The Ultra Tonic™ Pickup steel string version consists of four components:

#1 – Main sensor: a 10mmx72mm custom piezo sensor that is glued to the bottom of the bridge plate, right under the saddle. When centered left to right, it has sensitivity compensation such that the high E string comes out as strong as the others.

This sensor picks up the desired string response with great string-to-string balance and a very natural sound. The soft attack and lack of quack are noteworthy. However, it also picks up a fair bit of the undesirable top plate resonances which, if used just by itself, would result in low end muddiness and too much feedback susceptibility (boom). Remember, it is the main chamber and top plate resonances that are going to start feeding back first—the two strongest ones are typically the low G# and then the F above on the D string.

#2 – Feedback suppression sensor: a single 21mm piezo sensor that is glued to the far bass corner of the bridge plate. This disc is out of phase with the main sensor because it has opposite polarity. It picks up lots of the undesirable top plate resonances, but far less of the desirable string response. Its exact location is not critical. The pictures show it mounted on the far bass end of the bridge plate, but it is just as effective mounted off and behind the plate. In cases with small bridge plates, this is desirable.

#3 – A balancing circuit board with integrated endpin jack that mounts internally to your guitar’s end block in the usual way. This circuit is passive. It contains a 12 position switch that functions as a balance control. During a setup procedure using your ears with the guitar strung and plugged in, you select one of 12 possible switch positions which determines how much of the feedback suppression disc gets mixed in with the main sensor. When you’ve got it set optimally, you’ll experience crystal clear sound with very little boom and feedback. The setup procedure only takes a few minutes.

#4 – A sound-hole mounted volume control. It provides convenient and precise volume adjustment, and has cable capacitance compensation for no change to tonal balance as you adjust the volume. A small switch can be accessed to disable the cable compensation for use with very short cables into wireless systems.


Ultra Tonic Pickup mounting close-up in open back guitar
Ultra Tonic Pickup mounting in open back guitar
volume control mounting