Wednesday, December 28, 2011

Quick Tip IX : A-119 As a Clock Generator

A quick tip that i 'borrowed' from the Yahoo Doepfer A-100 User Group is this next one:

It could happen that you run out of MIDI or other signal-converters to synchronize your A-100 system.
If you have a free channel out on your soundcard you can use the A-119 Ext. Input / Envelope Follower to produce some kind of clock signal as an alternative.

To do this you should create a channel in your favorite sequencer/ sampler/ sound-card that sends out 16th notes of some short sounds like a rim-shot, snare,claves or woodblock for example.
The A-119 can simply turn this audio-signal into a (steady) gate signal, which can be multiplied/divided and used throughout your A-100 system.

Saturday, December 24, 2011

Merry Christmas from PatchPierre

PatchPierre wishes all the regular and occasional readers of my blog a very merry Christmas!
I am having a little writing-break these days, so here's an old video this time;

Usually i am not a huge fan of those free-running modular synth- patches, especially the noisey ones, but this video (by YouTube user belempa1) definitely has some musical value... and ehhh what a nice rack! ;-)

Video: Doepfer Monster Modular 2

" This is a patch that i always wanted, a dreamy sound like that from Tangerine Dream or Klaus Schulze.
A single oscillator; Audio Frequency Generator Livewire, has a strong personality and the quality is superb.
The A-149-1 and 2 Doepfer, which incorporates some features of the "Source of Uncertainty" by Don Buchla, are the essential elements of this patch. This patch in a loop without any external effect." *

roughly translated

Wednesday, December 21, 2011

A-132 Dual VCA

Module A-132-1 Dual Low Cost VCA contains two simple voltage controlled amplifiers, each with a linear response.
They are most suitable for controlling the level of all kinds of control voltages like LFO or ADSR amount,  Joystick or Wheels voltage etc.

In non-critical situations though, these VCAs can also be used to control audio signals, and i have to say it still sounds pretty good; audio controlled by an ADSR or Ribbon voltage through this module.
Amplification is controlled by the sum of the voltages patched into the two CV inputs.

Although these 'Dual' modules are small and don't have many other controls (like knobs or switches), they are very useful low-cost solutions for your amplification needs...

They are cheaper (two-for-the-price-of-one) than the A-130/131 VCA's so you could consider using one of these in your next setup if you are on a budget or want to spare valuable rack-space...

Saturday, December 17, 2011

CD-Tip VI : More Electronic Music by Badings - Henk Badings

Henk Badings is still pretty unknown to a lot of us, but he was a classical-schooled Dutch composer/ engineer who was born in 1907 and passed away in 1987.

He had been composing since his youth, but after the 2nd World War he discovered (early) electronic and tape-music.
From 1956 until 1963 he worked with other Dutch electronic music pioneers like Dick Raaijmakers (who declined Stanley Kubrick's request to make the Clockwork Orange soundtrack)  en Tom Dissevelt in the acclaimed Philips NatLab.

He has written symphonies, concerto's, electronic and film music in his life, but this 2CD-set contains 5 of his most important electronic works.
Did they already "partly cover Badings' Electronic Music on the Popular Electronics Boxset (Basta 3091412), here's the best of the rest, to say so" (so not containing tracks that were already on THESE CD's that i reviewed earlier)

Fans that like Wendy Carlos, other NatLab CD's that i posted and such will probably like this collection of weird and sometimes dreamy, well composed soundscapes and even the more progressive electronic poetry-slam track "Dialogues for Man and Machine" with lyrics by Dutch singer/poet Ramses Shaffy

  Capriccio (1959) for violin and 2 sound tracks - Henk Badings by Basta Music

More info and tracklisting HERE
Published by Basta Music
Cat. Nr.: 3091 722
A more comprehensive list of all his works can be found HERE (in Dutch)
- also see

Wednesday, December 14, 2011

Raul Pena's 12 Days of Modular (Complete Playlist)

Raul Pena just finished a new video series for the upcoming holidays.
It's called the 12 days of Modular, so he posted one video a day for 12 days,
themed around Modular Synthesis and sound.
Very nice demonstrations of Sound Sources and Modulation, accompanied by waveform views.
"Good for seeing wave-forms, annoying the neighbors, or lots of other uses."
No talking, just sound. Sound and Video by Raul Pena

As always feel free to leave feedback (on his YouTube playlist, not here...)

Full Playlist : 12 Days of Modular / Parts 1 - 12 /
                                      Total length 29 minutes and 36 seconds

Please take some time to fill out Raul's short survey regarding information, suggestions for future videos. 
(no sales or money involved) 

Just information that will help guide the interest/content of the videos.

Sunday, December 11, 2011

150th PatchPierre Post

Woooooot! ...all over again. :-)
My 150th post already, who would have thought that?
I didn't expect to still be able to post every 3 to 4 days, because i thought there wasn't much to blog about anymore, but it looks like i was wrong...
Okay, my posts are not always very long and pretty basic (so far), but that is the whole point of this blog; 'basic A-100 -news, -tips, -patches, sound-examples and other general (Eurorack analog modular) synthesizer info', for all modular synthesizer enthusiasts...

I found a good schedule to write now; when i am in the mood, a good part of my Sunday afternoons is spent on writing 2 or 3 posts and if there is any news (new video's / news from the forums / new thoughts) i try to fit them in between the 'regular' posting schedule.

The traffic-numbers are still going up, but slowly; I expect to reach 3000 page-views this or next month (was around 1700 last May, at the moment of my 100th post, and around 1000 in October last year).
The visitors come from 102 different counties, and it feels like my blog is slowly changing into some kind of Doepfer A-100 archive, which is also very cool.
I hope my numbers will keep on growing, but i'm not yet sure how to do that and where i could promote my site some more.
If you have an idea on how i could do this feel free to let me know, and feel free to let the whole world know about my blog... of course...
Spam it where you can ;-)

I must say i was very pleased to see Raul Pena's amazing A-100 tutorial video's popping up this summer.
Great video's that were very informative and clearer than i could ever have written for you in English.
It did save me the time to write about some hard to explain modules, like the A-188 for example...
Also check out his 12 days of Modular series HERE

So what can you expect in my next 50 posts?
I haven't even written about all the modules that i own, so you will see a bit more of that, even some more short reviews of the simple basic modules.
Sadly i don't have a big budget to invest in new modules at the moment.
A few more synth-books are on my book-shelf that i will write about.

Starting next year the CD-Tip section of the blog will include some more 'classic synthesizer albums', instead of the how-to-, sample- and more off-beat CD-tips i posted so far.
Although i am not a professional CD-reviewer i would like to let you know what CD's i find worth listening to.
Think of 70's and early 80's albums like "Cyborg" by Klaus Schulze, "Switched on Bach" by Wendy Carlos and Tomita's "Pictures at an Exhibition" or "The Planets".
I guess i should not name more now, but if you have any suggestions please leave a comment below.

Thank you all again for your feedback / re-tweets / +1's and Facebook likes so far.
I'm looking forward to write my next 50 posts...

(also check my 50th post from December 7, 2010,
                                          and my 100th post from May 22, 2011)

Wednesday, December 07, 2011

Booktip XI - Das grosse Buch zum A-110 Modular Synthesizer (in German Language)

A very interesting book by Andreas Krebs is almost out... although it is (still) only available in the German language.
The author has been working with analog (and other) synthesizers for around 30 years and has already written and maintained a pretty impressive blog.
His " Big Book to the Doepfer A-100 Modular-Synthesizer" will be available at the end of 2011/Now

In 320 pages he systematically goes through the most interesting modules in full detail and suggests unusual patches from his 'trick-book'
The book, illustrated with over 400 images, is nice for starters and also very interesting for the more advanced users.
Check out the table of contents HERE (pdf) and some preview pages HERE (pdf)

It is confirmed that an English version of this book is also in the making, but i guess it will take some time before that will be released...
I think i'll just wait for the English version...

Release date : early December 2011
Price: Euro 29,90 € plus shipping
Find more info and ordering details at:
German version available via Doepfer in early 2012

Sunday, December 04, 2011

A-130 + A-131 Voltage Controlled Amplifiers

A Voltage Controlled Amplifier ( VCA or variable-gain amplifier) is an electronic amplifier that varies its gain depending on an incoming control voltage (or CV).
It is one of the most basic building blocks for a modular synthesizer.
Find more on this on Wikipedia.
Modules A-130 and A-131 are very simple VCA's that can be found in most basic Doepfer systems.

For audio signals, you would normally use the exponential VCA (A-131), and for control voltages the linear VCA (A-130), but it doesn't always have to be that way, though.

The amount of amplification of the VCAs is determined by the voltage at the CV input and the position of the gain control, which sets the overall gain in the system.
The VCA has two audio inputs, each with an attenuator.
They are amplified by the combination of the gain and the two CV controls.

The old versions of A-130/131 (those with CEM3381/CEM3382, which are actually 2 VCA's on one chip*) are not able to process slowly varying control voltages (AC coupled in/output).
The newer versions of A-130/131 (those with CA3080) are able to process even slowly varying control voltages (DC coupled in/outputs).

*it might be worth investigating these a bit more for a future DIY treatment

Thursday, December 01, 2011

Most Wanted Update - MSY2 Module for A-100 System

Old Version of the MSY2,
the newer ones are in black
Great news...

It looks like the idea that i posted in December 2010 for some kind of extended version of an MSY2 module for the A-100 wasn't that bad.

In the Yahoo Doepfer A-100 Usergroup Dieter Doepfer recently announced that they "...are working on a modular version of the MSY2 with some additional features ( USB interface, several outputs with different clock dividing factors and polarity and some more )."

The MSY2 MIDI-to-SYNC/Clock Interface can be used to convert Midi clock into analog clock signals.

There is no release date or price available so far.

Monday, November 28, 2011

A-138 Linear/Exponential Mixer

Module A-138 is a simple four channel mixer that can be used for either control voltages or audio signals. (although i hardly ever use one for CV)
Each of the four inputs has an attenuator, and a master attenuator, so that the mixer can be used to interface directly with an external mixer, amplifier, etc.

There are two versions of this module:
A-138 a: potentiometers with linear response, especially suitable for control voltage mixing.
A-138 b: potentiometers with logarithmic/exponential response, especially suitable for audio signal mixing.

The latest version from April 2004 is an improved version of the module A-138b.
For the revised versions control In1 works as a DC offset generator (about 0...+5V) provided that no patch cord is plugged into socket In1.
If this feature is not required it can be deactivated by removing a jumper on the pc board.
In the summer 2004 the A-138a was introduced with this improvement.

In the summer of 2007 Doepfer also released a mix expander module A-138x, that increased the number of inputs of the A-138 by five.
That module was discontinued last year...

Friday, November 25, 2011

Sample and Hold with Doepfer A148 by Raul Pena

Raul Pena from just posted a few new video tutorials.
Here are the first six (of seven!) in a series dedicated to Sample and Hold,Track and Hold, and comparisons with the two.

Video 1 : Track and Hold Vs. Sample and Hold with Doepfer A148 S/H

" Demonstration comparing Track and Hold with Sample and Hold using the Doepfer A148.Sound and Video by Raul Pena."

All other A-148 video's after the break

Thursday, November 24, 2011

Most Wanted VI - Special Vocoder MIDI-interface

I read the following text on one of Doepfer's A-129 vocoder system pages a long time ago, but it is still on Doepfer's website;

" A special MIDI-interface for the vocoder system is planned.
The basic functions are a 16-way CV-to-MIDI interface and a 16-way MIDI-to-CV interface (way 16 will be used for other functions like controlling slew-rate or voiced/unvoiced).
The CV-to-MIDI section converts the CV outputs of vocoder analysis into MIDI controllers which may be recorded by a computer sequencer. 
The MIDI-to-CV section converts incoming MIDI controller information into CV's for the vocoder synthesis section. 
Additionally we plan to store some factory and user definable 'vocals' in the MIDI interface so that you may call up complete vocals (like 'a', 'e', 'o', 's', 'sh' and so on) by MIDI program change events (may be we use another MIDI event type for this purpose). 
Thus the vocoder system will become a universal MIDI controlled filter system not limited to the standard vocoder features. "

Okay, i must say that it all sounds impressive and also very useful.
I do hope this module will be taken into production, but i believe this has been
on Doepfer's webpage for a while now, which makes me think that this module will probably never be made.
It might be in the Universal 12 bit AD-processor-DA module plans, because these things do need some processing power but i'm not so sure about that...
With all the announced features you could imagine this would not be a cheap module to make, but we'll see though...

Find more of my 'Most Wanted' posts HERE

Monday, November 21, 2011

Wooden Ribbon Controller Project Part 2

My project is going great so far.
Most of the woodwork seems to be finished.
I carved out the whole  59.7 x  2.4 cm. strip where the fingerboard should come, about 3 mm deep across the whole surface.
I carved a bit too deep at places, but i will fill that up a bit with filler, so that should turn out fine.
The pressure sensor needs a flat surface, so that needs a little bit of extra attention.

I painted the wood 4 times now, with a glossy mahogany varnish, and it looks quite amazing IMHO...
It will get one last layer of varnish after the final assembly of the whole project
I screwed an iron ring at the top (but that might become an brassy one), and i am planning to screw one at the bottom for  attaching a shoulderband.

I changed my mind a bit about the old fingerboard that i wanted to use, but i will order a new pressure-board from Doepfer next week.
I also need to find a smaller piece of wood that can cover up the USB-connector or find another good way to hide the connections.

That does mean i have to wait a few weeks before i can take the last steps and finish the whole project.
I will keep you updated...

Friday, November 18, 2011

A-146 LFO2

Module A-146 (LFO 2) is a Low Frequency Oscillator, which produces periodic control voltages over a wide range of frequencies.
The LFO can be used as a modulation source for a series of modules (for example pulse width and/or frequency modulation of a VCO, modulation of a VCF cut-off frequency or amplitude modulation with a VCA).

It is quite different from the A-145 and A-147, that i discussed earlier HERE

Three outputs are available, with different waveforms: sawtooth / triangle; square wave, and positive-voltage square wave.
The waveforms are continuously adjustable from rising sawtooth, through triangle to falling sawtooth.
The same control affects the pulse width of the square wave.
A three-way switch can select one of three frequency ranges, spanning from one cycle every few minutes, at the lowest, up to audio frequency at the highest.

A nice LFO, but i don't own one myself... yet.
Too bad it has no CV input  and that it doesn't have a reset input...

More on waveforms:
also see Wikipedia for more indepth info on the different wave-forms:
Pulse wave             Sawtooth wave
Sine wave               Square wave
Triangle wave

Tuesday, November 15, 2011

Wooden Ribbon Controller Project Part 1

Today I decided to pick up an old idea that i had for a long time.
Whenever i play the Ribbon Controller, i tend to hold it like a guitar, not like most do on a tabletop surface.

I have always loved the combination of wooden elements and synthesizers.
This combination was/is still very popular since the early 1970's.
Look at all those (Mini)Moogs and many other synths with wooden side-panels for example...
That is why i also decided to make my Ribbon Controller out of wood.
It looks like a found a nice solution to an earlier project too.

So today i bought myself a nice piece of wood in the local woodshop.
On forehand i had the idea that the handle of an axe might be the kind of thing that i needed.
They had a few different sizes, but i found a hardwood unpainted axe hande that was 90 centimeters (3ft.) long and perfectly shaped and curved.
I might make it a bit shorter later, but for now this will do just fine.

I dismantled my old Ribbon Controler (i do own another one, the newer version) and drawn out the shape of it on the axe handle. I used 3 screws to fixate the fingerboard while doing that.
Next up is the carving... i want to sink the fingerboard into the handle, but that means i need to carve at least half a centimeter deep.

I already carved the first bit like the last picture shows, but i still have a long way to carve.
But i need to get myself a new chisel now so you will have to wait how this project will continue.
I will keep you updated... but don't expect this to be finished before 2012.

Sunday, November 13, 2011

Ribbon Controller versions

Ribbon controllers, old model on top
One of the most used parts of my modular setup is without doubt my A-198 Ribbon controller.
You can read all i ever wrote about it so far HERE.
I love improvising with the manual controller and the sensitivity of the manual makes it fun to play with.

In combination with the A-156 Dual Quantizer and a A-170 Dual Slew Limiter it is quite easy to play, even for beginners.*
Together with and the different scales that are available on the A-156 you can make your ribbon-sliding-skills sound very impressive.
* I should note that is also easier to play the Theremin modules using these two modules.

From 2005 the A-198 (and R2M) manuals are equipped with an even more sensible pressure sensor.
The improved sensor now works along the entire manual.
So how can we distinguish these two models?
The newer version is white on top, instead of the greenish grey color of the old model's touch-surface.
The new version also does not have the text 'A-198' printed on it.

Ribbon controllers, new version at the bottom. Note; the orange stickers are not standard

The Doepfer R2M (Ribbon-to-Midi) is the stand-alone version of the A-198 with MIDI and CV/Gate outputs. R2M offers a lot more features than the A-198 (e.g. quantizing, gate function even in the hold mode, inverse scaling and many more)

Currently from June 2011 the cases have changed from silvergrey with black printing to black with white printing... also very slick...

Tuesday, November 08, 2011

Doepfer A118 Filtering with A120 VCF Low Pass Filter

More Video from Raul Pena (of
This time almost 45 minutes long tutorials on using the A-118 Noise/ Random Voltage Generator in combination with the A-120 Moog Style Low Pass Filter... creating some interesting wind-effects...

Video 1 : Doepfer A118 Filtering with A120 VCF Low Pass Filter

" Part One Discussing the features of the Doepfer A188 Noise and Random Voltage Source module. Followed by a Demonstration of Filtering white and Colored Noise with the Doepfer A120 VCF Low Pass Filter. Sound and Video by Raul Pena. "

Video 2 : Doepfer A118 Filtering with A120 VCF Low Pass Filter Part Two

"Part Two Ongoing Demonstration of Filtering white and Colored Noise from the A118 Noise module with the Doepfer A120 VCF Low Pass Filter. Modulation Capabilities also explored with A147 VC LFO and A145 LFO. Sound and Video by Raul Pena."

Read more on the A-118 HERE
Read more on the A-120 HERE

Friday, November 04, 2011

Special Designs

Don't go calling or emailing Doepfer right away,
but if DIY-ing is not your thing you might find this next thing interesting:

" In principle Doepfer is able to make special designs, but most customers underestimate the time and consequently the costs for a special design.
Normally there are three steps for a custom design:

Development of the hardware (provided that none of their existing hardware products can be used), development of the software (provided that the design includes a microcontroller) and design of the mechanics (e.g. controls, housing, provided that the customers is not able to built his own case).

The hardware and software design is carried out at Doepfer, i.e. design of the schematics, PCB layout and software.
All mechanical parts of the design - i.e. PCB manufacturing, housing, treatement of the housing like drilling holes, milling slits, varnishing, printing and so on - is carried out by other companies specialized in such things.
Doepfer has no mechanical working place in their company.
The main problem for a special design is that all nonrecurring costs - i.e. design of schematics, pcb layout, programming the software, initial charges for the pcb manufacture, case/housing production and silk-screen printing - have to be payed by one customer only.

Even for a small design these nonrecurring costs reach the few thousands Euro range.
Normally these charges are divided by the number of devices that are manufactured (a few hundred or thousands as a rule).
Please keep in mind all these notes if you ask for a special design.
If you are willing to pay for all these steps of work they might make a quotation for you. "

from the Doepfer FAQ page

Tuesday, November 01, 2011

A-140 ADSR Envelope Generator

Perhaps i should have started my whole PatchPierre blog with writing about the most basic and essential A-100 modules first.

How the four parameters A, D, S and R
change the shape of an ADSR envelope
The A-140, Doepfer's envelope generator was released back in 1995/96, and was one the first modules available.
It is a simple ADSR (Attack, Decay, Sustain, Release) generator.
When this module is triggered it generates a variable voltage, changing in time, called an envelope.

The shape of the envelope is set by four variable parameters: Attack, Decay, Sustain and Release.
The envelope is started (triggered) by a gate signal either from the internal gate voltage on the system bus or, if a signal is put into it, from the gate input socket.

The varying voltage (visualized by an LED) is output in normal (positive) and inverted form, and can be used for all kinds of voltage controlled modulation of any VCO, VCF,  VCA or other CV controlled inputs.
The envelope can also be re-triggered, but that only works when the gate is opened.
The module  has a three-position toggle switch between three time ranges.
The envelope time can be set from about 50 microseconds up to several minutes.

Okay... There's not much extra to write about this elementary module, although i do like the inverted output (plus that it has two 'normal' outputs).
I should say that there are more economicly priced other envelope generators available.
My advice is to get yourself one of the Quad envelope generators for example... if your modular gets bigger you will probably need more EG's anyway.
I do have the four-fold A-143-2 Quad ADSR, but the A-143-1 Quad AD with only Attack and Decay, or perhaps the A-142-4 Quad Decay with just decay are just a few of the other options if you are looking for expanding your modular with basic EG's...

Friday, October 28, 2011

Doepfer A110 Filtering Demo's with A-101-2 and A-120 by Raul Pena

Raul Pena ( from ) made another excellent set of tutorial videos.
This time it is all about filtering; In a few episodes he explores all functions of the A-101-2 Vactrol Low Pass Gate filter, in comparison with the A-120 Low Pass Moog-style filter.
Very interesting stuff again...

Video 1: Doepfer A110 Filtering with A101-2 and A120 Intro
" Short Introduction into Filtering the Doepfer A110 Standard VCO. Dicusses Features and Functions of the Doepfer A101-2 Low Pass Gate and A120 VCF Low Pass Filter.Sound and Video by Raul Pena. "

Video 2: Doepfer A110 Filtering with A101-2 Low Pass Gate
" Demonstration of the Filtering of the Doepfer A110 VCO with an A101-2 Low Pass Gate. Next More Filtering with the A101-2 Low Pass Gate."

More video after the break -

Thursday, October 27, 2011

Hardcore Modding the A-182-1 Switched Multiples

I must admit i am not a very sophisticated modifier / solderer.
I don't have an electronic background, find it hard to concentrate at times, and i can easily lose my patience when i'm working on stuff.
I am quickly satisfied with the modifications that i do, as long as my projects look good on the outside and are safe (i.e. no loose wires inside that can cause short-circuiting etc.)

A good example of my somewhat rude approach is my A-182-1 Switched Multiples modification.

Originally this module is a simple passive multi-connector similar to the A-180 Multiples module.
In the A-182-1 each socket is equipped with a 3-position switch that allows to connect the corresponding socket to the internal bus #1 (left position), bus #2 (right position) or to turn the socket off (center position).

A-182-1 Modification detail
I wisely decided to split up the A-182-1 into a 2 x 4 Multiplier, like i did with my A-180 because I found this this modification very handy.

I can now use my modified A-182-1 Switched Multiple for quick switching between my keyboard ( via MIDI ) and my A-198 Ribbon Controller.
For this i split up the Multiple in two halves, the upper half controls the Gate, the lower half controls the pitch ( CV )
More info on this HERE

Okay... I know i could have scraped of some of the wires on the PCB to do this modification, but i wasn't completely sure if that would be enough. To be sure that there were no other connections i just took a junior hacksaw and cut the whole PCB in half. 
As this is a passive module (not connected to the busboard) i thought my mod could hardly go wrong with this.
It might be a bit rude perhaps, but it works!

Sunday, October 23, 2011

SiteTip VI : MIT Open Courseware Music and Technology: Algorithmic and Generative Music

It's kinda weird that, if you search well, there are 2 Music and Technology Courses on the site of the Massachusetts Institute of Technology (MIT) with the same course number (21M.380).

I blogged about one earlier (Contemporary History and Aesthetics, find the blogpost with an interesting 80-minute video HERE) and i am still very enthusiastic about it, but the other one is also very informative.

This course, Algorithmic and Generative Music, as taught in spring 2010 by Christopher Ariza examined " ...the history, techniques, and aesthetics of mechanical and computer-aided approaches to algorithmic music composition and generative music systems. Through creative hands-on projects, readings, listening assignments, and lectures, students will explore a variety of historical and contemporary approaches. "

Surfing through the pages of this course you will find a lot of interesting information on (analog) sound, music history and much more, again accompanied by many links to other interesting reads and audio-examples.

Find the course homepage HERE
Download the lecture notes HERE ( 11.8 Mb PDF )
Full course Materials can be downloaded from HERE

Licence info:
Ariza, Christopher. 21M.380 Music and Technology: Algorithmic and Generative Music, Spring 2010. (Massachusetts Institute of Technology: MIT OpenCourseWare), (Accessed 16 Oct, 2011). License: Creative Commons BY-NC-SA

Wednesday, October 19, 2011

A-157 Trigger Sequencer Update

Here's an update on the long-awaited A-157 (or whatever the module-number will be) Trigger Sequencer module.
I wrote about this highly interesting module earlier, you can find that post HERE

This is what Dieter Doepfer's feedback was, when this step-sequencer got mentioned this week in the Doepfer A-100 Usergroup :

A-157 Prototype(s) , as shown at NAMM 2010
" will definitely come !
At present we are waiting for the new PCB prototype with 16 x 8 buttons and LEDs.
Our first plan to use two pc board with 8x8 buttons and LEDs did not work because this would cause a gap between the steps 8 and 9 because of the space required for the PCB connectors.

Our plan is to separate the 16x8 button/LED board from the control unit as it seems that there are two groups of users: those who vote for a simple, easy to use (and soon available) version and those for a "sophisticated" version with additional features (probably with LC display to handle all functions).
The plan for the simple version is to have only two clock/start/stop inputs available (clock #1 for the units 1-4, clock #2 for 5-8) and a simple memory management (similar to the TR808).

For the "sophisticated" version there are plans like independend first/last step for each row, copy and paste functions between rows and memories, right/left shift of complete rows, longer patterns (A, AB, ABCD), maybe intros, fill in's, track programming, more than two clocks and some more.

To handle these additional functions probably an LC display and additional buttons will be necessary.
But this information is very preliminary.
One could use the standard control unit at first and then replace it by the high end version as soon as it is available. "

Tuesday, October 18, 2011

Quick Tip VIII : Mounting the A-174-2 Wheels Module

Please be aware of this when you want to install an A-174-2 Wheels Module in your A-100 rack;

A-174-2 Wheels Module, note the pot on the left
As the potentiometer of the left wheel projects about 10 milimeters beside the rim of the front panel, a 2 or 4 HP blind panel has to be mounted left from the module. "

A-174-2 Sideview

Unless the module left to the A-174-2 has sufficient space in this area of course.Like an A-174-1 Joystick Controlled CV, for example.

None of the A-100 modules that are 4 HP wide fit there...

Saturday, October 15, 2011

Installing the A-100NT5 +5Volts Adapter (old type)

Some of the A-100 modules, for instance the A-113 Subharmonic Generator and MIDI-modules A-190 or A-191, need an extra 5 Volts power supply.
The old way was by doing this with the A-100NT5 5 V supply, but because installing it was 'suitable for qualified personnel only because of electrical safety' Doepfer doesn't sell these adapter anymore.

The 5V power supply needs to be mounted near to the main power input, on the blank upper back panel with four stand-offs, nuts, serrated washers, and bolts. 
Newer back panels (since summer 1999) are already equipped with the 4 mounting holes required for the 5V supply.

If you are considering installing and connecting the A-100NT5, it’s crucial to take note of the following safety instructions:
• The installation and connection of the A-100NT5 must only be carried out by a qualified electrician or technician.
• If no suitable expert is available, the rack must be sent to a service centre or direct to Doepfer Musikelektronik
for the power supply to be fitted.

• Danger! Before installation and connection of the power supply, it is essential that the whole rack is isolated completely from the mains current.

Note: The new A-100 AD5 5 V adapter module can simply be plugged into a free socket on the bus board; The current is taken from the 12V supply! 

Find info on both adapter(s) HERE
Find the full installation instuctions of this adapter in THIS PDF

Monday, October 10, 2011

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
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 "

Wednesday, October 05, 2011

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 ) "

Saturday, October 01, 2011

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
" 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

Tuesday, September 27, 2011

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 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
"Overview of functions and features of the Doepfer A188-1 BBD Delay module.
Video, voice, and sound by Raul Pena."

Saturday, September 24, 2011

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

Sunday, September 18, 2011

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 (order no. 3GP-60), in USA from (order no. Varta 3/V80H / 672-55608303059)

More info HERE

Thursday, September 15, 2011

A-100 Knobs Change

Special announcement from Dieter Doepfer, in the Doepfer Yahoo Usergroup:
Updated Feb. 13, 2012, see below...

" I just wanted inform you that the knob manufacturer (ReAn Sulzer / Switzerland) has stopped the production of the knobs that were used in the A-100, MAQ16/3 and other products. 
We tried to buy the productions tools from ReAn as they are no longer used. But ReAn was not willing to sell the moulds.

We are about to find another manufacturer who is able to produce a copy of the knob but I'm not sure if the copies will look exactly the same. 
I assume that all modules manufactured until end of this year will still be equipped with the original ReAn version of the knobs. 
But from early in 2012 the modules will be delivered little by little with the new knobs. 
We will try to get new knobs that look as close as possible to the old ones but I'm not sure if there may be a small noticeable difference...

...Sorry - but we will try to continue with the A-100 as it is (same knobs,same panels). It's all a matter of taste. 
And if we change to other knobs I'm quite sure that many other customers would complain. 
If someone wants other knobs he may replace the knobs as the 6 mm 18 theeth shaft is a standard. 
From my point of view continuity is important for a product like the A-100 system. 
I would probably change some things if I could put the wheel of history into reverse (but not the knobs, the panels and the printing as I still like them). "

Best wishes
Dieter Doepfer

Update Feb 13, 2012:
" There is still some "fine adjustment" to do (exactly the same "grey", exactly the same width of the marker and so on). 
At first sight the samples of the new knobs look identically but if you compare an old and a new knob next to each other you see some minor differences (grey color and line width). 
But I'm confident that the manufacturer will be able to change these small details."

Monday, September 12, 2011

Booktip X - Onder Stroom by Jacqueline Oskamp (in Dutch Language)

It took me a while to get through this book, but here is finally my long promised book review.
"Onder Stroom" ( the book is in Dutch, "Under Current" might be a fitting English translation ) by Jacqueline Oskamp is a book that tells the history of early Dutch electronic music.
You have probably seen my earlier blogposts on this topic too, if you didn't, HERE's a link.

With 6 portraits of the groundbreaking and/or pioneering Dutch composers like Ton Bruynèl, Dick Raaijmakers, Jan BoermanMichel Waisvisz and others you get an amazing insight on how the Dutch electronic pioneers worked and struggled with electronics, audio, speakers and tapes in a very conservative post-war musical era.

Each in their own way, they were driven by their curiosity, found new ways of sound-creation and explored the spectrum between noise and sound.
Their influence lead to a pretty diverse electronic music scene in the Netherlands; from the pure electronic and almost mathematical approach to the pure tape-music, along with live electronics with orchestras and electro-acoustic setups you could say these early 1950s and 60s were 'our' golden years ( i'm Dutch too).
And that all started for us only half a century ago (!) If you just look around and see what has changed in recording and sounddesign.
I know we were a bit behind on the rest of the world or Europe; Leon ThereminEdgar Varèse and Karlheinz Stockhausen, to name just a few great minds, already paved the way and had also inspired some of our pioneers.

This book is very interesting if you're into this kind of stuff, but also very pleasant to read if you have little or no knowledge of electronics and the techniques at all.
Very impressive is the list at the end with read- and listen-tips, and the book has a section of  8 pages with b/w pictures of the composers, sadly not many pictures of the equipment...

- An interview (VPRO Vrije geluiden / in Dutch) about this book with the writer can be found HERE
/ interview starts after 19 minutes - with music by Dutch artist TokTek
- Read more on the worldwide history of electronic music on Wikipedia HERE

Published in 2011 by Ambo/Anthos
Paperback 251 pages.
Info ( in Dutch ) HERE          ISBN: 9789026323249

Wednesday, September 07, 2011

Bla-Bla Blue LEDs

And again, i have been too busy lately with replacing some red LEDs by blue ones. I believe this was my final batch, but you'll never know...

As i mentioned before on this blog i like those blue LEDs a lot, but some modules weren't available with blue LEDs at the time i bought them.
I'm not considering making my whole A-100 system with blue LEDs, that would be too much, but just a few blue lights make my machine just look sooo cool. (in the dark)

This kind of work also helps me to practice my soldering-skills.
I'm (still) not the best in it, but i am slowly improving... and i do these replacements in less time.

I do not pick my LED-replacements completely at random. Most of my new blue LEDs have a  'deeper' meaning; better see it as a kind of color-coding.
Some of these LEDs need special attention, others sometimes act (slightly) different than the red LEDs next to them, and if there is no direct reason to change a red LED into blue i'll always tend to find one...

Take a look at the new overload LED of my A-126 Voltage Controlled Frequency Shifter ( that is no longer available ) for example. This little LED just screamed for attention every time i used this module.
Earlier i replaced the overload LED of the A-119 External Input, so it seemed logic to replace this one too.

The other LED that i replaced was one of the A-147 Voltage Controlled LFO.
I'm not sure why exactly, but three blinking red lights in a row... Who needs that?
I replaced the middle one, the one that displays the output of the rectangle wave.
It is the only one that does not gradually fade out and in like the other two, it is either on or off, at a CV controlled variable speed...

...I told you I'd find a reason... ;-)

A-147 VCLFO with 1 blue LED
More on replacing LEDs HERE

Friday, September 02, 2011

Filters IV : A-103 18 dB Low Pass TB-303 Filter VCF6

The A-103 18 dB Low Pass filter (VCF6) is Doepfer's own 'TB-303 filter clone' ;
It uses a so-called transistor ladder with a slope of 18 dB/Octave as frequency controlling element.
It is very similar to the transistor ladder of the A-120 24dB Moog type Low Pass filter, but the ladder of the A-103 is a modification of the original Moog ladder and identical to the ladder used in the Roland TB-303.

The in -and outputs are very basic; Three CV inputs are available, and the sum of the voltages from these affects the filter cut-off.
And an audio in- and output are also available, with one level knob.
That is the same layout as the A-102 and the A120 so sadly there is no CV control over the resonance. 
Luckily the resonance cán be adjusted with a knob, all the way up to self-oscillation.

And how does it sound?
I've always loved the sound of a real Roland TB-303 and the sound of it's filter.
This one sounds very nice too, it has that nice warmth in the lows, and the typical sharp edge when resonating, but don't expect that you can re-create a whole TB-303 with just this single module.
Some of the TB-303's other features, like the glide, accent and envelope modulation are missing here, and they (partly) give the legendary acid machine it's very original character.With some creative patching you should get very close to re-creating that original Acid sound...

I got pretty close by using my MAQ 16/3 for the sequence, and the A-160/A-161 Clock Divider/Sequencer combo for additional 'accents'. (You can add an LFO, or Noise for more random accents to experiment with / ,an  A-142 VC Decay/Gate envelope is also a useful addition with CV modulation to CV2 of the A-103 to create basslines like that* )
Overall this filter module can be a nice addition to your Eurorack. (7/10)

Video: Doepfer A-100 does TB303

* thanks to Jakob Paulussen  (@Jakobsweb) for that last tip and the kind permission to embed his video here. More info on the video after the break:

Monday, August 29, 2011

CD-Tip V : Anthology of Dutch Electronic Tape Music Vol 1 and 2 - Various Artists

These summer weeks i have been too busy to blog regularly, but i did have time to read and listen.
The main topic of this summer's research was Early Dutch Electronic (Tape) Music, you can expect the review of the book "Onder Stroom" (in Dutch) by Jacqueline Oskamp later, but first this quick quadruple CD-Tip.

This 2 x 2CD collection gives another nice overview of the early Dutch Electronic and Tape-pioneers.
It shows the listeners that there were more creative people interested in the spectrum between noise and sound besides the people who worked at the Philips NatLab (more info HERE and Wiki HERE).
A collection of work from throughout the Netherlands from Dutch legends like Dick Raaijmakers, Henk Badings, Ton Bruynèl, Tom Dissevelt and more from the years 1955 to 1966 fills up Volume 1.
Volume 2 has music from the years 1966 to 1977 and contains compositions of lesser known tape-artists that were not included on the first volume.

"Anthology of Dutch Electronic Tape Music Volume 1 Electronic music has been the subject of intense activity in the Netherlands since 1955, and the variety of this activity is reflected in the histories of the large number of electronic studios. The aim of Anthology I is to illustrate both the work of the various studios and that of individual composers; we have tried to represent as many composers from each studio as possible with preferably their earliest and most characteristic works...

... The second and last volume of the Anthology of Electronic Tape Music contains works composed after 1966, during a period when electronic music broadened its horizons and established links with other disciplines, a period when the studios opened their portals to influences and involvement from outside. Although electronic music from 1966 onwards became very fragmented and manifested itself in many different forms in Holland, the present volume of the Anthology aims merely to give an overall picture of pure tape music. "

Overall i find this a perfect compilation series. Most of the compositions sound fresh ( also because of the brilliant remastering by Kees Tazelaar) and at times make you feel excited and amazed on how this could be made half a decade ago without 'modern' effect machines.
If you are new to Dutch Electronic Tape-Music and you need a good starting point, try these 4 CD's.
Together with the 2 thick inlay-booklets (in English), that provide info on each track and a short composer biography this is a very complete and diverse overview...

Published in 2008 by Basta Music
Volume 1 2CD: Cat. Nr.: 3091 822 / More info HERE
Volume 2 2CD: Cat. Nr.: 3091 832 / More info HERE

Friday, August 19, 2011

More Blue LEDs

Okay... I haven't had much time to write and post these last weeks because i'm too busy working this summer, but i'm not completely sitting still.

The new blue LEDs that I ordered arrived, so the next few weeks i will only be replacing some red LEDs by blue ones.
It's not the most exiting modification, but it will make my A-100 system more pretty IMHO.
( Info on replacing LEDs HERE )

I do have time to read during my work, and i'm reading a very interesting (Dutch) book called "Onder Stroom" by Jacqueline Oskamp at the moment.
This book tells the story about the history of electronic music in the Netherlands, so expect a book-review of that in the near future.
( The book is slightly related / overlapping  THIS )

I will be back with some more interesting posts in a few weeks... so please stay tuned!

Saturday, August 13, 2011

CV / Gate Cable Length

A few times I've been asked about how patch-cable lengths ( of CV and/or Gate signals ) can affect signal strength.
I found a few interesting posts in the Yahoo Doepfer Usergroup that might make things a bit clear to you.

First of all;
Gate cables even longer than 10 meters usually are no problem.
Although a gate signal might get slightly weaker when you use extremely long cables, the (simple) gate signal will often stay strong enough to trigger your modules.
CV-Cables of this length may have a slight loss depending on the electrical characteristics of the input and the output.
There are ways to measure it,  but it is very difficult to judge whether a not completely clean octave tracking is caused by long cables.
Real loss of signal quality starts with asymmetric audio cables at such a length, and you have always to keep in mind that electromagnetic and electrostatic influences (hum and sizzle) can affect longer cables more than shorter cables.

" From a theoretical point of view (for anyone interested) the key things are output and input impedance, cable capacitance and resistance.
If you take a relatively standard low-cost coax cable of say 380pF/m and 128 Ohms/km this will not cause any noticeable loss in audio top-end from a 1k Ohm output impedance until you exceed 20m or so but you are more likely to get increased noise and interference.

From a CV point of view the cable resistance is a more important parameter (if your CV is controlling VCOs that is) but even 20m is only 2.6 Ohms so this can be ignored compared to the high input impedance of most VCO CV inputs; again long lengths are more prone to pickup so 50Hz mains can modulate the CV.
( you may also experience hum loops by just connecting gear together that is powered from different power outlets across the room ). " *

( * thanks to Tony Steventon from Synovatron for the 2nd half of this post )