its note detection range is between E2 and E6 and that notes outside of this range will be detected, but that "performance is not guaranteed" (whatever that means). Also, that notes played on the ukulele didn't sustain seemed to affect the MIDI reproduction. Making noises into the ukulele's sound hole produced interesting results, including legato I haven't been able to get with an electric guitar and the G2M.

So, I taped the same pickup to a plastic kazoo and plugged it into the G2M. The results were cool (click here). The linked audio sample uses the alto sax sample from Steinberg's Halion 1. I hadn't turned off the pitch bend in my sequencer, so the sample occasionally sounds like something other than a saxophone, but the speed at which different notes were reproduced is something that I hadn't been able to achieve with an electric guitar. The score of the sample also shows some impressive results from a plastic kazoo.