Well, perhaps he sort of knew what he was doing, but didn't want to go to the trouble of sourcing the correct kit. It can be made to work, but echo switching is a bit problematic. You can't leave the console load resistor (R1 32 ohm) in place. It's much too low an impedance for the organ pre-amp to drive. On the other hand with just removing the resistor will cause the Leslie to hum when you switch to main. A resistance of a few hundred ohms may work, low enough to ground out hum pick up in the cable, not so low as to reduce the pre-amp output. You also have to think of a way of switching both the G-G lines to the PR-40 off and on together.

On 02/01/2022 17:30, Bob Pasky wrote:

So, it looks like the guy that installed the kit (before I purchased this whole setup) didn't know what he was doing.
Kinda figures when he left the Leslie's cable connection inside the B-3!

On 1/2/2022 3:08 AM, Chris Clifton wrote:

That kit is intended for use with a spinet organ with a built in amplifier and speaker. Not ideal for connecting to a console with G-G output from the pre-amp, there never was an official passive kit for connecting a 9-pin Leslie to a console.

Did a little more digging around the Fish Organ list, this kit uses the connector box with the number you gave in your original post.

On 01/01/2022 23:18, Bob Pasky wrote:

Hi Chris,

Thanks, but the circuit is not even close. What I've got is a totally passive circuit.

I see your point about shorting the "unused" speaker, but that's not how mine works. My MEE switch
only has three wires going to it. The "center" wire connects to Main, both or Echo, depending on the
switch position.

The thing is, this used to work. But the guy that installed the kit just put the box inside the organ case,
next to the preamp. In order to connect the Leslie, you had to leave the back of the organ off. That
looked strange, so I extended wires from the box to the pedal case and put the 9-pin connector
where it's supposed to go. In doing so, I might have messed something up in the kit's wiring and
haven't found the schematic for it. This is as close as I got to the right circuit. At least, the MEE and
Tremelo switches match what I have.


-- Bob

On 1/1/2022 10:36 AM, Chris Clifton wrote:

I'm guessing that it will be similar to this one, . All the kits I've looked at for connecting 9-pin Leslies to console Hammonds seem to use the same basic circuit.

When the MEE switch is set to echo, the brown and orange wires are connected together. This effectively puts a short circuit across the input terminals of the PR-40, muting it. The two 820 ohm resistors, R2 & R3 isolate the G-G terminals of the organ from the short circuit. When thinking of MEE switching on console type organs, I find it helpful to think in terms of the switch muting the unwanted speaker, rather than enabling the wanted speaker.

To use a two channel Leslie with a single channel organ, you will need a crossover between the organ and the Leslie. These crossovers are usually built into a short piece of tube with a 9-pin plug on one end, and a 9-pin socket on the other. The crossover ensures that bass notes always go to the stationary channel of the Leslie and sound through the 15" speaker, only mid to high frequencies go to the rotary channel as the speakers of this channel can't handle low frequencies.

On 01/01/2022 14:49, Bob Pasky wrote:

Does anyone have schematics for this Leslie Connector: 113910 ?
It's for adapting a B-3 to a Leslie 710.
I've looked in the usual places, but haven't found this particular model.

Barring that, can anyone tell me how the signal to the PR-40 should be terminated
when the MEE switch is set to Echo? (The PR-40 is Main, the 710 is Echo). It appears
that the Main signal just floats and I'm reading something like 5v to Gnd. It makes an
awful "sproing" noise from the PR-40 when it's switched from Main/Ensemble to Echo.
That can't be good for the PR-40 amp.

Thanks,
-- Bob

--

Virus-free.

--

--