Treble Booster by A. Russell, Practical Electronics, Page 71, April 1972.

[mac]

This is a circuit I have had in my hard drive for years but never tried or simulated.
It's based on a LT700 small output transformer. This site says specs are 550mH 63 ohm Primary, 2.25mH 0.63 ohm Secondary.

TB1 at the right is the original circuit. Basic guitar circuit added.
Simulation shows a "bell-like" response (TS808 ?) when the pot is at zero and a bass boost when maximized 
So I modified it a bit to make it more like a Rangemaster.

TB2 mods adds C2 and C4, and TB4 C2, C4 and the secondary.
Note that both mods can be transformed to the original with a double switch --> in TB2 SW1 bypasses C2 and SW2 breaks C4 path to ground.
At around 5k the curves "look like" a Rangemaster with a 8.2nF input cap, just a bit more Q-ish.



The PDF is available at the other forum,
or do a google search: practical electronics treble booster russell

mac

[PRR]

https://worldradiohistory.com/UK/Practical-Electronics/70s/Practical-Electronics-1972-04.pdf
12MB PDF file
I find the article on magazine page 320, PDF file page 58

[mac]

Thanks Paul. I got caught at the next article, the silicon controlled switch fuzz

mac