I don't think it was a Rangemaster take, although you could simply use a smaller input cap (or a switch with a few various values) to get close.
Back in the early '70s (pre MV days) a few of us used them to boost the big ol' monster valve amps to get some rawk happening. They were great .... there were two versions back then ... they both had a solid jack plug sticking out of one end .... one variation plugged directly into the guitar, the other version plugged directly into the amp. 
In those days, we would build simple one-transistor boosters, and early fuzz box designs, and we could see how simple the LPB was, but they used some weird transistor that we could never get hold of. I'm not totally sure, but pretty certain it was silicon, not germanium.
Yeah, they were great, in a nice simple way. Just boosted yer signal to make yer amp work harder. Nowdays, some amps may have more sensitive inputs and not respond well to too much boosting (talking about amps designed for higher gains, ugh), but i'm sure they still work great for most vintage-style amps, that's what they were designed for.