Saturday, 3 July 2021

NLC VCAs - build notes - part 1

 Some build notes for the Nonlinear Circuits VCAs module.

Looks like a pretty straight forward build. 
This is quite a compact module, packing 3 VCAs into 8 HP.
Should match nicely with Andrew's Triad - triple envelope generator module.
If you combine this with a triple VCO & triple filter module we could do chords.

It might also work well with the NLC Choral Generator.
(I'll build this soon).


Some pics of the unpopulated PCBs
 

Some NLC words of wisdom

Excellent advice


Indeed !

I usually place the ICs first. They are the most fiddly part of the build.


These rectifiers protect your module if you accidently plug it in backwards.

 According to R.G. Keen; Ge gives fuzz (Tayda: A-1716), Si gives buzz (Tayda: A-157) and LEDs give crunch. If you use Ge or Si, you can leave the 10k* resistor at 10k. If you use LEDs, the gain will be too hot so change the 10k* to something in the range of 33k-51k.

Andrew reckons that Ge diodes sound best .
these are 1N34A 1N34 GERMANIUM DIODE DO-7

I don't have any Ge diodes in store and Tayda is out of stock.
But i have plenty of Si diodes .
1N4148 switching signal diodes should be OK.
So I'll use a 10K resistor in the 10K* slot.

Apparently this gives the VCA buzz sound
 

we want BC857s - these are PNP trannies

 
Get the rest of the resistors on


Time for the Caps
 

Waiting on some parts.

To be continued......
Part 2 is here:



Links

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Friday, 2 July 2021

Alesis Andromeda - The Clock, Arpeggiator & Sequencer

 
This is part of my exploration of the Andromeda synth.
It's a wonderful synthesizer, which even after owning it for over 5 years I'm still just scratching the surface of what it can do.
 
Some links to earlier posts:
 
The official manual is really long (as you'd expect) from such a complex synth, so this is my attempt to break things down, into smaller parts for myself. If this helps someone else, that great too. 

I'll constantly add to these posts as I discover more about this wonderful instrument.
 
 
 Tempo Synchronization.
 
The clock module is the A6's internal tempo source.
 
It is a global function that provides global synchronization.
Any A6 function that relies on tempo can get its timing from the Clock. 
 Such functions include the Arp or sequencer. 
 
You can also slave modulation sources such as LFO rates and Envelope stages to the Clock when their timing needs to coincide with a song’s tempo. (Normally however, LFOs and Envelopes have their own rates).

The timing can be steady or variable . The clock ranges from 0.458 BPM to 500BPM.
 
Conversely, you can modulate the Clock’s tempo by an LFO or Envelope or any of the A6’s 71 modulation sources. This is accomplished using SYNC/MOD as described below.
 
The CLOCK module is symetrical.
The left is a mirror of the right.
It's divided into 3 parts:
a) CLOCK settings
b)  ARP
c) SEQUENCER

 CLOCK settings

Turning the centre tempo knob will display this page.

The display shows things like;
Tempo - 0.46 bpm to 500 bpm.
START - normal (Freerunning) vs KEYDN (starts with the first key down)
MODVOX - Tempo Modulation by Voice
MODCHN - In Mix Mode, this parameter determines which Mix Channel will modulate the Clock.
SYNSRC - Selects the sync source- local or external midi
CLKOUT - Selects whether MIDI Clock is sent out the MIDI port. 
                    This is a Global Parameter, so it keeps its setting even after changing Programs or Mixes

 ARPEGGIATOR

The left is the ARP section. Pressing its view button will display the page BELOW.

You can see TRIG, PROGRS, SYN and MOD parameter pages.

Similar to a sequence, an arpeggio is musical term that refers to the playing of notes of a chord one after another instead of playing them simultaneously.
 

Arpeggiator settings are made per Program and stored in memory with each Program.
The A6 Arpeggiator is nearly identical to the Sequencer in its basic design. The main difference lies in the display layout.
 
Also, unlike the Sequencer, the Arpeggiator is a per Voice function rather than a per Program function. This means that each playing voice is linked to its own arpeggiator. This results in 16 possible arpeggiators – one per Voice – each with their own status, position, and voice variables. 

 START/STOP Button 
Enables and disables the Arpeggiator. This is a programmable function for all voices in Programs or Mixes. 
 
 
 
SYNC/MOD 
Button Pressing this button displays the Arpeggiator’s SYNC page on the screen. 

 VIEW Button 
Pressing this button recalls the page of Arpeggiator parameters that was last used (it defaults to the CONFIG page).

SEQUENCER

 The right is the sequencer section. Pressing its view button will display this page.
You will see Graph, Config , TRIG, PROGRS, SYN, MOD, run and step parameter pages
The Sequencer is a per Program function: each of the 128 user Programs can have its own sequence that is saved in memory along with all of its other settings.
The sequencer has 16 steps (labelled A to H and I to P)
(You can only see 8 steps at a time)
Each step has 4 properties: Note, Velocity amt, Gate time, Rest on or off (called TYPE)
 
Press soft button 1 to move between NOTE,VEL,GATE,TYPE.
Press soft button 8 to move from one step to the next.
The soft knobs will change the note values (when you are in the note section).
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NLC - Beat Freq - build notes - part 1


 These are my build notes for the NLC Beat frequency module.
This is a indicator module not an oscillator.

Beat frequency indicators are used to indicate whenever the  frequency of a signal  exceeds a reference frequency.
This module uses LEDs to indicate when the two frequencies match.

"the ring of 4 LEDs would light up in a clockwise or anti-clockwise direction. The speed of rotation would indicate how close or disparate the frequencies are. If the signals have the same frequency then just one LED is lit."







Some pics of the virgin PCBs

I'm not exactly sure how I'll use this.
As far as I understand it takes 2 incoming signals, then spits out CV or audio???
plus XNOR of the 2 signals and gates to give a ring modulator effect.

The two inputs can be either audio or clock (LFO) rates.

Maybe I'll feed it with some VCOs and use the outputted CVs and gates to control a filter and some drums. ???














 
 
 
 
 
 
 
 
 
 
This is version 4 of the PCB, .... its missing a trace, so a wire will need to be added if you want 5V gates. If you can’t be bothered it just means one of your gate out signals will be 10V rather than 5V.

I personally like 10V gates. So I may keep this as is.

I always start with the ICs first.

We need one of each of these
4555 1 soic Mouser: 595-CD4555BNSR 
40193 1 Soic Mouser: 595-CD40193BNSR 
4070 1 Soic Mouser: 595-CD4070BM96

The CD4555 is a CMOS decoder/demultiplexer.

The CD40193 is a up/down binary counter.


The CD4070 is a  Quad Exclusive-OR Gate.


power rectifier diode
821-S1JL

BC847
there are six of these

 
Two diodes
LL4148
 


Links
+ BOM

To be continued.................

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Thursday, 1 July 2021

Port Arthur - Tasmania

 Some Pics of Port Arthur in Tasmania.
 

It's a beautiful place in the world, however it's past is coloured with much pain and suffering.

The Island of the Dead, Port Arthur cemetery.

 

Sitting on the Tasman Peninsula, it was a 19th-century penal settlement and is now an open-air museum. Ruins include the huge penitentiary and the remaining shell of the Convict Church, which was built by inmates. 
 

over 30 buildings and ruins to explore.
 

It is worth contemplating that the inmates of this huge prison had spent three months on cramped boats traveling to at that time must have seemed like the end of the world.
 


 

The centrepiece building at Port Arthur is The Penitentiary. 
This was originally built as a flour mill and granary in 1843, however in 1857 it was converted into a penitentiary. It housed 480 convicts. 
 

The building is now just a shell. It was destroyed by fire in 1897. 
 

The Asylum was built in 1868.
 
 


Port Arthur Court House





These are pics of Port Arthur village.


The old convict church. It's unnamed.
Built 1836/7