SYNTHESIS TECHNOLOGY MOTM SYNTHESIZER
by Robert Rich
Electronic Musician, Mar 1, 2001
A modular analog synthesizer that surpasses all expectations.
Lately I've been asking myself, "What madness would induce a musician to
invest thousands of dollars in an analog modular synthesizer when everyone
is moving toward software emulations?" Software synthesizers offer more
features at a lower cost and don't take up the space of hardware synths.
However, they lack the immediacy and physicality of a real instrument.
When I first encountered Synthesis Technology's MOTM system and its wall of
conservative black faceplates covered with large gleaming knobs, I recalled
the excitement I felt before the days of MIDI. Creating electronic music
then was a tactile and visceral experience, and the instruments were big and
messy. MOTM stands for "MOTher of all Modulars," and though that's quite a
claim, the exceptional quality of Synthesis Technology's system might
validate such hyperbole. The MOTM system balances modern audiophile
standards with some of the more desired quirks of retro analog synth design.
BACK TO THE FUTURE Whereas a MIDI-controlled synthesizer, by its nature,
operates in terms of discrete note events, a modular synth works from a
continuum: sound is created by complex swings in voltage and the interacting
patterns of clocks and switches. A patch on a modular synth is an
environment for inflection and nuance: a living and changing entity far
removed from the preset mentality brought on by recent keyboard
developments.
The physical accessibility of each function in the various components of a
modular synthesizer makes it easy to explore new sound possibilities.
Anything that creates a voltage can become a controller, and anything that
makes a sound can become part of a patch.
A modular synth can be integrated into the modern studio in ways that were
not possible during the instrument's heyday. A MIDI-to-CV converter and
sequencer software give substantial control over the modules through MIDI.
The recording and sampling capabilities of a digital audio workstation
further increase the usefulness of an instrument that requires repatching to
get new sounds.
Although the idea of programming with patch cords is primitive by today's
standards, it's more direct than programming a preconfigured synthesizer.
You don't have to spend hours fussing with routing assignments, SysEx
parameters, and device IDs as you do when you set up a hardware controller
for a soft synth. Using a modular hardware synthesizer is a truly satisfying
plug-and-play experience.
SELF-SERVICE A modular synth might even inspire you to grab a soldering
iron. Although preassembled and tested MOTM modules are available, Synthesis
Technology also offers each module in kit form. The kit versions are about
30 percent cheaper than the preassembled ones. Besides the satisfaction you
will gain from creating a system by hand, you might have enough money left
over to buy a few extra modules. For those new to DIY, the Synthesis
Technology Web site has a regularly updated tutorial page that includes a
list of supplies and books for getting started, as well as MP3 demos of each
module.
Synthesis Technology grades most modules by difficulty (1 is the easiest, 5
the most difficult) and, in some cases, indicates the amount of time it will
take to build the module. For this review, I built the MOTM-110 VCA/Ring
Modulator module, which has a difficulty rating of 2. It took me about four
hours to build.
The documentation that comes with the modules is clear and precise,
featuring thorough assembly and testing instructions, schematics, and
calibration procedures. The kit includes everything except a soldering iron,
tools, and a voltmeter. The wires are even precut, stripped, and tinned. The
module worked perfectly the first time I plugged it in, and I calibrated it
in a few minutes to within a millivolt of specification. Now I have a deeper
respect for the thought and precision that goes into the design of this
high-quality system.
Perhaps you don't want this kind of intimacy with your instrument. Even if
you choose to buy your modules completely assembled, you could find yourself
getting your hands dirty: the MOTM system encourages hands-on interaction,
and you'll get better mileage from it if you have a knack for DIY (see Fig.
1).
KICKING THE TIRES The various modules' components - 1/8-inch-thick aluminum
faceplates, large instrument-grade knobs, high-quality Switchcraft 1/4-inch
jacks, sealed Bourns pots, and low-leakage capacitors - show attention to
detail throughout. The circuit boards have solid ground planes and mount to
a steel backplate that helps shield against unwanted hum and noise (see Fig.
2).
Through its care in the design process, Synthesis Technology has overcome
the problems that plague most modular systems. One interesting and useful
design feature is the placement of the I/O jacks in the module's lower
section, which keeps the patch cords away from the controls. Synthesis
Technology's modules have a high signal-to-noise ratio, impressive thermal
stability, and low leakage and hum. The sound is neither dry nor clinical;
you can easily saturate the filters and make them growl, just as you can
with an old Minimoog or a Sequential Circuits Prophet-5.
Synthesis Technology also has a conservative approach to design. MOTM
modules will never fulfill the addiction to blinking lights that some analog
junkies have; only four of the modules sport LED indicators. According to
the designer, each LED adds noise to the system in the form of added current
drain and switching transients. By avoiding gratuitous flashing, each
module's sonic performance is improved. It seems like a fair trade-off, but
I wish a few of the modules (especially the envelope generators) gave a
visual indication of activity.
The MOTM modules fit neatly into a 19-inch rack by mounting to steel
brackets (available from Synthesis Technology) that horizontally span the
rack rails. Each module is 5U high and comes in multiples of the 1 3/4-inch
width: single-, double-, and triple-width. Five double-wide modules fit the
traditional 19-inch rack.
The modules are less than five inches deep, so they are shallow enough to
fit into a 12-space SKB pop-up mixer case. Depending on the configuration,
those cases can hold 10 to 12 modules (see opening photo).
The MOTM system is continually evolving, and new modules are due for release
every few months. Although the current module selection seems a bit
conservative, it provides a strong foundation for a system that will grow
into a monster in the near future. (Synthesis Technology says that three new
modules will be shipping by the time this goes to press.)
The current module selection includes a VCO, an LFO, a sample and hold with
noise, a VCA and ring modulator, an envelope generator, a voltage router, a
suboctave multiplexer, and three filters.
OSCILLATORS MOTM-300. The MOTM-300 Ultra Voltage-Controlled Oscillator
sports a frequency range of 0.2 Hz to more than 38 kHz, and it exhibits
better tracking and thermal stability than any other analog oscillator I
have used. In typical Synthesis Technology fashion, this module includes a
host of useful features without gimmicks. Each of the VCO's four waveforms -
sine, triangle, sawtooth, and pulse - has a dedicated output jack that can
be used simultaneously with the others (see Fig. 3). The module also
includes a 1V/octave input and two FM inputs. The first FM input has
dedicated switches for exponential or linear FM tracking and AC or DC
coupling. Control knobs are included for pulse width, pulse-width modulation
(PWM) depth, coarse and fine tuning, and depth control for the FM inputs.
The MOTM-300's sync feature is particularly interesting. The sync jack emits
a pulse that can drive other VCOs. However, the jack can also accept an
external sync signal, depending on the position of the Hard and Soft Sync
switch. In Hard Sync, the sync jack acts as an input only. In Soft Sync, it
acts as both an input and output simultaneously. The harmonic richness that
results from Hard Sync, in which the pitches of the oscillators are locked
together, is part of what gives an analog synth its characteristic sound. On
the other hand, Soft Sync, a rare innovation that first appeared on the E-mu
modular synth, latches two oscillators together when they are close in
frequency but allows for drift when the frequencies are farther apart.
MOTM-320. The MOTM-320 Voltage-Controlled LFO has the same high stability as
the VCO, as well as sine, triangle, ramp, and pulse outputs that you can use
concurrently. The frequency range is from one cycle every 30 minutes to 2.8
kHz. Along with a 1V/octave input, the MOTM-320 has a Hard Sync input, an FM
input, a rate control, an FM-scaling control, and a wave-shape control.
The MOTM-320 provides voltage-controllable waveshaping through the Shape
input. This feature narrows or widens a pulse wave, makes a sine wave
asymmetrical, or morphs a sawtooth from an upward ramp to a downward ramp.
However, more sophisticated processing is also possible. For instance, to
create syncopation in a particular piece, I synched the LFO to a clock and
triggered an envelope generator from the LFO sawtooth. That turned the shape
control into a continuous groove control that moved the trigger timing
earlier or later in relation to the beat. To hear an example of this, visit
http://www.emusician.com/emlinks.FILTERS The MOTM system really shines when it comes to filtering. Each of
the three filter modules sounds both stunning and unique. For signal
processing alone, these filters might inspire an investment in a small MOTM
system.
MOTM-420. The MOTM-420 Voltage-Controlled Filter has a 12 dB/octave response
and emulates the filter on a Korg MS-20 synthesizer. A switch selects among
highpass, notch, and lowpass types of filters. The MOTM-420 has three audio
inputs (each with its own level control), two scaleable FM inputs, and
cutoff and resonance controls.
You can push the MOTM-420 into full resonance, causing it to cross-modulate
with the incoming audio signals in fun and nasty ways. At maximum input
levels, the filter sounds good and fat as it begins to distort. The 2-pole
response lets some of the harmonics leak through, so the MOTM-420 tends to
sound more open and cutting than the MOTM-440 filter.
MOTM-440. The MOTM-440 Discrete OTA Voltage-Controlled Lowpass Filter (with
VC Resonance) has a 4-pole response that emulates the old SSM filter chips.
Filters designed with SSM chips gave the Octave-Plateau Voyetra 8 and the
Rev 1 and 2 versions of the Sequential Circuits Prophet-5 their thick, meaty
sound. Those filters got their famous growl from subtle overmodulation
within the filter itself, and the MOTM-440 manages to improve on that sound
with a better signal-to-noise ratio.
Synthesis Technology considers the MOTM-440 to be its signature filter, and
I can see why: it is one of the best-sounding filters I have ever heard.
Like the MOTM-420 filter, the MOTM-440 has three audio inputs and two FM
inputs, and, of course, you can push the filter into full resonance. You can
also make it distort, and the resulting overdriven sound differs
significantly from that of the MOTM-420. The MOTM-440 also includes a Bass
Enhance switch that increases the bass frequencies for an absolutely huge,
throbbing low end.
MOTM-410. Based on the Korg PS-3100 filter, the MOTM-410 Triple Resonant
Filter complements the other two filters with its interesting
formant-shaping abilities. The MOTM-410 contains three sweepable bandpass
filters and two asynchronous sine-wave LFOs (one of the LFOs runs 20 percent
slower than the other). The filters have a fixed resonance that lets them
evoke the vowels of the human voice or impart shifting articulations to the
source sound. Each frequency band has a dedicated tuning control and output,
so you can pan a sweeping signal across several speakers or sum the output
to mono.
The MOTM-410 allows voltage control over the LFO rate (from 0.02 Hz to 100
Hz), modulation depth, and Sweep. Sweep controls all three frequency bands
simultaneously. Also, a Mix control varies the amount of unprocessed signal
in the output.
A three-position LFO Mode switch determines how each filter tracks with the
LFOs. When the switch is in the Single position, LFO 1 controls all three
filters. In Dual mode, LFO 1 controls Filter 1, and LFO 2 controls Filters 2
and 3. In Dual Reverse mode, LFO 1 sweeps Filter 1 upward, while LFO 2
sweeps Filter 2 upward and Filter 3 downward.
I wish the module provided an output for each LFO. It would give me two free
LFOs to use elsewhere. I also wish I could control the filters' resonance.
The circuit's topology doesn't allow for that, but that's okay. As it is,
the MOTM-410 sounds fresh and unique; I would need five simpler modules to
get the speechlike formant shifts this module provides.
SOUNDS AND PROCESSING MOTM-101. The MOTM-101 Noise/S&H module performs
several duties at once. The noise and the sample-and-hold sections are
internally patched together, but you can use them independently, as well.
White, pink, and randomized noise are available simultaneously from the
lower row of jacks. The module also includes a randomized vibrato output,
created from band-filtered noise centered at 7 Hz. A vibrato control adjusts
the filter's Q, which creates a random signal, more or less. Although you
can't adjust the frequency of this random LFO, it's useful as it stands.
The sample-and-hold part of the module has an internal clock and a rate
control. It can also lock to an external pulse, and a control knob scales
the output. A unique feature of the MOTM-101 is the Track/Hold switch. In
the Hold position, the module steps to a new voltage every time it gets a
trigger. In the Track position, it mirrors the moving input voltage while
the gate is low (below 1.5V) but freezes that output when the gate is high.
It's like the child's game of red light, green light played with voltages.
MOTM-110. Another dual-function module, the MOTM-110 VCA/Ring Modulator has
a simple but high-quality VCA with audio input and output jacks, a gain
control, CV input, and a corresponding sensitivity knob. Like the other
modules, the MOTM-110 sounds impeccably clean and punchy. The gain knob
boosts the signal above unity, which lets you use negative control voltages
for attenuation. With two VCAs, you can crossfade between timbres - a nice
touch, though confusing at first.
The Ring Modulator works independently from the VCA, with separate carrier
and modulation inputs and associated level knobs (marked X and Y),
modulation output, and two AC/DC switches to pass or remove DC offsets. An
extra control lets you unbalance the modulator, which has the sonic effect
of adding grunge and saturation to the sound while letting the carrier
signal bleed through. That adds an extra timbre-shaping twist to the
familiar clangorous tones of ring modulation.
MOTM-800. The MOTM-800 envelope generator is the simplest MOTM module. Just
as expected, you have front panel control over attack, decay, and release
times, along with sustain level. The module has gate and trigger inputs and
positive and inverted outputs. The time values are on the fast side and
allow some snappy attack transients. Techno mavens will love it.
I wish the MOTM-800 had an LED so I could see when it triggers. I also think
Synthesis Technology needs a full-featured envelope module with
voltage-controllable durations. In the meantime, the MOTM-800 is affordable
and functional.
MOTM-120. The MOTM-120 SubOctave Multiplexer includes two digital counters,
a digital multiplexer, and four digital ring modulators. The module converts
an input signal to a square wave and then divides the frequency by 2, 4, 8,
and 16. You can mix the octaves with the original, but that's only the
beginning.
The MOTM-120 works with both audio and ultra-low frequencies, and it lets
you modulate the first input with a second input. In the Cross mode, the
module acts as a ring modulator when A and B inputs are audio. If A is audio
and B is an LFO, you hear rhythmic, sequenced pulsing among the four
suboctave pitches. When a clock is sent to both A and B inputs, strange
syncopation occurs. Things can get wacky fast with this module.
MOTM-700. The MOTM-700 Dual 2:1 Voltage Controller Router allows you to
assign one input to two outputs (or vice versa) and use control voltages to
flip between the two. The module has two routing sections that can be used
independently. The MOTM-700 accepts any frequency, so you can route control
voltages or audio signals. You can even force the switches to flip at
certain audio frequencies, which creates composite waveforms with some
bizarre and messy modulation artifacts. The MOTM-700, by design, invites
creative misuse.
POWER AND VERSATILITY The two remaining MOTM modules are utilitarian in
design. The MOTM-900 power supply uses a medical-grade, low-ripple power
block with enough juice to drive about 30 modules. The power cord plugs into
the front of the power supply module, which makes cabinet mounting easier.
The power switch has a mechanical indicator for the on position, though no
lighted switch.
For systems using more than 30 modules, Synthesis Technology sells a larger
power block that doesn't quite fit behind the front panel. Some drilling and
soldering is necessary to mount it into a cabinet.
The MOTM-940 Patch Panel includes eight rows of three jack types - 1/4-inch,
3.5 mm, and banana jacks - so you can integrate voltage and audio signals
from modular synths (such as Buchla, Serge, Modcan, and Wiard) or other
instruments that don't use 1/4-inch cords. The 3.5 mm jacks accept 1/8-inch
plugs, and each of the banana jacks has a second banana jack next to it for
grounding purposes.
Also, the bottom of the MOTM-940 panel includes two handy 4-way mults using
1/4-inch jacks. Each mult group gives you as many as three output signals
from one input. The MOTM-940 is the only panel that doesn't come in kit
form. However, it is a panel that you could use in other parts of the
studio, wherever there's a need to convert from one plug type to another.
A DREAM COME TRUE Like most analog modular synthesizer manufacturers,
Synthesis Technology is a small company, and its size has certain advantages
and disadvantages. On the one hand, it means that a certain clarity
permeates the modules and few compromises creep into the design. On the
other hand, you might experience delays when ordering modules, and the price
won't drop if a large quantity of modules are produced. The MOTM system is a
boutique product aimed at open-minded electronic musicians, audiophile sound
designers, and serious DIY tweakers. Such a select market doesn't lend
itself to mass production, and I suspect these modules will remain a
specialty item.
Yet for the high standards they meet, the Synthesis Technology MOTM modules
are quite a value. Each module costs less than a comparable Moog or Buchla
module did in 1970, which makes this system a bargain after 30 years of
inflation. In addition, Synthesis Technology has updated seemingly retro
analog gear into an audiophile 21st-century sound designer's dream. The MOTM
system is the real deal. There's nothing virtual about it.