Hooking up Hammond M3 to Leslie 142/122

I have a Hammond M3 I have previously modified to pad the speaker output into an attenuator pot and finally to a 1/4" unbalanced out.  Was using this into a neo-ventilator (worked and sounded great!), but now I am graduating to a real Leslie 142!

I was planning on building the following schematic, with a Jensen JT11 FLCF.  I'm wondering if I just need to tie connection 4 on the primary to ground, and 1 to tip on the unbalanced jack?  Is this the best way to do this?

I would also like to be able to plug in guitars, reamp line level signals, etc.  I'm considering building a tube preamp and I could wire that like a typical preamp with an output transformer into the stock balanced circuit shown below.  Maybe it would be best to build this into a box with an input for my switch, a TS output for unbalanced and an XLR for balanced (know I could only use one input at a time), along with the power jack.  Then I wouldn't be tied to the organ.

The easy option is a preamp pedal.  this should work for guitars and with your 1/4" out of the M3.

https://trekii.com/products/leslie-speaker-accessories/uc-1a-pedal-110v.html

That's not very DIY!!

rockinrob86 said:

That's not very DIY!!

Click to expand...

TRUE. But DIY is not the end all be all at times. IF it were me I would buy a Leslie kit.

rockinrob86 said:

I was planning on building the following schematic, with a Jensen JT11 FLCF.  I'm wondering if I just need to tie connection 4 on the primary to ground, and 1 to tip on the unbalanced jack?  Is this the best way to do this?

Click to expand...

Connecting an unbalanced source to a balanced input usually works. The transformer is good at minimizing ground loops. What kind of signal do you want to connect to the unbalanced jack?

I would also like to be able to plug in guitars, reamp line level signals, etc.  I'm considering building a tube preamp and I could wire that like a typical preamp with an output transformer into the stock balanced circuit shown below.  Maybe it would be best to build this into a box with an input for my switch, a TS output for unbalanced and an XLR for balanced (know I could only use one input at a time), along with the power jack.  Then I wouldn't be tied to the organ.

Click to expand...

What is the question? 

haha, yea reading back this wasn't the clearest.

I need to connect my unbalanced hammond to the leslie.  I would also like to plug guitars in on occasion, along with anything else including reamping tracks.

I was asking about how to/if I should wire the above transformer in the schematic to interface with unbalanced signals, and if this was ok.

Now I realized I can use an amp attenuator I have with a balanced line out (for guitars) and my studio interface can feed line out balanced, so I think I am going to build the above schematic stock.  I can either plug the hammond into my powered DI for acoustic guitar stuff, or option 2 is connect a transformer at the organ to convert the unbalanced signal to balanced.  I may need to redo the attenuation to increase the voltage some for this option.

But I think this solves the issue.  I thought it wasn't good practice to just plug in an unbalanced signal to a balanced input?  I guess I can try and see how the organ sounds this way.  If it doesn't matter then I don't need the DI/transformer!

rockinrob86 said:

I was asking about how to/if I should wire the above transformer in the schematic to interface with unbalanced signals, and if this was ok.

Click to expand...

It is ok, but beware that the amp is not very sensitive and you need quite a high level there. Guitar level is certainly too weak.

But I think this solves the issue.  I thought it wasn't good practice to just plug in an unbalanced signal to a balanced input?  I guess I can try and see how the organ sounds this way. 

Click to expand...

This won't work for two reasons.
The Leslie needs a floating signal in order to receive the rotation control voltage.
The Leslie amp cannot deliver full power with only one leg active.