any tips on adding Foldback to the lower manual of the L-100 p ?

[Hans S. H.]

I have recently bought myself a L-100 p, its made in 1968 and it works nicely whitout any problems.
But i have been thinking that it would be nice if i could get a more "bass" sound on the lower manual.

I have heard of different ways to get such a sound on the lower manual, one of them being "foldback" or some thing like that.
I have also read somewhere, cant remember where, that its possible to somehow hook the pedal drawbar into the lower manual to get a few lower frequencys.

I am therefore wondering if anyone knew about a good way to get foldback for the lower manual or if its acctually possible "hook" the pedal drawbar in too the lower manual, and if it is, how one can do this.

Is there any parts i will need to do any of theese tings?


I am studying electronics, so i have some experience whit electronics, but i have never worked on something like a hammond before.

I once again wish to excuse my bad written english and want to say thanks in advance, to anybody who can give me some information about this.

[Papus]

You can do this modification purely via accessing the lower manual terminal strip which should be located beneath the lower manual, there is a metal cover visible from the front of the organ.
You'll need to move the entire wiring harness up one octave (thats right: UP), and add jumper wires to foldback the lower 12 frequencies to the first 12 terminals on the strip.
Usually there is insufficient slack in the wiring harness to simply grab it and move everything up by one octave - so you have two options:

1. Free up some more slack by opening up the top and back of the organ and finding a way to loosen up the harness, also some people have resorted to cutting away the wood cabinetry to allow the cable to pass closer to where it needs to go.

2. Solder extension wires onto the ends of every wire in the harness, this will allow the entire harness to be moved up one octave. I did this with my T202, it was a lot of work, but for me it was preferable instead of messing around in the guts of the organ. I colour-coded my harness extension wires by octave for ease of identification.

With the modfication completed, you simply set the lower manual drawbars to the three lowest drawbars fully out, this will create notes one octave lower compared to the stock organ.
Note that this allows your lower manual to go down to F one octave lower than normal, you will still be missing C-E at the bottom of the range - those notes are available on the pedals only, even after the modification.
The notes "created" one octave lower are not real frequencies generated by the organ - it is simply a pychoacoustic effect of combining the existing lower manual notes in a precise manner which causes the notes one octave lower to be generated in the air as the frequencies are produced by the speaker.
Pipe Organs use the same effect to create notes one octave lower than the notes physically produced by the pipes.

[Hans S. H.]

Thank you for this reply.

If it consists of mostly soldering and moving wires, then this should be quite ok for me to do.
Its nice to know that i dont have to mess around whit the guts to do this.

[Hoaxel]

Look on YouTube. Bass foldback on a M3, its just the Same way to do. Good for lefthandbass, but you leave higher frequences in treble

[Papus]

Yes - I forgot to mention this, you will lose an octave from the upper drawbar on the lower manual, not a big deal if you mainly use the lower manual for 8880000, 8888000, 8888800 and the like.
The bass foldback works best at 8880000 anyway.

[Hoaxel]

Sorry, loose, not leave😁

[Hoaxel]

look here
https://www.youtube.com/watch?v=PYj2hIgirmo