Introduced in 1976, the EMT 250 is one of the earliest digital reverb/modulation effects ever made. It is still regarded as one of the best-sounding reverb units by many world-class producers for its lush and open reverb.
The EMT 250 was introduced by EMT Technical Director Karl Otto Bäder in 1976 at the Zürich AES Convention. Designed to be an alternative to the EMT 140 plate reverb systems that were enormous by comparison and required strict isolation to avoid sympathetic resonances, the EMT 250 offered a new sound in a relatively compact, easy-to-use package. The digital hardware portion of the EMT 250 project was farmed out to Ralph Zaorski through a Massachusetts electronics company by the name of Dynatron. MIT professor Barry Blesser was hired to perform the algorithm design. Karl-Otto Bäder was then instrumental in moving the project from the research phase into the product phase, and also performed the listening and voicing for the EMT 250.
The EMT 250 is obviously most famous as a reverb, but in reality is more than that. It is the first multi-effects unit. We were particularly impressed by the complex Chorus program and the Phaser, which interestingly has no LFO and must be “phased” by hand with the unit’s white lever.
Since Chorus provides a different result from each output, combining different physical outputs from the unit can create different sounds. This added another layer of complication to the setup because it was best served when each output had its own fader on the desk. The result was worth it though, as the sound was very pleasing, especially on acoustic guitar and electric bass. Similarly, the Reverb and Phaser gave variations on sound when auditioning the additional outputs of the EMT 250. I actually preferred the “rear” outputs from the Phaser versus the “front” outputs.
f=1KHz : 0.4 to 0.5 seconds controllable in 16 steps;
f=300Hz : Factor of 0.5 to 2.0 referred to the basic reverberation time; controllable in 4 steps;
f=6KHz : Factor of 0.25 to 1 relerred to the basic reverberation time; controllable in 4 steps;
Basic Delay of First Reflection : 0, 20, 40, 60 ms;
Outputs: 4, useable as mono, stereo or quadrophonic outputs;
Delay Times: 0 to 315 ms, selectable in 5 steps, additionally 0 to 60 ms, selectable in 20 ms steps;
Outputs: 4, each programmable with freely selectable delay times;
Phasing: Changing of the amplitudes oI the harmonics;
Chorus: Tonal duplications;
Space: Extremely Iong reverberation time of 10s;
Echo: Repetitive slap-back with an attenuation of 10% in the time intervals between 5ms and 315 ms;
Frequency response 30 Hz to 10.8 kHz;
THD < 0.5% at normallevel (f = 1 kHz);
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