Tuesday 20 February 2024

Mun - Build notes - NLC Vocoder - part 1

These are my build notes for the nonlinear circuits Mun module.
tHIS eurorack 22HP module is a 10 channel vocoder based on the Syntovox 222

The word Vocoder is a combination of two words.
Voice + Code = Vocoder
Vocoded signals were essentially a form of data compression for voice.


The module is more easily understood if you divide it into 3 sections : Voice, Carrier & noise

For the Voice section, there is a TRS/mono 6.35mm input for mics, a stereo/mono 3.5mm input for line level sources (like a tape/CD player or phone with a jack output) and 
a synth level input (+/- 5V).

The Carrier section has a synth level input only.

The Carrier input expects a +/-5V synth level signal. One tip - the
vocoder output is only as good as the carrier signal, so mix a few
signals together via phasers, filters or wave-folders to get interesting
sounds……or drum hits are fun too.

This is a transistor based noise source with pots for level and colour (white/pink). 
The noise signal is mixed with the carrier signal on channels 9 and 10. 
The level pot determines how dominant it is. 
This is simpler than voiced/unvoiced switching seen on some vocoders but I found
it sounds good and like having the option of patching the envelope inputs so the noise turns
on a lot more frequently than it should. Of course, you can turn the level pot down to 0 
and have no noise too. 

It basically works this way:
You plug in your mic a one end where you voice is converted into control voltages.
(in this case CV envelopes, that exit from the envelope out jacks).

Those CVs are plugged into the envelope in jacks (of the carrier section). 
They are used to control the synth plugged into the carrier input.

The filter and envelope outputs can be used without affecting the main
vocoder operations. Patching into Envelope In, disconnects the
internally generated envelope. A 0-5V signal is expected.

Shall we have a little talk? .... Robert Sheckley
It's the title of a Neubla Award nominated novelette which originally appeared in Galaxy Magazine, October 1965.

The story can also be found in the collections The People Trap (1968), The Wonderful World of Robert Sheckley (1979), The Collected Short Fiction of Robert Sheckley: Book Three (1991), The Masque of Mañana (2005) and Store of the Worlds: The Stories of Robert Sheckley (2012).

The name of this module "Mun" comes from this novelette.
It's a unique novel as it explores communication & specifically linguistics in science fiction.

Basically, the Alien society's language mutates so fast that a Earth linguist attempting exploitative First Contact is barely able to keep up and retires defeated when the latest iteration reduces the entire language to inflections and stresses of a single syllable: "Mun, mun, mun-mun." ......................Quite an appropriate name  for a vocoder.


"Mun," said Erum, shaking his hand enthusiastically.

"Same to you, kid," Jackson said.  He had no idea what the word meant.  Nor did he care.  He had plenty of other Naian words to choose among, and he had the determination to force matters to a conclusion

"Mun!" said the mayor.

"Thanks, pop," said Jackson.

"Mun!" declared the other officials.

"Glad you all feel that way," said Jackson.  He turned to Erum.  "Well, let's get it over with, okay?"

"Mun-mun-mun," Erum replied.  "Mun, mun-mun."

Jackson stared at him for several seconds.  "Erum, baby, just exactly what are you trying to say to me?"

"Mun, mun, mun," Erum stated firmly.  "Mun, mun mun mun.  Mun mun."  He paused, and in a somewhat nervous voice asked the mayor: "Mun, mun?"  (pp. 64-65)


There are lots of caps and resistors ... Its a big build.
Though parts are all pretty common ... nothing rare.
TL072 or TL082 x 16 Soic Tayda: A-1139... cheaper from mouser
TL074 or TL084 x15 tayda A-1137 or A-1140 ..... cheaper from Tayda
BC857 10 tayda A-1345
BC847 3 Tayda A-1339
LL4148 24 sod-80 Tayda: A-1213

LM13700M or V13700M x5 Mouser Part No 926-LM13700MX/NOPB or
V13700M at synthcube (cheaper)... order

5V1 zener 20 Tayda A-6014 (5V6 but ok).... order these

I've run out of op-amps.
To be continued when they arrive................... mun, Mun, munmun MUN

Monday 19 February 2024

LED Matrix - Connect, Power & Control - Setup Guide


These panels are normally designed for chaining 
(linking end-to-end into larger displays)…the output of one panel 
connects to the input of the next, down the line.

The rear of the panel will have two connection points
On some panels, if you’re lucky, the sockets are labeled INPUT and OUTPUT (sometimes IN and OUT or similar), 
so it’s obvious which is the input socket.

Mine has 
Din (Data in)


multiple panels can be connected either in Series or Parallel.


Each LED in our WS2812 RGB LED Strips has a built-in micro-controller IC chip which allows you to daisy-chain the LEDs and control them individually - all from a single digital pin! The constant-current driver in each LED ensures that colour remains consistent, even if supply-voltage varies slightly from the optimal 5V.

we can control which LED should light & what colour it should be.

really cool.

Saturday 17 February 2024

Boss DR -55 drum machine

I've been revisiting an old fav drum machine of mine - The Boss DR-55 Dr. Rhythm.
(Mainly as it's awesome for triggering the arp of a Roland JP 4).
This classic drum machine produced by Roland Corporation has been in my collection for decades.
It was I think one of the first I ever owned.

The Dr55 was sold under Roland's guitar pedal Boss brand. 
Introduced in 1979/80, it quickly gained popularity due to its affordability, portability, and ease of use. 

You can still find these on Ebay quite cheaply. They haven't yet undergone 808/909 price inflation.

The DR-55 was one of the earliest programmable drum machines available to musicians and became a staple in many home studios and electronic music setups.
It was one of the first step-write-style drum machines, and it was the first rhythm machine in BOSS' successful Dr. Rhythm Series. 
It inherited much of its sounds DNA (an appearance) from the CR 68 & 78 drum machines.

I love this machine so much as it highly portable and sounds great ....suitable for both studio and live use

The FS-1 jack is for a footswitch. It's an input.

Connecting a (latching footswitch) such as the Boss FS-1 will make it possible to start/stop the DR-55 remotely, when in PLAY mode.

The DR-55 features 4 analog drum sounds:
kick (BD), snare(SD), rimshot(RS), hi-hats. 
You can globally adjust the master Volume, master Tempo, master Tone and master Accent for the drum sounds.

Only the BD, SD, and RS can be programmed.
The HH has a switch to select between OFF, 8th, 16th/12th preset pattern
These sounds are generated by analog circuits, giving them a warm and characteristic tone.

Accent Function: 
Accents can be programmed.
You can globally adjust the accent volume.
This feature allows users to emphasize certain beats within a pattern, adding dynamics and variation to the rhythms.

Users can program their own drum patterns using the DR-55's step sequencer. 

There are 8 memory slots to store up to 8 patterns:
This is divided into 
a. six different 16 step drum patterns (4/4 rhythms) b. two 12-step patterns (3/4 and 6/8 rhythms). 

In each memory slot you can record 2 variations : 
A or B.
These is a switch to select either variation in rec or playback modes.

The centre variation switch position (AB) records and plays both A & B variations consecutively.

To Program:
1. set switch to WRITE mode.
2. select a drum sound to program.
3. Steps are entered with the start button. 
    Rests are entered with the stop button.
4. The beginning of a pattern is indicated when the RED LED 
     lights up.
5. Pattern playback is enabled by setting the switch to PLAY mode and pressing START.

Audio Output: 
Unbalanced 1/4 inch.
 Note that a cord must be connected to 
 this jack for the drum to be turned on.
 This is like many of BOSS's 
 guitar effects pedals

Foot switch 1/4 inch input - use with a FS-1 pedal. (Like with the Roland CR 78).

DBS : outputs a pulse for each step. (+5v, 8ms) ... use to drive the arp on a Roland Jupiter 4

CSQ: outputs a pulse for each accented step. (+4v, 10ms)... use o drive a CSQ-100/600 sequencer
When this jack is used, accents no longer occur in the programmed rhythm patterns.

It can also be connected to the Roland modular System 100M.

It runs on 6V DC (four AA batteries

I purchased a new 6V battery holder on Ebay. I have two DR 55s and both had a broken battery holder
when I initially bought them.
These are made of really weak plastic which will definitely break one day. So buy a few as backups.

While the DR-55 lacks some of the advanced features found in later drum machines, its simplicity and iconic sound have contributed to its enduring popularity among musicians, particularly in genres like electronic, synth-pop, and new wave. Despite being over four decades old, the Boss DR-55 continues to be sought after by vintage gear enthusiasts and remains an important piece of music technology history.


I'm in two minds about modding the drum. But here are some links if you're up to vandalising a piece of music history :-)
I think simple mods like external clocking & adding a DC input (to eliminate batteries) are harmless.

+ Dr 55 mods

There are also plenty of modern clones of this machine, which have all the bells and whistles ... so maybe leave the original alone and buy a clone to mod to your heart's content.

The circuitbenders.co.uk CB55 is an exact clone of the voice board of the Boss DR55 drum machine. It has the four fully analogue percussion sounds, bass drum, hat, snare, and rimshot, but leaves out the clunky and arguably useless sequencer. There is also an overall accent feature that adds a little extra punch to the whole mix when it is triggered.

Friday 16 February 2024

NLC - This 2 shall pass - passive analogue XOR - build notes

These are my build notes for the Nonlinear Circuits "This 2 shall pass" module
It's a eurorack format 2HP module.

Should be a simple build ... It's a passive analogue XOR circuit

No CMOS ... which is different & nice to see.
How to build a logic gate with transistors is a basic circuit which is a handy piece of knowledge.

There are 2 ways to use this:
1. If you want to get close to XOR behaviour, use the top and bottom inputs, leave the middle one empty. 
2. if you want a voltage controlled “XOR”  feed your signals to the top and bottom
     inputs and a CV signal to the middle input.

Feed it anything: CV, audio rate, gates, mix them up. Generally with audio signals it sounds like a Ring Modulator, adding CV to the middle input (but feel free to experiment) it sounds like a VC Ring Modulator.


XOR Gate (Exclusive OR gate)
Will only output a high signal when one input is high and the other is low.
It allows the signals to pass Except when they happen simultaneously.
It's like when 2 people try to squeeze through a narrow door at the same time.
(use this for your two snare drums - to prevent them triggering simultaneously)

 In1 In2 Out
 0         0 0
01 1
 1 0 1
 1 1 0

1k 2 0805
4k7 6 aka 4.7k 0805
22k 2 0805
BC847 6 sot23-3
3.5MM SOCKET 8 Tayda: A-2563

The red tape is to prevent any shorts

You can find more NLC builds here.

Thursday 15 February 2024

Wednesday 14 February 2024

NLC - LET'S BRONZE UP - build notes

These are my build notes for the nonlinear circuits "Lets Bronze Up" module.
Its eurorack format

The module is a signal multiplier. It's similar to "lets Splosh"..... ie you patch in 2-4 signals
and get multiple complex but related outputs ( however in this case the results are glitchy).
You'll  get lots of envelopes. Use these to modulate filters or open VCAs, etc.


The inputs are labelled – Head, Shoulders, Knees and Toes. The rest are all outputs, the two centre columns are partial outputs that emit positive or negative aspects of the signals, 
so turn off at times. 

The right side column outputs contain the full spectrum and are rarely quiet.
If just using two inputs, patch them into Heads and Knees, as the
signals will then switch Shoulders and And Toes as well.

There aren't any hard to find parts:
TL072 or TL082 x2 Soic Tayda: A-1139
TL074 or TL084 x4 Soic Tayda: A-1140 or A-1137
LL4148 16 sod-80 Tayda: A-1213

ICs on first ... just 072 & 074 op-amps

LL4148 diodes next

Start putting on the jacks. Make sure they line p with the panel.

headers ... these join the two PCBs ... electrically & physically.

You can find more NLC builds here.