Hi everyone, back when beta testing for the ARIA version of JABB was full speed ahead,
I posted a fun way to produce a Leslie effect with the B3 organ.

Here it is, it may seem complicated but it's not, it's easy if you have a sequencer.

Load two of the same organ sounds into ARIA into midi channels 1 & 2.
Assign the two organs to separate stereo group outputs ie. 3-4 and 5-6 respectively.

Create two midi tracks in your sequencer assigned to ARIA Player-1-1 and ARIA Player-1-2.
Name the first track "high" and the second "low".

Copy all of your organ notes from your first midi track and paste them into
the second midi track... in sync of course

Set the tremolo level (cc22) to 50% in the first loaded organ in the ARIA player,
this CC data does not need to fluctuate.

Set the tremolo level (cc22) to 40% in the second loaded organ in the ARIA player,
this CC data does not need to fluctuate.

For midi track one, (high rotor) draw the tremolo speed (cc23) so that
the low speed is 0, and when you want to switch to the high speed Leslie effect, this cc23 value should be drawn to gradually increase to a CC value of 90, which will remotely change the ARIA's TrmSpd to 71%.
From the time you want the speed to go from low to high, (CHORALE - TREMOLO) the cc23 value will change from 0 to 100 in just one second. The high rotor is lighter than the low rotor, so it takes less time to get up to speed.


For midi track two, (low rotor) draw the tremolo speed (cc23) so that
the low speed is 0, and when you want to switch to the high speed Leslie effect, this cc23 value should be drawn to gradually increase to a CC value of 85, which will remotely change the ARIA's TrmSpd to 67%.
From the time you want the speed to go from low to high, (CHORALE - TREMOLO) the cc23 value will change from 0 to 85 in three seconds. The low rotor is heavier than the top rotor and takes more time to get up to speed.

Make sure that both midi tracks' TrmSpd begins and ends at the same time since in real life, a single switch would control the speed of both rotors.



Create a stereo audio track in your sequencer (high) program for the organ loaded into ARIA's number one slot, (high rotor) and insert an EQ into that audio track to roll off (filter out) all frequencies below 1200 cycles, approximately 18db per octave. Don't forget to assign the first loaded organ in the ARIA player to audio group 3-4 in case you didn't earlier.

Create a second stereo audio track (low) for the organ loaded into ARIA's number 2 slot, (low rotor)
and insert an EQ into that audio track to roll off all frequencies above 1200 cycles, approximately 18db per octave. Don't forget to assign the second loaded organ in the ARIA player to audio group 5-6 in case you didn't earlier.

It is more realistic to have the high rotor..... speed up quicker than the low rotor, since this is what happens in a real Leslie speaker. Also, when going from high to low speed, the high rotor slows down quickly almost as if it has brakes. The low rotor takes much more time to slow down and speed up due to it's rotating mass, mentioned earlier. It's all just physics and Doplar effect that turns tremolo (volume fluctuation) into vibrato, (pitch fluctuation) as we hear the sound reaching our ears from different times. An ingenious idea of Leslie.

Ultimately, the tremolo level (cc22) would change also as the speed is changing, but for now these tips will create a reasonable sounding Leslie effect, and will be good enough in context.

Have fun and here's the midi file.

Dan
midi file...
http://www.dankury.com/midi/B3JABB.zip

WINDOWS movie
http://www.dankury.com/beta/B3JABB.wmv

QUICKTIME movie
http://www.dankury.com/beta/B3JABB.mov