Using MOTU's Volta with a Synthesizers.com Modular System
- Andrew Horton, FM Towns, EEP Society
Sept 2009

I've been using MOTU's Volta plugin with my Synthesizers.com 22-space
system for a few months now, and am in the middle of recording an
album using this setup for 90% of the sounds. Since I've had time to
work with this setup - which literally changed the entire way that I
work - I figured I'd write up a testimonial/review for other DotCom
users or prospective users. Since there are already plenty of Volta
reviews out there, I'm not going to focus on the ins and outs of the
program as much as specifically on its utility when combined with a
DotCom modular system, especially a smaller system like my own. For
all of the following anecdotes, I'm running Volta in Logic 8 on a
late-model iMac with a MOTU 828mk3 audio interface.

First, a quick Volta summary to get everyone to speed; Volta is an
audio unit software plugin by MOTU that essentially "hacks" your
computer's audio interface to transform it into a MIDI-to-CV
converter, allowing it to transmit control voltages through its audio
outputs. To achieve this, Volta requires that you use a DC-Coupled
audio interface (all current MOTU interfaces are compatible, as well
as some third party devices) so that the CV will pass. In addition to
functioning as a standard MIDI-note-to-CV conveter, Volta also
generates high-resolution software envelopes, LFO's, step and trigger
sequencers, adjustable clock output, as well as the ability to use
ramp automation data and standard MIDI CC's as control voltage
outputs. All of the aforementioned integrates seamlessly into your DAW
so that Volta operates like any other software instrument plugin, even
bringing your synth's output back into your DAW through Volta so that
it can be rendered, frozen, processed, etc. like any other plugin
instrument if you so desire. Additionally, Volta has a one-click
calbiration utility that will instantly calibrate Volta's output to
all of your oscillators so that they tune and track perfectly.

My experience: I really can't understate the extent to which Volta has
transformed my workflow. It really is the closest thing to a
"one-click" solution for integrating my DotCom modular into my
computer-based sequencing and recording setup without making any
analog sacrifices.

Calibration of my two Q106 Oscillators is a breeze. MOTU recommend
using a sine wave for best calibration, and this seems to work fine
for me - I get a pretty broad octave range when going straight out of
the oscillator into the 828. MOTU recommend going directly out of the
oscillator and getting the hottest possible signal for best
calibration results, but I've even filtered down the sine's little
notch with a LPF and gotten similar results. You're not going to get
the fullest possible pitch range, as MOTU interfaces can't quite put
out a full +5/-5 DC voltage range (more on that later), but I have no
complaints since I don't tend to play notes at the absolute highest or
lowest extremes of the scale. I patch up the oscillators, then click
calibrate and after a few boop-boops I have perfect tracking. Genius!
I don't tend to adjust the oscillator footage at that point, instead
making any octave switches with my controller or in the DAW's
sequencer itself.

The simplest use of Volta is as a traditional MIDI note to CV
converter. To this end, Volta offers a "voice" module, which at its
simplest matches a pitch component with an envelope component. This
twosome is dragged to two of Volta's outputs, corresponding to two of
the audio interface's physical 1/4" outputs. I patch the first (pitch)
either to my Q106's exp. input or to a multiple, but Volta's Envelope
component is where it gets interesting. It can be set to either
envelope, gate, or trigger - basic gate being fine for triggering my
DotCom's Q109 Envelope Generator - but "Envelope" setting provides a
high resolution digital envelope, with full graphical editing, that I
can patch right to my VCA, leaving my Q109 totally free to do other
things. And these envelopes are just incredibly snappy; I don't have
any sort of technical specs to offer, but they're significantly
snappier than the Q109 (no slouch itself), really getting into Roland
SH-territory, which is just outstanding for creating percussion
sounds. In a small system like my 22-space one, leaving my Q109's free
for other uses is a godsend. My one complaint about this feature is
that the envelope component is always part of a "voice" (pitch and
envelope) module, so if you just want envelopes, you have to take up
two slots in Volta/your interface just to get them. I hope they'll fix
this in a future update, because when I'm just doing percussion, I
don't need to send out pitch values, and would rather just use all 8
slots on my interface for outputting envelopes.

Next module...LFO. It's what you'd expect - a high-quality/resolution
digital LFO that can be patched out to wherever. All of the usual
waveforms are available, and then "sample and ramp" and "random walk"
with provide sample and hold variations. Though I agree with Roger
Arrick's reasons for not making a dedicated LFO module, it's nice to
have LFO's available for modulation without giving up one of the two
oscillators in my small system. The LFO's can be free-running or can
sync as a division of your project's master tempo, which is nice for
nesting rhythmic effects and subdivisions. I mentioned earlier that
MOTU interfaces cannot output the full -5/+5 CV range, though they get
close, and I definitely hear this when working with LFO's. I find that
I always route Volta's LFO through a Q125 Signal Processor to close
the gap when working with wide modulation swings. That aside, I have
no complaints about the quality of the digital LFO - no "stepping" at
all or any digital character. If there's one thing that both the Moog
Little Phatty and now Volta have taught us, it's that high-resolution
digital LFO's can be a seamless substitute for most standard
modulation uses. The one glaring omission is that the LFO rate (and
most of Volta's module parameters in general) is static, "set it and
forget it," and can't be modulated by anything else or even automated
within the DAW. I'm assuming and hoping that more of that
functionality will appear in future updates.

I honestly can't say much about the Ramp module, though I imagine that
for ambient guys or people into long, slow modulation, it'll be a
game-changer. The ability to just draw in ramp automation data and
send it out as a CV is pretty cool - you could have one ramp running
the entire length of a track, slowly morphing values. And yet, since
it's incredibly high resolution, it's probably great for more
complicated, quick-change modulation. I'd be curious to see someone
use it on a per-note basis for classic step sequencer-style
modulation. Likewise, I haven't used the Clock module, but it should
be perfect for clocking analog sequencers or syncing anything that
responds to a voltage pulse, such as the rate of a Sample and Hold
module.

The MIDI module is a simple utility that allows the user to use any
MIDI CC or value as a control source. As a player that always has one
hand on the mod wheel, I'm excited to finally be able to set up
modular patches that incorporate it as a source or articulation, to
say nothing of velocity, aftertouch, etc. There are already some
pretty cool videos online of people using MIDI faderboxes and things
to control big modular systems using a series of these modules running
in Volta. A great touch is the ability to slew the MIDI data using
"attack" and "release" controls like a standard voltage slew limiter
in order to avoid MIDI stair-stepping. With a slight tweak, my mod
wheel goes from clicky stepping to smooth, analog control.

Rounding things out are the analog-style step and trigger sequencer
modules, each of which automatically slave to your project's master
tempo. These are just instant fun; I've created some amazing sequencer
jams by setting up five or six step sequencers going to different
oscillators, filters, and other parameters on my DotCom and then
setting them all to different lengths and ranges. Even one step
sequencer and one trigger sequencer, set to two different lengths,
provide endless variations on a series of values. While these two
sources are the most fun and interesting, they're also the most
rudimentary and half-baked; the sequencers just run indefinitely
instead of stopping and starting with project playback, gate duration
of the trigger sequencer is "set it and forget it" style rather than
per-step or programmable by automation, the step sequencer won't
quantize to specific scales or modes, etc. Nobody's going to mistake
it for Numerology. But allowing for a product that was clearly built
around getting it out on the shelves THEN worrying about improvements
and tweaks, the two sequences have provided the most "fun factor" so
far.

As someone who embraces the modular approach but still likes to work
quickly and efficiently, Volta has completely streamlined my workflow.
Everything that used to feel like a big pain the butt - even down to
tuning and calibrating before committing to tape - is essentially
"one-click." I feel like I can just turn on my system and go instead
of fussing with equipment and parameters for 15 minutes first. This is
an inspiring development. Volta has also breathed life into my
comparatively small 22-space DotCom system - and I'd imagine that the
LFO's, sequencers, Ramp automation CV's, and Envelopes will be a
Godsend for people with similarly compact setups.

Volta definitely needs some work, and there's a ton of room for
improvement - the ability to automate parameters like LFO rates and
sequencer gate lengths is an absolute no-brainer, but I'd even like to
see more internal interaction between Volta's different
modules...imagine using one LFO to modulate the symmetry of another,
and so on. Even better, imagine an update that allows Volta to RECEIVE
CV's as well, truly integrating into your modular in a bi-directional
manner...not to mention CV sampling/recording, CV-to-MIDI conversion,
etc. But maybe that's all going to be saved for Volta 2. Even as-is,
Volta is a no-brainer choice for anyone working with modular
synthesizers in a DAW recording and sequencing environment.

End