DIY “Sondol” echo-location device

In March 2008 I built an echo-location device for a performance of Alvin Lucier’s 1968 composition Vespers. The piece was performed by a quartet of Alex Vittum, Brendan Aanes, Stefan Smith, and myself for a concert presented by the graduate seminar in Electronic Music Performance at Mills College. The original “Sondol” device used by Lucier has not been commercially available for many years, so the four of us built our own using the following simple circuit design:

The device is a simple low frequency square wave oscillator using a 74C14 CMOS Hex Inverter, based on a design from Nic Collins’ book Handmade Electronic Music. A 50k potentiometer controls the rate of oscillation within a range specified in Lucier’s performance notes. A LM386 is used as a simple amplifier to drive a highly directional tweeter horn. Thanks to James Fei for his guidance in the construction of the echo-locators.