Monday 31 July 2017

Serge Bi-directional Quad switch - build notes

I've been searching for the perfect synthesizer router for my Serge.
The Serge Bi-directional router is fine but I would love to have more ins/outs.
Recently I built a NLC 32:1and NLC Router for Eurorack.
All excellent and I might one day adapt one for the Serge.
One I haven't tried is the serge Quad switch which seems to be an adaptation of the earlier
Serge Triple Bi-directional R.

The module I'll build is the Cat Girl Synth CGS 88.
Ken's Build notes are here:
https://cgs.synth.net/modules/cgs88_bds.html

The Quad switch uses a CD 4013B.
Its a CMOS Dual D-type flip flop that works as a two bit binary counter.
Looks like the switch used in the vintage 1970's module was a Motorola MC14007UB.
It was mounted on a separate board off the original R4 PCB.
You can still find these.

D = Drain, S = Source.





to be continued..... waiting for parts.

Fixed Filter Banks

 I love Fixed Filter Banks.
They are a beautiful way to process audio. There are many types in lots of formats.
 
Some of the earliest appeared in the Buchla & Moog formats.
 
This is a Buchla 194.
Probably from around 1969 ????
... maybe early 1970s ??
 
A filter bank is an array of bandpass filters. 
They separate the input signal into multiple components.
Each channel carries a single frequency sub-band of the original signal. 
 
The process of splitting the signal is called "analysis".
The output of analysis is referred to as a subband signal.

This output of each channel is then recombined. This process is referred to as synthesis.

Notice that the 194 doesn't have a level/vol control for any bands.
Nor does it have a summed output.



This is a Buchla 195
It's a 10 band fixed filter.
The 194 above is a 4 band filter.
Neither filter has level controls. I usually patch these into a mixer.
 
Moog of course produced the other very famous fixed filter
The venerable 907
 

 Usually, filter banks consist of a low pass filter on the lowest band and a HP on the highest band.
Between these there are bandpass filters.
 

  It's really simple. The 907 has just one input & one output.
Unlike the Buchla 195 & 195, there are level controls for each band.
The Moog 907 is a 10 band filter. The Moog 914 consists of 14 bands. 
 


 

The Buchla 194 & 195 belonged to Don's first modular synth .. the Buchla 100
 These modules developed in his Buchla 200 system.
On the left is a Buchla 294.
 
Notice the level controls for each band, plus a summed output.
 
 











The path of evolution didn't stop here for Don.

He went on to produce the Buchla 296.
There are now 16 channels.
 
Don named the 296 the "Spectral Processor" as it allows you to do a spectral analysis of an audio
signal. The module generates corresponding control voltages of  each band. There are also envelope followers
for each band. 

Two of these can be patched to form a vocoder.

In the early 2000s Don developed the 200e. And along came the 296e.
Each band has a touch sensitive plate and all setting can be store and recalled.
 

You don't need to be rich to have a taste of these filters.
There are plenty of examples in the Euorack format

 
 



This is of course based on the original Serge Resonant equaliser
 
Great for feedback looping







 
 
This is a Mooger Fooger guitar pedal.


Sunday 30 July 2017

Router - NLC build notes

Some build notes for the Nonlinearcircuits router.
I'm hoping this will function something like the Serge bi-directional router, but with 4 outs rather than two.
A router can also be found in the NLC Chopper.

The new NLC Router is a voltage controlled switch that can deliver 1 into 4, 4 into 4 and 4 into 1 at the same time, 2x 2 into 2 and, with a simple mod to the PCB, 2x 1 into 2 



This looks like a easy build.
ICs on first.
The module uses a DG412 which is a CMOS analog switch.

Control inputs are pins 1,8,9,16 (in)
D1–D4 : Analog Switch Drain Terminal
 S1–S4 : Analog Switch Source Terminal

Passives, resistors, diodes, caps
The thru hole stuff.


Jacks & pots.
Nice.

Input 1 is internally connected to the switches on jacks 2, 3 & 4.
CV 1&2 is internally connected to the switch on the CV 3&4 jack.
The signals to the OUT ALL jack are summed together

The Router pots can be used as switches, 0 is off and 10 is on. At these settings the switches will ignore incoming CV or gate signals. For the switching to be controlled by CV or gates, set the pots to an appropriate turn-on point.

 Links:
- NLC build notes.
- NLC blog
- Facebook
- Muffs2016

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You can find more NLC builds here.
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Saturday 29 July 2017

I, Robot - Isaac Asimov

This is a classic of Sci Fi
Most readers will be familiar with the 2004 Will Smith film adaptation.

This is actually part of a series of novels & short stories that  Isaac Asimov wrote called the "robot series". The Series comprises 37 science fiction short stories and six novels

The main ones comprise:
1. I, Robot (1950). Later robot stories included:
    The Complete Robot (1982), Robot Dreams (1986), and Robot Visions (1990)
2. "The Bicentennial Man" (1976) & The Positronic Man (1992
3. "Mother Earth" (1948)
4. The Caves of Steel (1954)
5. The Naked Sun (1957)
6. "Mirror Image" (1972)
7. The Robots of Dawn (1983)
8. Robots and Empire (1985)




This is the cover of the first edition.
Publisher    Gnome Press
Publication date December 2, 1950
Media type    Print (hardback)
Pages    253

The 9 stories comprising I, Robot originally appeared  in two magazines:
Super Science Stories & Astounding Science Fiction (1940 to 1950).
They were then compiled into a book  by Gnome Press in 1950
The first edition was of 5,000 copies





 The 9 Stories that make up I' Robot are:



1. Robbie - September 1940 under the title "Strange Playfellow" - Super Science Stories

This 1st story was republished in a 1950 revised edition

https://www.wikiwand.com/en/Robbie_(short_story)












2. Runaround (March 1942 - Astounding Science Fiction)















3. Reason (April 1941 - Astounding Science Fiction)

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4. Catch That Rabbit (February 1944 -
Astounding Science Fiction

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5. Liar! (May 1941 - Astounding Science Fiction)
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6. Little Lost Robot (March 1947 - Astounding Science Fiction)
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7. Escape! (August 1945 - Astounding Science Fiction)

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8. Evidence (September 1946 - Astounding Science Fiction)
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9. The Evitable Conflict (June 1950 -  Astounding Science Fiction)
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You will notice that the dates of publication for the stories are not chronological.
They are independent stories that were collected and turned into the I, Robot novel in 1950.
It's facinating to read these old magazines.
The "world of the future" as it was viewed 70 years ago.

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sci Fi Index

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Friday 28 July 2017

Modular in the CarPark - inagurial event - Wollongong

Sunday, 16th July, 2017. 
Many thanks to Claude Spinelli & Andrew G for helping put this event together.

The location was Prosound and Lighting, Wollongong.
Address: 16 Flinders St, Wollongong NSW 2500


Anyone with a synth, drum machine, etc was welcome to come,watch and perform. The synth didn't have to be modular.

 Keyboards were welcome too. 

The event was free, with sausage sizzles and barista coffee.
A good place to network with electronic musicians in the Sydney/Illawarra area.
l
Lots of great tunes too.

If you would like to perform at the next gig please leave a message here or contact Claude at Pro Sound and Lighting. (02) 4226 1177