Leslie Preamp Question

Tech Questions Regarding Hammond Organs and/or Leslies

Leslie Preamp Question

Postby Bryce on Sat Jul 25, 2009 4:19 pm

Hey Guys,

Leslie pre amp question here. I have what looks like a custom unit called a "Leslie Box" that powers up a 122 and accepts +4 line input to send through the leslie. It currently powers the motor and the speakers, but the moment I plug a source into the TRS on the side, I get nothing but a low and loud hum from the leslie. Some signal does pass through, but it's very distorted and completely unusable with the hum. The ground switch does nothing. Everything here is on a dedicated circuit, and it doesn't seem to be a 60 cycle. I've taken the unit into a local electronics repair, and they said there's nothing wrong with it. Obviously, I'm missing a part of the equation. Any suggestions on what I should be looking at, and is there another unit that you guys would suggest for this purpose?

Best regards,
Bryce Francis
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Re: Leslie Preamp Question

Postby jordankersten on Tue Jul 20, 2010 8:00 pm

Assuming that the box is wired correctly and the Leslie amp is in working orders, a Leslie amp is not capable of accepting a line-level signal. If there is no preamp in that box, a line-level signal will have to be boosted to a level that the Leslie amp can accept. The Leslie 122 was designed to accept a signal from a Hammond preamp. The Hammond preamp delivers a signal from approximately 3-6V into the Leslie amp.
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