Thanks for jogging my memory Alan, I had actually spoken to Maurice a few times in the late 80s (he's a local... in that he was in the same city) and I was about to buy one of these doublers from him, but then a 2nd hand M1 system came along which had one in it. I remember saying to him that I would buy one in kit for and assemble it myself but he pointed out it needed a CRO to adjust the pre-comp which seemed like too much room for error for me.

It's mainly the reason why I went with the doubler design I sell now because it doesn't have pots which end users could inadvertently fiddle with and run into problems.