Compression might seem to be one of the more esoteric effects available to musicians. Although the idea is simple enough—compressors “squeeze” the signal’s dynamic range, thereby shrinking the difference between the loudest and quietest parts—the variety of compression circuits on the market can overwhelm the potential buyer. Each pedal has its own character, and although compression is, at least in theory, a transparent effect, some characters are more popular than others.
One of these compression types, dubbed "optical compression," can be found in Demeter Amplification’s solid little Opto Compressor. Demeter’s unit is an optical compressor because a small light inside the unit will glow in direct proportion to the strength of the incoming signal. A small, light-detecting resistor will, when shined upon, “clamp down” on the signal, quieting it. Optical compression came into favor during the ‘60s and ‘70s and now has a very “vintage” character. Demeter Amplification’s Opto Compulator is a prime example of how good optical compression can sound.
The Opto Compressor is about as simple as a pedal can be. It features an on/off footswitch and two knobs, Compress and Volume, that allow one to control the amount of compression and the outputted volume of the compressed signal. Demeter Amplification also included an internal trim pot that controls the master gain. The whole unit comes in a solid, textured black metal housing that unscrews so that one can access the battery connection inside. However, like all good pedals, the Opto Compulator also accepts a standard 9V DC power plug, which is a good thing because the pedal won’t work if the 9V battery loses enough juice so that it puts out 7V or less.
At the lower levels of the Compress knob, the pedal will make the classic country compression that can be increased even as high as the 12 o’clock position. It’s also the perfect amount of compression for playing along to, say, the Law & Order theme. The pedal handled the percussive, lawyerly blues riffs with the finesse of a seasoned “good cop” who needs answers from a suspect, and needs them now.
At and above the noon Compress knob setting, the OC will compress one’s signal a fair amount. When placed before an Electroharmonix Small Clone, itself behind a Boss DS-1 distortion, the OC leveled out the inputted signal without taking away from the warbly, metallic sound. If anything, the OC helped to push some of the signal that would have otherwise faded much sooner.
The Opto Compulator will also play the “bad cop:” just crank up the Compress knob to really put on the squeeze, and those notes will sing. Only in these higher compression settings did the pedal’s otherwise pristine tone begin to break up. At this high level, a strummed chord might seem to take on a slight vibrato, almost as if the pedal were doubling as a tremolo. Yet it was easy enough to clean up the signal by adjusting the pedal’s internal gain tone pot. Nevertheless, the signal break-up was more of a subtle coloration of the sound than a harsh distortion, and was nothing that detracted from the pedal’s otherwise smooth, ear-pleasing compression.
Compression, like so many effects, is a matter of taste. Fortunately, the folks at Demeter Amplification have excellent taste in compression, and an eye for quality construction. For easy to use, classic compression, the Opto Compulator is the prime suspect.
What we like: Dependable optical compression that will range from subtle to squeezed. It won’t destroy one’s tone.