Maxon AD-900 serial number 000001!!! purple

The AD-900 Analog Delay was created after careful examination of other analog delay units (including the AD80). While most players voiced a preference for the warm, organic tone of analog, many complained about the short delay time (generally 300 milliseconds) that they were limited to. In addition, distortion and added noise due to hot input signals were becoming a common if undesirable consequence of analog circuitry.

The AD-900 was designed to eliminate these problems in order to provide the longest, warmest, smoothest delay tone ever. Controls and features were kept to a minimum to free the circuit from unwanted noise and complexity of operation, as evidenced by the unit's simple three-knob layout and single output. Delay Time, Repeat, and Delay Level controls allow for precise adjustment of the delay effect with zero guesswork.

The AD-900 circuit runs at a higher voltage than typical analog delay circuits, which provides the unit with significantly more operating headroom. This increased headroom eliminates input overload distortion and creates a more accurate reproduction of the input signal in both dry and delayed modes.

The 12-volt power supply (included) powers four Panasonic MN3008 (high voltage BBD IC's, now out of production) that offer 40-600 milliseconds of delay time. With this increased delay time a much wider variety of echo effects can be attained, from tight slap echoes and long trailing delays to overlapping "sound on sound" textures. The AD-900 is custom-calibrated for self-oscillation at higher Feedback settings, creating wild "ray-gun" and "UFO-landing" special effects.

Early versions of the AD-900 feature two Panasonic MN3005's instead of four Panasonic MN3008's (MN3005 delay time is 300 mS, while MN3008 is 150 mS ­ therefore 2 x MN3005 = 4 x MN3008). These IC types were changed due to the unavailability of the MN3005