From simon@alphabeck.co.uk Thu May 17 04:20:16 2007
Subject:Re: Leslie 3300 Insides

Has anyone thought of making a rotor from balsa wood? Light weight but with the sound-reflective and structural characteristics of a wooden rotor. Just a thought...

Simon

----- Original Message -----
From: Keith H Clark
To: CloneWheel@yahoogroups.com
Sent: Thursday, May 17, 2007 11:13 AM
Subject: RE: [CWSG] Leslie 3300 Insides

You can shim the foam rotors where they sit on the rubber mount that will
eliminate they wobble and noise.

From: CloneWheel@yahoogroups.com [mailto:CloneWheel@yahoogroups.com] On
Behalf Of Bruce Wahler
Sent: Tuesday, May 15, 2007 5:40 PM
To: CloneWheel@yahoogroups.com
Subject: Re: [CWSG] Leslie 3300 Insides

Hi All,

>Yes, all new production Leslie's have a foam rotor.

... and have been doing so for *at least* 15 years.

The plywood rotor was one of the first changes to the "new era" Leslie. It
was used on the 10" and 12" speakers of internal Leslies as far back as the
late '60s. My first Leslie, a Fender Vibratone I bought used in 1971, had a
foam rotor.

The foam rotors are easier/cheaper to make, lighter than the originals, and
they start out quieter. Over the years, they sometimes loosen from the
mounts and/or the counterweights and start to flutter a bit; if this
happens, the result is *at least* as noisy as a wood rotor without the scrim
cloth. You can always replace it with another foam rotor, though. So, H-S
wins all around: lower cost rotor, less motor torque required, potential
repair service down the road.

On the other hand, if treated right, the wood rotors last forever. If done
right, you don't even *need* the scrim cloth. I took mine off my Leslie 251
in 1996, because it was rotting away. Rather than buy a replacement, I was
encouraged to clean it well, let it thoroughly dry, then paint it with a
couple of good, heavy coats of satin black spray paint. Painting the rotor
seals up the openings in the wood grain -- whose turbulence accounts for
about 90% of the noise -- and prevents any future de-lamination or other
problems with the wood. Seven years later, my wood rotor still looks great!

Regards,

-BW (whose wood rotor was built in '67 or '68, and is still going strong!)

--
Bruce Wahler
Design Consultant
Ashby SolutionsT http://consult.ashbysolutions.com
978.386.7389 voice/fax
bruce@ashbysolutions.com

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