Tuesday, 26 December 2017

Christmas fun with the Roland 100m

Getting familar with the basic D-set

A simple patch using just 5 modules: 112 Dual VCO, 121 Dual filter, 130 Dual VCA, 140 Dual envelope, 150 Ringmod, SH, Noise. The 1st VCO supplies the bass & second VCO, the drums.
The full unedited video is here:
https://www.youtube.com/watch?v=y_QU--2VCrc&t=19s

Tuesday, 19 December 2017

Master Clock & utilities Eurorack case

 Utilities are pretty boring, but necessary.
Over the years Ive struggled to find ways to clock everything that I have.
Is it possible that one device can to it all ???
Probably not, but you can build a case with the modules to do it all.
I think I finally have it.
 
 
The trigger, drum modules and compressor arent necessary, but they are useful to have and certainly do 
make the case even more handy.
 
The main clock source is the cyclic slew 1U. 


The Synthrotec CVGT1 does all the Buchla / Euro conversions. 
Both control voltages, triggers and gates.
 
We need a clock divider/multiplier (2hp), a CV sequencer (Pico).
The mutant brain allows me to trigger drums with MIDI 

The Disting is a mark 1. Its enough.
 
 
 
 
 
 
 
 
 
 
 
 
I can clock my ARP 2500 easily with a gate from the Synthrotec.
 
The CVGT1 has a silver ground jack. (banana).
 
I needed to make a conversion cable -- on one end is the 6.5 mm jack which plugs into the clock input of the ARP sequencer.
 
The other end of the cable has two ends...  a banana ground jack & a banana tip jack.
 
These plug into your CVGT1 ground & gate outputs

Works flawlessly
 
 

You can also clock old Moog, Korg & Yamaha gear which needs V-Trig to S-trig conversion.
You need to make a cable for this,

 
 
 















Some more pics


 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
Links

Abelton - Instrument chains

 These are related to drum racks, but different.

You dont have the MPC layout.


I have made an instrument rack with 4 instruments.
One impulse drum rack (dub delay), one Analog inst, One operator and a Collision pad.
 
Look in the  Browser.:
Display Categories / Instruments, and drag the Instrument Rack folder onto the first MIDI track 
You can drag whatever instruments you like into the window below the list of chains.

In a earlier post I talked about using the macros to control launching of instruments.
   
We now need to assign each instrument a unique Chain Selector value.
 
Clip 1 launches when MIDI = 0
Clip 2 launches when MIDI =1
Clip 3 launches when MIDI =2
Clip 4 launches when MIDI =3
 


 
To automate the clip selector
Ive added in the clip launcher  4 midi tracks.
 
 
 
 

Here, Im going over how to use envelopes to select which midi clip triggers the instrument.

 
Set the channel to chain select.
And
The first midi clip has an envelope drawn to level 0
Keep is flat ... at level zero along the entire clip
 

Clip 2 will have a level of 1.
 
Clip 3 a level of 2 .... and so on.
 
 



You can download this demo project here:



Wednesday, 13 December 2017

CES Digital Systems trainer - Ed-Lab 702

This is a educational tool to teach students digital logic and give basic microprocessor experience.
I'm hoping it will teach me a thing or two.

I believe there was a suitcase version. This is a console configuration.
The manufacturers website can be found here:
http://cesindustries.com/ces702.htm



There are manuals that accompanied this console. Sadly I don't possess them.

Some closeups:













Saturday, 9 December 2017

Philosophy

 Philosophy is the study of  fundamental questions about the world...., such as those about existence, reason, knowledge, values, the mind, AI vs natural intelligence, soul, life after death, etc etc.

You might think its odd to find this page in a blog about synths, but I think  such concepts will actually help make better music.
 
If I suffer writer's block , or life seems too much to turn that synthesizer on, then reading a bit of Aristotle or Marcus Aurelius helps refocus on whats important. Usually I can get going again.
 
 This page will be constantly edited and added to over the years.
The study of Philosophy is a lifetime endeavour.

+ Thales - the Father of Science

Tuesday, 5 December 2017

Buchla 200e explores space

Have you ever wondered about the origin of the names of some of Don Buchla's instruments?
Esp the later 200e series. Skylab, LEM, Aquarius, Spider, Snoopy ????
I must thank my friend Justin for enlightening me.
They are all references to NASA space exploration vehicles.

Skylab
Skylab was the United States' first space station, orbiting Earth from 1973 to 1979.
 The Buchla Skylab. It's a 10U size system designed to be portable.
LEM
The Apollo Lunar Module (LM), originally designated the Lunar Excursion Module (LEM), was the lander portion of the Apollo spacecraft built for the US Apollo program




 An amazing piece of engineering to say the least.

Named the LEM 208, it's a BEMI easel, minus the 218 keyboard.

Aquarius
"Houston we have a problem"

The Apollo 13 mission almost ended in disaster. An explosion on board forced the crew to circle the moon without landing. Oxygen tank No. 2 blew up, causing the No. 1 tank to also fail. 
The command module's normal supply of electricity, light and water was lost, and they were about 200,000 miles from Earth.  Apollo 13 "Aquarius" was used as a lifeboat. It burned up in Earth's atmosphere April 17, 1970 but saved the lives of all crew. An incredible achievement.


Below is the Buchla LEM7 Aquarius, with a 218 keyboard.
Its a great interface module ... esp for eurorack systems, providing MIDI, usb, CVs, gates etc.
The Aquarius LEM Includes:
a 3 module powered boat
225h Midi to CV converter
202u multiples & utilities module
4 half module blanks

Spider
Apollo 9 was the third manned mission in the United States Apollo space program and the first flight of the Command/Service Module (CSM) with the Lunar Module (LM, pronounced "lem"). It launched on 3rd March 1969. It was a luna module test flight. This was the first space docking of two vehicles with a crew transfer between them. The CSM was named "Gumdrop" and the LEM was named "Spider".


The Buchla LEM Spider.
The Spider LEM includes:
3 module powered boat
225h MIDI-CV interface
226h CV-MIDI interface
252e Polyphonic Rhythm Generator


 Snoopy
Apollo 10 was the fourth manned mission in the United States Apollo space program, and the second (after Apollo 8) to orbit the Moon. Launched on May 18, 1969, it was the F mission: a "dress rehearsal" for the first Moon landing, testing all of the components and procedures, just short of actually landing.
As you have probably worked out my now, Snoopy was the name given to the LEM.

The Buchla LEM Snoopy
Snoopy consists of :
3 module powered boat 
226h (CV to Midi converter),
225h Midi and CV interface,
292h Dual Dynamics Manager
281h Dual Function Generator
261e Complex waveform Generator


Tokyo Tower - Japan

Some pics of Tokyo Tower in Japan.

At 332.9 metres (1,092 ft), it is the second-tallest structure in Japan. Built in 1958, Hisakichi Maeda, founder and president of Nippon Denpatō, the tower's owner and operator, originally planned for the tower to be taller than the Empire State Building, which at 381 meters was the highest structure in the world at the time.

Inspired by the Eiffel Tower in Paris, France, it is claimed the tower can withstand earthquakes with twice the intensity of the 1923 Great Kantō earthquake.









.


Sunday, 3 December 2017

Vactrols - Optocoupliers

 Vactrols and Optocoupliers 
 
Vactrols are sometimes called Opto-isolators, photocouplers and optical isolators.
They all use a similar idea, though this post is mainly about vactrols.

One side has a a light source of some sort
This could be a LED (or an incandescent bulb).
The other side uses something which is photo sensitive.
This could be a LDR (Light dependent resistor) or a  photosensitive transistor.
Applying a voltage to the LED causes it to light up. The light falls on the LDR.
The intensity of the LED directly controls the photo-transistor / LDR.

Thus this resistor becomes voltage controllable.
 
 
This is a Doepfer LPG... based on a Buchla 292 module.
It uses vactrols.

Through the use of a vactrol, anything which is normally controlled by a potentiometer or variable resistor can become a voltage-controlled parameter. Applying a voltage to the vactrol's LED is just like turning the knob on the potentiometer.
 
In addition, since the LED and LDR can be controlled by different circuits we are thus electrically isolating the two different circuits.
Thus, vactrols are sometimes called opto-isolators.

The hollowed space between the LED and photo-transistor/resistor can be made using glass, air, or a transparent plastic.
 
The resistance of the LDR doesn't change instantly.
It takes time ... the change is not linear either.
"It may take a few seconds until the LDR reaches it's dark resistance (i.e. the maximum resistance without illumination)" Doepfer.
 
A brief History
In 1967 Vactec introduced a compact RO (resistive optocouplier) branded as Vactrol. Unlike the tube-coupled ROs of Fender and Gibson, Vactrols were sealed and sturdy devices. They originally used incandescent bulbs. In the early 1970s, Vactec replaced the incandescent bulbs with LEDs. This increased the switching speed and probably also their reliability.

In 1983, Vactec was purchased by Perkins-Elmer. Their vactrol division was spun out from the company and changed their name to Excelitas in 2010.

In the European Union, the production and distribution of Cd-based photoresistors was banned after January 1, 2010. This decision marked the beginning of the end of Excelitas vactrols. However, CoolAudio started manufacturing the VTL5C3 and Xvive is manufacturing the complete range.
 
Commercial vactrols usually contain LEDs that usually produce infrared light.
The detector is a semiconductor-based photoresistor made of cadmium selenide (CdSe) or cadmium sulfide (CdS). 
Resistive opto-isolators are the slowest type of opto-isolator .
Switching times usually exceed 1 ms, and for the lamp-based models can reach hundreds of milliseconds.
Cadmium-based photoresistors exhibit a "memory effect": their resistance depends on the illumination history; it also drifts during the illumination and stabilizes within hours.
 

 -----
Since it's getting more difficult to find vactrols, making your own may one day be the only option.
 
These are the light dependent resistors which I  like to use.
GL5549
The type of LDR is impt.
It should have a dark resistance of at least 0.5M ohm.
I like a slow attack (or response time). 
VTL5C3s have a slope of 20, a dark resistance of 10M Ohms and a very slow response time.

  LDR type nr 5516.are good too.
 The 5516  specs say  it gives about 5 to 10 kOhms at full brightness 
 
 
Suggested LEDs are red/green/orange/yellow.
 

The colour of the LED will have a bearing on how the vactrol works.
So experimentation is in order.
 
This is an example of a DIY vactrol.
Its part of a Eurorack module:
The NonlinearCircuits Dual LPG 
 
 
I read somewhere, that yellow LEDs make the most efficient circuit.
The best match is I think between green and green/yellow.  A blue LED is probably the worst possible choice.
Also remember that LED colours are normally not standard or very precise from one manufacturer to another.
 
 Here is another example of a DIY vactrol.
I used black shrink wrap. 
 
 
To get the best possible performance, the LED and LDR should have equal wavelengths.
This will require checking datasheets to find a good match.  
 

Model

-

 Size   (mm)

Light resistance(ohm)

Darkness resistance(ohm)

Max voltage (DC): 

Max power consumption

Operating temperature

GL5506

-

5X2

2K~5K

0.2M

150V

100mw

-30C° ~+ 70C°

GL5516

-

5X2

5K~10K

0.5M

150V

100mw

-30C° ~+ 70C°

GL5528

-

5X2

10K~20K

1M

150V

100mw

-30C° ~+ 70C°

GL5537-1

-

5X2

20K~30K

2M

150V

100mw

-30C° ~+ 70C°

GL5537-2

-

5X2

30K~50K

2M

150V

100mw

-30C° ~+ 70C°

GL5539

-

5X2

50K~100K

5M

150V

100mw

-30C° ~+ 70C°

GL5549

-

5X2

100K~200K

10M

150V

100mw

-30C° ~+ 70C°

 
 
 A bit about the Buchla 292 LPG
The 292 Quad Lopass Gate is very famous for its use of vactrols, 
The LPG is kind of a VCA
You will find that the minimum release time associated with a vactrol is a lot longer than that of the typical (non-Vactrol) VCA, 
It is thus impossible to produce snappy drum sounds using a 292
The drum sounds tend to ring for about 30 ms after triggering 
This occurs even if the 281 envelope generator that is controlling the LPG is set for 
its minimum value.

------
There are a few commercial vactrols you may come upon.
 This is a NSL type vactrol

The single vactrol NSL. the white dot marks the cathode.


Below are some Perkins-Elmer/Excelitas VTL 5C3/2
VTL 5c3/2..... I used them a lot in the buchla "clones"..
These are getting really hard to find.
 
 You may come across these Xvive versions.
I understand they are made in China

The manufacturer says they are a modern clone of the old Perkins-Elmer VTL53C
 
These are I understand also Xvive vactrols