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FDP Forum / Rock-it 88's - Keyboard Forum / My Leslie upper rotor prototype

ECS-3
Contributing Member
********

USA / Virginia

Oct 30th, 2013 04:55 PM   Edit   Profile   Print Topic   Search Topic

My latest science experiment - adding a Leslie upper rotor to my Hammond HR-40 Tone Cabinet. There's no lower rotor, so it's not a complete Leslie, but check this video out. Just an upper rotor sounds decent, I think.

Youtube linkage

Steve Dallman
Contributing Member
*******

Merrill, Wisconsin

Age is just a number...mine is big
Nov 1st, 2013 09:28 AM   Edit   Profile   Print Topic   Search Topic

Yamaha's version of a Leslie had stationary lower speakers. Only the upper rotor turned. One model had a 12" stationary lower and one rotor, the other two 12's and two upper rotors.

Steve Dallman
Contributing Member
*******

Merrill, Wisconsin

Age is just a number...mine is big
Nov 4th, 2013 07:37 PM   Edit   Profile   Print Topic   Search Topic

There are two types of modulation that are produced by a Leslie speaker, AM (amplitude modulation) and FM (frequency modulation.)

AM is basically tremolo...a modulation of volume. FM is the pitch changing Doppler effect. Each rotor puts out a different mix of these two modulations.

The upper rotor has a higher amount of FM. The lower rotor is more AM, mostly because of the frequencies it gets below the crossover frequency.

Over the years, many Hammond players have modified their Leslies to get "more" from them. One mod is to remove the baffle in the upper horn to try to get more volume and projection. But this increases the AM over the FM and many who used to do this went back to using the baffles.

In order to increase output of the Leslie, some run the lower rotor speaker full range, bypassing the crossover. This increases the FM of the lower rotor and adds midrange punch.

And more relevant to this discussion, some turn off the lower rotor, preferring not to have the modulation in the low end, AM or FM. This can clean up a Leslie's response and makes the low end more solid.

The effect of the upper rotor is what most are looking for. The lower rotor is found by some to be sort of distracting, taking away from the drama the upper rotor creates.

The Yamaha crosses over their speaker and rotor at about the same frequency as a Leslie...maybe slightly lower. Even though the Yamaha rotors (two in my model) turn differently (end over end, instead of sideways) the effect is the same.

Yamaha didn't use a two speed motor, but a motor speed control that switched from a preset slow setting to an adjustable fast speed. It didn't use any braking action when slowing it down, unlike a Leslie rotor.

The sound of a Leslie cannot be accurately captured in any pedal in a live setting. Most pedals are little more than two speed chorus pedals. Some get pretty close. Line 6's Leslie modeling pedal even models the effects of the wood cabinet.

In stereo, a pedal simulation can do side to side, but a real Leslie throws the sound around the room. A pedal can do side to side, but not front to back, not to mention the bouncing off the walls, floor, ceiling etc.

Granted, mic'ing a Leslie, for recording or live, loses some of this "magic."

ECS-3
Contributing Member
********

USA / Virginia

Nov 16th, 2013 04:40 AM   Edit   Profile   Print Topic   Search Topic

Leslie also made many differents versions, including single rotor versions.

Agree with your comment that the Leslie throws the sound around the room. The upper rotor, even with the diffuser, is still directional and as it rotates the sound bounces off various portions of the cabinet, different walls, etc.

The built in Hammond vibrato using the scanner is a cool effect but it can be a bit much, whereas the, Leslie / Chorale to me is just about perfect for a subtle effect.

I'm currently on the fence about adding the lower section with the bass rotor. I'm using the (9) 10 inch bass speakers in the HR40 cabinet and it's got a huge low end. The low end is solid down to the low "D". The bottom two notes ( C and C#) are starting to loose it a little but still pretty solid. I think it's got better low end than the single 15 / Leslie 122 does.

(This message was last edited by ECS-3 at 06:42 AM, Nov 16th, 2013)

FDP Forum / Rock-it 88's - Keyboard Forum / My Leslie upper rotor prototype




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