Need Help getting Line-Level Signal out of Conn Serenade 633 Organ

[Paul789]

So there is an "Electro Music 251 Tone Cabinet", 6-pin female jack on the power supply
of my Conn 633 organ:

It appears to have the same pin-outs as the Leslie 251, and when
I hooked my o'scope to pin 5, I appear to get a good signal, from
both the 2 manuals, and the bass foot pedals. There is also a signal on
pin 6, but the bass pedals seem to be MUCH louder than the manuals,
on this particular pin.

What is the reason for the difference in the two pins? I assume pin 6 is
meant to mainly amplify the bass pedals, and should go to some sort of
sub-woofer? Which pin should I use, to go to an external reverb unit, and
my keyboard amp? I would like to amplify both the 2 manuals, and the
bass pedals, equally.

Also, I was worried that it looked like you could insert the male plug the
wrong way, but after looking at some pics, it appears two of the pins have
a larger diameter than the others, to prevent incorrect insertion, right?

And is this the correct male plug to buy, if I want to install a 1/4" female jack
into this organ?

https://www.--------/itm/1-Vintage-6...oAAOSw1rxc9XEP

Thanks for any good advice! :->

[Paul789]

Ok, this explains it pretty well:

http://www.organplus.com/technique/l...lesli251um.pdf

Although I seem to be getting the pedal voices on both channels (pins 5 and 6).

I supposed what I will do, is listen to each signal, and decide which one is best
for adding reverb, and then amplifying with my Roland keyboard amp. If I feel
I will need both signals, I'll just put them through a small mixer first.

;-)

[jbird604]

You will want to mix the two signals before you reverberate and amplify them. One is the "string" or "pulse" channel and the other is the "flute" channel. As you note, the pedals play in both channels. But you'll have a serious imbalance if you only use one or the other. Both are in fact full-range channels, even if it seems that one is heavy on the bass. That would be only because the pedals happen to be turned up louder in that channel, or that is the "flute" channel, which by definition is bassier.

[Paul789]

Ok, I've gotten both signals on pins 5 and 6 mixed, reverberated, and amplified, and I am
very pleased with the results. Now I have to build a simple 6-pin amphenol Leslie connector,
to two 1/4" mono female instrument jacks, in some sort of metal project box.

I bought an old male Leslie connector came from Ebay, but I don't know how to remove the
sheath:


Do I fit a screwdriver in the slot, under that dimple, and pry it off? I don't
want to damage it! But I need to access the pins, so I can remove the
wires coming from pins 3 and 4, so that I won't have 120 Volts AC, dangerously
exposed on the wires.

I also want to solder two audio cables to pins 5, 6, and 1 (ground), to go to the
1/4" instrument jacks. Should I use shielded audio cable for this job? That
might be overkill, because the audio wires don't look shielded, coming from the
innards of the organ, but it might make me feel better!

:-> Thanks for any good advice!

[Paul789]

Ok, for any other newbies out there: Yes, the Leslie connector's metal sheath is easily
removed by prying it off with a screwdriver.

And I ended up just cannibalizing an audio/video cable I had lying around, by
cutting off the video connectors, and the audio RCA connectors on one side. Then I
tied a knot into the end I had cut off, and used a tie-wrap to reinforce the knot, so
there will be strain-relief if someone ever yanks or trips on the cord:

Then I removed all the wires soldered to the 3 pins I will not use (the two AC voltage pins, and the
tremolo relay pin), and bent loops into the remaining wires, to create a bit of mechanical strength,
and not relying completely on solder strength:

Then I soldered the two grounds to pin 1, and the audio signal wires to pins 5 and 6, and
replaced the metal sheath (it's harder to put back on, than to take it off!).

And, Voila! I have a Leslie 251 connector to two RCA outputs:

:->

[andyg]

That output is going to be hot, at speaker level, to drive a 251. You'll need to pad it down a fair amount to get to line level.

[Paul789]

That output is going to be hot, at speaker level, to drive a 251. You'll need to pad it down a fair amount to get to line level.

The microphone gain trim pots on my Mackie mixer are turned down, but not completely, and there is no
noticeable distortion at all. I ended up turning on the 75Hz Low Cut on both channels.

[andyg]

There's still a mismatch and I don't like having to turn trim pots down that far, but if it's working fine then fine!

[Paul789]

The Leslie 251 still amplifies the signals on pins 5 and 6, before they reach the speakers:

[Silken Path]

Wow - cool information. My 643 has the same connector on the amp (and two more connectors on the sidewall beside it). I'm going to save this info!