Hooking a Hammond L-112 up to a Leslie 25. How can this be done?

[Guest]

So, i just got a free leslie 25, and i have a feeling it will sound better than the speakers in my L-112. I have a 26-1 Leslie connector kit (with both half moon switches), and a leslie cable. Unfortunately, i don't have any idea how to hook the leslie up to the Hammond. I've got an A-100 too, and this is somewhat of a backup organ, but it's a chop and good for small gigs. What should i do to get the leslie hooked up to the L?</p>

[Guest]

Re: Hooking a Hammond L-112 up to a Leslie 25. How can this be done?



Hi,</p>

I'm salvaging a water damaged L112 for the electronics and getting familiar with the design so I can suggest a few things. All signals are fed around with RCA jacks just like a piece of A/V gear so it makes things simple. The side of the power amp chassis has three jacks marked Red, White and Gray. The White is the signal that comes from the expression pedal and before that, the output of the percussion amp. Assuming you want to keep the vibrato and perc amps in the signal path, you can tap off from the power amp input (white), or from the reverb driver output (red). The input side has signal level of 45mV (0.045V) and the reverb amp output has a healthy 3V output so it really depends on what sensitivity the amp in the Leslie exhibits. I suspect it will work better with the 3V signal. If you want the reverb as well, that's trickier since the connector is not an RCA. The Yellow wire in the three pin Reverb Switch connector has the recovered reverb signal at around 120mV (0.12V), and the Green is the switch return with a 55mV (0.055V) signal level. Beyond that, there are no easily accessible tap points other than the speaker outputs. From there, you'll need to substitute the speakers with an 8-ohm 20 watt resistor and pick your signal off from that. Mind the polarity as one lead is grounded internally in the chassis.
</p>

You can use RCA Y splitters to get at the signals or just shut down the internal amp by disconnecting the Red jack. Obviously, you'll need suitable adapters on the Leslie side; I don't know what hookups are available there but be very careful since I think it provides high voltage DC on some pins. All signal points from the L112 I mentioned are AC coupled so you don't have to worry about the Leslie amp bias being thrown off by DC level. Also, don't disconnect the Gray jack from the amp chassis since its a sensitive input and needs to stay grounded by the reverb receiver to prevent hum and noise pickup.</p>

Hope that helps,</p>

expiano
</p>

[Guest]

Re: Hooking a Hammond L-112 up to a Leslie 25. How can this be done?



Hi again,</p>

</p>

Just thought of something; the reverb drive output (red) is in the reverb loop path and contains some fed back reverb signal, so you should be able to get some reverb signal without having to tap into the Reverb Switch wiring. </p>

</p>

exp
</p>

[andyg]

Re: Hooking a Hammond L-112 up to a Leslie 25. How can this be done?



Simple. If the colours on the 5 wire connector that comes with the 26-1 are
'standard' or 'standard' compared to all the ones I've installed, here
goes</p>

Grey and Blue wires from the kit go to switched mains AC - take it from the terminals inside the silver box top left on the shelf. IIRC, it's the outer two terminals, but check this with a meter to make sure.
</p>

Black wire from the kit. Attach it to the ground (black) terminal of the speaker.</p>

Cut
the green wire from the organ's power amp to the speakers/crossover (can't
remember which in an Ln but in my T, that green wire goes to a crossover mounted between the speakers). The Green wire from the kit goes to green wire on the speaker side
of this cut, red wire from kit goes to the green wire on the amp side.</p>

Job done. There is no reverb speaker to worry about in the L and you don't need to worry about connecting anything to the signal chain anywhere else. This is how the 26-1 is designed to work - straight off the speakers.</p>

Andy
</p>

.

</p>

[Guest]

Re: Hooking a Hammond L-112 up to a Leslie 25. How can this be done?



Sorry iamkellen, just reading Andy's excellent post, I'm afraid my response earlier may only serve to confuse. I came at your problem from the viewpoint of a hardware hacker and realize now that's not what you need. I guess I shouldn't have jumped so soon at your unanswered post but I've been dissecting an L-112s amp, vibrato, and percussion assemblies in preparation for conversion. Heed Andy's advice on using a meter; there are lethal voltages present on the connector and the wrong wire to the wrong place could do far more harm than just blow a fuse.
</p>

Good luck, and remember the "one hand at a time" rule when poking around with tube DC and mains power,
</p>

exp
</p>

[Guest]

Re: Hooking a Hammond L-112 up to a Leslie 25. How can this be done?

Hey thank you guys very much for you help. I'm going to have to tear the top off the L-112 to get in there ( i already custom chopped it so the amp/pre-amps/ reverb are all stuck close together). But, i'll be sure to put some pictures of the whole rig up soon, (it's got a psychedelic paint job.) thank you guys so much.

[Guest]

Re: Hooking a Hammond L-112 up to a Leslie 25. How can this be done?



Hey Andy, i'm finally getting around to trying to do this, and i'm a bit confused as to where the "Switched mains AC" is. I'm pretty new to all of this hammond buisness, so sorry if i sound very naive. Also, i didn't see a crossover after the amp before the speakers ever, there's just a black and a green wire, the way i understood what you wrote, it said to use this green wire twice. I'm not sure what i'm looking at wrong, but a little help would be much appreciated.
</p>

[andyg]

Re: Hooking a Hammond L-112 up to a Leslie 25. How can this be done?



Looking from the back, at the top left on the shelf, there should be a small silver metal box with a screw at each end. Switch off, then wait a minute or two, then unplug the organ from the mains and undo the two screws. That should reveal the mains wiring. Plug in, turn on and carefully measure the AC voltage on the outer two terminals with a meter. Then turn the organ off and measure again. IIRC, these two terminals are switched and the voltage will be zero with the organ turned off. If so, that's where the blue and grey wired go. These connections obviously need to be securely soldered. Unplug, then replace the cover and tighten screws.
</p>

If you've just got that one green wire going between amp and speakers, that looks like the one to cut. Red wire from the kit goes to the amp side of the cut and the green wire from the kit to the speaker side of the cut. You don't need to solder these wires, twist them securely together and fasten with a wire nut or tape them to insulate.</p>

Standard warning I always give. If you are in any doubt about doing this, then please get professional help. It will cost a little, but that's better than damaging the organ or leslie and WAY better than frying yourself! There are mains voltages and higher HT voltages in there, so be careful.</p>

And remember that the info I've given is for kits with standard (to me) wiring colours. Double check things to make sure.
</p>

Andy
</p>