Product Description for the MOTU Volta
Volta is a virtual instrument plug-in that turns your audio interface into a voltage control interface.
Any hardware device with a control voltage (CV) input can be placed under precise digital control from your favorite audio workstation software. You can play and automate modulars, analog synths - even effects processors.
Imagine being able to play and automate your CV-equipped analog gear from Digital Performer, Logic Pro, or Live with the same level of control, precision and convenience as a virtual instrument.
Here are just a few examples of what you can do with Volta:
# Perform MIDI sequencing with external modular synths with sample-accurate precision (if your host sequencer supports sample-accurate MIDI).
# Automatically calibrate and tune oscillators with the click of a button.
# Use ramp automation in your host audio software to control filters, envelope generators, effects processors and other voltage-controlled external gear.
# Apply LFOs, step sequencers and pattern sequencers to CV inputs and tempo-sync them to your host software timeline.
Whether you're a seasoned modular synthesizer devotee or simply a computer-based studio owner dreaming of adding that rich, coveted sound only true analog synths can deliver, Volta finally enables you to easily incorporate CV-equipped analog gear into your computer-based studio with all the control, precision and convenience of a virtual instrument.
To use Volta, simply instantiate it as an instrument plug-in in your host software.
You then trigger volta with MIDI notes and a variety of other control sources, and Volta outputs corresponding control voltage (CV) signals to the audio outputs of a DC-coupled audio interface. The resulting CV signals are routed to the CV inputs of your external hardware. Audio output is routed back to Volta.
The signal path for Volta is a simple loop: a control voltage signal goes out to the external hardware. Pitch information comes back in, through Volta, as a normal digital audio stream that feeds into your host audio software mixing environment.
From there, you can mix, process and master Volta's audio output just like any other virtual instrument.
Volta is easy to use but offers plenty of advanced programming features. The upper portion of the Volta window displays 24 output "slots", which represent the audio outputs on a connected audio interface. Simply drag any control source onto the desired output slot. Click the source to view its settings at the bottom of the window.
Volta provides seven types of control sources that perform a variety of different functions.
A single instance of Volta has 24 slots of output in which any combination of control sources can be applied. You can open as many instances of Volta active as your hardware allows.
Volta sources -- For example, a MOTU PCI-424 system with four 24I/O audio interfaces provides 96 DC-coupled analog TRS outputs which can serve as CV outputs. You can even mount the rack brackets on the rear panel of each 24I/O interface to mount it facing forward and use it just like a patch bay.
Voice -- A Volta Voice turns MIDI notes into voltages to control the pitch of your oscillators. A voice has a set of optional functions that appear as additional outputs. Usually, a voice needs an additional signal to gate the output of the oscillator. Volta produces up to four envelopes for controlling VCAs, filters or other modules. If you'd prefer to use hardware envelopes, these can be turned into gates or triggers.
You can also add initial and release velocity and LFO for each Voice. Polyphony with Volta is easy. Simply drag on as many voices as you need.
MIDI -- The MIDI source receives MIDI controller data and directly transforms it into a control voltage signal. This allows you to use MIDI controllers like aftertouch or your mod wheel. The optional smoothing parameter can be used to smooth out the stair stepping associated with 8-bit MIDI controllers.
Ramp -- The ramp source routes the high resolution automation data from your DAW to control voltages. As soon as you drop the ramp source into a Volta output slot, it publishes as an audio automation data source for the Volta instrument track. Insert or record automation ramp data using all of the powerful automation tools in your host DAW to then control your outboard gear.
Finally, intricate time-line based automation can be used to sculpt your compositions over time.
LFO -- Volta's LFOs provide the standard sine, triangle and square wave shapes, but each with adjustable symmetry. You can set the LFO period in real-world units, or sync the LFO to your project tempo.
A single LFO cycle can stretch over 16 bars for delicately evolving compositions. In addition, you have three random voltage generators, including sample and hold, sample and ramp and random walk for all sorts of interesting smoothed and stepped CV functions.
Trigger Sequencer -- Volta's Trigger Sequencer can be used to fire off envelopes, step external sequencers, reset LFOs - anywhere you'd need a trigger signal. You have up to 32 steps, two modes (forward and pendulum), adjustable trigger duration and swing.
Step Sequencer -- The Step Sequencer provides an easy way to generate stepped voltage sequences in sync with your project. Like the Trigger Sequencer, you have the same swing, mode and length options, but the Step Sequencer can be calibrated like the pitch CV outputs and quantize the result to the nearest semitone.
Clock -- The clock output allows you to clock external sequencers, hardware or drum machines to a user-selectable PPQ. Since you can have multiple clock modules running simultaneously, you can synchronize multiple external devices from a single instance of Volta.
Instant Tuning and Calibration
Analog oscillators are notorious for being difficult to get in tune and keep in tune. In addition, not all oscillators adhere to the tuning standard of 1 volt per octave. Volta can take care of these issues with one click of its Calibration button. By sending voltages and measuring the pitch response, Volta automatically creates a complete profile that addresses any non-linearities in both the audio interface voltage output and the oscillator. Volta can even tune self-oscillating filters using this closed-loop system. Users can click the calibration button at any time to instantly bring all external gear back in tune.
Virtual Instrument Operation
As an instrument plug-in, Volta produces mono or stereo audio output to the host software, just like any other virtual instrument plug-in. Volta's output consists of the audio signal returned from the external hardware synth. This means that external hardware, which is already sample-accurate with (and tempo-synced to) the host software timeline, can then be mixed and processed with all of the powerful features of the host software's mixing and effects environment. For example, the host software could be used to arpeggiate the MIDI notes going to Volta (and the external oscillator), and then Volta's resulting audio output could be processed with the host's tempo-synced delay, phaser and reverb effects.
Because Volta operates as a standard virtual instrument plug-in, all external hardware oscillator output playing through Volta can be bounced to disk using the host software's track freezing features. This means you can conveniently "print" external synth audio output at any time for archiving, mastering or future reference.
Volta allows users to automate continuously variable, CV-controlled parameters on their analog hardware (such as filter cutoff frequency, filter resonance or envelope depth) using MIDI CC data (sequenced in a MIDI track or played live from their MIDI controller). If users wish to achieve much higher resolution to avoid possible "zipper noise" and other pitfalls of MIDI resolution, they can instead control Volta using the audio track automation features in their host software. Audio track ramp automation can generate smooth, precise voltage changes at the resolution of digital audio.
In addition to these external automation sources, the Volta plug-in itself provides LFOs, a pattern sequencer, a trigger sequencer and even clock signals. These automation sources can be freely applied to any Volta CV outputs, and they can of course be synced to the host tempo and timeline.
A Simple User Interface
The Volta plug-in window displays 24 sockets at the top of the window that represent audio outputs on the audio interface(s). Control sources (MIDI notes, MIDI CC's, ramp automation, LFOs, etc.) are displayed as icons across the bottom of the window. Users then drag any desired control source icon onto any output socket they wish to control with it. Users can access settings for each control source simply by clicking it.
Each instance of Volta supports up to 24 output slots, and users can invoke as many instances of Volta as their hardware allows. For example, a MOTU PCI-424 system with four 24io interfaces provides 96 channels of output.