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Friday, August 2, 2013

Korg CX3

Modelling Tonewheel Organ

Reviews : Keyboard
The name may be the same as their old 1980 model, but the new Korg CX3 now employs physical modelling techniques in in the eternal quest for the classic Hammond/Leslie sound. Gordon Reid finds out if it measures up to the real thing.
In 1980, there were three ways to sound like you were playing a Hammond tonewheel organ through a Leslie speaker. The first was to play a Hammond tonewheel organ through a Leslie speaker. The second and third were to play a Korg CX3 or BX3 through a Leslie speaker.

You may think that all '70s and '80s combo organs were horrible, cheesy affairs and, for the most part, you would be right. Efforts such as the Roland VK1 and VK9, or the ghastly organ settings in Yamaha's multi-keyboards certainly support this view. More alluring, and a cut above their Far Eastern brethren, Crumar's Italian jobs were better, and usable within a mix. But the Korgs came close to emulating the true depth and passion of a vintage Hammond. Indeed, in today's inflated market, a dual manual BX3 in good condition will cost you more than a real Hammond such as an L100 or M100. Oh, all right, so it's still a fraction of the price of a C3 or the unaccountably more expensive B3, but that's another story...

Anyway, last July, Korg's UK product specialists asked me if I would like to play a CX3. As you might imagine, I was somewhat bemused. They know that I still have a BX3, so why would they think I would be interested in its single-manual little brother? The answer, of course, is that they were not inviting me to play a CX3. They were inviting me to try the (at the time) unannounced new Korg CX3.

On The Outside...

Now, as we turn 2001 (the real millennium, chaps... not the marketing managers' fiasco of 12 months ago) the new CX3 has arrived, and there's no doubting what it is. Even if you ignore the giveaway drawbars, its wooden case and vintage styling reek of Hammond. It's heavy, too, and certainly more so than your average 61-note digital synthesizer. But despite the CX3's appearance, its heart is pure digital, and beats to a system that Korg call... well, it doesn't seem to have a name. Korg simply call it a 'tone wheel organ modelling tone generator' and, since there's no pronounceable acronym to be had (I doubt that 'TWOMTG' counts) the company seems to have declined to name the technology in any way. Not that Korg are blind to the need for a silly name: the effects are modelled by REMS: the "Resonant structure and Electronic circuit Modelling System".

KORG CX3 £1799
The best emulation of the Hammond C3 I've yet heard.
The best onboard effects I've heard.
EX mode — a new family of superb Hammond-esque sounds.
The overdrive; not perfect, but quite usable.
Very detailed editing and MIDI controller capabilities.
It's a dream to play.
It's bitimbral, so you can't play two manuals plus pedals.
There's no Leslie output.
There's no spring reverb algorithm.
No effects send/return loop.
The manual is not great.
Not cheap. In fact, it's expensive.
The CX3 sets a new standard in Hammond emulators. It's flexible, but also simple to use. If you demand 'that' sound and have the cash, it has to be number one on your shopping list. Its only serious limitations are its single manual and bitimbrality, so I hope that it's successful enough to persuade Korg to develop an expanded, dual-manual version. They could call this... hmm, let's see... how about the 'Korg BX3'?

Of course, all of this is tucked away where the sun doesn't shine whereas, on the surface, the CX3 presents you with something that looks much like... a single-manual Hammond. There are two sets of drawbars, controls for percussion, overdrive, chorus/vibrato, reverb and Leslie effects, all complemented by the rather more contemporary display, patch selectors, and editing controls.

...Looking In

As you would expect from its name, the voicing on the CX3 emulates that of a Hammond C3, but with many additional tweaks, courtesy of its DSP. In the manual, although not in the Edit menu itself, Korg have divided the parameters into eight groups. You select these by entering Edit Mode, and then pressing the 'shortcuts' — the patch buttons 1 to 8 — which take you to the start of each group. Alternatively, you can also step left or right through the whole single-tier edit table if you prefer. This is the system that Korg first introduced on the M1, and it's very usable.

By and large, the edit groups divide the instrument into logical chunks — voicing, effects, controllers, and so on — so I can give you a good idea of what's going on by giving you a guided tour of the groups themselves. So let's begin with the first three...

The first defines the nature of the virtual organ within a patch, determining the character of the sounds that it will produce, even before you start to manipulate the drawbars, or add effects. For example, you can select whether the tonewheels have leakage (the 'Vintage' setting) or not ('Clean'). There are also parameters for the overtone level, the amount of leakage, and levels for the clicks that naturally occur when you press or release a key on a vintage Hammond.

The second determines the drawbar settings stored in the patch. There are two sets of drawbars, but, rather than being labelled 'Upper' and 'Lower' in traditional fashion, these simply emblazoned '1' and '2'. At first this may seem a bit weird because, in what Korg call Normal mode, the two sets act traditionally and determine the sound of the Upper and Lower sound generators either side of a key-split (or on the upper and lower manuals when an external MIDI keyboard provides the missing manual). However, as well as being labelled '2', the second set of drawbars is also annotated 'EX Drawbar' and 'EX Percussion'. There's something strange going on here, and it's time that we took a large detour...

EX-Panded? EX-Tended? EX-Cellent?

The CX3 has two playing modes: the aforementioned Normal and EX, and it's to the second of these that EX Drawbar and EX Percussion refer.

Simply stated, EX Drawbar allows you to add four further drawbars — and, therefore, four further pitches — to the standard nine provided by most drawbar Hammonds. The range of these extends in semitones from G4 to C7 (the 24th harmonic) where the reference is C5, the reference pitch of the 1' drawbar. Once set, you control these harmonics (although, strictly speaking, they are not necessarily harmonics) using the first four drawbars in the second set.
Speaker Parameters
A classic Leslie speaker, such as a 147 or 122RV, creates its unique sound by passing the output of two stationary speakers through two rotating assemblies called the rotor and the horn. The bass (anything below 800Hz) plays downwards into the single rotating 'rotor'. Meanwhile, the treble (frequencies above 800Hz) plays upward into what looks like two rotating horns (although one of these is a dummy, provided only to stop the whole assembly from shaking itself to bits). Each assembly has two rotation speeds — slow for chorus, and fast for tremolo. However, the resulting effect is extremely complex, combining the Doppler effect (pitch-shifting) with phase-shifting, timbral modulation, and amplitude modulation. This makes the Leslie nigh on impossible to emulate using analogue electronics. Fortunately, for those of us who object to shifting a couple of hundredweight of dedicated speaker system for every rehearsal or gig, the digital imitations are getting much more realistic. The algorithm in the CX3 offers the following Parameters, which cover all the important aspects of the Leslie sound: • Horn/Rotor balance.
• Horn Slow Speed.
• Horn Fast Speed.
• Rotor Slow Speed.
• Rotor Fast Speed.
• Horn Up Transit (acceleration).
• Horn Down Transit (deceleration).
• Horn Stop Transit (braking time).
• Horn Strt Transit (acceleration from stationary).
• Rotor Up Transit (acceleration).
• Rotor Down Transit (deceleration).
• Rotor Stop Transit (braking time).
• Rotor Strt Transit (acceleration from stationary).
• Horn Mic Distance.
• Horn Mic Spread.
• Rotor Mic Distance.
• Rotor Mic Spread.

You program the pitches of the EX Drawbars in Global mode, which offers four memories (or Types) that you can access wherever you program an EX patch. Now, you may think that this is all a bit of Korg-y extravagance, but there are precedents for extended Hammond registrations. For example, a handful of Hammond Spinet organs offered a single drawbar that controlled the 10th and 12th harmonics (1' is the eighth harmonic) on the lower manual. Nevertheless, it's a rare and unusual facility, and it makes the CX3 capable of some excellent sounds.

The second facility in EX mode uses the remaining five drawbars in the '2' group. You cannot program these, so what you're given is what you get. And what you're given is five more percussion settings lying at 4' or 2 2/3', (depending upon the status of a button in the Percussion controls on the far right of the panel) 16', 5 1/3', and at the pitches determined for the first two EX drawbars. I've never seen this on an organ — Hammond or otherwise — but very welcome it is. Indeed, I believe that, 65 years after the introduction of the original, Korg have actually improved upon the 'algorithm' of the tonewheel organ. There's just one shortcoming to EX mode. Because it demands so much more of the CX3's DSP, it limits you to just the 'Upper' registration, with the Lower being disabled.

You can use the drawbars 'live' in either Normal or EX mode. However (and this is where we return to our discussion of the parameters in the second edit group, from which we diverged a few paragraphs ago) you can save your registrations in any of the 64 Normal memories (eight patches by eight banks) or the 64 EX memories, as appropriate.

There's one extra parameter in Group 2, and it will be responsible for numerous furrowed brows over the next few months. In Normal mode it enables/disables percussion on the Upper registration. Consequently, even when the top panel controls tell you that percussion should be 'on', there are many times when it isn't. Beware.

This brings us neatly to the third edit group, which is the percussion itself. There are five parameters here. The first two control the percussion level, and the amount by which it is quieter when you select 'Soft'. The third depresses the level of the continuous voice when percussion is 'on' and not 'soft', further accentuating the percussion if required. The fourth and fifth parameters determine the decay speeds for the 'fast' and 'slow' percussion settings. Simple.

Effects & Controllers

Of course, the classic sound of the Hammond is as much a consequence of the effects, amplifier and Leslie speaker system as it is of the organ itself. Consequently, it doesn't matter how good the basic sounds are if the effects treatments aren't up to the job.
The first such effect is the chorus/vibrato which, as on the original, is not editable. You choose which of the seven options — V1, C1, V2, C2, V3, C3, or Off — you want, and leave it at that. That leaves three further treatments, corresponding to each of the stages through which the sound passes when you play a Hammond C3. These are: reverb, amplification, and the rotating speaker effect. Edit groups four to six control these.

Group 4 determines the type of amplifier you use for your sound. In broad outline, Type 1 is clean, Type 2 is more 'driven' with greater high frequency content, and 'Preamp' is the equivalent of a direct line out of the sound generator. I describe these as broad outlines because the next four parameters allow you to adjust a 3-band treble/mid/bass EQ, and adjust the gain of Types 1 and 2. This is where you'll generate (according to taste) the characteristic purr or distortion of your favourite Hammond sounds.
The Keyboard
Korg deserve credit for the CX3's innovative keyboard mechanism. This actuates a note immediately you depress a key, not when the key reaches the bottom of its travel. This makes the CX3 far more responsive than typical synth keyboards.
Group 5 sets the reverb parameters. The first three of these are trivial: Reverb type (room, hall and plate), Reverb time, and Reverb mix level. The fourth is not so trivial. Well... it is to operate, because there are only two settings, but you have to make a decision. Do you want the reverb to occur before the Leslie speaker algorithm (as it would on the many Hammonds equipped with spring reverbs) or do you intend to recreate the ambience of a room or hall? If the former, you set the routing to 'Rev -> Rot'. If the latter, set it to 'Rot -> Rev'.
On the face of it, the reverb is all fine and hunky dory, but there is a serious omission here. Since the entire raison d'être of the CX3 is to imitate the Hammond C3, where's the spring reverb setting? Hammond reverbs were springs, not plates. What's going on?

With that problem duly noted, we can now move on to Group 6, the parameters that affect the rotary speaker emulation. There are 17 speaker parameters (see box below) and they cover all the aspects of miking up a twin-rotor Leslie such as a 122RV. If you want to bypass the Leslie algorithm, you set the amp type to 'Preamp', leaving an unaffected signal that you can treat with external units, as desired.

The penultimate group, number 7, contains all the bits and pieces that you might want to use in live performance. Many of these relate to the pedals that you can use to augment the CX3, so let's take a quick look round the back to see what's available.

In addition to the expected stereo outputs and MIDI In, Out and Thru, the CX3 boasts three pedal inputs. The first of these takes a continuous controller pedal, and there are parameters in the Normal, EX and Global modes (see page 204 for more on the latter) that define its action. Next to this, you'll find a pair of sockets that will each take either an on/off pedal, or another continuous controller. Since all the Hammonds worth discussing have swell (volume) pedals, I'm not surprised that the CX3 has these. What's surprising is that Korg clearly intended to supply a continuous controller pedal with the CX3, but decided — at some late stage after the manual was printed — not to do so. This is a shame, but none of the other manufacturers does it, so I can't be too critical.
Quest For The Holy Grail
I've been hunting the perfect Hammond imitation for more years than I care to admit. I have a small collection of '70s and '80s analogue organs such as Crumar Organisers, the weird-and-wonderful Yamaha YP45D, and the classic Korg BX3. More recently, I've ploughed my way through numerous digital emulations starting with the Voce DMI64 MkII and V3, followed by the Hammond XB2, XB1, and XM1 module, culminating in my current module of choice, the Oberheim OB32. Likewise, I've tried and discarded Leslie emulators galore. I started in the '70s with various analogue failures, progressing through the Dynacord CLS222, Korg's own G4 (which I still use), and the Hughes & Kettner Rotosphere. I've experimented with the algorithms in the Korg Trinity and the Roland SDX330 effects unit. The system I now use for recording — the OB32, a Line 6 Pod and the SDX330 — is as good as any I've yet heard. Nevertheless, the only real Hammond is, for me, a C3 played through an overdriven Leslie. The reason for this is simple. Not only do the clones and emulators lack the presence of a C3, but recordings of the clones and emulators lack the presence of a recording of a C3. But, as of today, I have a sneaky suspicion that this has changed. Sure, the CX3 alone cannot sound exactly like a C3, but when I get round to recording my next track, I suspect that nobody will ever know the difference.

Now let's return to Group 7. Firstly, and quite incongruous on an organ, there are on/off Hold functions (sustain pedals) for both the Upper and Lower sound generators. You can also use on/off pedals for switching the keyboard split on and off, braking and releasing the Leslie effect, and switching between the fast and slow speeds of the Leslie. Continuous controller pedals modify the Reverb Mix and Amp Gain between user-defined minimum and maximum values. Yet more parameters define the keyboard split point itself, with user-defined octave shifts on either side.

Finally, Korg gift the patch-rename option with a Group all of its own.


The CX3 also offers eight edit groups in a Global mode that affects the operation of the whole instrument, irrespective of the patch chosen. Group 1 offers master tuning, and more pedal assignments. Group 2 sets the MIDI channels for the Upper and Lower sound generators, while Group 3 controls the pitch-bend range and MIDI Fixed Velocity.

The latter of these brings us to an interesting, and annoying point. Nowhere in Korg's pre-release publicity or the accompanying CX3 documentation could I find a definitive statement to confirm that the CX3's keyboard is velocity-sensitive. Indeed, the MIDI Fixed Velocity parameter suggests otherwise, allowing you to determine the MIDI velocity of any notes transmitted from the MIDI Out when you play. However... jumping back to Global Group 2, you'll find not one, but two output MIDI channel selectors for each sound generator. These are MIDI Upper TX Ch, MIDI Upper 2nd Ch, and their Lower equivalents. By default, the second of these is set to Off but, if you select a channel, you'll find that it transmits Note On, Note Off... and MIDI velocity! The keyboard itself is velocity sensitive! I have no idea why Korg have declined to make a bigger feature of this.

Moving on, Group 4 contains the MIDI filters, Group 5 allows you to determine the MIDI Continuous Controllers (or CCs) that transmit and receive drawbar settings, and Group 6 does the same for the front panel controls. Group 7 takes care of all the housekeeping such as copying and initialising patches, as well as SysEx.

I find the final parameter in Group 7 quite incongruous. Well, the parameter isn't, but its location is. This is called Wheel Brake, and when you press the Enter button, it simulates the slowing down and eventual grinding to a halt of the tonewheel generators that occurs when you switch off a Hammond. I love it! The only problem is the parameter's location. Because it's in a menu, you can't change patch while it's active (the patch buttons, as you will remember, act as edit group selectors when the menus are active).

There's one final group, and this too contains some strange bedfellows. The first option plays a selection of demo songs. The rest specify the pitches of the EX drawbars in each of the EX Drawbar Type memories.

In Use

Playing the CX3 as an out-of-the-box preset organ couldn't be simpler. Plug in the power, plug in to a stereo monitoring system (mono works, but you lose the spaciousness of the Leslie effect), and plug in some talent. You can then select from the 128 factory patches, and I promise that the hours will just glide past as you enjoy playing the thing. If you happened to be on stage in front of 20,000 screaming fans... well, that wouldn't be a problem. The controls are well arranged, and you're never more that a single button away from important functions such as percussion, mode selection, and patch selection. Then there is the traditionally styled chorus/vibrato selector, the knobs for overdrive, EQ and reverb level, plus — of course — the two sets of drawbars. In live performance, perhaps the only time that you'll need to press two or more buttons is when you want to change both bank and patch. Nevertheless, since the CX3 has a handy 'swap' option in the menus, you can place the required patches next to each other. Problem solved!
On Display
While I was getting acquainted with the CX3, I found the large, friendly letters on its screen very welcome. There are not many pixels (the resolution is 120x7, at a guess), but Korg have used them to maximum effect. There are three displays. This first is the text/edit page. The second and third show graphics representing the Upper and Lower drawbar settings of the selected patch, which may, of course, be quite different from the physical positions of the drawbars on the instrument itself.

The CX3's playability could also be a result of its the ability to use different treatments — different amp types, overdrive and reverb levels, and so on — while retaining the same drawbar registration as you play. This happens when you select drawbar set 1 or 2 for the Upper and/or Lower sound generators, rather than using the 'Preset' registrations within the patch itself. Then, when you select a new patch, everything jumps to the new settings except the registration itself. This is an elegant way to jump between 'comping' and soloing, while retaining the essential nature of the sound.

All this is well and good, but all the playability and convenience in the world wouldn't compensate for a bad sound. So it's fortunate that the CX3's sound is not just 'not bad', but first class. There are many reasons for this, but to explain the first and (for me) most important, we need to take another detour into the land of vintage Hammonds...

Not many people realise that a Hammond tonewheel organ is ever-so-slightly touch sensitive. This is because each of the nine drawbars has an associated contact beneath each key. The consequence of this is that, when you press a note slowly, you hear the initial electrical clunk and key-click, followed by the individual harmonics as they enter the sound. This means that, when you play a C3 or its siblings very rapidly, the nature of the sound is slightly different from when you play slowly. In particular, some notes do not 'speak' in their entirety, so you hear something that I can only describe as a suggestion of a note — the clunk, some key-click, plus a fraction of a second of perhaps the first one or two harmonics.

Laurens Hammond was convinced that these clunks and clicks were faults in his invention, but nowadays we perceive them as benefits that add character and presence to the sound. Yet the difficulty in recreating this has become the downfall of many Hammond emulators. And, if the characteristic 'spit' of the C3 goes AWOL, you lose the ability to make some notes cough, while other sing. I mention all of this because the CX3 imitates this better than any other digital organ I've tried, particularly if you set the 'key-click on' and 'key-click off' volumes close to their maximum values.

Likewise, the range and accuracy of the pitched percussion sounds impress me. This is especially true in EX Mode, which allows you to experiment far beyond the bounds of the traditional two, mutually exclusive pitches (4' and 2 2/3') of the original Hammond and its emulators.

Ah yes... EX Mode. This makes the Korg special. Despite playing the CX3 every day for the past few weeks, I still haven't begun to uncover all its possibilities. From tinkling percussion at unreasonably high frequencies, to delicate glassy tones (especially with Chorus3 and high-speed Leslie) that no real Hammond can produce... EX extends the CX3's palette into a whole new world of Hammond-esque sounds.

I should also praise the accurate chorus/vibrato section. Each of the six types sounds authentic to my ears, ranging from the traditional V1 warble through to a rich doubling effect when you select C3. Then there's the Expression/Overdrive knob. When I first saw this, I assumed that it was simply an 'amount of distortion' control, but it's a true Gain control, affecting the 'virtual' amplifier input level, so both the volume and amount of distortion are affected. Furthermore, at low levels it emphasises the deep bass and high treble frequencies (much like the 'loudness' control on a domestic hi-fi) so that it retains the apparent frequency response and tonality of the sound. Once you have the Expression/Overdrive set to taste, you then use the Master Level knob to control the sound's volume. Simple.
Gordon Meets The Fat Controller
The CX3 makes an unlikely controller keyboard. After all, it lacks aftertouch and has no joystick, modulation wheel or pitch wheel. Furthermore, it has just two zones — the Upper and Lower sections either side of the user-defined Split point. However, it has 18 drawbars, a bunch of knobs and buttons, and a superb MIDI CC (Continuous Controller) specification that allows you to assign controllers in the ranges 1 to 31 and 33 to 95 to just about everything on the panel. At first sight, this may not seem too special, and I didn't give it a second thought until I started playing my Yamaha FS1R from the CX3. For those of you who don't know it, the FS1R is a fantastic little synth that allows you to assign MIDI CCs to many of its parameters. So what happened when I connected the CX3 to the FS1R and moved a drawbar...? The sound produced by the FS1R changed, of course. What's more, it was simple to determine which drawbar changed the sound from this to that. Not that my little discovery was limited to the Yamaha. Most recent synths and modules allow you to control parameters in real-time using a computer or a box of sliders such as the Peavey 1600, the Kenton Freak... or the CX3. Interesting, huh?
True, there are many ways in which the CX3 is not as flexible as a true master keyboard. But how many master keyboards place 18 fully definable controllers, plus a handful of other knobs and buttons right under your fingertips? I rest my case, m'lud.

Excellent though the CX3 may be, it's not perfect. The fact that it sports just one physical manual is no problem... after all, it is what it is. But I'm disappointed that there is no provision for a pedal board. This places it well to the rear of the Hammond XM-series and the Oberheim OB32, both of which offer three independent MIDI-controlled sound generators — one for each of the 'logical' manuals, and one for the pedals. Of little concern to most rock and jazz organists, this will preclude the CX3 from a certain group of players who require all three.

As far as the sound generators go, I have only one complaint. In common with other DSP-based organs, the keyboard gates the drawbar leakage. If you sit at an old, leaky Hammond, one of the things you'll notice is a certain amount of leakage at all times, giving the Leslie a characteristic, throaty whirr, even when you're not playing. By gating it totally, Korg have made this background noise rather unnatural. I've no doubt that Korg can correct this in the software, so I hope that they will consider doing so. Oh yes, and while they're doing so, I would appreciate a global 'reset to factory patches' function as well as the patch-by-patch facility offered.

Another omission is the lack of a Leslie output. I would love to play the CX3 through my 122RV, but the only way to do so is to use a dedicated Leslie preamp/converter. Likewise, I would like to have seen a send/return loop lying between the sound generators and the preamp/effects. This is because, in common with all digital Hammonds, the CX3's weakest link is its overdrive effect. Since this must lie between the chorus/vibrato and the Leslie, the only way to replace it is with an effects loop. Korg clearly understand the need for this, because the original CX3 had one. OK, that was an analogue instrument, and adding a loop to the new CX3 would require a dedicated pair of D/A and A/D converters, but the all-digital Hammond XB2 has a send/return loop, so how about it, Korg?

I've reserved my final and most frustrated complaint for last, and Korg could have averted it. It's the manual. Sure, it explained all the obvious stuff, but when it came to discovering whether the CX3 generates velocity, or to finding out what EX Mode does, it's a complete waste of rainforests.


As you can tell, I liked the CX3 very much. Indeed, I have my fingers crossed for a new model with two manuals, tritimbrality, an effects loop, and a Leslie output. Big brother may be too expensive to be viable, but Hammond has travelled this route with the XB5, as has Oberheim with the OB5 and Roland with the VK77, so I would love to get my hands on the Korg equivalent.

But for today, the new CX3 sounds great. It plays beautifully. It has total polyphony across the keyboard, so those of you brought up on Keith Emerson discovering how many notes he could hold down simultaneously will not be disappointed. In addition, the effects algorithms are — for me at least — the equals of those in any other digital organ or module.

To prove this my final test involved a direct A/B comparison between the CX3 and my beloved OB32 module... no external help allowed, just the two organs, a MIDI lead, and an amplifier. Initially, they sounded quite different. The Oberheim was bold and brash, whereas the CX3 had a darker, more reserved character. But as I experimented, I found that I could make them sound more and more like each other until, remarkably, they crossed over and the Korg sounded more raucous. Then the Korg's superior flexibility took over, and it soon left the Oberheim trailing far, far behind. They're both excellent emulations, but the Korg is hugely more capable. In the last analysis, it's more realistic, too.

The bottom line? I'll say it again. The new Korg CX3 is first class. 

Published in SOS January 2001

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