Leslie stuff

[harry bissell]

Q: How many DIYers does it take to make a Leslie ???
A: Five, one to hold the speaker and four to turn the room...

But seriously folks...  Problems include isolation of the mechanical
noise from the microphone, the fact that the enclosure is too small to
suport bass wavelengths without seroius standing wave problems... Signal
level problems (you'll want the speaker to be loud and in a small box
that's trouble... Also, the room makes a big contribution to the sound.
Most leslies have two separate motors, one on a horn assy for the highs
and a big rotating drum for the lows. Different speeds and phase
relationships (and rates of change) contribute to the sound.

As someone pointed out, the actual "move the speaker on an arm" is never
done in practice. The best implentations of the low end use a drum with
an angled baffle with a hole facing out one side. An interesting unit
had the rotor made from molded styrofoam... The horn units can use a std
compression driver.

Don't use slip rings....

Are you more crazy for this than your previous projects... guess that
depends on your previous projects ???   ;^)  Harry (just kidding around)
Bissell

Doug Tymofichuk wrote:

> Greetings, all!
>
> I have decided to add another project to my list of stuff
> that I hope to get around to this fall (percussion synth,
> tape echo). I would really like to have a Leslie effect
> box, that I can patch anything into, and that outputs a
> signal that I can further modify, amplify, and listen to.
> An electronic version is tempting, but it would be more fun
> to build a miniature electro-mechanical-acoustical unit
> enclosed in a (reasonable) soundproof box. It would consist
> of an amplifier driving a small, full range speaker mounted
> on a rotor, with a microphone placed in one corner of the
> box feeding a preamp. Then a simple mixer to control depth
> of effect. The rotor would be driven by a small variable
> speed D.C. motor. A small car audio or portable radio
> speaker should work for this. Hopefully I could fit the
> whole thing into a standard 19" rack case. At this point, I
> don't see any major problems with this approach, as I have
> virtually all the necessary parts on hand already
> (including a rotary slip ring assembly for getting the
> signal to the speaker). Because of the size of
> construction, there will not be a great frequency response,
> particularly in the bass regions, but I am primarily
> interested in midrange/treble anyways.
>
> I have read everything in the archives concerning Leslie
> effects, and have browsed through information on Hammond
> sites as well, and I have not found anything like this. Has
> anyone tried to do a Leslie on this scale before? Any
> pitfalls to watch out for? Am I even more crazy for
> attempting this than my previous projects?
>
> I will keep the list updated as I progress on this (if and
> when).
> ----------------------
> Doug Tymofichuk
> dougt at cancerboard.ab.ca