Friday, 9 September 2016

FK1T - VCF build notes (NonLinearCircuits)

These are my build notes for the NLC FK1T VCF.
This VCF is based on the extremely rare Korg FK-1 pedal.
They are hard to find and often sell on Ebay in the $1000AUD range.
The FK1 is a similar VCF to the ones found in the 800dv, 770 and 700 synthesizers.
These early Korg filters consisted of high pass and low pass stages in series.



The virgin faceplate & PCB.
Labels are based on 70s Korg nomenclature as per the original module.

 Korg 800dv

 ..
Mainly surface mount passive components.  ... just one TL074 opamp.
 ...

  No NLC build would be complete without some words of wisdom
 Contemporary Art Hates You - John Waters.

The point of art is to "wreck whatever came before it," he believes. "That something is pretty and beautiful is probably the worst thing you could say today in contemporary art...unless it's so pretty it's nauseating."

This 074 is hopefully the only tricky part of this build.

Solder all the passive SMD components next then the 5 trannies.
The BC857 are PNP & are labeled "p" on the PCB.
The BC847 are NPN & are labeled "n".

Finally the through hole stuff : Resistors, caps, headers.

I'm using Silonex NSL-32 vactrols. They are cheap as chips. The white dot marks the cathode of the LED part of the vactrol. Andrew has labeled this as "K" on the PCB.

The pots are 100k linear (B).



Initial tests were good except for CV input 1 which was dead.
The connection between the jack and the PCB may be dodgy ???

This spot on the PCB responded to CV and it looks like its one of the feedback 100k resistors for the op-amp.


I'll probably build this module again using different vactrols and then see if the same issue with
my CV1 input occurs. It might just be a poor solder connection somewhere. ???
For the moment, I'll probably leave this mod as is. It sounds great.
 -----------------------------------------------
Edit ... From Andrew F himself.
"the 220k resistor between cv1 jack and the 100k feedback resistor connects the two. There are definitely traces there. It is not really good to connect the jack directly to the feedback resistor with a jumper, way too sensitive for a start and can damage the op amp.

The two pots ( Travel 1 & 2) may seem to affect each other as it will be a bandpass filter at some (most) settings and each pot will affect one side each (hp & lp) but the overall sound will change.
Inputs 1 & 2 are summed together at the 1st stage."
 -----------------------------------------
 So I'll remove my mod.:)

-----------------------------------
Links
++NLC Build notes
++NLC Blog 1
++Muffs... NLC 2016 modules
++ NLC facebook


To Be Continued. JP.

3Trins RGB + 1c

Testing the 3Trins with an old ARP 2500 video.



Wednesday, 7 September 2016

The 3Trins case

I'm putting this portable Video Synth case together for a future gig.

 An old Haliburton Zero came in handy.



3TrinsRGB Patches

Recording some patches.
The 3Trins patchbay is where all the magic happens.

This page will develop as I add to the number of patches.

video modulating the red oscillator (Vid -->Rcv)
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Video modulating red & blue oscillators.
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Palenque - Mexico

Situated in one of the northern states of Mexico (Chiapas), Palenqes famous for its Mayan ruins in the jungle.




Lots of climbing in the tropical heat.


There are 100s of ruins spread over 15 sq Kms.


A limestone relief from the "Patio de los Cautivos".... war captives.
A inscription on the stairway in House C mentions the birth of Pakal II (603AD) and a war that he waged against the Pomona.












An ancient Mayan football field.
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Thursday, 1 September 2016

sidechain compression - eurorack modular

 Sidechain compressors.
 
Compressors are essentially devices used to make loud sounds softer.
They enable a producer to boost the level of a track, thus narrowing the dynamic range.
This type of compression is evenly applied to the tack
 
Side Chaining is a more active type of compression.
It's sometimes referred to as "ducking".

It is a type of compression where the volume level of one instrument is controlled by the volume level of another instrument
That is, the compressor is only triggered when certain sounds appear.
This is the pumping effect  you often hear in electronic dance music.
Here, the compression level on a bass track is controlled by the output volume of a kick or snare drum.
The Bass line volume drops every time the kick is heard.
Another example of its use is when a song suddenly drops in volume when a radio announcer speaks.
 
 Daft Punk - Indo Silver Club (Official Audio)
 
Thus for side chaining, we need an external signal to act as the trigger.
 
To build your own side chain compressor using a eurorack system
we need a 
1. drum source 
2. Baseline
3. VCA
4. EG with an inverted output
 
The EG could be replaced with a Envelope follower & an inverter.
 
 
In this case, the VCAs gain needs to be turned up.
The baseline is passed through the "open" VCA.
Everytime the kick sounds, it triggers the envelope generator.
The inverted CV lowers the volume of the VCA 
 

These two videos are really good to watch.
  
 
They use the MATHs module
 
 
 
This second video is esp good
 
This is my usual setup.
 

 
I'm using the the Make Noise Function instead of a Maths.
I like to set Rise to full anti clockwise & Fall to about 11 0'Clock to get a ducking effect. 
A fast attack & a slower decay. 
Play around with these settings to adjust the amt of ducking.
The bubblesound VCA is set to expo and CV in to around 3 0'Clock

The Doepfer A-171-2 VC slew Processor works very much like Maths and Function
 

 
It's mostly a licensed copy of Ken Stone's vcs (voltage controlled slope)
 which is in turn based on the Serge vcs.
 
The VCS is a really useful module. Quite versitile.
In this instance it's being use as a voltage controlled envelope generator with an inverted output.
The top and bottom pot are the most important parameters to adjust.
 

Wednesday, 31 August 2016

Malekko - Wiard - Xmix


The  Malekko Wiard XMIX is a mixing/crossfading utility module.
I understand it's different from the 300 series Mixolator which used a  CA3280 transconductance amplifier.

 The XMIX is 8hp wide, 25mm deep, and consumes approximately 45mA power.

There are two inputs (X and Y). 

The Y input can be inverted via a switch.
Z controls the balance of X Vs. Y. 
Z has a CV input, along with an attenuator for CV amount. 
Positive and negative outputs are provided, as well as an Expand input which provides a unity input to chain the output of other modules (such as another XMIX).


Some uses for the XMIX (Manufacturer's manual):
– A 2 > 1 Mixer
– CV crossfading
– A signal inverter
– Audio rate amplitude/crossfading modulation
– With a single input, you can use the XMIX as a linear VCA
– Input different waveforms to create new wave shapes
– The X input normals into the Y input when nothing is plugged into Y. Invert the Y input with the switch, and crossfade the X signal VS the inverted version of itself
 
 
 
 
 
 
 
 
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There is a three pin connector on the back of the PCB that goes hot-ground-cold.

Connect this to an XLR or TRS and you have a low impedance balanced send.

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mAKING  a  ADSR Envelope.
You will need two Envelators. 
 

1. Set 1st to AD mode, and 2nd to AR mode.
2. send a trigger to the 1st Envelator.
3. send a gate to the second envelator .
4. take outputs of each Envelator into the inputs of the xMix
    AD Envelator plus output to X input of XMIX (X control set to max)
    AR Envelator plus output to Y input of XMIX (set Y polarity to plus and Y control to max).
5. The ADSR envelope is available at the XMIX plus output 
6.  The XMIX "Z" control acts like a "Sustain" control.  
     The "ZMOD" input can be used as voltage controlled sustain level input.   
 
Take the output of the xMix and input into a VCA 

The Wiard Xmix can be used as a mixer & as a VCA.
I find there is a little bit of audio bleed when I use the Xmix as a VCA.
I prefer to use a dedicated VCA for this task.
 
------------
Balanced (ring) modulation. 
  • 1. Make sure the X & Y knobs are at full.
    2. Connect your carrier sine wave (or whatever) to the X input.
    3. The Y input is normalled to the X input so the carrier is going to X + Y.
    4. Switch the Y input polarity to negative (minus).
    5. Monitor the plus output.
    6. Adjust the Z control to get the best carrier null.
    7. Now run anything into the Z control input (modulator), Z Control is the volume for the modulation input.
 Thanks to "shady smiles" for the ring mod patch.
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Unbalanced modulation (VCA)
 

 X in = Audio in
+ out = Audio out.
Zero both Y & Z pots.
Z control pot is set to Max
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
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Links:

Saturday, 27 August 2016

3TrinsRGB+1c build pics & initial tests

3TrinsRGB+1c is an analog audio/video synthesizer

 This build took about 3- 4 hrs. It's not difficult but it's not for beginners either.
Some closeups from various angles. Hopefully this will help future builders.




The pot in the foreground is the only 20K one . ... has the gold top.


There is a transistor missing in the above pic -- to the left of the 10uf cap.






This is the 2016 version
..
 Note the two resistors below "VidIn"
 In the pic below, the 10R is missing.
First tests:
The middle white LED didn't work, so had to be replaced... just like in GGs video.
I don't think the LEDs effect the operation of the buttons.






Nice, the video in works perfectly.
The manual is here:
http://gieskes.nl/instruments/files/3TrinsRGB1/3TrinsRGB1c-manualV1.pdf

Watch this video at least twice before you build anything.
Essential viewing.
https://www.youtube.com/watch?v=QqKOfuUpSV8

And GGs website is here:
http://gieskes.nl/instruments/?file=3TrinsRGB1
Assembly instructions:
https://www.flickr.com/photos/62323010@N00/26454192491/