These following notes are aimed for someone who is totally new to modular synthesizers.
They are the first part of the modular synth beginner class.
What are Modular Synthesizers??
Before we can answer this question, we should realise that all synths are made out of modules.
Even a keyboard synth is made out of modules. They are just fixed in position.
This is a Moog model D. It has a fixed architecture.
The sound starts on the left (Oscillators), passes through a mixer (middle), filters, and amplifier. The final sounds emerge on the right (output). The sounds are shaped with envelopes.
A modular synth is essentially the same.
But with a modular synth, these modules are not fixed in position or number.
You are not restricted by manufacturer. There are thousands of modules, from makers all around the world.
You can even make your own.
You can combine modules from Russia or Germany, with some from Japan or the USA (and even Australia).
These modules are combined using patch cables.
These are lots of different types of cable. The left is a 1/4 inch.
Middle, we have some 3.5mm -- used in Eurorack.
To the right we have banana cables .... used in Serge & Buchla synths.
On the extreme right are breadboard patch cables (used in synths like the AE modular)
The cables carry two types of signal:
1. Audio
2. Control Voltages (CV).
Control voltages are an analog way to automate the various module settings.
(this will be demonstrated in the class).
Because there is a huge range & number of modules to pick from, getting started can be a daunting process. But the basic modules common to all modulars are the same. These (in my humble opinion) are the essential ones to get the ball rolling.
1. Oscillators
2. Mixers
3. Filters
4. Envelope Generators
5. LFOs
6. VCAs
7. Sequencers
8. Midi to CV converters
The class will use a few synths ... a Eurorack Modular, a Banana Modular, an AE Modular, a WASP and a Moog Model D.
You are welcome to bring your own, if you have a synth.
There will also be an oscilloscope, so you can see the sounds.
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1. Oscillators
These Oscillators, or VCOs are what make your sounds.
VCO = Voltage Controlled Oscillator.
2. Mixers
These mix the sounds that come from the oscillators.
3. Filters
These shape the tones coming out of the synth.
It's a big part of whats called subtractive synthesis.
Subtractive ....meaning we are removing specific sonic frequencies from the oscillator.
Lots of different types...eg: Low Pass, High Pass, Band Pass & notch.
Low Pass (LP): allows low frequencies to pass through.
High Pass (HP): let the high frequencies through.
Band pass (BP): allows only a narrow band of the frequency spectrum to pass through.
Notch : (opposite of a BP) . It filters out a narrow band of the frequency spectrum
4. Envelope Generators.
These generate voltage envelopes.
They can be triggered by lots of different types of modules, but the most common is a keyboard.
The envelope has a particular shape which is set by the user.
The most common type of envelope has 4 settings or stages
A = Attack
D = Decay
S = Sustain
R = Release
5. LFOs
Low Frequency Oscillators.
These are another source of control voltages which you can use to automate various module settings.
You can use them like a simple envelope generator.
As the name suggests, they are also oscillators, similar to a audio VCO, but they operate a much slower frequencies, and (mostly) you can't hear them.
6. VCAs
Voltage Controlled Amplifer .
It's an amplifier whose level can be controlled by another module that produces CVs (such a a LFO or EG)
7. Sequencers
These modules generate a series of control voltages to tell a synth to play a series of notes.
They are like an human-less automated keyboard
8. Midi to CV converters
These modules are usually connected to a midi keyboard ( though there are other options too).
The Power Supply Comparison
This is a follower to the previous synthesizer module size post.
There are an ever growing number of manufacturers and many different PSUs (power supply units) to match.
This is a brief comparison of the main brands.
Do email me is there are any mistakes or recommended changes.(I'll try to keep this page up to date).
These PSUs changed over the decades so are confusing at times.
As I work my way through the modules that I own I'll update this post.
Please let me know if there are any errors.
Buchla 200e
Power on a Buchla 200e module is delivered from a edac
306-010-500-102 connector.
The 200e cases come with a12 volt DC wallwart that connects to 3 DC-DC converters.
This is much safer & probably also helps in reducing background noise.
I've made some backup Buchla power supplies and the DC-DC converters that I have successfully
used are:Cincon CHB75-12S05 (for the 5V),and two CHB75-12S15 for the +15/-15 lines.
CHB75-12S12 for the +12V.
If +24 is requited use a CHB75-12S24 DC/DC regulator. These codes are Mouser numbers.
1 Black - quiet ground
2 White: -15
3 Red: +15
4 Dark Green: +12
5
Orange: +5
6 Brown: noisy ground
7 polarizing key - no connection (use this to correctly orientate the EDAC.)
8 Yellow: i2c clock
9
Green: i2c data
10 no connection - (I often use this for supplying +24v)
Serge being mostly DIY in the early days is super confusing and some of the early paperface
panels used whatever colour wiring was available at the time.
I have a number of early paperface panels and some use different colour codes
Early Serge (Paperface) number 1.
This used +12v, -12V, +6V, one ground.
The Serge colour convention on this old synth is:
-12V - White
+12V - Black
+6V - Red
0V - Green
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Here is a second system I have.
It's from the late 70's or early 80's I think ..
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The current Serge PSUs use these types of cases:
This is a PS4A - enough power for 4 panels
The connectors are 5 pin DIN connectors
There is an inline AC/DC converter with a grounded
AC wall cord at one end and a Molex connector at the other designed to
mate with the distribution board inside.
The power connectors for these modern panels look like this:
Sound Transform Systems offers a “M-Boat” chassis.
It is approximately 17” x 7” x 4.5” in dimension.
MBoats have a central power/indicator (called the “Obelisk”)
which has LED indicators for +12/-12v, as well as a power LED.
PSD vs Obelisk
the psd (power supply distribution) is for shop panels while the Obelisk
is for m-odules. The obelisk contains a PSD like distribution board -
but with only 4 connectors instead of 5.
Power Connector
The standard inter-connector used by STS is a Tyco Rectangular 4 pin Connector. The body and pins are sold separately.
Pin & Socket Connectors PLUG W/O EAR 4P inline is PN: 770078-1
Pin & Socket Connectors 24/18 AWG TN/BR SKT is PN: 770146-1
Pin & Socket Connectors RECPT 4P DETENT LOCK in-line is PN: 770075-1
Pin & Socket Connectors 24/18 AWG TIN/BRASS is PN: 770147-1
The PSD has the female connectors.
Pin 1 is at the point. Pin 4 is at the flat (for both male and female).
Pin 1 = Ground 1, Black
Pin 2 = -12V, White
Pin 3 = Ground 2, Green
Pin 4 = +12V, Red
STS also uses a 5 pin XLR connector for power distribution. Coming from
the power supply (PS4 for example) is a 5 pin female XLR. It is intended
to be plugged into a panel mount 5 pin male XLR connector which then
terminates to a male Tyco Connector (for plugging in power to the PSD). I
used an Aphenol panel mount 5 pin male XLR connector, PN: AC5MDZ for a
replacement part and it worked fine.
Here is what my PS4 XLR connector pinout is (note, I am not sure if this
is standard or not, i would assume it is, but I dont want to be
responsible for plugging anything in backwards):
Pin 1 = +12V, Red
Pin 2 = Ground 1, black
Pin 3 = -12V, White
Pin 4 = Ground 2, green
Pin 5 = Not Connected
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EuroRack PSUs.
The first rule one must never forget is the stripe = -12V.
When I was a newbee I made the cardinal error of plugging in my module backwards.
Mostly, the stripe will be red, but sometimes it's blue.
As eurorack manufacturers don't have to comply to any laws re the position of the stripe
it's really up to you to check with the manufacturer what the correct orientation is.
So be careful when you plug your module in for the first time.
The power distro bus is usually made up of 16 DIP header pins (2 rows of 8).
I've also see some older distroboards made from 10 pins (2 rows of 5).
Most these days ccome in the 16 pin format.
Counting from the -12V pins, the bus goes thus:
1. -12V
2. Ground,
3. Ground
4. Ground
5. +12V
6. +5
7. CV
8. Gate
So your PSU needs to supply +12,-12, & maybe +5v.
The connections between the module & bus is achieved with a 10 or 16 ribbon cable.
This is a 10 wire cable. for a module that only uses +12,-12.
The 10 pin header fits into the module & the larger 16 goes to the bus board.
Mos Lab : +12v/-12V see above The Kobol VCO is +/-15V
The Oakley power buss comprises of +15V and -15V lines with two
grounds. These grounds are not connected together as in the MOTM. They
are joined only at the power supply in pure Oakley Modular.
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Modcan A & Cyindustries (Cynthia)
The Modcan-A format uses a module height of 9", and a horizontal unit of 2.25". Banana jacks are used.
A yellow jack indicates an output of some sort;
A gray jack is a signal input;
A white jack indicates a control voltage input;
A red jack is a trigger or gate input.
The format uses ±15V power. The power connector used is a 3-pin
MTA-156 connector.
It's very similar to the
MOTM format, in which a distribution board connected to the power supply
is connected to modules using short power cords with female connectors
on both ends.
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Building your own +/- dual power supply.
It's often difficult to find a PSU for non Eurorack Synths.
Anything from +/-9V to +/-15V.
For building a +/- 15 PSU you will need a
LM7815 +15V Voltage Regulator LM7815
LM7915 -15V Voltage Regulator LM7915
The Wall Wart should have a 15 VAC output.
The AC output of the wall wart is rectified it with diodes so that
positive voltage gets stored on the caps that serve the positive
voltage regulator (LM7815) and negative voltage gets stored on the
caps that serve the negative voltage regulator (LM7915).
Make sure that the caps have a voltage rating over 35V
And use as large a heatsink on those regulators as possible.
