Qhorus Effect: Roland Jazz Chorus Amp?

[tbryanh]

Why the chorus effect on the Roland Jazz Chorus amp considered to be so special?

Is it mostly because it was a stereo effect built into a stereo combo amp that was an amp dedicated to the Jazz community?

In other words, is the chorus circuit in the amp pretty generic, or is the circuit special too?

[Dr Kaos]

The chorus works the same as any other except as you noted the amp is stereo so a proper stereo chorus can be achieved.
When the chorus is off the amp is mono when you switch the chorus on a third dimension gets added.
The left speaker carries the dry signal and the right speaker carries the swept delayed signal. This can produce some odd effects if one or the other speaker is not working.
Some of the smaller JC amps only have one speaker so are not stereo.

Kaos

[teemuk]

In other words, is the chorus circuit in the amp pretty generic, or is the circuit special too?

In my opinion, it's pretty generic.

Lot of the reputation of that series is simply explained by it being the first amplifier with said built-in features, which allowed the series to gain sort of a "standard" reputation rather quickly when there still was very little competition. After that anything stereo, chorus and good clean cleans practically became synonymous with JC-120 design. But if you want an amp that in addition also does other tricks remarkablöy well there are many other, IMO better, options available as well. Have been for years and years.

e.g. I'd rather pick an Ampeg VH-140C, a Peavey Stereo Chorus or perhaps even a Yamaha VR6000 anytime over JC-120. The chorus in them leaves nothing to be ashamed of, cleans are great and in the Ampeg and Peavey the gain channel is actually something you even want to use. But studios and backline providers are far more lucky in getting you that JC-120 because it's a standard like an AC30 for the classic Vox tone.

You also need to heed that Jazz Chorus design dates back to mid 1970's and was at least in the early years revised almost constantly. Chorus and vibrato circuits in pre 1982 Jazz Chorus series amps are very different from the integrated chorus/vibrato circuits that were introduced in 1982.