Wednesday, 20 February 2019

Resistance is Futile - Wiard BORG filter

Some pics of a Wiard Synthesizer Company GR-1204 Joyrider module.
 This is a 4.5" Frac module with a pair of Vactrol-based Borg 1 Filters.

When I first came across this filter I thought it was a reference to the Star Trek movie "First Contact"
Then I realised the name BORG is a cross between Buchla & Korg.
Which is what it is... a.marriage of "two divergent influences, the Buchla 292 Low Pass Gate and the Korg MS20 filter". I promptly forgot all references to that ancient race of aliens from Star Trek until today.

Designer Grant Richter settled on the FracRak format for his series 1200 series modular.... probably early 2000 ish ???
Sadly the Frac Rack format is almost dead. But I intend to install this with other Wiard modules (Euro & series 300) and anything else I feel is worthy


Apparently, there are only 11 of these in existence so I will look after it.
Lovingly  hand-built, panel silk-screened &.hand wired by I guess Grant Richter himself.

The Joystick:
"x" controls the type 1 filter, joystick "y" controls Type 2.
There is a common resonance control called Peaking.
In the new eurorack version, If you turn the control all the way off this engages a switch which changes to VCA mode. Max setting will produce self oscillation.

Individual mode controls... one for each filter.
Each filter is adjustable through Low pass, Band Pass, and High Pass modes. 
LP= 12dB/oct
BP= Resonator gain of 1 except Peaking ... controls gain at Fc
HP= 6/dB/oct


The modern Borg 1 filter looks like this:
 Sadly the new filter has lost its joystick.
It's an interesting design. Two filter inputs.. Input 1 mixes 50/50 with input 2.


The PCB appears to be only partly stuffed. There are those famous vactrols that create the famous  natural, very musical decay. In Low Pass Gate (LPG) mode, the Borg will act as a filter and a VCA simultaneously. ... just like the Buchla 292.




The rear of the PCB. I'm amazed how deep this module is.



A close up of the top of the PCB:



The Star Trek reference returns.



Sunday, 17 February 2019

Make Noise Maths Revisited

The Make Noise Maths has been around for a long time.
This is one of the first modules I ever bought. It's often described as an analog computer.

It's basically two function generators & two attenuverters in one module. 
The circuits are loosely based on the Buchla 257, 281 and the Serge DUSG.
It has many uses. It can be used as a VCO, a mixer, an envelope follower, a slew limiter, 
an inverter, and do some basic logic functions.

One of my friends is going to buy one and wanted to know the difference between the two.
I have the "classic" (original) version on the right. It's pre 2013.
(Sometimes referred to as the Lighting Bolt version)

I've read that the two versions sounds different when used to process sounds as a filter or mixer.
If anyone out there has both I'd love to hear your opinion.


There are some obvious external differences between the two such as the different knob layout
and the addition of LEDs to indicate +ve & -ve voltages and to show the state of the (EOR) End Of Rise and (EOC) End Of Cycle.
You will  also see there are 13 outputs on the update & just 10 on the classic.

One important difference is the Function output (or Unity Output on channels 1 & 4) of the new module. 

The Signal OUT Multiple (from the original MATHS) has been changed to a Unity Signal OUTput which is the non attenuated output of the
function generator (different from Ch 1 & 4 outs)


This non-attenuated out is a good output to use when you do not require attenuation or inversion or when you want to use the signal both independently and within the SUM/OR Bus.


And an INVerted SUM OUTput has been added for greater modulation possibilities.
Finally, the new MATHS has added +/-10V offset range (CH. 2). User has choice of +/-10V offset at CH. 2 or +/-5V offset at CH. 3. (The original only has a +/- 5V offset on both channels 2 & 3),

According to the Make Noise manual
MATHS revision 2013 is a direct decendent of the original MATHS,  sharing the same core circuit and generating all the fantastic control signals that the original was capable of generating, but with some upgrades,
additions and evolutions:

The new Maths has a Cycle input (24)
This allows for voltage control of the CYCLE state in Channels 1 and 4.
On Gate HIGH, the MATHS will CYCLE.
On Gate LOW MATHS will not CYCLE (unless the CYCLE button is engaged).

It's useful to think of this module as a processor of equations.
There are 4 inputs: CH1, CH2, CH3, CH4.
The two outer channels are function generators. The 2 inner are basically simple inputs that are normalled to a DC offset using attenuverters.

 Each channel has a coefficient which multiplies the value by +/- voltages (using the associated attenuverters).
 

The outputs can be OR/SUM/Inverted.
The inverted is only present on the new version.

OR = MAX ie it takes the largest value.
Eg. if the outputs from channels 1-4 are 1V, 3V, 5V, & 5.2V , then OR will output 5.2V.
It does not respond to negative voltages, therefore it could also be used to rectify a signal.

SUM adds the outputs from all the channels.
Depending upon how the Attenuverters are set, you could add, invert or subtract voltages from each other using this circuit. This is a good output to use for combining several control signals in order to generate more complex modulations.

INV = inverted SUM. It allows you to modulate backwards!

When utilizing the SUM, INV and OR OUTputs, set any unused channels to NOON to avoid unwanted offsets.
The output jacks 1, 2, 3 & 4 are normalled to the output jacks OR, SUM & invert.
That is, if you plug a cable into any of those 1,2,3,4 jacks, that voltage is subtracted from the OR, SUM & invert output jacks.

Using the Function Generator:

Its different to a standard LFO in that the rise and fall knobs sculpt the envelope and set the frequency.
They determine the rise & fall times... that is the time it takes for the envelope to rise to the peak (10V) and then fall to 0V. Also you can use the Log/linear/exponential knob to determine the shape of the rise & fall. Longer cycles will be achieved with more Logarithmic response curves. The fastest, sharpest
functions will be achieved with extreme exponential response curves.

This style of envelope generation is classic "west coast" and follows in the footsteps of the Serge DUSG and the Buchla 281. It's so very different to the ADSR type envelope generators of the "East".



Wednesday, 13 February 2019

Dual LPG - NLC build notes

This is a  Nonlinear circuit eurorack module. It's DIY.
Andrew describes this as based on the buchla 292 except it uses the "black box vactrol method" seen in the Shat-noir Phaser and Noiro-ze VCF/VCA.
This involves making a light proof box. .... basically you will build your own vactrol using some light sensitive resistors and diodes.

The term "Low Pass Gate" was created by Don Buchla and stands for a module that can be switched between a gentle low pass filter (6db/oct) and a VCA.  (basically they are a VCFA). It's most famous implimentation is in the Buchla 292.

The control (manually and via external CV) is responsible for frequency in the low pass mode and for loudness in the VCA mode. Additionally a combined mode LP+VCA is available. In this mode the sound becomes more dull as the loudness decreases.

The old West Coast style Buchla 292 uses vactrols(VTL5C). It has an extremely organic response to control signals.



Your choice of resistor/ vactrol greatly influences how this circuit will behave.
Since we are building this in a non perfect light proof box, and your position of the diode, its brightness,  etc etc... there is a lot of variation.... ripe for experiment. Of course if you wanted reproducibility you could just use a factory vactrol, but that would be boring. :-)

DG analogue switches are used for changing between filter and gate modes.... so we have voltage control over the different modes which is nice. It would be nice to have a combo as well... LPF/Gate/Combo.
Maybe Andrew will add this in a future module ???

Clone #042 ???



Links:
https://www.nonlinearcircuits.com/modules/p/dual-lpg
BOM


+ Original LPG 
+ LPG - Jondent 




The virgin PCBs







Choosing the diode size

Op-amps & resistors first


fOR  REVERSE protection




bUILDING THE LIGHT proof box



LED - long lead into square hole.




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DG202 or DG212 - these are quad SPST CMOS analog switches.
What doe the DG stand for???

Double Gate CMOS  (DG)
 Traditional CMOS technology is approaching physicial limitations was we approach the nanoscale regime.
One such solution is the double gate transistor, proposed in the 1980s.
"Multigate transistors are one of the several strategies being developed by CMOS semiconductor manufacturers to create ever-smaller microprocessors and memory cells, colloquially referred to as extending Moore's law.




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You can find more NLC builds here.
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Monday, 11 February 2019

Beast-Tek Microbe - build notes

Some build notes for the Best-tek Microbe.
These arent official notes ... just a diary to help me trouble shoot.
I'm not associated with Beast-Tek.


This ia a 8 channel drum trigger module.
The official website describes it as a artificial intelligence based 8 channel algorithmic rhythmic engine with partial CV control.

The official site is here:
BOM & Build notes
Manual


There is a Rotating Clock Counter mode, a glitchy beat mode , a regular beat mode, a rotating clock divider mode and a Cellular Automation based mode.
The Cellular Automation mode allows the manipulation of organic trigger patterns from a cell grid based loosely on Conway's Game Of Life algorithm.  
I bought this mainly because of the cellular-automation section. 

The ATmega 328P-PU micro-controller comes pre programmed.
MCP602/MCP6022 High precision op-amp


cAREFUL  .. avoid any shorts.


The build manual is excellent, with lots of great illustrations.
A easy build.










I cut some of the metal jack supports to avoid shorts.




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For more Euro DIY builds click here:
http://djjondent.blogspot.com.au/2017/12/diy-index.html
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