Review: Motion Sound PRO-3T Leslie Simulator

by David Jacques

May 10, 1997


Like many of my fellow professional Hammond organ players,  I have been searching to find the most realistic Hammond sound that can be easily transportable.   Growing up with the sound of Hammond console organs, and playing my C-3 and Leslie 122 in bands has made me quite aware of the unsatisfactory sound of most Hammond clones--especially since I now have a mint B3 and 122 sitting in my living room that constantly reminds me of that wonderful, elusive sound.

Along with the tone quality of the tone wheel generator and pre-amp in the Hammond, a major element of that distinctive sound is the rotating speaker of the Leslie tone cabinet.  Until recently clone makers have chosen to electronically simulate this sound, with unfortunate results.  Like any electronic simulator, the three dimensional sound field of audio waves reflecting off the walls cannot be adequately simulated through a stationary speaker.

Motion Sound developed the Pro-3 a few years ago to address this problem (please refer to Mark Longo's review of the Pro-3 in this FAQ for a complete description).   The Pro-3 is used by countless musicians to create the elusive Doppler rotating effect of the Leslie speaker (only with a real rotating horn of a Leslie or Pro-3 can this three dimensional effect be achieved).  With the success of the Pro-3, Motion Sound listened to the comments and suggestions of these musicians and developed the new Pro-3T (released in May of 1997).   This review comments on the features of the Pro-3T in relation to the older Pro-3 after using both models in professional environments.


In many ways the basic design of the Pro-3T is similar to the Pro-3.  Both units use a real rotating horn to create the high-frequency Doppler effect in slow and fast speeds.  Frequencies below the cross-over point are routed to an electronic low-frequency rotor simulator, then to an 1/4" output on the front panel.  An external bass amplifier and speaker is required to reproduce this low-frequency simulation.  A speed control (foot switch) is included with two buttons: Fast/Slow and Stop.  The Stop button brakes the rotating horn and rotor simulator.  The unit is housed in a sturdy, black cabinet with a grill that protects the horn.  The dimensions are 6.5" X 20" X 16.5" and the unit weighs only 27 pounds.

Several design improvements have been incorporated into the new unit.  These include:

12AX7A pre-amp with pre- and post-gain controls
Tone control 147 contour or Pro-3 (4-10KHz)
40 watt FET .02% distortion horn amplifier
Superlife zero maintenance Pyrathane belt
Horn ball bearings
Fast Speed indicator LED
Enhanced low rotor simulator with front panel AM modulation control
Adjustable horn: slow, fast, acceleration
Adjustable low rotor: slow, fast, acceleration
Speed control: fast, slow, stop or variable (with the new "Gas Pedal")
Rear panel signal output connector for the new "Low Pro"
Crossover point of 800HZ

Warm Tube Distortion

One of my primary suggestions concerning the Pro-3 was the digital distortion feature.  Although effective for heavy Jon Lord distortion effects, this feature did not realistically simulate the wonderful "growl" of the slightly overdriven Leslie speaker.   The Pro-3T uses an analog distortion circuit incorporating a 12AX7A pre-amp with pre and post gain controls on the front panel.   This new feature makes it unnecessary to purchase an additional warm-tube distortion unit like the Blue Tube.  I always dial in a little distortion into my sound.  This adds the "grit" that really distinguishes the analog amplifier in the Leslie speaker.  The amount of distortion is adjusted using the pre and post gain controls.  I set-up with the Pro-3T within reaching distance so I can easily vary the amount of distortion during a set.    The tube is visible through a plastic window on the front panel and is easily replaced by removing four screws and lifting the top off the unit.  Several new owners of the Pro-3T have replaced the 12AX7A with the Telefunken 12AU7.  This tube is a lower gain version that allows a wider spread between a clean and distorted sound.   I have not considered this modification for my set-up as the distortion curve of the 12AX7A is adequate for my needs.   This distortion feature adds so much to the sound of the organ many keyboard players who have heard my band cannot believe that the organ sounds are not emanating from a real Hammond.   A little bit of warm tube distortion goes a long way.

Tone Control

The pre-amplifier in the Hammond console organ rarely created tones above 6KHz.  The older Pro-3 had a high frequency cut-off of 10KHz.   This allowed high-frequency sounds from poor organ samples to pass through the Pro-3--creating an unfortunate  "shrill" sounding tone.   You had to equalize the sound through your tone module to cut the high frequencies above 6KHz.  The new front panel tone control on the Pro-3T allows you to adjust the high-frequency roll-off from 4-10 KHz.  I have found that a setting of "3" gives the best tone to simulate the high-end roll-off of the Hammond and Leslie.  Of course, this depends on the amount of high-frequency hearing loss you have suffered over the years.

40 watt Amplifier

The digital amplifier has been increased in power from 30 to 40 watts.  Although my new band is relatively "low-volume", I used the older Pro-3 in my former band (a loud seven piece horn band).  I found the volume of this unit satisfactory to cut-through the intensity of the horns and guitars.  The old Pro-3 was loud enough for me without the increase in power...   This one goes to "11"!  That's one better, right?

Fast Speed Indicator LED

Working in dark clubs makes it nearly impossible to see the horn rotating in the enclosure.   The Pro-3T has a LED on the front panel that illuminates when the tremolo speed is engaged.  Unfortunately, there is no indicator when the brake (stop) is on.

Enhanced Low Rotor Simulator

The new low rotor electronic simulator is superb!  Like the upper horn, the slow, fast, and acceleration times are adjustable though internal pots.  Unfortunately, you must take the cover off the unit to adjust these parameters (too bad Motion Sound could not fit six more knobs on the front panel).  The low rotor simulator has an AM modulation control
on the front panel that controls the intensity of the rotor.  I found that a setting of "7" is ideal for a realistic Leslie simulation.   Because our ears are less sensitive to low frequency modulations, an electronic simulation of the rotating low frequency drum is much more successful than an electronic  simulation of a rotating horn.  There are stereo outputs on the front panel to send the output to two amplifiers creating a very effective low-frequency sound-field.  There is also rear-panel output for the new Motion Sound "Low-Pro".  This unit uses an actual rotating low-frequency driver.  I must say that the rotor simulation is so successful that the "Low-Pro" may be unnecessary in most band situations.

Motion Sound also changed the crossover point from 700Hz to 800 HZ (the crossover point used in the Leslie 147 speaker).  This development sends less of the low-frequency
tones through the horn, resulting in a cleaner high-end.  As Mark points out in his review, it is essential that a high-quality bass amplification system is used to reproduce the low rotor simulation.  It is even more critical now that the cross-over point has been adjusted.

Speed Control

The foot switch controller is unchanged from the previous model.  It consists of two buttons: Slow/Fast and Stop.   The real speed control advantage of the Pro-3T is in the new "Gas Pedal" feature.  This optional device is designed like an expression pedal, allowing you to remotely vary the speed of the rotors.  This is a very useful option, especially for guitar players.


As of this writing I have used the Pro-3T on a few live professional engagements.   I play in a Jazz/Blues/Lounge band in the Dallas/Ft. Worth area.  The music we play is quite
diverse--from "Fever" to "Over the Rainbow".  I play a Hammond simulation on most of the songs using a Roland A-90EX controlling a JV-1080 with a "Keyboards of the 60's and 70's" expansion board.  The low-rotor simulation is routed through a Roland KC-500 keyboard amp.   I mix a few patches from the JV-1080 to create a very realistic Hammond tone (listed in the FAQ).  My patches are based on the typical blues registration of 888000000 along with patches that simulate full organ stops.  I also use patches with C-3 vibrato.  The Pro-3T adds an amazing amount of animation to the sound of these patches.

The warm-tube distortion faithfully reproduces the slow growl present in the jazz tunes, and the higher distortion effects during the blues numbers.   Like my B-3,  when I add more volume with the expression pedal, the distortion increases. I found it quite easy to adjust the amount of distortion in a live situation.  The typical Hammond growl is present, the acceleration and deceleration of the rotors is incredibly realistic, and the percussion really jumps at you.  I love pushing the distortion until the percussion has that distorted "snap" to it.  What is really amazing is the sound of the rotors spinning during moderate distortion.  You can achieve that "Magic Carpet Ride" feel quite easily, and at the same time find the sound of Greg Allman's warm B-3.  We cover the Van Morrison version of "Lonely Avenue" and I can now match the B-3 sound exactly as it is on the record.  We also do a gospel number that is quite effective using 800000008 and fast speed.  "Highway Star" sounds pretty good too (although we do not play this one... it is not exactly a lounge number).

Don't limit yourself to using the Pro-3T just for Hammond sounds.  I also pump a few orchestral patches through the Pro-3T.  On a version of "Viva Las Vegas" I play a mixture of Mellotron and other synth effects through the slow speed of the Pro-3T.  The Mellotron goes into the Pro-3T and some of the synth sounds from the A90-EX bypass the
Pro-3T and go straight into the amp.   I get comments on this unique sound every night.

The chorale and tremolo effects are quite impressive.  We cover Lee Michael's version of "Stormy Monday" and the sound of a distorted Hammond through a fast Leslie that I achieve with the Pro-3T is very close to Lee Michaels' distorted C-3.  In fact, I can make it sound exactly like the version on his live album (a bit too distorted for my taste, thank-you).   The acceleration times and speed of the rotors are adjustable, but I found no need to adjust them as the factory pre-sets are fine.

There is one problem with the overall sound that has nothing to do with the design of the Pro-3T.  Most Hammond clones do not have phase-locked notes.  This creates an unfortunate phase-shifted "beating" sound in the high registers.  This is not a problem in many of my individual patches, but when combining patches the "beating" increases.  It is essential that you turn off all effects (except reverb) when using the Pro-3T to reduce this beating effect.

I was able to audition a new Roland VK-7 combo organ with my new Pro-3T.  I must say that the combination of these two devices is amazing!  I agree with many of my fellow Hammond list members that as of this date, the VK-7 is the most successful Hammond clone yet!   The VK-7 also has phased-locked notes which do not produce the phase-shifted "beating" of less accurate Hammond clones.

The Company and Customer Service

I received one of the first Pro-3T's from the factory.  When I hooked it up to my rig in my home studio I discovered a problem with the horn.  There was a strange buzz in the range of C6 that sounded like either a fault in the driver or the distortion circuit.  I called Motion Sound to inform them of the problem and John Fisher immediately returned my call.  After a few minutes of telephone diagnosis and repositioning the driver, John told me that he would send me a replacement unit immediately.  I informed John that I had a gig in four days.  He made sure that I received the unit in time.   This is not an unusual story from Motion Sound.  Large corporations have something to learn from this small Utah company.  No product is perfect, especially one of the first units off the line.  The difference is in how the company stands behind the product.   Motion Sound's customer service is exemplary!


The new Pro-3T is a wonderful example of how a company with a great product can design a better one by listening to its customers.  I highly recommend this unit to any Hammond clone player looking for that elusive sound.  After auditioning the Pro-3T with the Roland VK-7, I have found the perfect road replacement for my B-3 and 122.  I purchased my Pro-3T for around $600--and it is well worth it!  Now, if I can only find the money for the VK-7.....

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