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Analog 4-Voice Polyphonic Synthesizer with 37 Full-Size Keys


Behringer revisited its Model D. This time it's not a small table module but indeed a synthesizer with a keyboard of 37 keys of normal sizes (not minis, yuck!). The body and the front of the Poly D are made of metal, with pretty wooden sides. The layout of the pleasantly spaced Poly D buttons takes on the physiognomy of its model (minimoog model D), even fluted black buttons and black pointers with a plugged aluminum disc above, rocker switches in various colors, a wooden champlat 'back of the keys, all in a seventies seventies look. The Poly D models its model up to the control panel which can tilt forwards, adjustable in three positions, for comfortable use. The novelty comes from the fact that the Poly D has four oscillators, therefore polyphonic 4 voices, and that we can play a chord of four notes. Like the Behringer Model D, the Behringer Poly D is an analog with subtractive synthesis but with 4 voices taking up the principle diagram of the minimoog Model D: VCO, VCF, VCA. Behringer added analog effects to the Model D: distortion and chorus, as well as a 32-step arpeggiator and sequencer. The construction of Poly D is very neat. Behringer worked out a very nice synth there, as much on the architectural level - well "pumped" it must be said - as of the well polished realization.

I'm not going to go back to the “moog” structure of the Poly D which is like the Model D, that is to say like the minimoog D. For more details, I invite you to read the page on the Behringer Model D. The added value of Poly D is of course the fourth VCO and the UNISSON and POLYPHONY modes, Disto and Chorus, the sequencer and the arpeggiator.

Monsieur Plus…

In the CONTROLLERS section, to the left of Poly D, a MODE selector (MONO, UNI, POLY) and an AUTO DAMP switch (ON/OFF) have been added. I will come back to this later. For the rest of the synthesis, it's identical to the Model D, with one more oscillator, which I invite you to read here. So, in the OSCILLATOR BANK section there is an additional line named OSCILLATOR-4. To the left of this line I find the OSC 4 CONTROL switch which is called OSC 3 CONTROL on the Model D. Interesting detail, to the right of each RANGE switch (feet-pipe) is a red LED indicating the activity of the VCO.

The DISTORTION section has three settings. A DISTORTION knob controls the level of distortion, a TONE knob to filter the distortion (low pass), a LEVEL knob to adjust the distortion output level, and an ON/OFF switch to activate the effect. Below is the CHORUS section consisting of three buttons. This chorus is analog stereo with BBD. It was designed by TC Electronic, le JUNE-60, inspired by the chorus of JUNO-60 Roland. It only has three operating modes: Chorus I, Chorus II, Chorus I + II. There are no Depth and Rate settings. The CHORUS I switch gives a light, airy chorus, the CHORUS II gives a deeper effect. Either or both can be engaged. In the latter case the Chorus effect is very pronounced, strange. The chorus effects are more interesting using the stereo output of the Poly D.

On the bottom right is the SEQUENCER section. Here we have a 32-step polyphonic sequencer whose sequences can be recorded (stored) in 64 memory locations. As an alternative to the sequencer, an arpeggiator has 8 patterns. The order in which the arpeggiator notes sounding is offered in 8 patterns which are selected using the [<] or [>] keys when the arpeggiator is playing (after pressing/activating the [ARP] key ]). The LEDs named LOCATION indicate the selected arpeggio pattern : 1: UP 1, 2: DOWN 1, 3: DOWN and UP, 4: RANDOM, 5: UP (+1 OCT), 6: DOWN (+1 OCT), 7: UP (-1 OCT), 8: DOWN (-1 OCT).

To the left of the keyboard are the classic Pitch and Modulation wheels (lit from the inside by a red LED whose intensity varies according to their position, depth of the effect; unfortunately not deactivable), the LFO RATE knob , and rocker switches. Here ! there are three, while on the minimoog there are only two. I am pleased to find the GLIDE switch (ON/OFF) absent from the Model D, the LFO waveform selector to choose between square or triangle signal, and a new one that allows you to transpose the keyboard from one octave to low or high. All of these controls are well laid out. It just makes sense or it's the habits that prevail.

The keyboard is capable to generate CV and Gate as well as Aftertouch and Velocity as control voltages and/or MIDI data. The last two CVs each have their own potentiometer allowing to measure the amplitude of action in order to finely control the target to be piloted. The jack inputs on the rear panel allow additional control options for the modulation source, oscillator, filter and volume. Here, it's interesting to connect the aftertouch and/or velocity outputs to these inputs with a standard TS jack cable.

The rear panel is fitted with multiple connections. Looking from the back, from left to right, there is the 12V power connector for the external 110V-240V adapter, a USB type B connector (like on a printer), the MIDI IN OUT THRU trio (DIN 5-pin), an INT CONTROL OUTPUTS section comprising: the Aftertouch output and its small potentiometer for adjusting the amplitude of its CV voltage, a Pitch CV jack output, a V-Trig jack output, a Velocity CV jack output and its a small potentiometer to adjust the amplitude of control voltage, an EXT SIGNAL section with a jack input to connect an external audio source (line level), a SYNC section for a clock synchronization input and output, a section MAIN OUTPUT with balanced left and right audio jack outputs, an EXT V-TRIG section allowing the use of an external voltage to trigger the filter contour, and the last EXT CONTROL INPUTS section with: a LOUDNESS jack input for a CV controlling voltage the outline of e Loudness function, a FILTER jack input for a CV voltage controlling the cut-off frequency of the filter, an OSCILLATOR jack input for a CV voltage adjusting the frequency of the four oscillators. It should be noted that the LOUDNESS, FILTER and OSCILLATOR CV inputs can be controlled by a Behringer FCV100 V2 or FC600 V2 expression pedal via a balanced 6.35 mm jack cable. These pedals must be set to the CV position so that they can deliver CV voltage.

Poly, and well mannered

Polyphony is made possible by the four oscillators, each of which takes a voice. However, unlike traditional poly synths, all voices use only one VCF and VCA. So if, for example, I hit a new note, the old one is "replayed" through the filter and the amplitude envelope. She does not seem independent. This is why we speak here of paraphony, rather than real polyphony, although the name of the synth may make you think of it. Since the oscillators cannot be synchronized, they operate independently of each other in POLY mode, which can cause detuning between oscillators, different height and waveform.

MODE selector : MONO, UNI, POLY

The MONO monophonic mode plays the four VCOs in chorus, even if the VOLUME-ON switch in the MIXER section is not closed. it's the same mode as on the Model D. The UNI mode is particular. When I only play one note, the four VCOs give voice. If I press another key while holding down the first key, voices are split. The first key pressed has only two active VCOs (3 and 4), and the second also uses two VCOs (1 and 2). If I add a third note, then three oscillos will be used, the first key will be assigned to VCO-3, the second to VCO-2, and the third to VCO-1. A chord with 4 keys activates the four VCOs, one for each note. The POLY paraphonic mode plays a single VCO per key pressed. In UNI and POLY modes, it's important to set the four VCOs in the same way : same height RANGE, same waveform WAVEFORM, same VOLUME and especially ON. Otherwise, we hear strange things when switching from one chord to another (change in pitch and / or timbre). After nothing prevents you from experimenting. But the I do not guarantee that it will do the same thing twice in a row because here we do not control the allocation of voices.


The AUTO DAMP switch in the OFF position will sound all the notes in a chord until all the keys are released or a new key is played (a fifth). It's sort of a one finger CHORD mode. AUTO DAMP in the ON position plays only the keys pressed.


With MIDI System Exclusive commands or with the Synth Tool Behringer software, we are able to customize certain functions : MIDI channel (IN and OUT), transposition, velocity sensitivity, Pitch-Wheel range, MIDI Clock on DIN and / or USB, Aftertouch on DIN and / or USB, sequencer output on DIN and / or USB, arpeggiator output on DIN and / or USB, note priority on LOW or HIGH or LAST, Sync Clock source on internal or DIN or USB, etc. .

There is sound !

With its beautiful construction, a very neat finish, its 10 kilograms and its dimensions almost identical to minimoog (37 keys against 44), this synth is a device that is pleasant to use. Orders are not miniaturized. The keyboard with 37 normal keys is sensitive to velocity and aftertouch. All the jacks are 1/4", even the headphone jack. The stereo output is balanced. Good. The only tasks on the board are the disappearance of the switch "A440" for tuning and external power which seems cheap for some users. Between us, I prefer to see far away from my audio devices this AC adapter — switched-mode power supply — which generates relatively high electromagnetic noise. If it were integrated into the audio equipment, I think the induced noise would not be neutral. There is no program/patch memory. Behringer Poly D does not transmit the position of potentiometers and other switches via MIDI CC. It does not recognize incoming MIDI CC. The Poly D sounds minimoog. it's not a Polymoog, it's not the same technology. The four VCOs open up a new space, a sound universe. The UNI or POLY mode are very interesting from a musical point of view and search for ambiances, noises, drones.

If the compact size of the Behringer Model D pleased some musicians, for others it was rather a brake, or even disqualifying. By offering the Poly D, Behringer meets the expectations of those who want an analog synth with a keyboard with keys full size, buttons generously distributed on the control panel, and real wood cheeks made from tree wood. It looks like a real vintage synth. If in addition the Poly D has the sound, the sound of its model MOOG, it's even better. There are no presets, no configuration memory. I remind you. Everything is programmed by hand, by re-reading Recall notes or by calling on your memory (the one in your head).

The minimoog is a reference in the world of Electro music, but also Rock, Pop, Progressive, Symphonic Rock, Jazz, Fusion, R&B, Soul, Trip-Hop, Rap, Funk, even Variety, and so on, practically all musical genres. it's or was used, in disorder, by Pink Floyd, Krafwerk, Peter Bardens, Gary Numan, Klaus Schulze, Herbie Hancock, Manfred Mann, Patrick Moraz, Frank Zappa, Jean-Philippe Goude, Vince Clarke, Tim Blake, Radiohead, Depeche Mode, Moby, The Chemical Brothers, The Crystal method, Air, Daft Punk, Dr Dre… Impossible to name all the musicians who have used the minimoog. Note the memorable minimoog bass in Thriller by Rod Temperton (singer Michael Jackson), without missing the rock opera Journey to the Center of the Earth and Art-Rock The Six Wives Of Henry VIII by Rick Wakeman, as well as the classic Pictures at an Exhibition by Emerson, Lake & Palmer (ELP) and Switched on Bach by Walter/Wendy Carlos (Modular Moog used). Yes I know, it's old all that ! Robert Moog has inspired many designers and manufacturers with this minimoog, the most iconic synth in the world.

The principle of subtractive synthesis consists in filtering signals rich in harmonics. Simple to implement and economical, subtractive synthesis naturally imposed itself on the first synthesizers, from the sixties. Subtractive synthesis can take another source than the classic oscillator delivering simple periodic waveforms, whether it is analog or digital. Beginning in the late 1980s, many subtractive synthesizers used digital samples as a source of synthesis. They can be samples of acoustic or electric instruments, taken separately (piano, bass, organ ...) or recorded together (section of brass, strings ...), but also of various voices or noises. . The efficiency of a filter is a function of its slope, also called "rolloff" or "slope", expressed in decibels per octave (dB / octave) or in pole. The term "pole" refers to the typical diagram of a filter having a slope of 6 dB / octave. Thus, there are 1 pole, 2 pole (12 dB / octave), 3 pole (18 dB / octave) and 4 pole (24 dB / octave) filters. Adding the poles amounts to placing identical filters in series. Robert Moog is credited with the idea of ​​putting four low-pass filters in series, a scheme referred to as the Moog cascade. On a subtractive synthesizer, two main parameters allow you to adjust the filtering effect: the cutoff frequency which is the frequency from which the filter will come into action, and the resonance (available on some instruments), which allows to bring the filter into self-oscillation. This then behaves like an oscillator. It is also possible to modify the temporal evolution of the effect by adding an amplitude envelope to the filter.

Technical characteristics

Issue date November 2019
Synthesis type Subtractive
Resolution Analogic !
Memory Waveforms:

Triangle-Sawtooth (Oscillator–1, Oscillator–2, Oscillator–3)
Reverse Sawtooth (Oscillator–4)
Wide Pulse
Narrow Pulse
Keyboard37 Full-Size Keys
MIDI Expression Velocity, Aftertouch
Programs, Timbres, Singles, Voices (presets/progr.)
Combis, Patches, Performances, Multi (presets/progr.)
Polyphony 4 voice
Number of oscillators/generators4 oscillators
Multitimbral 1 voice
Drum sounds imitation (to set)
Effects Distortion, Chorus,
white and pink noise genetaror
Sequencer Yes 32 steps,
Arpeggiator 8 patterns
External storage Pencil and paper…
Audio output Stereo balanced
Headphone 6,35 mm front
Dimensions (width × length × height)648 × 361 × 90 mm
Weight 10,2 Kg
Options Can also be controlled using a Behringer FCV100 V2 or FC600 V2 expression pedal (with the CV polarity set to TRS, and using a TRS cord).
Compatibility Settings minimoog and more…

crayon I have the impression that warming up and stabilizing the oscillos of the Poly D is faster than on the Model D.

crayon The keyboard is of good quality, better than the Roland PCR regarding the action of the Aftertouch. On the poly D it is precise and of equal sensitivity/response between all the keys.

crayon Pitch wheel is a bit steep.

/!\ CHORUS I and II activated together produce a tremolo effect, which I do not find very pretty. When you deactivate a CHORUS (I or II, whatever) and one or more notes are played, you hear an unpleasant little “cloc”. To avoid emitting this "ploc", so I use the CHORUS ON/OFF switch.

/!\ Missing the red switch A-440 to activate the signal generator at 440 Hz (key A3) to tune the oscillators.

/!\ Missing the MAIN OUT switch which used to mute the main audio output, thus authorizing the synthesist equipped with a headset plugged into the PHONE 1/4" socket to adjust a new patch or to tune the Poly D without everyone hear. Well, there is the general volume button, but you can unbalance the general balance with others instruments.

/!\ The MIDI implementation is minimalist: note ON, note OFF, Pitch Bend, Modulation, MIDI Clock, Sequencer, Arpeggiator.

MacTalk This Behringer Poly D is already given other names : Para D, Super D.


/!\ Mandatory preheating

Like the minimoog, it's recommended to power on and let the Behringer Poly D heat for 10 to 15 minutes before using, see more if the device was cold. This allows the electronic components to reach their normal operating temperature and stabilize. This is necessary for the tuning to be reliable and constant for a moment. However, it will be necessary to adjust the general TUNE and TUNE OSC.2 & 3 setting again if the session, training or performance lasts long.


See Startup Guide of Poly D pdf (5,5 Mo) FRENDEESPT

See the sheet Patch Recall of Poly D pdf (161 Ko) WORLD

See minimoog Patch Book of Moog minimoogpdf (1,5 Mo) EN

See proceedings of tests and reset of Behringer Poly D.

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