Tuesday, 27 September 2016

NLC Serious Filter - ARP Odyssey 4023

The Serious Filter it is based on the Arp4023.

 This is what it should look like when finished.

The ARP Odyssey mkI (model 2800), has the 2 pole 4023 12db/oct filter

The MkI 4023 been described as the most "Arp-like" sounding filter, because it doesn't try to imitate a Moog. The NLC 4023 also makes a nice quadrature oscillator.
The mkII in comparison, has the 4035 24db/oct filter - with a steeper bass roll-off curve, just like the minimoog filter.

The Korg-ARP Odyssey has all 3 filters. Would be nice to compare this with them when the build is done.

The rear virgin PCB 

Some NLC words of wisdom first: "Sausage Fears"
"Sausage fears": a term to describe the actions of straight men who are afraid of showing any physical or emotional bond to the men they are friends with. (The Urban Dictionary) 
So true... we men are afraid of showing emotion.

Back to the build:
First solder the two SMD TL072 ICs

Now the rest of the SMDs & headers.

Next, the regular caps, variable resistors & through hole diodes & resistors.

The 4 pots I've used are 100k B.
You could use an A pot on the signal input if you really want.

Andrew F usually uses B pots on most of his modules (except on the ADSR module). It is very easy to solder a resistor across 2 pins if you wish to turn a B/linear into an A/log pot. This way, you can also adjust the slope to suit your needs.

Don't forget to connect the ground tabs on the 6 jacks.
The completed module.

1. ARP Tech schematics for the 4023 filter
2. NLC Blog
3. NLC Build notes

More links to NLC (nonlinearcircuits) projects.

Merida - Yucatan Mexico

Some pics of Merida in Mexico.
Mérida was founded in 1542 by Montejo y León ("el Mozo") and named after the town of Mérida in Extremadura, Spain. It was built on the site of the Maya city of T'hó
  The castle cathedral (Cathedral of San Ildefonso) is huge and imposing. Dates from 1598. It was the first cathedral to be finished on the American mainland. A very severe and imposing structure that I read as a statement to show the power of the church.

The system of vaulting used throughout the building was based on the ideas of Andres de Vandelvira, first applied to the building of the cathedral of Jaen in Spain (1249).

Jaen Cathedral. It was built upon the ruins of a Mosque.
Merida's cathedral was probably built upon the Mayan ruins of T'ho... the Spanish using these conquered people as slaves during construction. It must have been terrible for the inhabitants to see their capital destroyed and this structure built on top.... just as in Mexico City.

The Cathedral was commissioned by Pope Pius IV. The architect was Juan Miguel de Aguero. He also built the fortifications of Havana Cuba and the Cathedral of Mexico City.

The crucifix inside is 25ft high. It's supposed to represent friendship between Mayans & the Church.
I found this a bit unsettling considering the building's history.

Saturday, 24 September 2016

3 Trins video synth with FetidEye's comparator

I really love this comparator. Awesome job FetidEye.
This is a short video showing the effect of the comparator on a external video.
(a old Japanese Samurai film)

The comparator video is the one on the top left. 


Thanks to Cobramatic for borrowing his comparator

Friday, 16 September 2016


RIP Don Buchla.
He passed away on Wednesday at his home in Berkeley, Calif. He was 79.

So sad. Don will live on through his friends, family & instruments.
His life and achievements have changed so many people including myself.
He is Immortal.

Buchla 100

Buchla Music easel

These are all vintage 200 modules. 246 (Sequential Voltage Source ) on the top. From the left, 205 matrix mixer, 258 VCO, 281Quad Function Generator, a 296 Spectral Processor and a 221 keyboard controller on the bottom.

 Buchla 237 Keyboard.
The 237 was one of the very few conventional keyboards that Don invented. Though he studied piano
Don wanted to free musicians from traditional Western music.

“A keyboard is dictatorial,” he said. “When you’ve got a black-and-white keyboard, it’s hard to play anything but keyboard music.”

 The keyboard controller in the foreground is a 222e

 Part of my 200e collection.

Don Buchla is survived by his wife, Anne-Marie Bonnel; two daughters, Jeannine Serbanich and Erin Buchla; his son Ezra, and two grandchildren.

Tuesday, 13 September 2016

Euro build notes for a Serge Resonant EQ Mk. II

These are my build notes for a Euro format Serge Resonant EQ Mk. II.
Mk. II daughter board and Mk. II panel by Clarke

 First the virgin PCBs.
This Euro version still uses Ken Stones CGS 202 pcb.

Above is a pic of a vintage Serge Res equaliser.
It's the 3rd module from the top. It's very compact in comparison to the Euro version and doesn't have
the extra outs from the 10 filter bands. And pot's are used instead for sliders.

 Official BOM for the daughter board:

SMT Components
[3] TL074 (SOIC-14)
[10] 330R Resistor (0805)
[25] 47k Resistor (0805)
[2] 0.1uF Ceramic capacitor (0805)

Through-hole Components
[18] Kobiconn 16PJ138 jacks
[10] Bourns or Alpha 45mm LED sliders
[2] Alpha 9mm pots or similar, value 50k Audio.
[10] LED Current-limiting Resistors - value varies by slider brand and LED color.
        I'm using 1.2K.
[2] 22uF Electrolytic capacitors
[2] 1N4001 Diode
[1] 2x5-pin Eurorack power header
These are the 330R resistors.... outboard resistors.

Next the 47K SMDs.

[2] 0.1uF Ceramic capacitor (0805)
[2] 22uF Electrolytic capacitors
[2] 1N4001 Diode
[1] 2x5-pin Eurorack power header

SLIDER Pots, jacks, etc.

Now for the main PCB.
Resistors & headers 1st.

What capacitors should I use ???

Ken Stone's site says this:
"Traditionally, polystyrene capacitors are used for all of the smaller value capacitors in this module. I have not tried using other types and cannot say whether using the polystyrene capacitors makes any audible difference. From 10n, up greencaps were used. In modern terms these would be MKT or MKS. Note that there are also 10 x 10n decoupling capacitors. These decoupling capacitors can be MKT, MKS, monolythic ceramic, or anything else that will physically fit."

For this build I'm using ceramics for the 680pf & 220pf. The jury is out on whether axial polystyrene sound better. The price difference is considerable.
I'll use Axial poly's in my next build if I can detect a difference between this build and my vintage
Resonant Filter. .

It's now time to wire up the two PCBs.

Headers can also be used like this:

 This makes for easier trouble shooting.

This is not part of the original CGS build. Took a bit of schematic study and trial & error to work out where
to where to make the connections. they were basically the outs pins of the ten TL072s.. pins 1 & 7

1. Muff wigglers
2. Ken Stone - CGS
Video 1
Video 2

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.

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.:)

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

To Be Continued. JP.