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Monograf synthesiser

 

 

Monograf is a fixed signal path monophonic synth voice with many unique features, including a 
number of patch points for flexibilty within a modular setting. Our aim was to design the simplest 
full featured and good sounding single VCO synth within as small a space as possible, while offering a 
broad sonic palette and fast setup times. Monograf includes the following elements: 
 

 

Onboard LFO for PWM, 
and onboard sub osc for 
thick and juicy synth 
lines 

 

Super stable AS3340 
based VCO featuring 
sawtooth, triangle and 
square waveforms, as 
well as rotary switch 
control of octaves and 
an onboard LFO for 
PWM. Features highly 
accurate 1V/octave 
tracking, as well as 
extenal CV control of 
linear FM. 

 

Sub oscillator featuring  
-1 octave and -2 octave 
square waveforms. Add 
a big bottom to your 
sound. 

 

5 toggle switches for 
fast waveform 
selection, allows for 
super quick changes. 
Additionally, the 
triangle waveform is 
routed directly to the 
VCA, bypassing the VCF, to maintain a rumbling low end with higher resonance settings, this 
is a little known modular trick which was practised by the ancients (!?). 

 

12dB/octave OTA lowpass VCF based 

upon ARP Odyssey Mk1 ‘whiteface’. A very 

characterful VCF with cutting resonance whose audio inputs can be driven into clipping via a 
dedicated Drive control. The chosen level of drive can have a profound effect over the 
character of the filter, and heavy drive will saturate the input while simultaneously reducing 
resonance. Cutoff frequency can be controlled manually, from the LFO, from the ADSR, 
normalised from a 1V/oct source, or from an external CV. 

 

Vintage ARP style VCA with gated/ADSR/drone options via two toggle switches. 

 

AS3310 based ADSR for super snappy envelopes. CV control of envelope output is available 
for velocity controlled dynamics etc. 

 

Summary of Contents for Monograf

Page 1: ...s Add a big bottom to your sound 5 toggle switches for fast waveform selection allows for super quick changes Additionally the triangle waveform is routed directly to the VCA bypassing the VCF to main...

Page 2: ...s also mounted on this PCB CD4024 The Octave PCB interfaces to the Control PCB via a header Key to PCB screen print n This signifies NPN BC547 transistors Note the correct pinout as shown by the half...

Page 3: ...B100K x 9 B100K x 3 or these 4K7 trimmer vertical 5K is fine 10K trimmer x 3 100K trimmer x 3 Rotary switch SPDT x 7 3 5mm socket x 6 Male 40 pin header x 2 Female 40 pin header x 2 10 pin box header...

Page 4: ...citors 4 Solder all 3 voltage regulators 5 Solder all transistors 6 Solder all trimmers 7 Solder the power header if you re using box type observe correct polarity 8 Solder all electrolytic capacitors...

Page 5: ...ctly positioned Flip the whole lot over and solder the sockets into place Don t forget to ground the sockets to the PCB using cut off resistor legs 6 Place the 7 toggle switches then place the panel o...

Page 6: ...low them you will find another washer with a small flange at 90 the inner part of the switch has a number of slots drop the flange into the slot marked 6 then waggle the switch to make sure you re get...

Page 7: ...ion as I carefully chose associated resistor values to make it so Set the Pulse Width knob to 50 hard left and twiddle the trimmer until you hear the easily recognisable hollow sounding square wave 10...

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