Key Issues: Simulating A Leslie

I do my musical projects in Pro Tools and use Reason for most of my software instruments. Every once in a while, I need the sound of a Hammond B3 with a Leslie. But the Reason B3 sounds always disappointed me because they use vibrato rather than that wonderful swirling speaker sound a Leslie provides. Recently, I was working on a project where the organ sound was just too exposed to get away with that cheesy vibrato. So I set about to solve the little problem, and I came up with a pretty good solution. It should work for any program that uses Reason as a sound source, and the concept should also work for other sound sources.
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Fig. 1. Reason’s PH-90 Phaser showing the settings.

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Fig. 2. The Pro Tools MIDI Input and Output selector.

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Fig. 3. The Track View selector.

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Fig. 4. Some MIDI notes and controller data.


Many organ patches use vibrato to add movement to the sound. But vibrato is only a pitch change. Some even go as far as adding tremolo, which alternates between the loudness and softness of the sound. The wonderful texture of the Leslie speaker effect is the result of the Doppler Effect that occurs when the speakers rotate toward and away from the listener, and bounce off other surfaces. The real Leslie also has two speeds, and it takes a few seconds to change from one speed to the other. So to recreate that part of the effect, you need to find a way to duplicate the ramping up and down of the motor in order to make a simulation sound believable.


Let’s start by building the B3 instrument in Reason. Go to the Create menu and choose NN-19 Digital Sampler. Then create a PH-90 Phaser. Route the left and right audio outputs from the NN-19 into the left and right inputs of the PH-90. Then, take the outputs from the PH-90 and send them into the Reason Hardware Interface— in this example I’ll use inputs 1 and 2. (I don’t use the Reason mixer because I prefer to do all my mixing in Pro Tools.) Make sure the PH-90 is switched to the On position, and use these settings:
FREQ: 58
WIDTH: 127
RATE: 45
F.MOD: 44 (F. Mod)

Leave the SYNC button off, and check out Figure 1 to ensure all is well. Now, go to the NN-19 and using the Patch Browser, find the ORGAN1.smp preset in the Organ folder. Click the Save Patch button (it looks like a floppy disk, and it’s the third button to the right of the patch name), and name it B3 Leslie. Also, rename the NN-19 by clicking the little piece of tape that runs vertically on the left of the instrument and typing NN B3 in the little window. This will make it easier to find in Pro Tools.


Back in Pro Tools, create a Stereo Instrument track, and name it B3. In the Instrument area of either the Mix or Edit window, go to the MIDI Input selector drop-down (marked Dg002,Prt11 in the red circle in Figure 2), and choose your interface. In my case, I’m choosing the Digi002 Port 1, Channel 1. In the MIDI Output selector drop-down (marked NN B3 51-2 in Figure 2), choose the NN B3 you just created. That will send your MIDI notes out to the NN B3. In the Insert section, click the arrows to create a multichannel plugin, Instrument, and choose Reason from the flyout menu. This should bring up the ReWire dialog (Figure 3). In the drop-down next to Reason, choose Mix L – Mix R, which come from inputs 1 and 2 of the Reason hardware Interface we set up earlier. You could control the rate of the PH-90 on the B3 track in Pro Tools, but I’ve developed a method that allows me to both view and work with the controller modulation more easily by using a different track. To do that, create a new mono Instrument track and name it Phaser. From the MIDI Output selector drop-down, choose Phaser 1. You won’t need an instrument insert on this channel because you’ll only be sending out MIDI controller information that will affect the sound you hear on the B3 track.

There’s another reason to use a separate track for the controller. If you want to turn off the effect when the controller for the phaser is on the same track as the notes, you can’t do it without switching it off in Reason. MIDI controllers are not the same as automation in Pro Tools. However, if the controller data is on its own track, you can mute the effect by clicking the Mute button in the Instrument section of the track. Just keep in mind that the effect will continue to play at the setting it was at when you last stopped playback.


Okay, so now you should be able to play your MIDI keyboard and hear the organ sound. Go ahead and record a few notes or chords. Alternatively, you can just draw your notes onto the B3 track. To control the speed of the PH-90, go over to the Phaser track in Pro Tools and click the Track View selector as shown in Figure 3. Choose controllers, Add/Remove Controller. In the Automated MIDI Controllers dialog, select the radio button next to Controllers (1- 31). Then, double-click undefined (14) to send it to the list on the right. That’s the controller Reason uses to change the speed of the PH-90. Click OK. Now, just because you set up this controller doesn’t mean that Pro Tools automatically switches from notes view to the controller. You have to click the Track View selector drop-down again, go to controllers and choose undefined (14).

Now, you can use the Pencil tool (set to Line) and draw in controller data. I used a range from 45 to 95. Anything more or less is either too extreme or too subtle. In Figure 4, you can see the MIDI notes I played, and the controller data on the track just beneath it. A real Leslie never stops completely, so you’ll want to keep the speed line at 45 when it’s “off.” Of course, you can use a realtime outboard MIDI controller to change the rate, but you may find it hard to keep from going below 45 and above 95.

One other thing you might want to know is that sometimes organists will bring up the volume of the organ at the same time they switch to the high speed setting on the Leslie. You could also experiment with changing the Filter controls for the NN-19 to simulate pushing and pulling the stops on a B3.


What if you routed the left and right outputs separately to two Phasers? You might even try to separate the channels so that lower pitches come out of one Phaser, and higher pitches out of another in order to more accurately imitate the bass speaker and high-frequency drivers of the Leslie. Now that you have a handle on the process, it’s up to you to decide how far you’ll take it. As for me, I’m just happy to have that sound I’ve been missing all this time.