Buchla 156

 The  Buchla 156 is a very early example of a CV processor .... possibly the earliest.

It was developed to enable more flexibility in the 

Buchla 100 system.

Most of the early 100 modules (such as the Buchla 158 VCO) didn't have a any way to attenuate /offset voltages entering their often single CV inputs. 

So the 156 was developed to do this.

In the later 200 series Buchla added CV processors into modules like the 258 VCO. (see pics below)

As Buchla evolved, new CV processor modules were invented such as the 256, 257 & the Verbos 254v but the 156 is the grand daddy of them all.

The module consists of two independent CV processors.... left (A) & right (B).

Left CV processor (A)

The left CV processor has two inputs. They feed into a mixer (bottom knob) .

The centre knob (offset) adds a + voltage

offset to the input (0V-15V range). 

If you are using this in a 200 system the voltages will probably be in the range of 0-10V.

The top knob mixes between the external signals and the internal voltage offset . 

The output is at the top 

Right CV processor (B)

The right processor is similar to the left one except it has one inverting input. 

Buchla 158 & 144 VCOs

 didn't have many CV inputs so the 156 was useful in manipulating CV voltages from keyboards and sequencers before they touched the VCO.

The 258 incorporated CV processing circuits into the module.

other Buchla CV processors:

+ 254v (buchla format)

+ 256 Dual Voltage Adder

+ 257  Control Voltage processor

Verbos 254v (buchla format)

 This is essentially two Buchla 257 modules in one.....

 with an additional CV in. 

Great for smaller systems where in one panel space 

it can do most of the scaling , 

adding and modifying of voltages you would ever need. 

Each section has 4 inputs.

Input 1/2:  Inverts/attenuates and scales voltages 

                 from the input .... allows for -12 to zero 

                 to +12V control of whatever is plugged 

                 into the jack

Input 3/4 : The voltages can be crossfaded with 

                  the knob or a CV at the banana input 

                  between.

 V(Offset):  Adds a DC offset to the final output.

                   The offset knob's range of output is

                   -12 to +12V

                   (12'oclock is 0V if nothing is plugged 

                    into any inputs)

                   

Buchla 257

 The Buchla 257 is a really useful module.

The front panel is a bit intimidating, but once you decipher the symbols and letters its not too hard to understand.

[Va * K ] + {[Vb*[1-M]] + [Vc*M]} + Voffset = Vout

 A great module for mixing, scaling, and processing Control Voltages. (the 257T can also be used with audio voltages)

There are 3 inputs: Va, Vb, Vc.

There are 3 knobs: K, M, Voffset

You can add, subtract, scale, invert & multiply voltages.

The above equation can be simplified to:

K + M + V = output

Va * K (Attenuverter): Inverts/attenuates and scales the voltage from input Va.... allows for -10 to zero to +10V control of whatever is plugged into Va

{[Vb*[1-M]] + [Vc*M]}: blends inputs "Vb" and "Vc" . 

The voltages Vb & Vc can be crossfaded with the M knob 

or a CV at the banana input between Va & Vc

There is a switch that when turned on, will apply +0.5-1V (depending on your calibration) directly to the Vb input

V(Offset):  Adds a DC offset to the final output.

                   The V knob when increased will output 0-10V.

                   (with NOTHING plugged into the module, if you turn the V knob to 50% ,you

                   would have +5V show up at the output).

How I like to imagine this module is as a way to sum 3 voltages in creative ways.

Remember that you have two voltage processors. You can combine these.

For comparison see the Buchla 254v,  Buchla 256 & 156.

254v (buchla format)

Buchla 256

The Buchla 256 is a evolution from the Buchla 156 .

Its a voltage processor. 

The official Buchla name is "Dual control voltage adder".

There are two identical circuits.

The offset allows you to add 0-15V to whatever is 

plugged into any of the 4 inputs. 

(I've calibrated mine to 0-10V)

The 4 inputs are identical Attenuverters.

They invert/attenuate the voltage at the inputs.

eg if you plug +5v into a jack you will get +5V at the output

with the knob turned fully clockwise, and -5V at the output

with the nob fully anticlockwise.

At 12 O'clock it will be 0V

Allows for -10 to zero to +10V control of whatever is plugged into 

the corresponding jack.

Other Buchla CV processors:

+ 254v (buchla format)

+ 257  Control Voltage processor

3-Boat Buchla Modular System — In-Depth Look

...

good intro video if you're getting into buchla.

Sequencers using 1.2V/Oct (Buchla format)

Analog synthesizer manufacturers typically adopt one of several standards:

Hz per volt - used by Yamaha and Korg 

1V per octave - used by Moog, Roland, ARP and Doepfer

1.2V per octave - used by Buchla and EML 

0.32V per octave - used by EMS

0.26V per octave - used on oscillator 3 of the EMS VCS3 

I've been playing a lot recently with my old Buchlas esp after visiting Japan and seeing some great Buchla performances..

Buchla voltage specs vary a bit between 100, 200 & 200e series.

Not all modules react the same.

So be careful when you first test these sequencers out.

For safety, I start with the lowest pulse setting on my sequencer and see if it will

trigger a gate or envelope, then work my way up

A brief guide :

Pulses first.

Pulses from the 281e are +15 V, for about .5 ms.

Pulses from the 225e and 222e are a 9V to 10 V spike/short gate with a 5 V sustained "gate." 

One of the 3rd party modules that I use, the Pendulum/Ratchet has pulses 

which are 1 ms long. The pulses can be changed to either 10 V, or about 14 V.

(this depends on what resistor pack is installed).

The 250e outputs a spike of 8.5V. The spike duration is only 0.5ms.

Note: Buchla pulse outputs include a 10v trigger and a 5v gate/sustain and allow pulses to be combined and sustain to be held even while triggering new events. 

CVs

CVs are from 0-10 V. So try to refrain from using -ve voltages .

A module such as the 251e outputs CVs between 0.0V to 9.9V

--------------------------------------------

The precise  Buchla audio & CV levels fluctuated over the decades:
100 series Buchla had audio at 0dBV .... roughly 1 volt RMS.
Pulses are 15V and CVs range between 0V & +15V.
Early 200 series Buchla used audio levels of +4dBV... Professional line level  of +1.736 RMS
Pulses are 15V and CVs range between 0V & +15V. for early 70's 200.
Late 200 Buchla  dropped the CV range to 0-10V. Audio levels stayed the same at +4dBV
Buchla 200e dropped audio back to 0dBV. Pulses are 10V. CVs are 0 to +10V.

The Buchla Polygot manual is a good reference

https://buchla.com/guides/Polyglot_Users_Guide_v1_3.pdf

 Here is a brief list of sequencers that can output 1.2V/oct

Expert Sleepers

Disting Mk1/2 (Eurorack)

Disting Mk 3

Disting Mk4

Silent way - software

It runs as a plug-in for your DAW

Elektron

A4 - Analog 4

The synth's sequencer has a very flexible CV/gate

config. I use it with Buchla & well as Korg.

The CVs are digitally controlled which makes for high precision.

Endorphin.es

Shuttle control

PITCH 1V/OCT, PITCH 1.2V/OCT AND HZ/V are

the control voltages available

SHUTTLE CONTROL outputs +5V at C4 note 

(the highest voltage SHUTTLE CONTROL can transmit). 

Then 1 octave lower C3 will return +2.5V, C2: 1.25V, C1: 0.625V, C0: 0,313V, C-1: 0.156V and the last one C-2: 0.078125V (with pretty bad resolution however). 

As you may see, the accuracy in the lower octaves is bad and on the edge of SHUTTLE CONTROL's CV resolution possibilities. 

That is why the useful range for controlling such type of synthesizers is roundabout 3 to 4 octaves.

Keith McMillen

QuNexus - keyboard/sequencer

Use the editor to set this to 1 Volt per Octave, 1.2 Volts per Octave (Buchla) , or Hertz per Volt

Kenton

Pro-solo

Pro-2000

Modular Solo

+ Polyend

 

 Polyend 2 - eurorack MIDI to CV converter

   1-4 Gate (0-5V or 0-10V),

   1-4 Pitch (0-10V, V/Oct, Hz/V, Buchla standard 1.2v/oct).

   A really handy module that allows you to use the sequencer

   of your choice

XOR Electronics

Nerdseq - eurorack tracker sequencer

Synthstrom

Deluge - synth/sequencer

The Deluge has been designed to support the widest range of CV / gate standards possible. 

A number of settings are available in the settings menu.

Each CV output may be set, in 0.01V increments, to any value between 0.01V and 2.00V per octave, or to “Hz per volt”. 

Squarp 

Pyramid sequencer

CV V/oct or CV Hz/V, 

or exotic voltages like 1.2, 0.32 or 0.5 V/oct.

Korg SQ- 64

Tracks A,B and C are for melodic/chords tracks and all have GATE/CV and MOD control voltage outputs for modular gear 

CV out can be: Hz/V, 0.26V/oct, 0.32V/oct, 1V/oct, 1.2V/oct  - 

with voltage bias adjustment and 0V reference note adjustment (per track)

Gate out: 10V, 5V, V-Trig, S-Trig

Mod out: 0V-10V,  voltage bias adjustment

Track D - the drum track has 16 possible tracks, via MIDI with 8 drum trigger 

outputs for working with modular gear.

Sequentix 

Cirklon sequencer

Its a MIDI sequencer but the 

CVIO option adds 16 CV and 8 gate outputs.

The CV outputs support 1V/octave, 1.2V/Oct and Hz/V modes plus portamento/glide and micro-tuning options. 

The gate outputs can be configured in 5V v-gate or S-trig modes.

Pattern lengths are up to 256 steps.

Orthogonal devices

er101-102

This is a eurorack module, inspired by the Buchla 251e sequencer.

Its much cheaper than the Buchla version, but offers many of the same features.

Its perfect for a Buchla-TipTop euro system

• voltages between 0.000-8.192V at 2mV increments can be dialed in
• 4-track sequencer
• stepped and smooth voltage transitions
• each track has 3 outputs: 2 CVs + 1 gate
• each track has its own adjustable loop points

Arturia

Keystep pro

By default, the transmitted pitch voltage is compatible with the 1.0 V per octave standard,

To use a 1.2 V per octave or a Hertz per Volt (Hz/V) standard you can change the corresponding setting in the MIDI Control Center.

(Note: the simplier Arturia Keystep only does 1V/oct & Herz/V with the current firmware)

Microfreak

By default, the transmitted Pitch voltage is compatible with the 1v per octave standard.

To use the 1.2 V per octave standard, you have to change the corresponding setting in Utility>CV/Gate>Pitch Format or in the MIDI Control Center.

Gate signals can also have different output ranges (S-Trig, V-Trig 5V, V-Trig 10V). These too can be changed in Utility>CV/Gate>Gate Format or in the MIDI Control Center.

T-1 Algorithmic sequencer (Torso elecronics)

Added 1.2v/oct for compatibility with Buchla gear. CV voltage for pitch outputs is wrapped on both ends of 0-5 volt limit

Future Retro 512

The 512 is a  capacitive touch keyboard, packed with a unique blend of truly musical features to enhance your creative experience. 

The 512 is available with or without the optional rack ears that allow it to fit in a standard 19" rack enclosure, taking up only 4u spaces. 

Why is capacitive touch better? Quite simply, eliminating mechanical moving parts found in traditional keyboards makes a product that will never wear out, as mechanical keyboards do. No more intermittent key contacts, or failed aftertouch circuits to worry about! In addition, capacitive touch provides a much faster response time for playing notes, and allows multiple forms of expression to be executed by the performer. 

There are five main functions of the 512. It can act as a keyboard, arpeggiator, sequencer, MIDI to CV converter, and MIDI to MIDI converter. The 512 can control both MIDI and CV/Gate synthesizers simultaneously. Pitch, Pitch Bend, Mod Wheel, Gate, Velocity, Aftertouch, and Clock are all available in both their MIDI and CV form. 

CV's follow the 1V/Oct standard with positive polarity Gate signals, allowing the 512 to control the majority of analog synthesizers both past and present. The 512's CV output is adjustable providing a range of .47V/Oct to 1.34V/Oct. This then allows you to control other CV standards such as the 1.2V/Oct synthesizers used in Buchla and EML brands as well.

OXI ONE

- V/Oct (most modular and semimodular systems). From -3 to +5 V.

- Hz/V (Korg standard pitch tracking). From 0 to +5 V.

- 1.2V (Buchla standard pitch tracking). From 0 to +5 V

---------------------------------

Final thoughts.

After searching the net, it seems like there are lots of sequencers that you can use to sequence Buchla gear. You can of course use a real Buchla sequencer (of which there are many) , but if you are short of real estate in your system, then an external sequencer is a Ok solution.

In addition, if you have a Buchla Midi to CV converter such as the Bucha 225e or 225h you can of course use a midi sequencer.

Kaitlyn Aurelia Smith - Strictland House

 Kaitlyn Aurelia Smith

A call to the morning.

A very early start - 3 am 

But worth it.

Old Strictland House, on Sydney Harbour.

I used to get dragged here as a child for the odd antique fair with my parents.

The house itself was shut.

Sunday morning, 8/1/23

..

..

..

..

...

Buchla Music easel,

SEM

OP-1

Arturia Key-step

NLC build notes 2 for a LPG

These are some build notes for a Nonlinear circuits LPG version 1.

Its actually a really old NLC design with through hole components.

The old silver panel version too. I first built one back in 2015. 

I bought 4 panels/ Pcbs with the intention of building a quad Low Pass Gate (LPG).

like a 292 and only got around to building one module.

These are the original notes:

Low Pass Gate - Filter/VCA - Buchla Style - Build Notes

And these are Andrews blog notes:

http://www.sdiy.org/pinky/data/WAMOD4%20lpg.pdf

I decided to finally finish off the remaining 3 PCBs

This came about when a friend recently asked me what was the best sounding 

LPG module in Eurorack.

He was particularly interested in DIY.

There are many low pass gates out there.... eg:

Makenoise QMMG (ridiculously expensive)

                    ... might as well buy a real Buchla 292e and be done with it.

MakeNoise MMG

MakeNoise LxD MakeNoise Optomix

NLC Dual & single LPG

Meng Qi - LPG (passive)

Erica Pico LPG

Synthrotek LPG

Endorphin.es Grand Terminal Pittsburgh Modular Lifeforms Dynamic Impulse Filter.

Ken Stone's LPG Mystic Circuits LPG

Malekko/Wiard Boogie & Borg filter RYO Aperture Takaab 2LPG Pittsburgh Modular LPG

The synthrotek, Ken stone & NLC ones are DIY.

Below is the rear of a NLC single LPG... half built.

Notice the headers for the vactrol ... hopefully will make it easier to swap vactrols.

All LPGs are based on the Buchla 292 which is expensive and hard to find... esp a original vintage one.

Part of the problem in attempting rebuilding from the original schematics are hard to find components.

Esp the vactrols.

Anyway, I think it's pointless trying to rebuild the past.

Like a dog chasing its tail. 

Better (in my humble opinion) to use the past as inspiration and build something that

is of this time and place.

Andrew also did a later version of a Dual LPG

which is well worth checking out.

66. Dual LPG - build notes

This version used headers to make the dual vactrol.

The pic below is of the single NLC LPG.

I'm adding headers for the pots & vactrol to allow some experimentation

Both versions are designed for a dual vactrol. 

Some of my earlier 4U builds (eg of a "cloned" 208) use dual vactrols like the VTL5C3/2, 

If you have a few spare use them. 

Dual vactrols are actually two photo-resistors and a LED in the one package ....

The VTL5C3/2 are hard to find and expensive

You could buy cheap Chinese copies but another way around this is to build your own. 

I kinda like this as DIY is fun, I don't want to make a 292 and DIY lets you experiment and 

find your own unique sound.

My friend wants the module to be flexible ... with the ability to swap components to adapt the sound.

The LPG version 1 is best for this as the vactrol is standard.

Version 2 uses a box to make the vactrol.

The other mod I'm making is with the pots.

Do I use log, linear, anti-log?

The BOM indicated 100k linear .. but it will be fun to experiment with this.

With the first build, I liked the sound of the module with a log 100K pot for the frequency.

So I'm adding some trimmed IC headers for the pots and vactrol.

The 33k can be varied up to 51K .... It sets the Cv level.
I left it at 33k.

The 10K sets the gain of the output signal.

I started with this at 10K

Decided to use surface mounted resistors to make changing them easier.

After playing around with the module I deciced to up the 10K resistor to 22K

Better !!

upped it again ... this time to 51K

Yes !!!

Who wants to die for art?

Divine as Dawn Davenport in John Waters' Female Trouble, 1974. ..... ???

DIY Vactrol time.

(Dual vactrol)

This was my first attempt ... not very successful

You can find a bit more info on vactrols here:

+ Vactrols - Optocoupliers

I started with a 5mm green LED and 

 two GL5549 LDRs

It was really hard to encase this in shrinkwrap.

so opted to try making two separate  vactrols

I used two GL5549 & two 3mm Red LEDs.

I joined the two LDR in series ......there are 3 connections on the LDR side.

The LEDs were connected in parallel ... just 2 connections on the LED side.

In the pic below, the LED side is on the left.

The LEDs are sitting on top of each other .... sharing the same anode & cathode sides.

Pretty messy I know.

The pic below is the vactrol looking at the   LDR side (3 terminals).

I'll make the next one cleaner. however, the vactrol works.

The buchla 292 I think used a VTL5c3/2 which had a dark resistance of 10M ohms

and a slow response time.

which is pretty similar to the GL5549 LDRs which has a dark resistance of 10M and a response time of about 20ms

... probably best to just experiment.

Second vactrol.

I used two GL5549 & two white 3mm LEDs

Sounds great. I think better than the red LED.

In this test I used B100K pots for both Freq & res.