Filters V : A-120 24 dB/Oct Low Pass Moog Style Filter VCF1

Perhaps the best known low-pass filter in analogue synthesis was developed by Dr Robert (Bob) Moog in the late sixties.

It was used in the modular Moog synthesisers of that decade, but it got really popular in 1970 with the introduction of the Minimoog.

Moog's 4-pole filter is built with a co-called "transistor ladder" design with a cut-off slope of -24 dB/octave. That’s what gives it its classic, legendary Moog sound.
 Resonance is adjustable all the way up to self-oscillation - in which case the filter behaves like a sine wave oscillator.

The Doepfer A-120 is a very nice Moog emulator, but still most reviews say it doesn't sound 'Moogy' enough.
( i sadly don't have a real Moog to compare and verify that )
Moog's original circuit was flawed because it exhibited a small amount of distortion. Many engineers would have tried to correct this but Moog didn't.
He probably found that the sound was musically pleasing and he was probably right...
Maybe this module just sounds a bit 'too clean'.
It does still have a warm character, and it sounds very impressive in my opinion.
( and definitely unlike any of my other filters ).

Whenever i hear the name Moog i mainly think of great (Minimoog) synth-lead solo's or hand-played fat basslines, but you can also use this filter for wobbly dub-step basslines, sequenced loops and other (housey) basslines.

An interesting and more in-depth study on the Analysis of the Moog Transistor Ladder and Derivative Filters can be found in this PDF by dr. Timothy E. Stinchcombe.

Video : Doepfer A-120 (Moog) Low Pass Filter Demo by NetPierre

" Doepfer A-120 (Moog) Low Pass Filter Demo by NetPierre
created for my blog at http://PatchPierre.blogspot.com
A simple sawtooth wave from my A-110 into Audio in.
An envelope generator signal is sent into CV2, and some noise from the A-118 is fed into CV3.
Drums are provided by an Elektron Machinedrum "

My Main Live Configuration

An interesting topic popped up on the A-100 Facebook Group recently;
" How do you guys trigger your analogue synths sounds on live gigs? "
I do change my setup from time to time, but i do have some kind of basic setup for my live-sets and jams.
I have a total of 5 VCO's in my A-100 system, and i try hard to get the most out of it every time i play.

 Elektron SPS-1 Machinedrum

At the heart of my setup there is a drum-section, consisting of a Roland R-8 and an Elektron SPS-1 Machinedrum. The Electron is a perfect machine with plenty of  electronic drum sounds, i use the R-8 for the more 'organic' drumsounds.

MSY-2 MIDI-to-SYNC Converter

Synchronizing over MIDI is controlled by the R-8, through the Machinedrum and through a Doepfer MSY-2 MIDI-to-SYNC converter straight into the MAQ 16/3 Sequencer.
The MSY-2 is used to keep my TB-303 basslines in sync with the rest.
I also use the CV and Gate outputs from the TB, i get back on this later.

The MAQ 16/3 is Doepfer's MIDI Analog Sequencer.
It has 3 sequencer rows of 16 steps with Gate and CV outputs, i mainly use the top 2 rows for programming loops and basslines. From the MAQ 16/3 it all turns analog and goes right into my A-100 system.

MAQ 16/3 main controls

Row 1: main row, usually a 16 step pattern;
The  first row's CV goes through an A-180 multiple into two separate A-110 VCO's (with sometimes a slight de-tuning involved )
I often turn one of the VCO's 3 or 4 octaves up and send one of its output waves through an A-115 Audio Divider to add some extra (sub) bass.
These layers all mixed together with an A-138 mixer can be send from here to any other kind of filter or effect module, ending in an A-130 VCA somewhere.
The first row's Gate signal goes into input 1 of my A-143-2 Quad ADSR, that contains 4 independent ADSR-type envelope generators.
Gate input 1 is automatically connected to the switching contacts of the Gate input sockets 2, so from that single input i can retrieve 2 different envelopes.
One of them is sent to a VCA, the other one often goes to a CV 2 input of one of my filters.
That is basically my first (sequenced) A-100 Audio-source #1.

Row 2: Usually 6, but sometimes even 3, 8 or 12 steps long;
The CV signal from the MAQ's second row goes straight into my third VCO.
One or multiple waveforms can be sent from there and used for various different purposes, filters etc... coming together in A-130 VCA nr 2
Gate 2 goes into the third input channel of the Quad ADSR, i split up this with another multiple so i have 4 identical envelopes for use in the rest of my system. One of them goes to VCA nr. 2
So that's my second (sequenced) A-100 Audio-source #2.

VCO 4 is controlled by the CV coming from my (synced) TB-303.
The 303's gate signal triggers an ADSR for another A-130 VCA envelope.
I can send this audio-signal through all sorts of modules, resulting in A-100 audio-source #3

My 5th VCO ( and my only A-111 High End VCO ) is used for my solo's.
With an A-182-1 Switched Multiples i can easily switch between my MIDI masterkeyboard or my A-198 Ribbon Controller.
More info on this in detail HERE.
The Ribbon Controller CV goes into my A-156 Quantizer and an A-170 Slew Limiter for easier playing and a nice glide effect, as blogged HERE.
The Gate signal from my MAQ's row 3 (max. 16 steps or pauses) is sent to the 4th input of the Quad ADSR.
I like using this programmed (almost arpeggio-like) envelope to open a filter or amplifier with this, watch the video to see what i mean by that.
I have plenty options to do whatever i want with the wave-forms from this 5th VCO, but I like to keep the sawtooth wave for the A-129 Vocoder.
I guess that makes up audiosources #4 (vocoder) and #5 ( the VCO ) then...

What i did not mention here are the various other mixers and multiples used, the added noise, filters and LFO etcetera, but i hope you understand this is just the basic configuration of my A-100.

Video: Just me... and the Music take 1, an older jam by myself (from YouTube)


" Live Electronic Jam by NetPierre.NL feat. Doepfer A100 + Ribbon Controller, TB303, Machinedrum and effects, no post-production, and sadly no compession ) "

A-110 VCO Tutorials from Raul Pena

Raul Pena, who already brought us the A-188-1 BBD tutorials, recently published six new video tutorials.
This time the focus is on the A110 VCO:

Video 1 : Doepfer A110 Features and Functions
http://www.youtube.com/watch?v=E2BV4iYBpOY

" Explanation of Features and Functions of the Doepfer A-110 Standard VCO Module.

Next in this series Audio Demonstration of Waveforms and Pulse Width Modulation.Sound and Video by Raul Pena. "


More video after the break:

SiteTip V : PatchPierre Facebook Page

Time for a shameless self-promotion post;

In case you didn't know already, the PatchPierre Facebook Page is live since the end of august.
Feel free to follow me there too for the latest blog updates, extra video's, links and (perhaps) more in-depth information and discussions.

You will also find my modification pictures, neatly organized in a special Module Modification Folder. More pictures will be posted soon...

If you have questions, suggestions or other remarks you may also post them on my Facebook page.
( Your comments on the blogposts below are still welcome too )

Find it HERE

A-188-I BBD Tutorials by Raul Pena

Module A-188-1 is a so-called Bucket Brigade Device module.

A BBD circuit can be regarded as a chain of Sample&Hold units (S&H) which pass on their voltages to the next S&H in the chain at each clock pulse.
From this also the name Bucket Brigade Device is derived as each stage of the BBD can be treated as a bucket.

The sounds generated by module A-188-1 are very special. 

Typical applications for this module are: Flanger, Chorus, Analog Delay or Karplus/Strong synthesis.

Writing a post about the BBD has been on my list for a long time.
I own a 1024 stages version since the year it was released and i like it a lot.

The difficulty that i had was that it was pretty hard for me to understand all functions of this module completely, and than also have to write an explanatory post about it in English, which is not my native language...

I am very glad that Raul Pena (from http://raulsworldofsynths.com/) took the time and recently made some very interesting tutorial-video's explaining the whole A-188 in detail. 

This set of YouTube video's show you all the secrets of the module, with clear narration and pro sound-examples. Make sure you have some time, because in total this 4-part tutorial is longer than an hour (!)

Video 1: Doepfer A-188-1 BBD basics
http://www.youtube.com/watch?v=G8fKvbutgds
"Overview of functions and features of the Doepfer A188-1 BBD Delay module.
Video, voice, and sound by Raul Pena."

A-166 Dual Logic Module

" A Logic Gate is an idealized or physical device implementing a Boolean function.
It performs a logical operation on one or more logic inputs and produces a single logic output. Logic gates are primarily implemented using diodes or transistors acting as electronic switches. "

The A-166 Dual Logic Module is a double logic device that combines digital control / clock signals.
A typical application of this module is the combination of digital signals of the A-100 gates, clocks and triggers to obtain "gated" clocks or rhythmic clock patterns.

It contains 2 identical units with 3 inputs for each unit.
The logical states of the inputs ("1" = high / "0" = low) are linked together in 3 ways: AND, OR, EXOR (exclusive OR).
The input sockets of each triple unit are "normalized", i.e. the switched contact of socket 2 is connected to input 1 and the switched contact of socket 3 is connected to input 2.
The three functions are available simultaneously at three outputs with LED display of the output states.

Additionally two separate inverters ( like the A-165  ) are available that are very useful.
These can even be used to invert a signal before it is fed into one of the two logical units.
All other outputs can be fed back to the module's inputs also... in that way you can create very nice and very complex rhythmic triggers.

More on Logic Gates on Wikipedia

...and on Whatis.com

Quick Tip VII : Battery Check

In the A-112 VC Sampler /Wavetable Oscillator and some other devices rechargeable batteries (accumulators) are used for memory backup of preset data.
These electronic parts have a limited lifespan and have to be inspected at least every two years.

A-112 VC Sampler /Wavetable
Oscillator battery

Before the inspection the device has to be disconnected from mains voltage !
If the battery has a leak or if the measured voltage of the battery differs more than 10% from the target voltage the battery has to be replaced.
The target voltage (2.4V or 3.6V) and is printed on the battery.
The replacement should be carried out by qualified personnel only. 
The old battery has to be removed (desoldered) and the new one put in (soldered).
If you are able to carry out the replacement yourself you can purchase the rechargeable battery as a spare part from a supplier in your country. Any other rechargeable battery with the same voltage (e.g. 3.6V) can be used provided that it fits mechanically.

It is not allowed to put the old battery in the normal garbage. Please forward the old battery for recycling to a suitable receiving office.

The following Doepfer devices are (or have been) equipped with a rechargeable battery for memory backup:
2.4V rechargeable battery: LMK3/LMK3+
3.6V rechargeable battery, grid 10 x 20 mm.:
used in d3c, MCV24, A-112 VC Sampler /Wavetable Oscillator, Schaltwerk and Regelwerk.
Available e.g. from GP (3GP-60) or Varta (3/V80H), in Germany e.g. from www.reichelt.de (order no. 3GP-60), in USA from www.mouser.com (order no. Varta 3/V80H / 672-55608303059)

More info HERE