Here's the original speaker, nervously awaiting "surgery"...
My plan was to add a rotating horn, controlled by the MTCLogic speed controller, to take the speaker far from its humble origins to a baby 145. My purpose was two-fold; first to educate me in the ways of Leslies and second to avoid the expense of paying for a "real" 145 (the 125 cost me 31 pounds - you can't buy a 122, a 147 or a 145 for ten times that).
The most obvious external feature would be the additional "slots" in the top of the cabinet - so out came a router...
The result was pleasing enough - my compound cuts with two router bits made a passable impression of real louvres...
Whilst the sun still shone in the outdoor woodwork shop, I turned my attention to fitting some battens to hold the new top shelf. They were made from "available material" - the material having made itself available in a skip next to a building project - I hate paying for lumber...
With the battens in place, I could fit my new top shelf...
A little more modification gave me a pretty authentic back - with the original labels that proclaim the speaker's lowly origins as a 125...
Woodwork completed, I turned my attention to the electronics.
The can capacitor in the power supply filter was replaced, along with some other "mission-critical" capacitors and a power resistor in the power supply filter. There was also a capacitor missing in the amp - bypassing the output transformer's primary at HF and therefore (I suppose) important to HF stability of the circuit.
Also, I added a socket to take 240V and switched 240V to the speed control electronics...
Here's the amp with its new socket on the side...
With the amp running again, I needed a crossover unit to divide the signal between the original 12 inch unit and the new horn. The stock Leslie crossover looks a bit ramshackle, being built up on a piece of hardboard...
I knocked up some brackets to mount the crossover safely on the side wall of the enclosure...
Also seen in the photo above is a (massively over-specified) 240 - 110V transformer, which I'm using to provide the US mains voltage for the MTCLogic speed controller. It is important that I keep this in "stock" condition, as this speaker will be a test-bed for my future work on the new speed control system.
The modified 125 sounds like a dream - it is a joy to use and a pleasure to look at! There are a few more jobs to do (like replacing that massive transformer with something more appropriate and making a motor cover for the top motor to seal the main enclosure), but its is so good to play that these details can wait!
My thanks to George Benton of Benton Electronics for his generosity in sourcing parts, his expertise and his friendship.
...-.- de m0xpd
