hi i have recently purchased this amp which was made in britain.it was made as an answer to the mesa boogie mark 2.they never made many and is something of a collectors item,i have had it for 2 mths now and for a 30 year old amp it is magnificent.there is not an awful lot of info on the net about it but i did manage to find a little on http://www.studiomaster.com/1981%20-%201982.htm.i will take it in the near future for a service.this amp has effect send and return on it[i thought this was a fairly new development] and was meant for studio use but it is built like a tank.i hope to gig with it and my 5120 with magnatrons sounds fabulous through it.