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Moog Matriarch

Semi-modular Synthesizer By Gordon Reid
Published April 2020

Moog Matriarch

Much more than just an expanded Grandmother, the Matriarch has all the makings of a classic Moog synth.

Two years ago Moog launched the Grandmother — a fine entry-level monosynth with a name that we've learned to live with. But, even then, the company were thinking about adding a more powerful instrument to the range, and I was asked how I would enhance Granny to create a flagship synth for the post-Voyager era. Apart from insisting that it not be called the Great Grandmother, I suggested that it would need a wider keyboard with aftertouch, plus obvious upgrades such as more oscillators, more powerful filtering, a second contour generator and improved modulation. But I also made a right pain of myself by banging on about additional mixers and patchable VCAs because, in common with other semi-modular synths, the Grandmother has far too few of these (zero in this case), which can prove limiting until you connect it to a modular synth. Happily, Moog listened and, when I received the final rendering of the Great Granny concept — by this point renamed the Matriarch — it promised all of the above and more.

The Signal Path

If we ignore its paraphonic capabilities for a moment, the Matriarch is a powerful monosynth with four oscillators, twin 24dB/oct filters and two output channels, each of which comprises a VCA and a delay line. Shaping and modulation duties are undertaken by twin contour generators, two LFOs, and three patchable VCAs. Moog are keen to emphasise that its signal path — and therefore its sound — is determined by the historic modules on which it's based. The oscillators are distant descendents of the Moog 921s found in many of Moog's modular synths in the 1970s, the mixer is based upon the Moog CP3, the filters are based upon the Moog 904a, the VCAs upon the Moog 902, and the delay lines upon the Moog 500 Series Analog Delay module. Of course, there's still digital stuff in the Matriarch because it supports MIDI and has a digitally implemented step sequencer, but the signal path and the lack of patch memories (which some people believe can interfere with a 'pure' analogue sound) ensure that it's a synth for purists as well as pragmatists.

Each of its oscillators offers the same selection of four waveforms (triangle, sawtooth, square and pulse), with PWM of both the square and pulse waves. They also offer the same octave settings ranging from 16' to 2'. (Global transpose of ±2 octaves is available in the performance panel.) Where the oscillators differ is that numbers 2, 3 and 4 have fine-tuning controls, the range of which can be set in the Global Settings, and each can be hard-sync'ed to the previous. In contrast, you can only tune oscillator 1 using the global tuning knob on the back of the synth. Each oscillator offers three CV inputs — pitch, PWM and linear FM and, while their PWM and FM inputs are independent, their pitch inputs are cascaded so that, if you apply a CV to (say) oscillator 2, oscillators 3 and 4 will also be affected by this unless their own inputs are used. The final socket offered by each oscillator is a signal output that bypasses the Matriarch's mixer. This means that you can have up to four audio signals passing down the internal audio path, and another four routed elsewhere as audio or as audio-frequency modulators.

The internally routed signals now pass through individual gates (which are necessary to make paraphonic playing possible) before reaching the six-channel mixer. The first four channels receive the audio from the oscillators or any signals presented to the patch inputs marked OSC1 IN to OSC4 IN, while a fifth channel is provided for the internal white–noise generator or the audio presented to the NOISE IN socket. There's also a sixth, knobless channel that accepts the input from the audio signal input on the rear panel. Like the CP3, it will mix audio signals and control voltages (or even a combination of these) and it distorts each channel at input levels above 12 o'clock or thereabouts, doing naughty things now deemed desirable such as thickening the sound or adding a bit of sparkle. It will also favour any channel with a disproportionately high signal level, suppressing the signals presented to the others. The summed output passes down the internal signal path but is also available from the mixer's Output socket so that you can direct it to other destinations as you choose.

Don't be fooled by its colour scheme; despite their visual similarities, the Matriarch is far more than just an expanded Grandmother.

The internal signal path now reaches the Matriarch's dual 24dB/oct resonant filters. You can configure these in three modes, and their outputs then feed two signal paths, each comprising a VCA and a delay line. In Series mode, VCF1 is a high-pass filter and VCF2 is a low-pass filter, and the output from VCF1 passes through VCF2, which then feeds the VCA1 and VCA2 paths equally. In Parallel mode, VCF1 is again a high-pass filter and VCF2 is again a low-pass filter, but any signal presented to the filter section's input is split to pass through them in parallel before being recombined into a single signal that again passes to the VCA paths equally. In Stereo mode, both filters act as low-pass filters and the outputs from these feed the VCA1 and VCA2 signal paths independently. Rather than offer two cutoff frequency controls as one might expect, the Matriarch offers a single Cutoff knob and a Spacing control that allows you to offset the cutoff frequency of VCF1 with respect to VCF2. However, two CV inputs allow you to affect their cutoff frequencies independently. There are also knobs for the bipolar Envelope Amount and the keyboard tracking amount, both of which are applied equally to both filters. At its maximum the tracking is 100 percent, which allows you to play the self-oscillating filter(s) in the usual way. There are also five patch points comprising independent audio inputs for each of the filters (which, when used, disconnect the relevant filter from the mixer), independent outputs, plus a CV input to modify the Envelope Amount applied to both. The possibilities are intriguing.

The patchable signal inputs for the Matriarch's dual VCAs (which, as usual, break the internal signal path) are found in the output section to the right of the control panel, although the VCAs themselves lie between the filters and the delays. This is also where you'll find CV inputs for these VCAs' gains. There are three VCA modes: in AMP ENV mode the Amplitude Envelope is applied to both VCAs; in Split mode the Filter Envelope is applied to VCA1 and the Amplitude Envelope is applied to VCA2; while in Drone mode the VCAs derive their gains from their respective CV inputs or, if nothing is inserted into these, from a default voltage applied internally. Signals presented to the CV inputs sum with any internally applied CVs, so I was delighted to find that it's possible to create tremolo while shaping notes using the contours.

The penultimate stage in the internal signal path is a pair of BBD delays that can act independently or in ping-pong mode. Delays in the range 35 to 780 ms can be obtained using the Time knob, while longer, lo-fi delays are available using CVs and Tap Tempo. A Spacing knob allows you to increase or decrease the delay time of Delay 1 with respect to Delay 2, and this can be especially interesting when they're clocked by the arpeggiator/sequencer or an external clock, because the knob then causes Delay 1 to move up and down the table of bpm ratios with respect to Delay 2. Pressing Shift while adjusting the Spacing also gives you triplet divisions, so polyrhythmic delays become possible. Elsewhere, the Feedback and Mix controls do what you would expect, and high feedback settings will cause the delays to loop indefinitely and eventually oscillate, creating the sci-fi effects that are precluded on many other synths. The delay section boasts several audio I/O and CV sockets, with four on the rear panel (see box) and six on the top panel that offer independent audio inputs for Delay 1 and Delay 2, CV inputs for the delay times of each, plus the amount of feedback and the wet/dry mix of both. There are also a couple of 'hidden' capabilities but there's no space to discuss these here, so let me summarise by saying that you can use the Delays to obtain sounds ranging from simple echoes to strange effects, to things that sound like arpeggios, to screaming excesses of feedback and distortion. It's all excellent stuff!

At the end of the signal path, the internally routed audio reaches the Output section. This contains the Paraphony selector (which switches between the Matriarch's monophonic, duophonic and paraphonic modes), a multi-trigger on/off button, and a volume control that affects the main outputs but neither the Eurorack nor the headphone outputs.

Contours & Modulation

The Matriarch has two ADSR contour generators utilising the unusual 'three knobs plus a slider' controls introduced on the Grandmother. I was not a fan of this when I first saw it, but I don't give it a second thought any more. Their specifications promise fastest Attack, Decay and Release times of 2ms, with maxima of around 10s. Both offer trigger inputs that, when patched, override the internal keyboard gate and, when their Release stages are completed, both generate gates that are held until the next Attack is initiated. If you patch a contour's ENV END output into its Trigger In, you obtain an AR contour (sawtooth, triangle or ramp wave, depending upon settings) that loops indefinitely and provides an unusual modulation source without tying up either of the conventional LFOs.

The first of these LFOs is contained within the Modulation panel, which also provides outputs for S&H and Noise. It offers six waveforms and a frequency range of 0.07Hz to 1.3kHz. Of these waves, the most interesting is the stepped triangle (staircase), because its frequency is determined by the LFO rate, but the timing of its steps is determined by the ARP/SEQ clock. This is a fab idea that allows you to create everything from rapid glissandos to weird quasi-random shapes. In addition to its patchable output, three knobs allow you to direct the LFO's output via the modulation wheel to the filters' cutoff frequencies, to the pulse widths of any of the oscillators generating pulse or square waves, and to the oscillators' pitches. There are three pitch modulation options — All, 1&3 and 2&4 — the last two of which allow you to create duophonic patches with chorusing or sync sweeps. An LFO Rate CV input and a Sync input complete the package.

The Matriarch feels like a musical instrument... It's fun, it can inspire, and it sounds great. Moog are on a roll.

Whereas the Grandmother had a single Utilities panel offering a four-way multiple, a static high-pass filter and a bipolar amplifier controlled by nothing more than a knob, the Matriarch has two Utilities panels with an additional LFO (good!), two four-way mixer/multiples (even better!), and three patchable bipolar VCAs (yippee!). The LFO is a simple affair with a rate knob, a CV input to control the rate, simultaneous triangle and square wave outputs, and a range of 0.07 to 520 Hz using the knob, and the ability to go down to almost stationary using CVs. It's simple, but it allows you to create all the common LFO effects without tying up the main LFO, which can then be used for more esoteric purposes. But now we reach the bit that I championed so vehemently in 2018... The three VCAs (which Moog still call Attenuators) are hugely welcome, and they make the Matriarch a much better synth than it would otherwise be. In addition, they can act as ring modulators that can output the modulated signal alone or the carrier mixed with the modulated signal. They also generate a DC voltage if nothing is patched to their signal inputs. Furthermore, if you don't patch them otherwise, the VCAs in the first Utility panel are summed, so you can create even more complex modulations than would otherwise be possible. This is all excellent stuff.

Since the Matriarch has no screen or menus, you access its additional functions by entering a Global Settings mode and using a combination of key presses to select and programme various parameters. There are more of these than I had expected (46 to be precise) and they're collected into five groups, with Groups 0 to 3 having 10 parameters in each, and Group 4 having six. Some of these are as you would expect — things such as the note priority in monophonic mode, the nature of the portamento, the pitch-bend range, MIDI parameters and so on. Elsewhere, a group is devoted to the arpeggiator and sequencer while another concentrates on clock signals and CV ranges. But some reveal features that you're unlikely to know exist unless you study the manual; for example, the noise colour (a high-pass filter following the output of the noise generator), the brightness of the output from the delays (a low-pass filter following the outputs of the delay lines), and the ability to restore stolen notes when later ones are released. Having used the Global Settings to set up the Matriarch as I wanted, it played and connected to my external equipment just as I wanted. Well, almost as I wanted. I also had to discover that I could turn legato glide on and off using a combination of the Shift button and the Glide time knob, but eventually all was well.

Published April 2020