252e - my notes re using this module

This is Don's last module.
So it has a special place in the Buchla World.
The 252e ...... called the Polyphonic Rhythm Generator.
It's polymetric, & polyrhythmic as well as being polyphonic.
 
Quite a striking device and at the time of writing nothing else comes close to this (in my humble opinion) in terms of beauty, functionality and genius.

In it's most basic form, you can consider it to be a 3 voice sequencer.
It has 3 pulse outputs, 3  corresponding  (pitch) CV outputs, and 3 corresponding velocity CV outputs.

The central circle is made up of 11 concentric rings or sequencers.
The rings vary in number of steps. The internal ring is 3 step ... the next ring is 4 step, then 5 step, etc ... up to 16 stages... 

The rings can be synced or can have different clocks. There are 3 clocks and they can be distributed among the 11 rings. You can have 3 rings running at any one time. Each ring can create complex patterns but they can be synchronized and linked to generate two- and three-part polyrhythms and polymetric patterns. These can then be combined with the onboard Euclidian rhythm library for even more complexity.

You can sync the pulse & CV or separate them.
Pulses and CVs can be shifted independently within a ring.

The diagram on the right is an old one (from about 2014) ... part of the prototype... but it gives an idea of how the rings are broken up into cells.
The 3 pulse outputs and six CV outputs can be assigned freely among the cells.
The rings and cells can be interlinked to create interesting patterns and complex sequences.

 The 252e consists of 5 parts:
- Display Selection
- Clocks
- Rhythm Select (user defined or Euclidean)
- Cell & Pulse Edit
- CV editing

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

Display Selection

The ring display at the center of the 252e can show four different sets of cell properties using
the R/G/B colour scheme. At power on time, the “pulses” view is displayed.
This R/G/B colour scheme matches the LED colours next to the 3 pulse outputs.

The “pulses” layer indicates the presence of pulses in cells with the colours red, green, and blue.

The grey button in the Display section lets you choose
+ pulses
+ cv 1-3
+ cv 4-6
+ subdivide

The “cv 1-3” layer shows the presence of CV assignments for outputs 1, 2 and 3 using the same R/G/B scheme.
The “cv 4- 6” and “subdiv” layers show CV outputs 4,5 and 6 as R/G/B,
The Subdivide section divides the cells. These pulses are shown as Red.

This subdivide button is related to the cell subdivision bit of the Cell Edit section.

A fifth mode shows them all superimposed so you can see which cells are empty and which are occupied.

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

Clocks

There are 3 independent clocks (master, clock 2 & clock 3)
The master clock has each division as a quarter note value. .... following the master BPM
Each clock has 11 layers... each corresponding to a ring.
Innermost is called 3, the outermost is called 16

The clocks can be internally or externally controlled (using the CV & pulses)

The CV input (black banana jack) next to the “assign” knob selects the ring, and a pulse
at the pulse input (orange banana jack) next to the “assign” button starts the assignment.
Note that the assignment is not fixed when the button is pressed (or pulse
received), so if you turn the knob or change the CV before cell 1 is reached on the ring
currently assigned to the clock, a different ring will be assigned than the one that was originally
selected.

Sync
Press the “sync” button to change the clock synchronization method.
+ on 1 = cell 1 of all active rings will happen at the same time.
   The master clock will run at the indicated BPM, and clocks two and three will drive their
   assigned rings at whatever rate is necessary to get the ring to cell 1 on time.
   Remember that each ring can have a different number of cells.
+ “on cycl” = all cells will advance at the same rate.... so over time they will go out of sync.

If neither sync LED is illuminated, the clocks are not synced. In this mode you can press and
hold the “assign / Δt” button for a clock to enable its time scaling mode. In this mode, the
green LED is illuminated and the clock knob will scale the master BPM, from .5x – 3x, as does
the knob’s associated CV input.

Pressing the “reset” button will force all active rings to resync at cell 1.
----------------------------------------------------

Rhythm Select

 This can be either:
1. User defined
2. Euclidean

The cell encoder lets you choose a cell to work on.
You must be in Edit mode to do this .......  press this button

First press the “edit” button (in the Cell Edit section) to begin editing cell data. The cell cursor can
now be moved around the current ring using the “cell” rotary encoder.

You switch & choose the ring you wish to edit with the beats/cycle encoder.
When you switch rings, the encoder’s neighboring segmented display will show the number of cells/beats in the selected ring.

The Euclidian Library.
There is a built in Euclidian pattern library... to help generate rhythmic patterns.
 To generate pulse patterns using the Euclidian algorithm, select a ring using the “beats/cycl”
encoder, and press the “RHYTHM SELECT” button so that the Euclidian LED lights up.
Any pulse data in the selected ring will be erased and replaced by the Euclidian solution
rendered in red pulses (however, other pulses can be added).
Turn the “pattern #” encoder to generate each of the Euclidian pulse patterns for the number of
beats in the selected ring. The number of pulses in the current solution will be shown on the
segmented display to the left of the encoder.
To exit Euclidian mode, press the “RHYTHM SELECT” button, or turn the “beats/cycl” encoder
to select a different ring.
-----------------------------------------------------

Cell / Pulse Edit selection

First press the “edit” button to begin editing any cell data.
In cell edit mode the “edit” LED will be illuminated and a white blinking edit cursor will appear on the ring display. You choose which ring or cell to edit with the Cell Encoder or the Beats Cycle Encoder in the Rhythm select section

To assign a simple pulse to a cell, select the cell with the edit cursor and press one of the
“red”, “green”, or “blue” pulse buttons. The selected cell in the ring display will illuminate with
the pulse colour to show the assignment and the corresponding LED in the “PULSE OUTPUTS”
section will also illuminate. Adding more than one pulse to the same cell will mix their colors.
Pressing a pulse button a second time will remove the assignment.

The “pulse duration” knob changes the length of the gate pulse in a cell.
The range is from a transient pulse (10V pulse that immediately goes to zero) to the entire cell duration at the current BPM. That is, as you increase this knob you adjust the gate from zero to the full length of the cell.

(The standard Buchla pulse is a 10V transient to indicate the start of a trigger, and then a 5V gate for duration).

 The “behind/ahead” knob will cause the cell to be performed late or early relative to the cell’s position in the sequence.... allows you to create shuffles & swings on a per cell basis.

The “phase” knob rotates cell data in the ring forwards or backwards by single cell increments.



You can rotate pulse patterns, pitch & velocity CVs independently.
Basically, this allows you to shift the contents of a ring without having to stop & edit it.
You can do this live (while the sequencer is playing). ... great for live performance.

If you turn off the edit mode, you can see the numeric CV value in the "CV EDIT" display. Thus you don't have to rely only on the LEDs to indicate what's happening..
This layer rotation is really cool for live performance

Cell subdivide = divides the cell up to 7 times.
The button increments the number of pulses to perform, and knob distributes them in time.
0 = start of cell
1/3 = a third of the cel1.
1 = end of cell .... etc etc

So these subdivisions can be either evenly spaced or  crowded at the end (for example).
Allows for things like quick flams before a percussive sound.

The subdivided pulses exit from the top white banana

 Everytime the cycle reaches cell one, a pulse is sent from this white jack.
Really useful for resetting events, clocks , etc etc.

Copy, paste, clear  & fill
When a cell is selected, pressing the “copy” button copies all of the cell’s associated data:
pulses, pulse timing, and CV assignments.

The “paste” button replaces the currently selected cell’s data with
whatever was most recently copied. If you hold down the “paste” button and turn the “cell”
rotary encoder, the paste will be repeated into each successive cell. See the Ring Display
Modes section below for details about how data is pasted.

The “clear” button will erase all cell data from the currently selected cell. If you hold the “clear”
button and turn the “cell” encoder, the erasure will be repeated in each cell. See the Ring
Display Modes section below for details about how data is cleared.

As a convenience when editing pulses, you may hold down one or more of the R/G/B buttons
and turn the “cell” encoder to fill adjacent cells with pulses.

Adding Random Pulses
You can add random pulses in a ring of your choice using the RGB cell edit buttons and the edit button.
Eg to randomly add green pulses to a selected ring,
1. be in edit mode
2. press the green button,
3. press the edit button.

Pressing the edit button again will give you a new set of random pulses.
---------------------------------------

CV output and editing (& programming)

 You must first be in edit mode.

 To associate a CV value with a cell, select the cell using the “cell” and “beats/cycl” encoders as
described in the Rhythm select section above.

Next press the “select” button in the “CV EDIT” section until the desired CV output is selected.

Turn the encoder below the “select” button to assign a CV value.
Each "click: is a decimal point increase.
Each decimal point (0.1V) is a semitone or half step.

The Buchla standard is 1.2V/oct

If you prefer, you can make adjustments in milivolts rather than semitones.
To do this just press the encoder.

A fine tune mode is also available by pressing the encoder down; press again to return to coarse CV edit mode.

Up to six CV outputs (each with different values) can be assigned to any one cell.
When you are assigning a CV value you will see the associated LED light up if the voltage is above about 3V.


These LEDs will also light up when the cell is triggered by the sequencer. If the LEDs are not lighting up, then there is a very low or zero voltage associated with that cell.



The dashed display indicates a sustain.
This is the default for all cells.

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

MIDI Capability
You can think of the blue vs purple CV outs as Pitch vs Velocity pairs for each of the 3 voices.
It supports MIDI input either through a 225e/h or the internal busing from the 218e easel keyboard.

 Hold down the CV edit knob till the display changes to "in".

And whichever cell you have selected will be filled with a corresponding pitch & velocity CV to what is played on the MIDI keyboard or what midi event is sent to it. When you are in this mode the select button will select pairs of pitch & velocity so you know where the matching pitches and velocities are stored.

MIDI CLOCK - MASTER BPM
The 252e can synchronize to - or generate - MIDI clock.

The 252e supports MIDI clock sync receive and transmit.
For example you can sync a 250e to the 252e via internal I2C MIDI clock.
To enable these modes, press and hold the “MASTER BPM” encoder.
The display will change to “oFF”.
Turning the encoder selects “S rc” for “sync receive”, and “S tr” for “sync transmit”.

So if you wish the 252e to receive and be controlled by external midi clock follow these steps:
1. On the 252e, press and hold the Master BPM knob until the display reads Off.
2. Turn the Master BPM knob on the 252e until it reads Src (Sync receive).

Randomize
Use the “pulses” display mode.

In the cell edit section hold down the “blue” button and press the “edit” button.
This will fill the currently selected ring with a random pattern of blue pulses.
Use the clear button to reverse this. You can do this on the fly... great for live performance.
This function also applies to CV values and cell subdivide pulses.

-------------------------------------------------------------------
Recalling and Saving Presets without a preset manager 

Combining the 252e with a preset manager is the recommended way to name, save and develop your sequences and rhythms. But for users with no preset manager, presets can be called up with MIDI preset commands that are sent over the internal MIDI bus using the FirmwareCard’s USB MIDI I/O feature (called 225m).

 The USB Firmware Card’s alternate use is as a USB MIDI to internal MIDI bus interface.

To do this you need to plug the Firmware card to a Mac computer and use the Buchla firmware Utility application program to reprogram it's function as a midi interface for a 200e or 200h system.
In this mode, the USB device name for the Card becomes “225m”.


Patches are saved into that preset location by pressing the remote enable button. The LED will then go out.  

To return a Firmware Card’s function to do Firmware Update’s,simply use the FirmwareUtility again to Enable/reprogram the card for Firmware Update. 

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

The module ID can be displayed on the 225e preset manager by holding the remote enable switch on the 252e for about two seconds.  

You should see something like this:
Here, the 252e is on Buss A. 

-------------------------------------
Many thanks for all the Buchla users out there whose videos I've watched repeately. I have taken ideas from other users, the official manual and from personal observation and use to compile these notes.
Special thanks to Todd Barton. His excellent series on this incredible module was invaluable.
If there are any mistakes, additions and corrections please contact me.
-----------------------------------