The J200 was evidently developed during the latter half of 1969. It does not make an appearance at the "British Musical Instrument Trade Fair" at the Russell Hotel in London in August 1969, but figures fully formed in February 1970, in time for the other major European equipment show - the Frankfurt Musikmesse.

Very few of these amps survive. In its "Focus on Amplifiers", Beat Instrumental magazine prints a picture, however:

Notice from "Beat Instrumental" magazine, February 1970. Not much is said about the amplifier in the blurb, but its price is given: £150.

The drive of JEI was still fully solid state at this time, an article in January 1970 setting out the ethos in brief:

The ability to take a feed directly from the preamp - either to a mixing desk or perhaps valve power section - was potentially very useful. The organ, PA and bass amps - the O50, B50, 0100, 0100, PA50 and PA100 - certainly had lines in and out built in, so too the early J40 - see this page - but not the J100 nor its bigger brother, the J200.

The development of the J200 with its mighty 200 watts was clearly part of the view expressed in the article above. But later in the year, JEI reverted to valve, issuing the AC40, doubtless in response to market demand. Further valve amps followed.

From later sources, it appears that the J200 remained in production at least until late 1972:

Extract from the Beat Instrumental preview of the Associated Musical Instrument Industries fair (successor to the British Musical Instrument fair) in August 1971. If the J200 is the amp mentioned, then it had evidently become "general purpose".

A detail from the JEI pricelist of December 1972. The J200 still at £185.00.