MOOG Mavis Semi-modular Analog Synthesizer Kit Instruction Manual
- June 4, 2024
- moog
Table of Contents
MOOG Mavis Semi-modular Analog Synthesizer Kit
Get started with patching techniques, explore deeper synthesis concepts, and understand full patch bay functionality.
Patching with Intention
There are many ways to approach patching a synthesizer like Mavis. There’s no “wrong” way to do it, and often randomly patching inputs to outputs can lead to wonderful, unexpected results. Other times, however, you may want to patch with some intention. Perhaps you have a sound in mind that you would like Mavis to approximate, or an idea may strike you while falling asleep: “I wonder what would happen if I patched the VCO to the Filter Cutoff…” We hope that this guide will help you better understand how to patch Mavis and learn interesting new techniques for patching it as you get to know the instrument.
Initialized Patch
- Before getting started, match your Mavis to the initialized patch settings above. You should be able to press one of the keyboard keys and hear a note.
- Find full patch point descriptions on pages 11-14 to reference as you move through the patching exercises.
- Each section in this guide builds upon the last, so explore them in sequential order for best results.
First Steps
Some typical patch configurations are already available to you through Mavis’s internal routing. As a short exercise, let’s recreate one of those using the patch bay. Say you would like a nice little trill with each note. You can achieve this by patching the LFO to change the VCO’s pitch.
MAKE THIS CONNECTION
Connect the LFO output to the 1V/OCT input and then press a key on the keyboard to trigger a note.
The LFO, however, swings from -5 volts to +5 volts—resulting in a trill spanning 10 octaves! Since that is likely too extreme for most uses, Mavis has an attenuator, which is like a volume knob for a control voltage.
MAKE THIS CONNECTION
Patch the LFO output to the ATTN (+5) (attenuator) input and then patch the ATTN (attenuator) output to the VCO’s 1V/ OCT input.
With the attenuator knob fully clockwise you will hear the same 10-octave trill, but as you lower the attenuator knob that range will diminish until there is almost no modulation.
NOW YOU HAVE 3 KNOBS THAT SHAPE THE TRILL/VIBRATO EFFECT
- ATTENUATOR: Controls the interval of the trill (i.e. modulation depth)
- LFO RATE: Controls the speed of the trill
- LFO WAVE: Moves from a vibrato (triangle) effect to a trill (square)
This patch, however, is already present in Mavis’s internal routing. After unpatching everything, all you need to do is set the VCO MOD MIX knob fully clockwise to LFO and the PITCH MOD AMT knob will set the depth of the modulation.
- →Let’s now use the patch bay to do some things you can only do through patching.
Tremolo and Vibrato
Unpatch any cables and match the settings to the initialized patch. Then raise the PITCH MOD AMT knob slightly so you hear a nice trill. It might be interesting now to hear what happens if the LFO gets faster as the pitch gets higher. The KB CV output sends out a voltage based on the key pressed—the higher the key, the higher the voltage. Each key corresponds to a precise voltage to recreate a chromatic scale.
MAKE THIS CONNECTION
If we patch the keyboard output KB CV to the LFO RATE input, we can raise the frequency of the LFO at the same time that we raise the pitch.
- A related effect to vibrato (which moves the pitch up and down) is tremolo (which moves the volume up and down).
MAKE THIS CONNECTION
- Patch the LFO output to the VCA CV input.
Now you can hear the volume move up and down in time with the LFO—even when no key is pressed. This is because now the LFO signal is controlling the volume instead of the envelope generator. By turning the filter CUTOFF knob completely counterclockwise we can then silence Mavis when no key is pressed.
TRY THIS
With the VCF MOD MIX knob set to EG and VCF MOD AMT fully clockwise, the filter now acts as something similar to a low pass gate, with the envelope shaping both the filter and the amplitude of the signal, while the LFO adds a tremolo effect with the VCA.
- →Play with the envelope parameters and LFO RATE to explore this sound!
Exploring the Sample & Hold Circuit
For a more advanced exercise, let’s investigate the Sample and Hold (S+H) section. Unpatch any cables and match the panel settings to the initialized patch.
A sample and hold circuit takes two inputs: an input to be sampled (S+H) and a gate (S+H GATE). Whenever the GATE input receives a gate pulse, the voltage in the S+H input is held at the S+H output until a new gate comes in. On Mavis, the S+H input is normalled to the VCO, meaning that the VCO is already connected to the S+H input without the need for a patch cable. If anything else (say, the EG output) is connected to the S+H input, the normalled connection is overridden. Normally connections are indicated by parentheses on the Mavis patch bay: the VCO is normalled to the S+H (VCO) input and the LFO is normalled to the S+H GATE (LFO) input.
MAKE THIS CONNECTION
Connect the S+H output to the 1V/OCT input and press and hold a key down.
You will hear a new pitch in time with the LFO. If the VCO WAVE knob is rotated to the square wave you will hear only two pitches since the square wave being sampled only oscillates between two voltages. If the VCO WAVE knob is turned to sawtooth you will hear random voltages, as the sawtooth wave sweeps continuously between +5 and -5 volts and (typically) at a rate much faster than the LFO.
MAKE THIS CONNECTION
Rather than having to press a key, we can instead use the LFO to trigger a new note each time the S+H circuit is triggered by connecting the LFO to the GATE.
Now the LFO is connected to the GATE triggering a new note with each LFO pulse via a patch cable, and the LFO is also connected to the S+H GATE through normalization. Now you will hear a procession of distinct random notes. Remembering back to our first patch, you will probably note that, again, the range of notes is quite wide–far too wide for some musical purposes.
MAKE THIS CONNECTION
Use the attenuator to narrow that range. Patch the S+H output to the ATTN (+5) input. And the ATTN output to the 1V/OCT input.
Finally, we may want to break up the rhythm a bit and get some more motion in our patch. By patching the S+H output to the LFO RATE, the S+H will change the rate of the LFO. Higher S+H values will turn the LFO rate up while lower values will turn it down.
MAKE THIS CONNECTION
We can use the MULT to patch the S+H output to two places at once.
The MULT is a simple utility allowing you to patch one output to multiple inputs. Patch the S+H output (post attenuator) to the MULT input, and then patch MULT 1 to the 1V/OCT and MULT 2 to the LFO RATE.
- →Now you will hear that as the pitch of the oscillator goes up, so does the rate of the LFO–resulting in quicker notes as the pitch increases!
Expanded Wave Folding
Mavis is the first of the Moog synthesizers to include a wave folder. A typical component of the “West Coast” synthesis approach, the wave folder uses distortion to add harmonics to a signal where a filter removes harmonics from a signal. Unpatch cables and match the panel settings to the initialized patch.
When a signal gets distorted, it gets amplified past a threshold whereby the
tops and bottoms of the wave or any parts of the signal above (or below) stay
at that threshold instead. This adds the pleasing
harmonic overtones characteristic of distortion. Wave folding pushes the same
concept a little further. Instead of the tops and bottoms simply staying at
the threshold, they are folded back–the threshold acts a little like a mirror,
reflecting those peaks and troughs back on themselves. This technique also
adds harmonic overtones, but of a different timbral quality than distortion.
Increasing the folding amount simply amplifies the signal even more, causing
deeper reflections of the peaks and troughs.
MAKE THIS CONNECTION
Let’s play a little bit with wave folding by patching the VCO into the FOLD IN input.
Open the VCF CUTOFF knob fully clockwise so you can hear the folding more clearly. Now by rotating the FOLD knob you will hear the oscillator begin to distort and fold over on itself. Try changing the VCO WAVE between saw and square and listening to how that affects the FOLD. You’ll notice using a square wave that the wave folding has a much more subtle effect.
Looking at our wave folding diagram, you’ll notice that the square wave is already fully “squared off” and distorted. Sending this to a wave folder yields more subtle effects than with saw or triangle waves, whose linear shapes result in more “teeth.” While there is no voltage control of Mavis’s wave folder, you can use the LFO and the ONE+TWO mixing section to achieve something similar. Typically, audio oscillators are centered around zero volts. Therefore, since the ceiling and floor thresholds are always symmetric, the waves distort or fold symmetrically.
However, if we shift the entire wave up or down, the wave folder will now distort the top and bottom of the waves differently.
MAKE THIS CONNECTION
Patch the LFO to input ONE (-5) of the mixer and the VCO to input TWO of the mixer. Finally, patch the ONE+TWO mixer output to the FOLD IN input.
With this configuration, you can explore wave folding even further— playing with the VCO WAVE and LFO WAVE shapes, the ONE LVL (which scales the LFO shifting amount), and the FOLD knob. By adding the LFO to the VCO, we are actually shifting the VCO signal up and down in time with the LFO. When the LFO rises positively, the VCO signal is shifted in the positive direction and hits the top mirror of the wave folder, folding the positive peaks. When the LFO falls negative, the VCO signal is shifted in the negative direction and hits the bottom mirror of the wave folder, folding the negative troughs.
Further Exploration
Now that you have some intuition for how Mavis’s patch bay can be used, feel free to start exploring it on your own. Remember: there is no wrong way to patch—it’s all music at the end of the day.
Either begin from a sound that grabbed you while working through this guide (this being an analog semi-modular synthesizer, it will never be quite the same), or just start making connections and see what happens. Over the next few pages is a list of Mavis’s inputs and outputs (organized left to right by row) and some beginning ideas for how they can be used. Let your imagination and your ears be your guide.
Inputs
Listed in order left to right by row; R (Row) and C (Column)
FOLD IN (R1, C1)
Input to the wave folder. Plugging any signal in here will patch it through the wave folder (FOLD knob) and then directly to the filter. Experiment with both the VCO and LFO (at audio rate) patched here, and play with their respective waveshapes and the FOLD knob to explore the timbral possibilities of wave folding.
1V/OCT (R2, C1)
Controls the frequency of the VCO. 1V/OCT means this input is scaled such that every volt will correspond to a doubling of the frequency (i.e. a change of one octave). Patch an LFO (through an attenuator) here for vibrato or the S+H for random pitch changes.
PWM (R2, C2)
Controls the pulse width of the VCO’s pulse wave. Patch the S+H here for random pulse wave fluctuations.
ONE (-5) (R2, C3)
Input one for the mixer. The signal patched here will be attenuated by the ONE LVL knob and available at the ONE output and mixed with TWO at the ONE+TWO output. Patch any audio or control signals here and another to TWO to add those signals together. You can add the VCO + LFO for a two-oscillator synth, the EG + LFO for wobbly envelopes, or the S+H + EG for random note strengths! The (-5) indicates that a negative five volt offset is normalled to this input, allowing you to shift the signal in TWO down five volts with nothing patched to ONE.
LFO RATE (R3, C1)
Controls the frequency of the LFO. Patch the KB CV here to control the LFO rate with the keyboard or the S+H to get random LFO rate changes.
CUTOFF (R3, C2)
Controls the filter’s cutoff frequency. As with PITCH MOD and PWM, the EG and LFO are already available for modulation, but patch the S+H here for random cutoff fluctuations or the VCO for audio rate filter modulation.
GATE (R4, C1)
Triggers the EG with a rising edge gate signal. Patch the LFO here to cyclically trigger the EG, or the S+H to sporadically trigger the EG. You can also use this input with an external keyboard to trigger the EG.
VCA CV (R4, C2)
Controls the VCA. The EG is pre-patched here (and can be removed with the VCA MODE switch), but patch the LFO through an attenuator here for tremolo or the S+H for notes of random velocity.
TWO (R4, C3)
Input two for the mixer–added to input one at full strength.
S+H (VCO) (R5, C2)
The signal to be sampled by the Sample + Hold circuit when a gate is registered at the S+H GATE input. The VCO output is normalled to this input. The saw wave VCO is a good choice since, at audio rate, it can provide an even range of voltages to be sampled, while the pulse wave can restrict the sampled voltages to either the high or low voltage values of the VCO signal. You can replace the VCO with the VCA output for more flavors of randomness, while replacing with the LFO or EG will provide slower signals to sample.
S+H GATE (LFO) (R6, C2)
A gate high here will sample the signal in the S+H input and hold that sampled value available at the S+H output. The LFO is normalled to this input, but a short attack envelope can also be used as a gate here.
ATTN (+5) (R6, C3)
Input for the attenuator module. The signal patched here will be attenuated by the ATTENUATOR knob and available at the ATTN output. Use this to scale LFOs or S+H signals, or to give channel two of the mixer its own attenuator knob. The (+5) indicates that a positive five volt offset is normalled to this input, allowing you to shift the ONE input up five volts by patching the ATTN output to TWO when nothing is patched to the ATTN input.
MULT (R8, C1)
Input for the MULTIPLE utility. Patch any signal here to get two copies of that signal at MULT 1 and MULT 2 outputs.
Outputs
Listed in order left to right by row; R (Row) and C (Column)
/VCA (R1, C1)
The output of the VCA scaled by the VOLUME knob. Mavis’s main output, which can be sent to mixers, audio interfaces, or headphones. Be sure to turn the VOLUME knob down before connecting this output to anything!
KB CV (R1, C2)
Outputs a voltage corresponding to the key pressed on the keyboard, scaled by the KB SCALE knob, and slewed by the GLIDE knob. This output is already patched to the VCO pitch, but you can also use it to control the LFO rate (faster LFOs with higher pitches), the filter cutoff (higher pitches open the filter further), or VCA (higher notes are louder).
ONE (R3, C3)
The signal at ONE input scaled by ONE LVL knob. Use to attenuate any signal and patch to any destination.
VCO (R5, C1)
VCO signal, oscillating from –5 volts to +5 volts (10V peak to peak), at a frequency and shape determined by PITCH, VCO WAVE, PULSE WIDTH, and any modulation. You can use the VCO to do audio rate modulation of any of Mavis’s parameters or patch it to FOLD IN to explore wave folding.
ONE+TWO (R5, C3)
The mixed output of ONE input scaled by ONE LVL and TWO input at full strength. Use to add two signals and create interesting, compound audio or modulation signals.
LFO (R6, C1)
LFO signal, oscillating from –5 volts to +5 volts (10V peak to peak), at a frequency and shape determined by LFO RATE, LFO WAVE, and any modulation. The LFO is internally routed to many parts of Mavis, but you can also use it as an S+H input, patch it to the VCA for tremolo effects, or patch it to the GATE to continually trigger Mavis’s EG.
EG (R7, C1)
Envelope signal triggered by GATE and with a shape determined by the EG parameters (Attack, Decay, Sustain, Release). Like the LFO, it is internally routed to many parts of Mavis, but you can also use it as an S+H input or patch it to the LFO RATE to increase and decrease the LFO rate over the course of the envelope.
S+H (R7, C2)
Output of Sample + Holds circuit. With normalled signals and VCO set to SAW WAVE, this will output pseudorandom voltages at the rate of the LFO. You can use this to inject randomness anywhere in Mavis, from the VCO (1V/OCT) to the filter (CUTOFF), VCA, or the LFO RATE itself.
ATTN (R7, C3)
Attenuator output. The output signal at ATTN input is scaled by the ATTENUATOR knob.
MULT 1 (R8, C2)
The first output of MULT. Exact copy of signal input to MULT input.
MULT 2 (R8, C3)
The second output of MULT. Exact copy of signal input to MULT input.