Lexicon Prime Time 93 Digital Delay

Photo by Grant White


The Lexicon Prime Time Model 93 is a digital delay rack effect unit released in 1978. It is capable of delivering completely unique and singular sounds.

The Prime Time 93 is a mono delay line with two inputs and two independent taps. You can invert either signal, mix their levels, and bypass the delay completely with the front panel switches.

There are a few special features that really make the Prime Time 93 a secret sonic weapon for people Daniel Lanois. Because of the technological limitations present in 1978, the Prime Time 93 (not to be confused with the subsequent “95” and “97” models) must reduce the bandwidth of any delay longer than 256ms; and that’s with the optional memory expansion installed.

From the owners manual:

“The indicated delay settings can be multiplied by factors of 2, 4, and 8 with the delay multiply switch to achieve delay times up to 128 msec X 8 = 1.024 seconds (or 256 msec x 8 = 2.048 seconds). The 1, 2, 4, and 8 positions also program the system bandwidth so that the 12 khz bandwidth (available at 1 x position) becomes 6khz at the 2 x position, 3khz at the 4 x position, and 1.5khz at the 8 x position.”

Basically, the longer the delay, the more lo-fi the output since you’re cutting out bandwidth. Just to give you an example, a telephone line operates at 3khz bandwidth. The same as when you’re using the 4 x delay multiply. Combine tone mangling delay with an oscillator and infinite repeat and you’re off to the races.

Lastly, there seems to be some confusion online about the Prime Time 93’s VCO. I heard it referred to as an LFO in one video and that didn’t sound right to me. I contacted Gary Hall, creator of the Lexicon PCM42 digital delay, who worked for Lexicon at the time the Prime Time 93 was in production. Here’s what Gary had to say:

“Actually, the Prime Time has both an LFO and a VCO. Internally, the digital circuits are all run by a clock at ultrasonic rates. In the fixed delay mode, the clock is a crystal oscillator. When you click the knob to ‘UnCal’, the clock is taken over by a Voltage-Controlled Oscillator running at similar high speed which you can change with the manual sweep or with the LFO. 
The clock oscillator itself is a true VCO, however it’s not in audible range (I don’t have numbers in front of me, but it’s dog-whistle territory). It’s also linear-response only. No effort was made to have it conform to synth specs. So, VCO modulated by LFO and/or manual offset.”

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