The M3X is the first product from Macbeth Systems, the Scottish company founded by former DIY analogue synth enthusiast Ken McBeth. Will all turn out well, or is the M3X destined for a tragic end?
Avid readers of Sound On Sound will already know the name of Ken McBeth, a self-confessed analogue fanatic and digiphobe for whom the word 'algorithm' conjures up images of the murderous computer HAL in the film 2001. He is also the electronics engineer whose adverts for 'custom-built' Moog and ARP synthesizers caused SOS contributor Paul Nagle to dash up to Scotland to interview him a couple of years ago (see SOS February 2000). As Paul discovered, McBeth is a prog-rock aficionado and DIY synth enthusiast, a man who, in the late 1970s, succumbed to the urge to build his own synthesizers. Early experiments were — to be polite — less than entirely successful, but McBeth persevered throughout the '80s and '90s, eventually developing two Moog-inspired units intended for commercial release, the S3 and M3.
Is This A Voltage-controlled Synth I See Before Me?
McBeth claimed that the S3 was the 'world's smallest fully-featured three-oscillator synth'. Housed in a plastic case, but clearly modelled on the Minimoog, this offered three oscillators, a 24dB-per-octave filter, three modes of filter tracking, and dual ADS(D) envelope generators with switchable release. There was also the added bonus of a ring modulator. The M3 was a more substantial beastie, with a Minimoog-style front panel in a 4U rackmountable case. This offered a very similar specification to the S3, with individual CV inputs for each oscillator (a radical and very nice addition for a non-modular synth) and direct oscillator outputs.
McBeth intended to release both synths as commercial products, but this never quite happened, and he built very few. Fortunately, his work was not wasted. The S3 and M3 became the prototypes for the M3X, a substantial wedge-shaped synth that you can use as a tabletop module (with the control panel sloping at 45 degrees) or as a 6U rackmount module. McBeth has now formed his own commercial enterprise, the slightly differently titled Macbeth Studio Systems, and the M3X is his first fully manufactured synth.
Several months ago, I received the unit that I thought was going to be the definitive M3X for review. Unfortunately, I had very mixed feelings about this instrument. It felt solid and sturdy, and it looked much like the main panel of a Minimoog, which is often enough to endear any synthesizer to me. But even before switching it on, I had begun to find faults. For example, the oscillators offered just three waveforms: sawtooth, triangle and square, making it impossible to program a huge number of important analogue sounds. There were also the wobbly knobs that scraped against the front panel, and which would eventually have worn grooves in the paintwork, and arcane names for various controls... Things were not looking good for the M3X.
Worst of all, the M3X's envelope generators deviated from the design of the Minimoog's on one small but important point. Unlike the Minimoog's envelopes, which allow you to apply Release to the contour or not, the M3X fixed the Release time as equal to the Decay time in all cases.
This may seem to be an esoteric point, but it's not. Let me give you a couple of examples. Many synth bass sounds use contours with Attack=0, Decay=4 (or thereabouts), Sustain=5, and no Release. This is particularly important for the filter contour, because it creates a nice, aggressive filter sweep at the start of the note. Likewise, brass patches — which also demand instant Release — require the slow Attacks and slow Decays that are vital for the 'parp' at the start of the note. Clearly, this M3X couldn't create either of these sounds.
There were other niggling problems and omissions, too. The multi-trigger mode didn't work, there was no obvious master tuning control... and more. As you can imagine, I was not happy. Indeed, the M3X was rescued by just one quality; in my opinion, it sounded superb. That left me with quite a problem. Should I present the M3X as technologically crippled, or as sonically excellent but limited to a narrow range of sounds?
Fortunately, matters were taken out of my hands a couple of weeks later when Ken McBeth contacted Sound On Sound, offering to replace the first M3X with a significantly revised model that addressed almost all of the deficiencies described above. The new M3X offered more waveforms, there was an envelope Release On/Off switch, the knobs were more solid and felt nicer, and multi-triggering now worked. There was even a ring modulator (as found on the S3 and M3) although the addition of this had necessitated the removal of three modulation routing options.
The M3X had come of age — or so I thought. But for some reason, the magic was gone. Sure, the new model still sounded good, but to my ears, it didn't sound great any more.
I decided to contact Ken McBeth to discuss this, and was relieved to learn that my ears were not playing tricks on me. Apparently, the addition of the ring modulator had interfered with the M3X's delicate internal balance of signal levels and control voltages, and the difference — though subtle — was enough to take the edge off its sound. So the second M3X went back, and a couple of weeks later a third model arrived. With the ring modulator re-removed and the modulation routing restored, this was the final version, so, finally, it was time to review the Macbeth Studio Systems M3X.
- Oscillators: Three.
- Audio waveforms: Sawtooth, triangle, pulse wave (nominally 10 percent, 25 percent, and 50 percent), mixed sawtooth/square wave, ramp wave.
- Range: Approximately 10 octaves.
- Noise: White/pink/red.
- Pitch-bend range: 0-12 semitones.
- Filter: 24dB-per-octave resonant low-pass.
- Filter contour: four-stage ADS(D).
- VCA: Approximately 80dB.
- VCA contour: four-stage ADS(D).
- LFOs: One (digitally generated).
- LFO waveforms: Nine.
- Modulation sources: Six (plus all MIDI continuous controllers and performance parameters).
- Modulation destinations: Six.
- MIDI Controllers accepted: Pitch-bend, velocity and aftertouch.
- MIDI controllers 0-120.
- Note priority: Low, High, Latest.
- Triggering: Single/Multi.
- Analogue inputs: External audio, pitch CV, filter CV, S-Trig.
- Analogue outputs: Audio (high impedence), audio (low impedence), pitch CV, S-Trig.
- CV Interface: One Volt per octave.
- Trigger interface: S-Trig.
- MIDI: In, Thru.
- Weight: 5.5kg.
- Dimensions: 486 x 266 x 170mm.
- 19-inch rack space required: 6U.
The Scottish Synthesizer
The M3X will appeal to players who lust after large-scale controls and the ergonomics of yesteryear. A million miles from the busy front panels of some modern analogue synths, it sits happily alongside the granddaddy of all integrated monophonic synthesizers, the Minimoog. And, let's face it, the cosmetic similarities between the M3X and the Minimoog are overwhelming. The three oscillators, the mixer, filter and amplifier sections one above the other, the ADS(D) envelope generators... these define the look and feel of the Minimoog. However, there are as many differences between the two instruments as there are resemblances. All is not as it seems.
The M3X uses a stabilised oscillator design similar to that employed in the final revision of the Minimoog. This retains much of the warmth of older Moog circuits, but employs temperature stabilisation to ensure that the oscillators tune quickly and remain drift-free in a wide range of playing conditions.
Unlike Minimoog oscillators, which sport six waveforms, those on the M3X offer just five each. Sawtooth, ramp and triangle waves are common to all three. To these, Oscillator 1 adds a narrow pulse plus red noise, Oscillator 2 adds a wider pulse and a square/ramp mixture, and Oscillator 3 adds a square wave plus the square/ramp mixture. I suspect that this is a wider selection of waves than you will find on any other integrated monosynth.
Tuning is accomplished using 10-turn potentiometers, as found on the EMS VCS3. However, unlike Minimoogs fitted with these (Rick Wakeman was a strong advocate, claiming that they made fine-tuning simpler and more stable) the M3X has no vernier scales and no octave-tuning controls. This means that the pots must double as both uncalibrated coarse- and fine-tuning knobs, which some players will find annoying. After all, how are you supposed to shift an oscillator up or down by precisely an octave, quickly and without fine-tuning again? The answer is: you can't. But on the positive side, all three oscillators track accurately over a very wide range, and without any perceptible drift once the unit has warmed up.
For some reason (probably a lack of isolation between the circuits) the first M3X's oscillators locked together when tuned to unison or in pure harmonic relationships. To a lesser extent, the latest version does the same. However, I was pleasantly surprised to find that I could now tune two oscillators close to unison, whereupon they would beat gently against each other in the way so beloved of most analogue enthusiasts.
To the immediate right of the pots (see pic above), you'll find three LEDs that display the frequency of each oscillator. Unfortunately, when running at anything above a few Hertz, each LED appears permanently lit. And, since the oscillators don't go low enough to be used as true LFOs, I have to say that I find the LEDs redundant. You may not agree.
The M3X's Mixer section emulates that of the Minimoog, with five volume controls that determine the contribution to the mix of Oscillator 1, Oscillator 2, Oscillator 3, a pink/white noise generator, and the external audio input. You'll also find the external signal input socket in the Mixer section (it's at the rear of the Minimoog), together with the Master Volume control.
The next stage in the signal path is, of course, the filter. This is a 24dB-per-octave transistor ladder circuit that McBeth derived from the classic Moogs of the '70s. This will self-oscillate merrily at high 'Q' settings and, at high levels, the oscillators overdrive the filter input, thus imparting the mild distortion that characterises the Moog sound.
If the electronics of the M3X and the Minimoog are similar (and they are) the front panels of their Filter sections are almost identical, with cutoff frequency, resonance (called 'Emphasis' on the Moog) and envelope generator 'Amount' controls sitting above an ADS(D) contour generator.
However, two controls differ from their equivalents on the Minimoog. The first is annotated 'Kybd Control 100%/200%', and the other is 'Mod OS2 Off/On'. The first of these replaces the Moog's keyboard-tracking switches and, together with the filter-scaling option in the MIDI control system (of which more elsewhere in this review), allows you to determine filter tracking across a huge range, from settings of zero to many hundreds of percent. The second routes the envelope generator to the pitch of Oscillator 2. This is no trivial addition. It allows you to create pitch contours, dynamic 'sync' sounds, and all manner of weird modulation effects. Oh yes, and there's one other thing... unlike on the Minimoog, you can apply the M3X's filter envelope positively or negatively to the cutoff frequency, which is excellent.
The Amplifier section boasts just four controls, with three knobs that control another Minimoog-style ADS(D) envelope generator. The fourth is the Release On/Off switch that, on the Moog, you would find on the performance panel to the left of the keyboard.
MIDI & LFOs
Although the M3X provides one Volt-per-octave CV in/out and S-Trig in/out (yet more evidence of the Minimoog legacy), plus a filter CV Input, it is as a MIDI module that many are most likely to use it. So McBeth has provided MIDI In and Thru sockets with a comprehensive MIDI control system. However, rather than design his own digital electronics and software (remember, McBeth is a self-confessed digiphobe) he has incorporated an existing unit built by another company; a modified Kenton Electronics 'Pro Solo'. This provides a range of functions which fill what would otherwise appear as glaring holes in the M3X's functionality.
Firstly, the internal Pro Solo offers portamento. Parameter 1 sets the portamento rate, although you can modify this in real time using any assignable joysticks, wheels or faders that your controller keyboard may offer. You can also control the portamento status over MIDI, with parameter 7 allowing you to choose which MIDI controller or program-change number will enable or disable the effect.
Secondly, the Pro Solo provides the M3X's digitally generated LFO. This offers nine wave shapes: triangle (for conventional tremolo and vibrato), sawtooth down, sawtooth up, 10-percent pulse, 20-percent pulse, 30-percent pulse, 40-percent pulse, 50-percent pulse (ie. square) and a pseudo-random sample and hold. You can change the LFO waveform in real-time using MIDI continuous controller number 19. Parameter 2 sets the LFO rate, and you can synchronise it to MIDI Clock using parameter 4. The 'sync' function has a clock divide, so you can set the LFO to retrigger from once every semibreve (a single 4/4 bar) down to once every demi-semi-quaver triplet (1/48th of a 4/4 bar), making possible a whole range of musical effects.
Still on the subject of the LFO, parameter 5 allows you to define whether the LFO depth applied to the pitch CV is controlled by pitch-bend, velocity, aftertouch, or any MIDI controller from 0 to 120. At the same time, parameter 6 also lets you use any controller from the same list to determine the LFO depth applied to an Auxiliary CV route. Parameter 8 then allows you to control the Aux CV directly using a MIDI CC or performance parameter, while parameters 9, A and B define maximum and minimum levels, and the value to which the Aux CV level jumps when you reset it.
Parameters C, D E and F are more mundane: C sets the range of the pitch-bend, D offers transposition over four octaves in semitone steps, E fine-tunes the synth, and F adjusts the scale.
Parameters G and H offer three modes of note priority: low, high, and newest note, plus two modes of triggering: 'normal' which only retriggers once all notes have been released, and 'multi' which retriggers every time a new note is played. These allow you to mimic all the keying/triggering modes found on vintage synths, and you can choose a combination that suits your playing style.
Like the original Pro Solo, the one in the M3X remembers the last five notes played. This means that, although only one pitch CV can be output at any given moment, 'trills' can be played by holding down one note and trilling on a second. The extra registers also make short arpeggios much simpler because, if you keep the notes depressed as you move up the keyboard, you can release them again as you come back down (or vice versa). In addition, bum notes become less of a problem, because the CV of the right note is held in a register, and is re-instated immediately you release the wrong one. This is very neat, so it's a shame that it isn't explained in the manual.
The final three functions are Octave Select, Hold, and Filter Tracking. The first of these allows you to shift the whole instrument, but does not replace the individual octave selectors of the Minimoog's oscillators. The second causes the M3X to sustain indefinitely, which could be useful for treating external signals. The third, as mentioned earlier, helps to replace the Minimoog's four filter-tracking options with a far wider and more variable range. Finally, the M3X responds to sustain pedal (MIDI continuous controller number 64).
M3X MIDI Options
The Kenton Pro Solo offers just three buttons: Select and increment and decrement buttons, plus three seven-segment LEDs. And so it is on the M3X, although Macbeth has seen fit to change the names to 'Select', 'Neg' and 'Pos'.
The Select button has three functions. In normal use it scrolls up through the menus. If you hold it for a second or two, subsequent presses will then scroll down through the options. Finally, if you depress and hold it for more than six seconds, the current configuration is stored in the unit's non-volatile EPROM. If you get it wrong, you can restore the factory defaults by switching the unit off, and then holding down the three buttons while switching it on again.
The M3X offers 21 options in its non-hierarchical menu, and fortunately for those whose memories are not what they were, the options are all listed at the bottom of the M3X's front panel. The original Pro Solo lacked options 'I', 'J' and 'K', but offered two others as 'I' and 'J' — CV/Hz Select, and Gate Type Select. Personally, I would have imbued the M3X with an octave switch in the oscillator bank, a tracking control in the filter, and left the Pro Solo as it was. After all, this would have made it possible to hook the M3X up to any other analogue system rather than mucking around with all that S-Trig nonsense. On the brighter side, I understand that Ken McBeth has plans to make available an S-Trig-to-Gate converter cable, so this (minor) niggle should soon disappear.
The M3X retains the Pro Solo's MIDI Monitor, displaying note numbers, received channels, program changes, velocity, aftertouch, controller numbers, any controller value, note on, note off, MIDI Clock, start, stop, continue, and the presence of SysEx. However, given that the unit has only three buttons and three digits, controlling the Monitor is utterly arcane, requiring a mixture of short presses and long presses, and a grasp of the strange display system used. But if you're really stuck and need to find out why something is not responding as you think it should, the system works.
To jump from playing mode to analyser mode (or vice versa) you must switch off the M3X and power it up again. This is a pain.
Controllers & Modulation
On the Minimoog, LFO duties are undertaken by Oscillator 3 which, together with the noise source, provides modulation for Oscillator 1, Oscillator 2, and the filter. You then use the mod wheel to determine the modulation level. Fortunately, the modulation routings and capabilities of the M3X are much more comprehensive...
Let's start by returning to the oscillator section (on the righthand side). To the right of each Frequency control, you'll find a Route knob that determines how each oscillator is to operate. Oscillator 1 offers five such routes; Oscillator 2 and Oscillator 3 offer four each.
The first two options are common for all oscillators, and these are Audio and FM Filter. To these Oscillator 1 adds Mod Oscillator 2, Mod Oscillator 2&3, and Sync Oscillator 2. In similar fashion, Oscillator 2 can modulate Oscillator 1 and Oscillator 1&3, whereas Oscillator 3 can modulate Oscillator 1 and Oscillator 1&2. If this sounds a bit confusing, it isn't. It simply means that everything can modulate everything else, with the additional option of sync'ing Oscillators 1 and 2. Oh yes... when you use any of the oscillators as modulators, their associated mixer levels act as modulation level controls. That's sensible, and simple to use.
The fourth modulation routing control lies somewhat uncomfortably in the Mixer section, and this determines the destination of the Aux Controller CVs generated within the Pro Solo. The three options are Filter (cutoff frequency), Amplifier (gain), and the pitch of Oscillator 2. In may not be immediately obvious, but this innocuous little control hides one of the great strengths of the M3X... that you can route velocity or aftertouch (although not both simultaneously) to the filter, amplifier, or the pitch of Oscillator 2. As you might imagine, this opens up a wealth of performance possibilities.
You can think of the three oscillators, the Pro Solo's LFO, the LFO routed through the Auxiliary Route, and the Auxiliary CV itself as sources within a modulation matrix. Therefore, ignoring the 100+ MIDI controllers and performance parameters that you can assign to the Aux CV, you have six primary sources and six primary destinations. And don't forget, you have seven oscillator waveforms from which to choose, nine LFO waveforms, and you can set the amplitudes of each modulator in the patch. This is way, way beyond Minimoog territory.
The current M3X is a world apart from the first unit I received. Gone are the crippled envelope generators, the paucity of waveforms, and many minor niggles that I haven't even bothered to mention. In their places, there's a range of facilities much more in keeping with the 21st century. But despite these changes, the third M3X shares an important attribute with the first: classic synth sounds just leap out of it, and it offers bucketfuls of classy basses, leads, and other voices.
So, does it sound just like a Minimoog? Well, the M3X is certainly closer to a Moog than it is to any other vintage synth. It's quite unlike an ARP or Oberheim, and a million miles from the early Rolands, Korgs, and Yamahas of the era. Perhaps the nearest thing to a non-Moog sibling would be the Crumar Spirit, but since this was designed by Bob Moog, Tom Rhea, and others from the original Moog Music design team, this should be no surprise. But identical to a Minimoog...? Of course not.
For one thing, the filter on my Minimoog sounds slightly more 'open' than that of the M3X, having what I judge to be the same response at around +3 (on a scale of 5 to +5) as the M3X has at +10. Having said that, sweeping the resonance of both instruments demonstrates that the M3X cutoff frequency is capable of going supersonic more quickly than the Minimoog. Odd, huh? The difference in the perceived sound therefore lies in secondary factors such as the drive levels, and the exact slopes of the filters near the cutoff frequency. Since these are subject to tiny variations in component tolerances, it's no surprise that there are marginal distinctions between the two instruments.
I also found that the unfiltered outputs from the oscillators were different. However, minor changes in oscillator levels proved more significant than the inconsistencies in the waveforms themselves.
In other words, the differences proved to be so subtle that I had no difficulty tweaking things to make both synths sounded as near identical as makes no difference.
I even fetched my original Minimoog patch book and proceeded to set up some sounds on both instruments. OK, the calibration of the knobs is very different on the Minimoog and the M3X but, after suitable experimentation, I persuaded many of the patches to sound very similar.
If there is one quantitative difference, it's that the envelopes on the M3X are not quite as snappy as my Minimoog's, nor do they have the same amount of effect on their destinations. I understand that McBeth has already eliminated the latter discrepancy by increasing the gain of the VCAs driven by the envelope generators, but I'm not sure how he can speed up the Attacks. After all, manufacturers of analogue synths have been trying to emulate the Minimoog's sub-millisecond Attack for more than three decades, and, in my experience, only the enormous Technosaurus Selector has managed to do so.
Having tested the obvious, I also investigated a few famous Minimoog tricks. The first of these is the well-known strategy of patching the 'spare' audio output into the external signal input. On the Moog, this results in a characteristic thickening of the sound that many players use to give a patch more presence. On the M3X, the result is entirely different: it produces positive feedback around the filter that, with a high Master Volume, sends the Q sky-high, causing self-oscillation. Low output levels also raise the Q, but without self-oscillation.
Far less well known is the fact that you can persuade the Minimoog's VCAs to exceed their nominal 100 percent gain. You do this by retriggering the envelope generators quickly so that — due to a fortuitous circuit 'flaw' — each new contour peaks at a slightly higher level than the previous one. It's a measure of McBeth's deference to Moog's designs that the M3X demonstrates the same behaviour.
Of course, nothing is perfect, and the M3X still exhibits a number of annoying niggles. For example, it still has all its connectors (with the exception of the external signal input) and its on/off switch on the rear panel. When the M3X is screwed into a rack, this is a right pain. I also found myself bemoaning the lack of a physical switch to control whether portamento is enabled. You can only switch portamento On or Off using the Pro Solo menus and a MIDI controller, and that presupposes that you have a suitable MIDI command available, which may not necessarily be the case. Then there's the Pro Solo's user interface itself, which is nothing short of arcane. It will take some users considerable time to become fluent in its use.
I also found a bug in the portamento, which came nowhere near to its claimed hundredth of a second-per-octave maximum slew rate. Setting the rate to its minimum and playing two notes at opposite ends of the controller keyboard demonstrated this clearly.
Another particularly curious anomaly occurs when you select the ramp waveform in any of the oscillators. When you do so, the pitch of that oscillator drops by a tiny amount. This is probably due to a small current drain in the inverter that converts the sawtooth wave to the ramp. Too small a difference to be significant in conventional patches, this has a more pronounced effect when you create sounds that rely on FM or other modulation effects.
Finally, if I had a chance to specify an M3X 'Mk IV', I would ask for a modulation attenuator to make it easier to create gentle vibratos and so on (the Minimoog suffered this omission, too, making it difficult to use the modulation wheel to create subtle effects). Oh yes, and I would like to add the pink/white noise generator to the modulation sources. Currently, only the red noise in Oscillator 1 can be used in this way. Nevertheless, these are minor gripes. The new M3X is a fine synth, with much to recommend it, and little left to criticise. Let's face it: a velocity/pressure-sensitive Minimoog... isn't that what you always wanted?
The Playing's The Thing
It's worth remembering at this point that no two Minimoogs sound the same, and it's likely that no two instances of the M3X will be identical either. Consequently, an ostensibly identical patch set up on two Minimoogs and two M3Xs may well yield four subtly different sounds. Nevertheless, the M3X looks like a compact Minimoog, and sounds like a Minimoog. It's still a mistake to treat it as a Minimoog, because its additional capabilities make it a markedly different, more powerful instrument, and a 'touch-sensitive' one, at that. Nevertheless, the M3X retains the characteristic 'voice' of the Minimoog. So, should you buy one?
On one hand, if you're thinking about spending £500 on a tiny, 20+ voice polyphonic virtual analogue module with a squillion modulation options and effects processors, it's unlikely that the M3X will be of much interest. After all, McBeth's synth costs nearly twice as much, is merely monophonic, has no effects, and takes up a sizeable chunk of studio real estate.
On the other hand, if you're thinking of splashing out somewhat over a thousand quid for an nth-hand Minimoog, I would suggest that you take a very careful look at the M3X. It's far more flexible, both in terms of the sounds it makes, and in the ways you can use it. It's at least 20 years younger, and should have far more of its life ahead of it. And, for the most part, its sound is classic, vintage Moog.
Moreover, the M3X is almost certainly going to be cheaper than any working Minimoog, leaving you with enough spare cash to buy a powerful effects processor to spice it up even further. Who said that the British synth industry is dead?
Displaying Numbers Over 99
The limitations of the seven-segment displays require some unusual alphanumeric jiggery-pokery to display the menu 'names', as well as a curious method for displaying the 128 permissible values.
For values from zero to 99, you see conventional digits, but when displaying values above 99, the following arcane format applies:
- A dash at the bottom of the left-hand display means 100+.
- A dash in the middle of the left-hand display means 110+.
- A dash at the top of the left-hand display means 120+.
Strangely, McBeth also uses a range from -27 to +100 for at least one parameter. It's all very weird.
- Sounds and feels like a vintage synth.
- Comprehensive modulation and MIDI capabilities.
- Velocity and pressure sensitivity.
- The digitally generated LFO frees Oscillator 3, making the M3X a true three-oscillator synth.
- Inaccessible inputs, outputs and power switch when racked.
- Some of the MIDI menu operations are confusing.
- CV/S-Trig interfacing, rather than the more useful CV/Gate.
- There's one bug (portamento) to be fixed.
- It's hand-built, so it's not cheap.
If you're after a true analogue synth that produces the classic Moog sound, but fancy more facilities and modulation capabilities than any integrated vintage synth, this may be the instrument for you.
Macbeth Systems +44 (0)131 446 9022.