User:Pinoaffe/Modular

Project Modular Synth
A do-it-myself modular synthesizer
Status	In progress
Contact	pinoaffe
Last Update	2017-09-20

Working Modules

• Attenuator
• CV-Source
• Signal Copier
• Signal Selector
• Buttons

Presumably Working Modules

• Auduino 2
• Sequencer
• Amplifier
• Speaker

Work in progress Modules

• Clock/Frequency Divider
• LFO
• Auduino 1
• Auduino 3
• Atari Punk Console

Plans

Here is an outdated version of the plans I've been working with. I wrote em for myself, so they might not be very useful for others.

Plans for a DIY Modular Synth

System

Dimensions

• close to 4U: 180 mm
• module width will be x*10mm, so far smallest is 30 mm
• front panels will be 2.7mm high
• standard pot knobs are ....... mm in height

Design

• CV and audio both on banana jacks
• folding box with piano hinge, collapsible feet and removable back panel?
• serge modules might fit, though i might have to do minor adjustments to my cases
• front panels and pot knobs will be made from 2.7 mm plywood using a lasercutter
• front panel design will incorporate arrows and curves to signify what knob/plug does what
• so far, i've mostly used the "Arial" font on frontpanels
• maybe:
  • standardized rectangular wooden format with dovetails and a back?
  • make these 200mm * x00mm in outer dimensions, with a standardized inter-connection system?
  • same format as modular book cases i plan to make?
  • threaded inserts?
  • wooden pegs?
  • wont use rails, but screw directly into the wood?

Voltages and Power Supply

• use desktop power supply, optionally decased?
• chinese step up/down converter
• diy powersupply
• 5
• 15
• -15
• maybe:
  • 9
  • 12

Modules:

Oscillators

VCO:

• x4046
• 555-based
• http://www.electro-music.com/forum/topic-54623.html
• stepped VCO
• sync out
• triple vco with one input and with an attenuator each at the point where exp voltage has been generated: this would be an oscillator with undertones

LFO:

• 555-based

Stepped Tone Generator

Atari Punk Console

Amplification and Deamplification

VCA:

• opamps?

Mixer

• VC?

Sequencer:

• 4017 and opamps
  • Dual or triple channel
  • Add a lfo for clock, allow one of the channels to be used as an input for the lfo clock allowing for configureable step length
• blue pill, step length, direction, ping-pong, multi/single gate, normal length,

Function Generator

Clock Subdivider:

• 4017

Frequency Subdivider:

• 4017
• max clock frequency = 2mhz @5volt, 6mhz @15volt

Clock Multiplier

• 4046

What you need is a Phase Locked Loop. There is a 4046 CMOS IC that implements one, but you also need a digital divider so you could build a phase comparator and use a synthesizer VCO. The principle is to divide the VCO output down by the ratio you want and then compare the phase with your input signal. The phase comparator produces a CV that makes the VCO track the input frequency at a multiple set by the divider. The simplest is an XOR gate followed by an RC filter, but there are better more sophisticated circuits. The 4046 has two alternatives.

CD4046 application report

Or just Google "Phase Locked Loop"...

Frequency Multiplier

See "Clock Multiplier", but with a higher frequency

Envelopes:

AD

AR

ADSR:

• 555-based
  • http://schmitzbits.de/adsr.html
  • yusynth adsr

Envelope Follower:

<code>a basic ac-dc converter, outputs the dc voltage of the peak (the amplitude) when given an ac waveform</code>

Filters:

cap and inductor

Notch Filter

Low-Pass Filter

• most popular in modular synths
• passes low frequency content
• moog's version: ladder filter

High-Pass Filter

• passes high frequency content

Band-Pass Filter

All-Pass Filter

• can be seen as a phase shifter
• changes phase based on frequency
• popular sound on guitars
• when summed with input signal, the frequency-parts that are 180 degrees changed will negate eachother

Moog Ladder Filter

• http://www.yusynth.net/Modular/EN/MOOGVCF/index.html

Maths

Summer

Substractor

Multiplicator

Integrator

Quantizer

Equalizer

Comparator

Noise

Pink

White

Blue

Red/Brown

Arduino

• auduino granular synth
• ginko modular grains
• blue pill
• quantizer
• inspired by ardcore
• midi to cv converter
• http://playground.arduino.cc/Main/ArduinoSynth

Chord Maker:

either:

• cv-adder (with maybe an internal VCO)
• or frequency multiplier and divider, optionally combined with external or internal waveform changer

Could turn into a modulator when CV-ed and supplied with either the output of an LFO (probably quantized)

or the output of a sequencer (also probably quantized)

Modulator

• Basically a Chord Maker with a changing interval
• Could also have an option to switch different inputs to an output rapidly
• External clock?
• Decade counter?
• either:
  • cv-adder (with maybe an internal VCO)
  • or frequency multiplier and divider, optionally combined with external or internal waveform changer

Arpegiattor

Waveform Changer

TODO: Look into what changes/shapes waveforms

Slew Effect

Trigger Extractor

DC-Offset Remover

TODO: See whether this is useful, what an implementation would be, whether just a cap in series inbetween the in- and output would suffice

Portamento Adder

Simple Passives:

Attenuator

CV-Source

Splitters

Signal Selector

Signal Switcher

Signal Copier

Suite of Connections

• has been done before: https://www.muffwiggler.com/forum/viewtopic.php?t=183581
• negation, sum, difference, integration, multiplication, etc

Visualizing / Analyzing Gear

Oscilloscope

Buy Chinese oscilloscope kit on aliexpress, make new front panel Maybe change firmware? Sell as kit? Could maybe be used as tuner, with changed firmware

Tuner

arduino?

Level Translators

• What CV/sound levels will I even use?

Input Controllers

Keyboard

• polyphonic
• speed/force-sensitive
• gate output
• digital scanning

Ribbon Controller

• pressure-sensitive
• gate output
• polyphonic????
• also known as:
  • linear controller
  • stringer

Theremin

• YEEEESS

Early Experimental Instruments

• trautonium
• hellertion
• crea-tone
• oscillion
• emiriton

Drumset-like thing

MIDI-CV Converter

CV-MIDI Converter

Ring Modulator

• No clue what this is, apparently useful for synthesis

Complete Synth Voices

YM3812 (OPL2 aka "SoundBlaster")

• YM2413: same thing, but you can only configure settings for all voices at once
• Use a kit? (20 dollars + shipping costs) #### YM262 (OPL3)

Parts:

• sliderpots
• exponential pots
• other jacks
• switched jacks
• rotary switches
• YM3812
• YM2413
• YMF262

Books

• Electronic Music Circuits, chapter on filters

• Analog days, page 149 ext, 132 int

• Wireless World, the circuits by Tim Orr