Sunday, 22 November 2020

Presenting AE Modular at ELK ELEKTRONIK Synth Meet


Thanks to the 5th Volt for the AE Modular presentation.

Thanks to Ed for kindly letting us use his space in Wollongong.
(A new Synth centre of NSW).

Elk EleKtroniKs - Synth Meeting Nov 21, 2020

 Great meeting.

Gee, it's so good to be able to catch up again during these Covid 19 days.
NSW has had nearly 20 days of no virus infections or deaths.  Hopefully we are out of the mess of 2020.
Thanks to Ed for kindly letting us use his space in Wollongong.
(A new Synth centre of NSW).

tHANKS to everyone who showed up. From The local Illawarra regions, to Sydney, and as far as Bega.

AE Modular.

Hopefully the next meeting will be soon.... maybe early 2021.

tHE  after party.




ARP 2600 - Envelope Generators

 The 2600's & TTSH's Envelopes


 The ARP 2600 has two envelope generators.

The first is a full four-stage (ADSR) Attack, Decay, Sustain, and Release Envelope. 





The second EG  is a simpler AR offering variable Attack and Release only. 

The Manual Start button allows both the Envelopes to be retriggered at any time, without using the keyboard. 

 Usually, however, the EG is triggered with a +15V spike of voltage (trigger pulse) from the keyboard. As soon as the key is pressed, the keyboard also begins generating a gate signal.

The cord that connects the keyboard is on the left side of the tolex cabinet. It has six prongs.



The envelope module also provides both Gate and Trigger outputs for patching to external modular gear.

The S/H Gate jack is an input.
It's wording is rather misleading. 
When nothing is plugged into the jack, the internal clock (that is used in the sample & hold circuit) triggers the envelopes if the switch is in the lower position

It seems that the 2600’s designers considered the electronic switch, the internal clock and the sample-and-hold units all part of the “Sample-and-Hold module.” Hence the label on the jack below the EG’s. However, it is really the internal clock which is responsible for causing the EGs to fire, not the sample-and-hold unit. (Fundamentals of Music Technology  by Samuel Ecoff)

If you wish to externally trigger the ADSR or AR envelopes, connect a clock (+10V  pulses) or a +10V gate.
The switch should again be in the lower position.
The eurorack Winter Modular Eloquencer triggers these envelopes perfectly.

The internal clock’s connection to the EGs can thus be broken by returning this switch to the upper position.
You can now trigger the EGs with the keyboard.
The ADSR EG is normalled to FM inputs on each oscillator, as well as one of the control inputs on the VCF. 
Thus, the EG’s can be used to raise the filter’s Fc every time a key is pressed

They can also be used to modulate the VCA.
The ARP 1601 sequencer is a great device if you can get your hands on one.
Quite rare these days, though I understand there is a clone available.

This is a basic patch for connecting the 1601 with a 2600.

The quantized CV outs of the 1601 are connected to VCO 1 + 2's CV inputs.
The 1601's "clocked Gate 1 Out" is connected to the 2600's S/H GATE input jack

A second way to connect is just plug the clock out into the  2600's S/H GATE input jack.
The Clock out is a +10V pulse.

 I have also tested a ARP2500 sequencer with the 2600.
This basic patch works very well.
Clock out of the 2500, to the 2600's S/H GATE input jack.
You can also connect the gate outs (of the 2500) to the 2600's S/H GATE input jack.

 This is only a brief introduction but. should get you started. I'll cover more features of the 1601 in later blog posts.

Sunday, 15 November 2020

Oscilloscope Basics for Synthesizers - Modular Synthesizers 102

This is part of the Elk Elektroniks synth class on the 21st November.
The class will be held in Wollongong, NSW, AUSTRALIA.
Check out the FB link for more details
The first part of the class will cover the topic:
" What are Modular Synthesizers??"
We will be using scopes and the question of how to use them will probably also come up.
Thus this second part.
Oscilloscopes look complicated. There are many thousands of models. 
The models used in this tutorial have 2 ports.  They accept probes with BNC connectors.
You will commonly see scopes with 1, 2 & 4 channels.

When buying a scope, there are a few things to consider.
The first is Bandwidth. This is the maximum frequency range the scope can measure.
The ideal is to choose a scope with a max bandwidth at least 5 times the maximum frequency you intend to measure. Most entry level scopes have a bandwidth of around 100MHz. This means that they are really only good at accurately measuring sine wives of around 20MHz.

Sample Rate:
This is really only applicable to digital scopes.
The greater the sample rate, the better. 
It's the number of times a second a signal is read. Get a scope at least 5 times your expected highest frequency.
Most entry level scopes have a sample rate of 1 to 2 giga samples/sec
                                                An Analog Scope - Using a cathode ray tube.
In the world of synths, being able to use a scope is really useful. 
Most electronic musicians have a multimeter. This allows us to measure & "see" a voltage at a specific time.
What a  scope enables  is the visualization of a "moving" or constantly changing voltage over a much longer
period of time. I like to use the analogy of a still photo vs a movie.
                                                         A modern Digital Scope
The Multimeter, takes a photo.
The Scope does the movie.
To properly take a photograph you need to set the shutter speed correctly & frame the image.
It's no different with a scope. You will even find a focus setting and filters on your scope.

Being able to visualise your sounds will make music production more predictable and you will be able to trouble shoot your DIY builds easier..
 All scopes whether they are analog or digital have 4 basic sections:
1. Vertical
2. Horizontal
3. Trigger
4. Screen (digital or analog CRO)
1. Vertical

This uses the volts/div control .
(remember Vertical = Volts)
It adjusts the amplitude (height) of the signal on the screen.
The vertical controls are specific to each channel. 
So if you have a two channel scope, you will have two individual  vertical controls.

Common vertical controls include:
+ Voltage Scale. (volts/division)
+ position / Auto
+ Coupling (DC/GDN/AC)
+ Invert (on/Off) 
+ Bandwidth Limit

This control is useful for also pulling a signal into view (if you initially can't see anything on the display).
It moves the waveform up and down to exactly where you want it on the screen.
Some scopes have an "auto" button which helps to position your signal on the centre of the screen.

DC vs AC vs Ground Coupling
DC coupling shows all of an input signal.
AC coupling : you see the waveform centered around zero volts
Gnd  lets you see where zero volts is located on the screen.

Bandwidth limit
By limiting the bandwidth, you reduce the noise that sometimes appears on the displayed waveform, resulting in a cleaner signal display.
The BW limit setting can also effect (clip) the display of the actual waveform  ... be aware of this.
2. Horizontal
This is the time base.

This uses the sec/div control. 
It will position & scale the waveform correctly.
This control effects all channels

Common Horizontal controls are:
+ sec/div control.
+ Time Base
+ Delayed Time Base
+ XY Mode
+ Position
+ Z axis
sec/div control.
Here you control the time period that the signal is displayed on your screen.
The position moves the waveform left and right to exactly where you want it on the screen.
Many oscilloscopes also have what is called a delayed time base. Here, the sweep can start at a pre-determined time relative to the main time base.
 XY mode that lets you display an input signal, rather than the time base, on the horizontal axis. 
This allows you to do phase shift measurements.
3. Trigger

This is how you stabilize the waveform. 
Without choosing the correct trigger the scope will sweep horizontally across the screen,  and your display will repeat & appear to move.
Triggering will make the moving waveform appear static by repeatedly displaying the same part of the waveform.
The trigger setting effects all channels.
You need to also set a trigger level.
The most basic form of triggering is "Edge  Triggering". 
It could be on a rising or falling edge.

Common trigger modes include normal and auto:
(a) Normal mode: the scope only sweeps if the input signal reaches the set trigger point.
     (the screen will be blank (analog scope) or freeze  (digitalscope)
(b) Auto : the oscilloscope sweeps, even without a trigger. 
      A timer will trigger the sweep even if no signal is present, so the display will not disappear.
Most of the time, you just need to set the scope to trigger on the displayed channel.
Some Oscilloscopes can also use extra trigger sources that may not it be displayed.
So be careful not to trigger on channel 1 while displaying channel 2.

If you are trying to display a trace from a modular synth, the easiest way is to set the scope to external trigger mode (EXT).
Then connect a trigger or gate from your modular synth.

 4.  Screen
This is where your waveform will be drawn.
The screen is divided into a grid.

My analog scope has a 10 by 8 grid
The horizontal is your time base.
Vertical = voltage.
Each Vertical division can set to represent a specific voltage.
The horizontal can either be set by the user, or it may be an automatic setting (if you don't know much about the signal you are measuring, at the start).

My digital scope shows the actual horizontal time division
 (demo in class)

Auto setting -- 

Great for quickly capturing a signal
(Digital scope obviously)
It's like the auto button on a camera. Great in most cases.
 But to capture a signal really well, the manual controls are the best.

The scope must be in the Green "Run" mode.

Like on a camera, you need to first zoom out to see the object you wish to photograph.
Then zoom in to get a detailed image.


Friday, 13 November 2020

Modular Synthesizers 101 - Elk Elektroniks Class

I'm looking forward to the upcoming synthesizer meeting on the 21st November at
Elk Electronics. It's just 1 week away. The class will be held in Wollongong, NSW, AUSTRALIA.
Check out the FB link for more details

Ed has kindly let us use his work space to spread the word about electronic music.
On the 21st, we will be starting at the beginning and asking the fundamental question:

What are Modular Synthesizers??
So if you are new to modulars and interested to begin the journey, this class is for you.
In addition, There will be demos using Eurorack , banana and AE modular synths,
plus a Wasp & Minimoog D.
Contact Ed via his facebook link to book a spot. This is a Covid safe event and numbers are limited , so contact him first.

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.

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 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). 
They convert midi signals into control voltages.

Sunday, 8 November 2020

EMS Synthi E - Using the keyboard

 The EMS Keyboard is not standard I think... I purchased mine separately in the hope it would work.
(EMS Rehberg .. Germany)
And yes it did.

The 5pin din cable is very similar to a midi cable.
Plugs into the left (envelope follower section)
Make sure the slider is set to external.
and take a cable to  the VCO 1/2 F input.
The gates to trigger the envelope shaper are generated internally ... no patching is needed.

The keyboard is powered from the synthi e.
I probed the socket with my multimeter 

Saturday, 7 November 2020

Befaco Eurorack Power Supply - Lunchbus

 Some pics of the Befaco LunchBus

It's a super easy kit to build ... perfect for beginners.
The Befaco page is here:
I purchased a full kit . Befaco is located in Barcelona, Spain.

The power supply needs to be DC 9V to 18V.
This is an old generic PSU from a laptop.

 The novel and cool design makes soldering the headers really easy.
The PCB is double sided ... half of the header is soldered on each side

tHERE  is on board +5V, along with the standard +/-12V

I decided to use an old school case.