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Dynacord CLS222 Compact Rotor System

Leslie Simulator

Article from Sound On Sound, December 1992

Is it a bird? Is it a plane? No, it's a stimulating Leslie simulation that'll set your head spinning — after trying the CLS222, Nick Magnus will never use his 'ghetto-blaster in a tumble drier' trick again.

The Leslie rotating speaker is a wonderful thing. Consisting, typically, of a large cabinet containing a pre-amplifier, a crossover unit, some relays, a bass speaker projecting sound vertically into a revolving drum, and a counter-balanced rotating high-frequency horn, it is also a very heavy wonderful thing. It is no surprise, therefore, that a number of attempts have been made to produce an acceptable imitation which bypasses the wails of dread at the prospect of carrying the original more than two feet at a time. There is one major problem, however. This unique mechanical chorus unit has been elusively difficult to simulate, due to the complex and very specific nature of its sound. I won't bore you with a turgid account of the physics of Doppler effects, but for those aficionados of the real thing, it has become clear that a simple chorus or modulated delay line is not the answer.

Many companies have, over the last few years, introduced dedicated instruments which attempt to produce acceptable imitations of the classic Hammond/Leslie sound. These include Korg (with the CX3 and BX3 organs), Voce (who introduced the rackmount DM164 Mk II), Hammond themselves (with the excellent XB2), and Roland, who scored with perhaps the best Leslie simulation of the bunch on their VK1000. In addition, most synthesizers are also capable of producing basic (untreated) organ sounds, and while many of these feature internal effects units that offer 'rotary' simulations, it's now common to find suitable programs in digital multi-effects units for those that don't. Some of these effects can be quite tolerable. Others are — bluntly — criminal.

If it's so difficult to emulate the sound of a Leslie convincingly, perhaps it's worth briefly observing some of the ways in which a rotary speaker modifies the sound being fed into it. Most importantly, a Leslie imposes a colouration to the sound. The signal is split into two frequency bands by a crossover and fed to the Bass 'drum' and the horn respectively. This, the resonance of the speaker enclosure, and the surrounding ambience, give a very distinctive quality that changes the original tone considerably. The action of the rotating horns serves to 'pick out' and emphasise particular areas of the sound, especially the low mids (around 300Hz) and the upper mids (around 2KHz). Listen to your average simulation and you find that the original sound is by and large unaffected, with the 'rotary' element superimposed onto the signal.

Included among dedicated rotary speaker simulators past and present are the Schaller Rotosound, a unit called the 317537, (write that in LED typeface, turn it upside down and it spells 'LESLIE'), the Univibe, and the recently released Rolls Rotorhorn. They are all variations on the chorus/pitch/filter modulation theme but, as already mentioned, there is more to the sound of the real item than this. So what about the CLS222?

The device is housed in a 1U, 19" rack. Earlier models (for it has been around for three years) had an ivory-coloured front panel with two large handles. Current ones are in a more contemporary '90s grey with no handles. There are few controls and no memories — after all this only does the one thing. So let's take a look at the front panel. At the far left is the pre-amp (input gain), a misleading title, as it suggests a drive stage to produce distortion. (The only distortion you get if you push it is an undesirable digital one.) An LED is provided to announce the onset of clipping. Next is Rotor Balance. Yes, Dynacord have realised that a Leslie has two rotating elements, the bass and treble horns, allowing you to set the relationship between the two to taste. Following on is Basis; this is actually a 4-position switch to vary the stereo spread from mono to full stereo separation. The stereo is created by each of the speakers panning independently from left to right. Next up is the output volume control, and to the right of this is an effect bypass toggle switch. Lastly we have the power switch, a pair of LEDs for visual speed indication, and a 3-position toggle switch to select fast, slow or rotor stop. Rotor stop is interesting in that the tonal colouration (as mentioned later) of the unit is retained, and as such is a different sound to bypassing the effect. On restarting the rotor, its movement picks up gradually until the selected speed is attained; a very pleasing effect. Dynacord also provide a footswitch for these functions which plugs into the rear of the unit.

The rear panel sports a mono input, left and right outputs (the right can also feed stereo headphones), and a separate mono out. There are also balanced XLR outs for those special occasions. The remote footswitch jack is found here, as is the mains input on standard Euroconnector.

Finally, two trimpots are provided to adjust the overall speed range of the Bass and Treble horns respectively. On receiving the unit from the factory, you may find that the preset speed is not to your taste. In fact, my own unit needed to be tweaked a little slower.

You will not be disappointed to hear that the rotors' acceleration and deceleration effect is extremely accurate and gratifying. The constantly shifting stereo image adds richness and animation to a wide variety of sounds, and it is here that the CLS222 seems to really capture that 'essence of Leslie'. Having in the past experimented putting numerous instruments through the pukka original item, I discovered that certain sounds respond better than others — information which is very useful for getting the most out of the Dynacord. Organs, of course, sound great. Voices sound weird and wonderful. Guitars are simply orgasmic. Just listen to some classic recordings by, for example, The Beatles, and you will hear the Leslie used on lead vocals, backing vocals and guitars, all to great effect.

However, certain families of synthesized sounds gain little or nothing from the process. This is especially true of some complex sounds that have a lot of inherent movement of their own. Thus if you are using a synthesized organ patch at source, the Leslie's effect is usually at its most dramatic when you remove all forms of chorus from the original sound. Strangely enough, the CLS222 seems to favour and disfavour exactly the same areas of sound, even imparting a tonal colouration very similar to a real Leslie.

One other important area is that of overdrive/distortion. The rich throaty growl associated with a great rock organ sound is the result of overdriving the valve pre-amp found in older models of Leslie. As the CLS222 doesn't provide its own means of overdrive, it is up to the user to provide their own. I have in the past used a Roland GS6 to add distortion to Korg CX3 samples, and thence fed them to the CLS222 with reasonable success, but now I use a Hammond XB2 which sports a fairly respectable overdrive effect of its own. However, having recently substituted both the built-in overdrive and the GS6 for a real valve preamp, I can happily say the results are more than satisfying.


I was surprised, even three years ago, to find no MIDI facility on the Dynacord. Not that there's much to control, but having to concentrate on doing a 'live' Leslie performance by toggling manually between fast and slow whilst running a sequence became rather tiresome. Hence I can heartily recommend Kenton Electronics' MIDI retrofit, which puts fast/slow speed under the control of velocity, aftertouch, control changes... in fact just about anything you like. Fortunately, there is enough room on the back panel for the addition of the requisite MIDI In and Thru sockets, and an ingenious single Edit button via which the various MIDI response parameters are programmed. All settings are stored in non-volatile memory.

Obtaining a CLS222 has, up to now, been problematic, as Dynacord seem to have changed distributors as often as Julian Clary changes his outfits, but dealership has finally come to rest with Shuttlesound, details of whom you will find at the foot of this article. Ultimately £760 is a lot of money to pay for one effect. But for many people, the quest for a believable Leslie substitute has been up to now a frustrating one.

It's a testament to the effectiveness of the CLS222 that a growing number of well-known professionals have, for live performance, ditched their Leslies in favour of the Dynacord — Dire Straits, Joe Cocker and Steve Winwood among them. For such people, it would seem, the results are worthy of this investment. I myself know of no better, let alone equal, alternative to a Leslie than the CLS222. I suppose I'd better wrap this review up in time-honoured fashion, so... "I liked it so much I got out my chequebook." Three years ago, in fact.

Further information

Dynacord CLS222 £760.25 ire VAT.

Shuttlesound, (Contact Details).

Also featuring gear in this article

Previous Article in this issue

Amiga Notes

Next article in this issue

Dr. T's QuickScore Deluxe

Publisher: Sound On Sound - SOS Publications Ltd.
The contents of this magazine are re-published here with the kind permission of SOS Publications Ltd.

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Sound On Sound - Dec 1992

Gear in this article:

Studio FX > Dynacord > CLS 222 Rotating Speaker Simulator

Gear Tags:


Review by Nick Magnus

Previous article in this issue:

> Amiga Notes

Next article in this issue:

> Dr. T's QuickScore Deluxe

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