Connecting a Leslie to Wurlitzer 4430 reed organ

[skippy]

Hi again,

I plan to install an 11pin Leslie connection socket on my Wurly 4430 reed to accommodate my Leslies 720 and 705. This is a single channel organ and it looks like everything, incl. the pedals will end up in the tremolo channel. It is bad enough having to listen to a wobbly bass with the Spectratone going. I guess there is no way to send just the flutes to the rotary channel and the rest to the main channel. ?????????

Thanks,
Skippy

[andyg]

I guess there is no way to send just the flutes to the rotary channel and the rest to the main channel

Not if it's designed and built as a single channel organ, Skip.

Can't recall 100%, but I'm pretty certain that the 720 and 705 do have the built-in crossover that sends all bass through the stationary woofer. If so, just hang the cabinet on the organ, sending everything to the cabinet's rotary channel and let the x-over do its job.

If it doesn't have the x-over, then it should be easy enough to make one up and make it part of the connector kit, sending all low lows to the stationary channel.

[skippy]

Thanks Andy,

The Leslies 705/720 have no crossover in front of the amp. I suppose most 2 channel organs deliver the bass signal to the stationary channel anyway. There are post-amp crossovers in the Leslies for both channels - eg. splitting the signal for the 720's horn and bottom rotor on the rotary channel and the 15" and 6x9s on the stationary channel.

But as you say, it is just a matter of finding where to get a full range audio signal on the reed Wurly and then feed it into the rotary channel and let the post-amp crossover do the sorting, ignoring the stationary channel. The reed Wurly is a unique animal. It is actually a pseudo 2-channel setup whereby the lower reeds are processed in the amp as Bass and the rest as Treble. Without the schematics I just dont know where this mix ends up. I assume the treble ends up in the Spectratone. And I am fairly confident that the full range signal is present at the main speaker with the Spectratone settings Off or on Chorus. And I think this is where I will get the audio for the Leslie.

Ken Griffin only used the Leslie Horn and thought that the Wurli tremolo was quite sufficient for mid to lower frequencies. The problem with the Wurli tremolo appears to be that it modulates the pitch by a set frequency measure across all notes thus making a lot of difference in the lower range and very little in the upper range. Most other organ manufacturers apparently used a set percentage across the range – so the wobble was the same bottom and top.

Well, I now have a 4300 in good nick. First I gave it a good clean and lube. Not knowing what oil to use I just used Castrol Handy Oil, or often called sewing machine oil. Better than nothing I suppose. The oils recommended in the owners manual have died a long time ago. I think in a couple of weeks I will re-oil with normal motor oil. Any suggestions out there?

Another issue is the Spectratone. As soon as the organ is turned on it starts spinning at fast speed and it will remain doing so regardless of the tab settings until the organ is turned off. The Chorus tab just appears to bring additional sound to the large main speaker. But no speed change. Is this correct?

Thanks,
Skippy

[andyg]

Having now checked the schematics, there is a 100Hx high pass filter in the rotary channel to avoid sending 'real' bass to what is still a relatively small bass driver but, as you say, no proper x-over, so the bass then goes nowhere! A simple x-over in the kit should do the trick.

[skippy]

Thanks Andy,

At this stage I will just hook it up with the generic 7850 kit I used on all my other 2 channel organs, leaving the stationary channel idle and see how I go with the bass. The bottom rotor speaker in the L720 is 10". But as you say, it will only get 100Hz plus and have the Leslie wobble. I can always later on channel off the low bass frequencies in the connection kit and feed them into the stationary.

Playing the Wurli 4430 through the Spectratone is a weird sound experience to the ears. A Leslie is pretty much predictable. This thing has a life of its own. Just playing down the keyboard with flutes 16,8,4,2 reveals a different AM/FM reiteration rate from note to note - sometimes double or half from one note to the next. The pulley that drives the Spectratone rotor has an excentric type of plunger attached to it that enters and exits a coil with each revolution. This modulates the signal that is coming through the main speaker while the Spectratone is on. I'm not sure how. This may have something to do with this crazy sound experience. But I like it. It is a rich sound that continuously changes throughout a song - especially playing multiple notes and chords on the upper.

Cheers,
Skippy

[skippy]

All done! Sounding, well - different. I don't think the Leslie 720 is a perfect partner for the Wurly reed. Pure flutes sound sweet and exiting. But anything else from scratchy to weird. It may be a mismatch of frequency ranges. I'm not complaining. With the right settings it makes a beautiful noise.

I hooked the Wurly reed to the Leslie using a mix of the schematics of the generic 7850 kit and a kit I used for my Hammond M102.