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MIDI to Control Voltage (VCO pitch) and gate (trig)

Philip Rees have been manufacturing respected high-performance, easy-to-use MIDI to CV converters since 1988. The purpose of these devices is to enable the MIDI control of analogue (analog) synthesizers.

MIDI to CV reviewIndependent product review by Sound on Sound, the world's best music recording magazine.

Philip Rees MIDI analog monosynth VCO VCF CV gate Roland Korg Moog Phillip ReeseLittle MCV MIDI to CV Converter

The Little MCV is an up-to-date high-resolution, high-speed interface unit. It offers great functionality, performance and quality at a low price.

Little MCV midi to cv with Korg MS20 photo

V/oct and V/Hz control voltages

Comparison of lin. and log. lawThis up-to-date interface midi to cv unit lets you use your MIDI keyboard, computer, sequencer or other MIDI master device to control your irreplaceable old analogue monosynths, with their fat bass sounds and friendly knobs.

The Little MCV responds fast and can generate control voltages for the common one-volt-per-octave (logarithmic VCO, as used by Roland and Moog) system and the so-called volts-per-hertz (linear VCO, as used by Korg) system. CV type is selected by a slider. The voltage law of the two types is contrasted in the adjacent graph.

Little MCV midi to cv block diagramSuperb 16 bit resolution

The use of a high quality, modern 16 bit DAC means that the logarithmic pitch CV output can be perfectly in tune across the full note range, with fine steps (a stunning 512 steps per semitone) for the firmware-implemented pitchbend, pitch vibrato and portamento. 16 bit conversion also lets the Little MCV generate an accurate linear CV of superlative stability over a very wide pitch range.

In V/oct mode, unlike other low cost units, the Little MCV responds properly to pitch over the full 128 semitone MIDI range. The CV output also has a wide range available: from -10V to +20V. A tuning preset adjustment is provided to set the V/oct offset or V/Hz slope. A trim preset lets you finely match your target instrument with respect to the slope for V/oct, or the offset for V/Hz.

Smooth pitchbend, LFO, and portamento effects

The pitchbend firmware can use the full 14-bits of the MIDI pitchbend value. This combines with the 16-bit conversion to give clean stepless glissando if you have a suitable high resolution source of pitch wheel data. The default pitchbend range is plus-or-minus one octave. The standard MIDI 'pitchbend sensitivity' Registered Parameter is observed, so you can alter the bend range if required.

Under MIDI control, the Little MCV digitally generates a precise triangular low frequency oscillator (LFO) signal, which may be added to the CV output - to create a high quality pitch vibrato. The LFO depth is controlled by the product of the MIDI Modulation Wheel and a value derived from the Tremolo Depth Controller (see graph below). The LFO speed is conveniently set by MIDI Non-Registered Parameter Number 00.

The portamento (pitch-to-pitch glide) response is exponential and free of irregularities. The MIDI 'Portamento On/Off and Portamento Time messages are observed.

The table below lists the MIDI controller (Control Change) numbers used in Little MCV, and summarises what they do.

Little MCV implementation of MIDI controller Numbers
DecHexMIDI Controller NameUsage in Little MCV
101HModulation Wheel MSBCoarse setting of LFO depth
505HPortamento Time MSB Coarse setting of pitch glide speed
606HData Entry MSB Coarse setting of LFO speed and bend range
3321HModulation Wheel LSBFine setting of LFO depth
3725HPortamento Time LSB Fine setting of pitch glide speed
3826HData Entry LSB Fine setting of LFO speed and bend range
6440HDamper pedal (sustain)Sustains all subsequently released notes
6541HPortamento On/OffEnables and disables pitch glide function
6642HSostenutoSustains only subsequently keyed notes
6844HLegato FootswitchSelects gate logic for overlapping notes
6945HHold 2Switches background hold feature
8050HGeneral Purpose #5Selects highest-note or last-note priority
8151HGeneral Purpose #6Enables and disables LFO synchronisation
925CHTremolo depthSets LFO depth gain parameter
9660HData IncrementStep setting of LFO speed and pitchbend range
9761HData DecrementStep setting of LFO speed and pitchbend range
9862HNon-Regd Param LSBSet to zero when setting LFO speed parameter
9963HNon-Regd Param MSBSet to zero when setting LFO speed parameter
10064HRegistered Param LSBSet to zero when setting bend range parameter
10165HRegistered Param MSBSet to zero when setting bend range parameter
12078HAll Sounds OffCancels Hold and clears all keyed notes
12179HReset All ControllersClears pitchbend and all Control Change values
1237BHAll Notes OffClears keyed notes but does not override hold
1247CHOmni Mode OffUnit will respond only to selected MIDI channel
1257DHOmni Mode OnUnit will respond to any MIDI channel
1267EHPoly Mode OffClears keyed notes but does not override hold
1277FHPoly Mode OnClears keyed notes but does not override hold

The best gate modes

Little MCV default gate modeThe default trigger mode is multiple for legato playing, but you can change this via the Legato Footswitch MIDI message.

Little MCV also defaults to last note priority, but overlapped notes are not lost, and hidden notes can restart when a more recent note is released - this is generally the most favoured algorithm. MIDI Controller Number 80 will switch over to highest note priority.

The three MIDI Sostenuto, Sustain and Hold 2 commands are all fully implemented.

A simple slide switch lets you choose between 5V positive, 10V positive and S-trig (negative current gate, Moog style) for the gate output.

The ACTIVE lamp indicates when the gate signal is asserted.

[PHOTO: LMCV midi to cvGreat package

You can easily set your Little MCV to receive on any of the sixteen MIDI channels using the straightforward front panel rotary control.

The Little MCV has a MIDI In DIN socket. The CV OUT and GATE OUT connections are standard quarter-inch jack sockets.

The case of the Little MCV midi to cv is 109mm x 109mm x 40mm.

A 50/60Hz mains (ac) power supply is built-in, obviating the need for an external adaptor. Versions are manufactured for 110 - 120 Vac or 230 Vac – simply specify when ordering. The integral mains lead comes with a plug – please state your plug-type requirement when ordering. You can tell when the unit is powered-up as a power indicator lamp is provided. Power consumption is very low.

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