Friday, December 31, 2010

Most wanted III - DIN Sync

The DIN Sync (or Sync24) standard, was introduced by Roland in the 80's for synchronizing sequencers, drummachines and (synth-) arpeggiators. The name Sync24 is derived from the frequency of the pulses, 24 pulses per quarter note (PPQN). A clock signal  of 2.51 V, at 24PPQN, defines the speed of the sequence or drum pattern. The start/stop signal defines if the sequence is running and has a voltage of 0 or +5 Volts. A lot of Roland's products were using this standard at the time, so some have sync-in, -out, or switchable sockets.

After the wide adaptation of the MIDI standard, the DIN sockets started to dissapear from most instruments. Syncing instruments via MIDI is now handled by the MIDI Beat Clock at a same 24 PPQN rate.
The SYNC plugs look the same as MIDI plugs ( DIN-standard, round with 5 pins ) ,but the pins have a different configuration as the MIDI plugs. The Din Sync standard can only handle clock signals (for tempo) and start/stop signal, so it sends no pitch-control. More info on Doepfer's SYNC FAQ page.

I know the DIN-Sync standard is now close to death. Only a few 'modern' drum-machines still have a SYNC In or Out, like for example the Novation Drumstation that i own.

The idea of a A-100 SYNC converter module doesn't sound bad in my opinion, perhaps a kind (extended) modular version of  MSY2 MIDI-to-SYNC Converter that Doepfer sells? 
( A-190-X maybe? )

If i might suggest some extra features, why not add a 16 (or more) trigger outputs (A-160/A161-style) , SYNC-in possibility, reset output(s) and switches on the front for choosing dividing factors.

That, together with a set of MIDI In and Thru, or an internal link possibility  to the A-190, would make an awesome (and not too expensive) module that for example could be used for percussive effects like triggering drumsounds in Sync with your old equipment.

Tuesday, December 28, 2010

Gate vs Trigger

Both the terms Gate and Trigger are commonly used for a signal out event type, mostly generated by a keyboard or sequencer, to start the process of generating a note or sound.

A trigger is typically of short (fixed) duration, where a Gate is usually continuous and muted when a key is lifted.

Gate-times can often be altered, in fact an Envelope Generator is not much more than a trigger-to-gate converter, often with different kinds of variables.
Most commonly used types of EG's are from the ADSR type ( adjustable Attack, Decay, Sustain and Release time ), but you can also find simpler AR, AD or ADR modules in other analogue systems.

Friday, December 24, 2010

CD-Tip III : Analogklang - Modulsystem A-100 Demo CD

This CD was published by Doepfer in 1995 to show off their then brand new A-100 modular system. It has 29 tracks and a large, colorful, fold-out booklet (in German) with a description of most of their early modules.

All the basic modules are demonstrated on this CD, that was produced by Andreas Merz from Weltklang and  narrated in German by a vocoded voice. The tracks are short, between 25 seconds and 3½ minute, what brings the total length of the CD to just 30 minutes.
This CD itself must be a collector's item by now i guess, because the item isn't available anymore on Doepfer's website. I'm quite sure i won't sell my copy... ever. This CD still means something special to me, and i did listen a lot to it, even before i bought my first modules.

Although the CD isn't available anymore, all tracks ( and some other sound-examples ) are still available for download HERE ( ...sadly enough in a poor ( 16Kbps) quality due to file-size decisions, but if you really need better audio-files you can contact Doepfer for better ones )
A must-have /or at least must-listen CD for all the real A-100 geeks and you might even get some new, fresh ideas out of it.

Tuesday, December 21, 2010

Modifications III : A-127 Triple Resonance Filter Expander (part 2)

Hmmm... that went faster as i expected.
My brand new self-made A-127 Expander Module is now almost finished.
( Find part 1 HERE)
The switches are wired too, and the overall look of the module is even better as expected.

I did have some trouble with drilling holes through the aluminium front-plate at first, but it seems i aligned the sockets nice enough with the output sockets of the A-127 itself.
The switches work smoothly and the 'new' 12 dB filters sound sweeeeeet.

I'm very happy with this module, and glad that i went with this option instead of just putting switches on the A-127's front panel.

The wiring of the modules on the backside was quite simple. Red wires were used for switching between the different filter-modes, the blue ones the the audio-multipliers, and yellow ones (not visible in the picture) for the lower switch.
I did the soldering without removing anything from the module, but you might want to remove some components for easier access.

Instead of soldering you can also use small (0.1") wire-sockets at the board's jumper-spots. An example with detailed information of this can be found HERE

Update March 10, 2014
Doepfer announced an official Breakout Module for the A-127,
find out all about it at

Monday, December 20, 2010

Modifications II : A-127 Triple Resonance Filter Expander

Now that i finished my first 'real' module-modification i couldn't wait to start with the next project.
At first i wanted to replace a red LED for a blue one on one of my modules myself, but i couldn't decide which module i should pick for this... and i'm still not sure, but that can wait....

Another plan that was in my head from the beginning was the placing of 3 switches on the front-plate of my A-127 Triple Resonance Filter. There are 3 jumpers inside this module that allow the user to switch the filter-type of each of the three channels between Band-Pass (standard) and 12 dB Low-Pass. I have seen some examples on the web of this modification, most of them just with the switches mounted on the A-127 itself, but unexperienced as i am, i was too afraid to damage the front-panel and went for an Expander Module design.

So that is why i am building it into an official 4HP blind-panel that i bought from Doepfer. Each of the three A-127 channels on my expander module design will have a switch to switch the channel's filter-mode and will also provide an extra (linked) audio output.
( mainly to fill up the space, but i aligned these with the A-127's original outputs to make it look more like an official Doepfer module ) .

To complete the expander module i also want to place a switch at the bottom that has the function of the J3 jumper that is inside the A-127 module on the mix circuit-board. This switch can put the module in a mode so that both levels of the filter and the original can be controlled with attenuator 1 ( audio level in )

I am not finished with the project yet, the mounting of the switches and extra outputs is done. Wiring is the next step, i'll write another post on that later this week...
Find Part 2 at

Update March 10, 2014
Doepfer announced an official Breakout Module for the A-127,
find out all about it at

Sunday, December 19, 2010

Modifications I : A-156 Quantizer Follow

A-156 with modification
Yesterday i picked up the spare parts that i ordered from Doepfer; a few switches, 3.5 mm sockets, LEDs and blindplates of different types and sizes. Now that i have them i couldn't wait to start with my first project.

One of my personal little annoyances that i have with the A-100 system are the tiny internal jumpers inside of some modules. Behind these jumpers are sometimes great functions that make these modules a lot more flexible.
Where i can, i will try to replace the internal jumpers with switches on the front on more modules, but i started with the A-156 Dual Quantizer Module.

A-156 after removing all the knobs
and frontplate
This module has two separate Quantizers, one that only uses a semitone-scale and Quantizer 2 that has much more options like minor/major/chord/quint/6th and 7th scales. There is a way to let Quantizer 1 follow Quantizer number 2 by replacing an internal jumper, but why there? It is probably a cost-saving thing from Doepfer's side but there is enough room on the frontplate of the module to place a switch with the same function. You can find a neat step-by-step guide with pictures on how to do this HERE , but it is quite easy.

Wiring the new switch
After removing the frontplate and drilling a hole for the new switch ( there is enough room above or under the printed 'Options Quantizer 2' text ) i could fit a new Doepfer 1-0-1 (on-off-on) switch in the hole and mount it back together again.

A-156 detail close-up
The wiring was quite simple, so even with my mediocre soldering-skills this was a piece of cake for me. The result is a simple and invisible modification that works perfect. Switch down couples the 2 quantizers, switch up puts quantizer 1 in it's original mode.

Okay... a similar result can be obtained with the use of an extra multiplier, but i found this one more adventurous... and rackspace-saving.
Now its time to experiment with the new options that i have. I can think of some nice patches already, but there are also some good suggestions for the use of this module and this modification at Synovatron's blog.

Saturday, December 18, 2010

PatchPierre Mobile Template (beta)

Good news for visitors on Android, iPhone and other mobile devices. As of now the site is visible in the mobile template, with quicker loading times and easier browsing through the posts.
The site now automatically  changes into the new template when you visit it, but you can also get there by scanning the QR code or following this URL:

Nokia / Symbian users can still download the
PatchPierre Mobile App HERE ( 3500+ downloads already )

UPDATE December 25th 2010:
Thanks to the OVI-store, people on Android,iPhone or other mobile devices can also use the OVI-Template of the PatchPierre site... it even looks better than Blogspot's own template.
Try it out and point your browser to 
( Don't forget to bookmark it! ) 

Friday, December 17, 2010

SiteTip II : Doepfer A-100 series modifications by Nick Keller.

Another nice site i stumbled upon in the last weeks in my search of Doepfer DIY info is the Doepfer A-100 series modifications site by Nick Keller at

This site offers some great (and easy-looking) Doepfer-modifications, complete with step by step explanations and pictures. Most of the modifications are simple but very usefull and consist of adding more switches, inputs and outputs to the frontpanel. Very interesting stuff... I'm looking forward to try some of the examples and hope that the parts i ordered from Doepfer will arrive soon, so i can start experimenting on my first Doepfer-projects.

The mods described will most likely void any warranty and, if not done carefully, can damage the circuit board, IC chips, and faceplates.

Wednesday, December 15, 2010

Quotes III : Robert Moog

" I'm an engineer. 
I see myself as a toolmaker and the musicians are my customers... They use my tools."

Sunday, December 12, 2010

DIY Projects I : The Beginning

I bought my first prototyping board (or breadboard) and some jumper-wires last week, it's time for me to start learning about electronics and electonic circuits.

The board i got was of the Velleman brand, and to be sure i had enough room on it i bought one of the bigger boards, still for under 20 Euro's.
I also bought a small Velleman Voice Changer Kit (MK171 - 9,95 Euro) , the only audio-related DIY-project i could find to experiment with. Like i said earlier this stuff is quite new to me, and my first attempt will be the mounting of all the parts of the kit onto the breadboard. This seems like a good practice for me to learn more about the components and their functions.

I did learn a lot on YouTube last weeks about the basics of breadboarding and electonic components, and there are a few good (and free) tutorials on the MIT OpenCourseware site ( both video's from lecture 12 are highly interesting and deal with basic sound creation with electonics ) The 559 pages thick lecture notes PDF  that completes this course is also free available at the site, and features the whole course on paper.
The kit is a voice changing kit that can basicly changes your voice into a high, low or robotvoice. I haven't heard yet how it will sound, but the idea and basic modification possibilities are looking great.

I see this as a sort of a side-project, that will hopefully merge into my A-100 system at one point and i'm looking forward on how it will sound. I'll keep you updated.

Saturday, December 11, 2010

A-114 Dual Ring Modulator

A Ring Modulator is a signal-processor that produces a signal out of two different audio inputs.
This output signal is the sum and the difference from both inputs, and leaves the original frequencies out.

It is an ideal module for producing metallic or bell-like sounds, but you can also (re-)create other weird sound-effects with it, like for example the distinctive "Daleks"-voices from the classic Dr. Who series, created in 1963 by the BBC Radiophonic Workshop.
Besides voices, you can also input all kinds of other (amplified) instruments through the ring-modulator.

The Doepfer A-114 Dual Ring Modulator is in fact two ring-modulators in one, which makes it even more flexible. Theoretically you can use the output of the first ring-modulator as input for the second one. The A-114's manual has some nice other examples on how to start patching, but with a bit of imagination you will quickly come up with your own ideas.

You can find some more interesting ring-modulation (DIY) info HERE

Wednesday, December 08, 2010

PatchPierre Mobile App for Symbian Update

Version 3 of the PatchPierre Mobile App is now available in the OVI-store. 
The ultimate way to watch PatchPierre's content on your Nokia device. It works on all Symbian and selected S40-devices.

The app enables easy browsing through the PatchPierre posts and comments and also links to the original articles.
Added in Version 3 are the PatchPierre Twitterfeed and my YouTube Videosection with jams, demos and other music made my me. Find it on the web at

The app will stay free in 2010, the 1 Euro that it will cost in 2011 will be spent on upgrading my A-100 system and maintaining the blog. 

All other donations are welcome too, there is a PayPal donation button in the blogs' right column.

Click HERE for a direct link to the OVI Store

More screenshots after the break:

Tuesday, December 07, 2010

50th PatchPierre Post


Funny how time flies....It's time for a small celebration.
The reason is because this is my 50th PatchPierre post.
What started out as a personal  hobbyblog has turned out to be quite an impressive collection of interesting posts... (if i may say so myself...)
When i started it, in March of this year, i never expected it to go this fast, and i am still impressed by the number of readers and the variety of countries where they come from.

I would also like to take the opportunity in this post to thank a few people here for their inspirational and motivational support throughout the process of shaping this blog;
In the first place i would like to thank Marc Weerts ( @MarcJX8P ) from the band 87PM ) for the idea of the subtitle of the blog (Connected Chaos), and for his valuable feedback in all these months.
I would also like to thank Loek van der Helm ( @wonderhelm ), mainly for his technical (PatchPierre-app)-support.
Last but not least i would like to thank Tony Steventon from Synovatron Electronic Music for his most recent input and all the positive feedback.

Thank you (and all other regular readers) for the support and for keeping this blog alive. Without you all it wouldn't be what it is now. Please feel always free to comment/react on my posts, and if you have any topic-suggestions, tips or sites that i should know about, please let me know.
I hope this blog will stay interesting in the future, i still have many (wild) plans for posts and DIY-projects ( My first set of switches,sockets and LEDs will probably arrive next week ).
I'll keep you updated!

Sunday, December 05, 2010

Booktip IV - The Complete Simmons Drum Book by Bob Henrit

Perhaps a bit of an outsider on this blog, but this 104-page book about Simmons Electronic Drums is in fact quite an interesting read.
The British Simmons company produced drum modules since the late seventies and is perhaps best known for their distinctive sounds and their 'hexapad' drum-surface design.

This book tells the whole story, their conception, development, and even their problems.
Allmost all their drumkits are included in this book, from their first SDS-3 (SDS series), ClapTraps and expanders up to models that were never released.
The book was written and published in 1987, seven years before Simmons produced their last products so only a few models are not mentioned in this book ( like the TurtleTrap and the SDS-2000 )

I have no idea why this book was written, but it looks like a nice thick brochure to sell Simmons products.
It is filled with (b/w) pictures, background stories and stories by players and is very well-written.
I recommend this if you are interested in (drum)-synthesizer history.
A good read from beginning to end.

Wise Publications ISBN: 0-7119-0933-4
Order No. AM 63173

Thursday, December 02, 2010

Most Wanted II - Drum Modules

Drum-synthesizers and drum-machines have been around for a long time.
The first analogue drum synthesizers were introduced in the 1970s, and everyone remembers those classic analog and digital rhythm-boxes made by big companies as Roland, Korg, Simmons and Linn.

 The Mid-nineties analogue revival triggered a whole bunch of new manufacturers like MAM, Vermona and MFB (to name a few) to produce (modular) drum synths.
I always wondered why Doepfer hasn't come up with a modular drum series yet.
The only drumsound-providing module they released so far was the A-117 Digital noise/808 Source, a module that only produces two 808 sounds... ehh well... building blocks.

Wouldn't it be nice if you could fit a variation of different Doepfer drummodules in your rack, perhaps an A-117-X series? How about dedicated Basdrum, Snare, Hihats, Cymbal, Clap and Toms modules etcetera, with (dynamic) triggers and CV-controllable functions like decay, tune, attack and so on, so you could use any CV signal ( like from an LFO or ADSR) to change the different parameters. I see a world of interesting possiblities.

In combination with trigger-producing modules like the A-160/A-161 Clock Divider, the A-166 Logic module and/or a sequencer i'm sure modules like this could create very interesting and vivid rhythms. And how about control with one of the forthcoming touch-sensors...? Hmmmmmmm.... Want!

Tuesday, November 30, 2010

PatchPierre.Net is live

Another small but important step in PatchPierre history;

www.PatchPierre.Net is claimed and live now... easier to remember if you are 'on the go' and want to check out the latest posts.

Service provided by in Sassenheim / The Netherlands.

SimpLL Solution offers IT-products and -services for businesses

Sunday, November 28, 2010

Blind Panels

The regular Doepfer 19-inch Euro-rack system has a usable width of 84 HP. If the modules you install don’t use up the entire 84 HP, you are advised to cover up the empty spaces with blanking panels due to safety and EMC reasons.

As i wrote in an earlier blogpost, the (static) electricity from the system causes the A-100 to be a real dust-magnet.
Blind Panels are available in the following sizes;

A-100B1  : 1   HP
A-100B2  : 2   HP
A-100B4  : 4   HP
A-100B8  : 8   HP
A-100B42: 42 HP
A-100B84: 84 HP

Doepfer also sells the A-100B1.5, a 1.5 HP wide blind panel that for example fits the  Analogue Solutions modules together with eurorack modules of other manufacturers. 

Thursday, November 25, 2010

Volts per Octave

The Volts-per-Octave standard luckily turned out to be a quite good one.
A lot of (early) synthesizers manufacturers adapted this standard, 'invented' and popularized by Bob Moog.

Best known manufacturers of early products using the 1V/Oct standard are Roland, Moog, Sequential Circuits, Oberheim and ARP. The big benefit of standards like these is inter-compatibility between products of different manufacturers. It allowes them to communicate better.

The V/Oct standard was wider adapted as other standards, like for example Yamaha and Korg's Hertz-per-Volt standard, that  represented an octave of pitch by doubling the voltage. 
A few synths that use the Hz/V standard are:
Korg: 770, 900-PS Preset, M-500 Micro Preset, M-500SP Micro Preset, Mini Korg, MS-10, MS-20, MS-50, Synthe-Bass, X-911
Yamaha: CS5, CS10, CS15, CS15D, CS20M, CS30
Moog: Taurus I Bass Pedals
Paia: 2720, 4700 Series

The Hz/V standard was used before the log converter was used in VCO's and is essentially linear control as can be found on various signal generators and function generators like those used by the BBC Radiophonic Workshop before they got a VCS3*. There are/were solutions available that convert from  Hz/Volt to V/Oct and vice-versa.  ( like the Korg MS-02 ).

No wonder that the A-100 system uses the V/Oct. standard. You can easily synchronize your system with almost any (old) machine that you have lying around, and most MIDI-to-CV converters use the same standard too.

For example i love using the CV (and Gate) output of my Roland TB-303 to control my A-100 system. The signal arrives at my system via a  A-180 2x4 multiple, so i have 3 copies of both signals available at any time.
Sometimes i use the CV slightly detuned for an interesting effect, sometimes i put it through a voltage inverter first, something that doesn't work out with all your 303-lines because of tuning.

The Gate output (trigger) of the TB-303 can be sent through a delay for some more interesting echo-like effects.
There are so many possibilities for your other gear to communicate with your A-100 with the 1 V/Oct standard... just go ahead and try... and amaze yourself.

*thanks to Tony Steventon for additional info

Monday, November 22, 2010

SiteTip I : Tone's Analog Synthesizer Projects and Products

I stumbled upon this interesting site last week; Tone's Analog Synthesizer Projects and Products. You can find it at
The overall site looks like a good start for everyone who is busy with, or starting on eurorack synthesizer DIY-ing and is operated by Tony Steventon, a UK electronics design engineer with a long interest in synths.
"Like most ideas it came out of trying to solve problems..." he wrote to me "... I could not fit either the jack sockets or bracketed pots on to standard 0.1" perfboard and came up with this idea over a year ago".

He continues "...several people have expressed an interest in learning how to take an idea through to a design and onto a prototyped module which I am quite tempted to do as a future 'learning' page on my blog..." "...I am working on my CV Tools module at the moment, which I have prototyped using my kits, but when that is ready for manufacture I am happy to consider some more ideas, I already have four promising ideas which may get developed either on my own or in collaboration with the idea originators."

Along with selling different DIY sets and prototyping kits, you can also order additional components for reasonable prices here. Listed are various Control pots (50k linear supplied as standard but 10k linear, 100k linear, 1M logarithmic or a mixture are available upon request), Pot mounting brackets, Decoupling capacitors, 16-pin headers, 3.5mm jack sockets, Red/green 3mm 2mA LEDs, TL084 quad op-amps (DIL), 14-pin IC sockets, 16mm soft-touch knobs (red, grey, orange, green, white, blue, yellow pointers), 10uF 16V electrolytic capacitors, 100nF ceramic capacitors, Headers - single, double, straight, right-angle, DPDT toggle switches to fit DIY2,  ...and more on request.

The site has an interesting (and growing) support page with all the datasheets and other practical tips on synovatron products. More info and discussion is possible at his dedicated Forum.

For sales, support and combined shipping enquiries you can contact
CAUTION: These kits are intended only for experienced experimenters and constructors to prototype their designs. It is possible for you to destroy components or damage your synth if you are not careful. It is recommended that you use a separate regulated ±12V power supply for experimentation.

Saturday, November 20, 2010

Filters I : A-127 Triple Voltage Controlled Resonance Filter

It is hard to say what my favorite A-100 filter is. Every filter has its own distinctive sound, and they all have a lot of Control Voltage input possibilities. I must admit i prefer low-pass filters... and filters with many outputs.

The A-127 VC Triple Resonance Filter is 3 bandpass-filters in one, each with its own LFO (sine) with adjustable frequency. The module has 3 individually adjustable outputs plus a mix output, and with all the controls for filter frequency and resonance it is a very flexible module.
\All 3 filters have an external CV input too, that by-passes the LFO when a plug is inserted in the socket. The amount of incoming CV's can be attenuated with a knob.

I love the sound of it, one of the characteristics of the 12 dB/Octave filters is that it can produce almost vowel-like sounds.
The LFO's can create amazing filter-sweeps as well with the frequency-rate adjuster.
As modulation inputs various CV's can be used like ADSR's and other LFO's (triangle/saw/rev saw).
Inputting voltages from any Wheel, Joystick or Theremin modules are also awesome ways to control this massive module.

You can even turn this module into a Triple Low-Pass Filter by changing internal jumpers, another nice feature. It might not be my most favorite filter of all, but this one is still the most-used filter that i own at the moment...

Wednesday, November 17, 2010

Busboard Access

Updated August 25th 2011

A good patch can sometimes turn out to a whole spaghetti of patchcables.
Luckily Doepfer provided the A-100 system with a subsystem that makes the routing of some Gate and CV signals through the internal busboard-system possible.

It's too bad that not all modules have this ability, but for some modules this is a good way to avoid "over-wiring" your system with patch-cables.

Only modules A-110 (Standard VCO), A-111 (High end VCO), A-111-5 (Mini Synth. Voice), A-140 (ADSR), A-164-1 (Manual Gate), A-185-1 (Bus Access), A-185-2 (Precision Adder) and A-190-1,2,3 and 4 (Midi Interfaces) have access to the CV or Gate signal of the A-100 busboard.

The A-164-1, A-185 (-1 and 2) and A-190 (-1,2 and 3) can be used to "write" the busboard, i.e. they can output the signals to the bus.

The others are able to "read" the busboard, i.e. they pick up the signals CV (A-110, A-111, A111-5) resp. Gate (A-140, A-164-1) from the bus.
The A-111-5 can pick up CV and Gate from the bus. Also the planned A-143-4 Quad VCLFO/VCO will be able to read the A-100's busboard.
For details please refer to the user manuals of these Doepfer modules.

Most of the modules come with jumpers inside that can connect or disconnect the signal from and to the busboard. If other modules should be able to "write" or "read" the bus some of them can be modified. More on this in a future modding blogpost.

Doepfer warns on their DIY-site for shortcircuiting modules and/or busboard, so please take note:
Pay attention that only one module is allowed to "write" to the same bus signal.  If two or more modules write to the bus this leads to a short circuit of the corresponding outputs.
Please let me know if i forgot some modules in the Feedback section of this post, thank you!

Sunday, November 14, 2010

Quotes II : Tom Rhea

" Sound is sound. There is no such thing as an 'artificial' sound - only sound or silence.
A synthesized sound is not a replacement for a 'real' sound; all sounds are real "

Dr. Tom Rhea - Electronic music historian

Wednesday, November 10, 2010

Happy Knobbing III - New Joystick-Lever

The latest minor modification to my A-100 system  is the replacement of the A-174 Module's joystick.

I finally changed my black plastic lever with a newer aluminium one that i ordered at Doepfer last week.

Modules before 2007 had the black plastic lever as standard, all modules delivered after 2007 already have this aluminium lever.

It's just a small optical change, nothing more. The new lever is a bit shorter, but does have a nice/better grip though. And that for only 10 Euro's...

<  Old vs. new lever

Sunday, November 07, 2010

A-134-2 Dual Voltage Controlled Crossfader

 My latest ( my 60th! ) Module is the A-134-2 Dual Voltage Controlled Crossfader.

This module, that contains two identical voltage controlled crossfader units can be used in combination with controller modules like the Wheels or the Joystick controller to make fades between different sounds  ( or even control signals like LFO's ) 

Each unit has two voltage controlled amplifiers (VCAs) with opposite control behaviour.
In standard (assymetrical) mode, with 0 volts CV added to CV1, input A is fully closed and input B fully opened.
Adding more control voltage to the CV1 input will result a volume increase at input A and a decrease of the volume at input B. In the middle position you will hear a nice mix of the two inputs.

Different settings for the module are available, by switching the internal jumpers you can make the CV inputs ready for bi-directional voltages ( positive and negative ).
By coupling both units you can even control 4 inputs with, for example the A-174 Joystick Module's control voltage, where the centre is the 50% mix and each 'corner' of the joystick is an individual input. A truly amazing and very versatile little module...

Friday, November 05, 2010

Booktip III - Synthesizers by Hans de Vries ( in Dutch Language )

This little Dutch book, written in 1983 (!) is probably one of the best synthesizer-technology-books that I own. The fact that it is written in Dutch wasn’t enough reason to keep this book out of this blog.

In 144 pages, Hans de Vries explores the basics of sound creation.
The first half clearly explains the basic building blocks of synthesized sound, very clearly written (... but in Dutch, remember...) and with lots of graphs and explanatory pictures ( b/w )

The second half of the book delves more into the use of synthesizers in practical situations like (home-) studio’s etc.. The book ends with an overview the most popular or groundbreaking (analog) instuments of that time, like the Korg MS20, various Moogs, Oberheims and Rolands, up to the fisrt digital synthesizer; the Yamaha DX-7

Funny detail in this book is the writer’s skepticism towards MIDI and Computerized sequencing. Remember... around 1983 there were only a few instruments equipped with MIDI, and computers weren’t cheap. Above that, computer-sequencing-programs were not widely available back then.

ISBN: 90-201-1642-8

Tuesday, November 02, 2010

Oscillator Synchronizing

Interesting sound-effects can be obtained by the synchronising of (multiple) oscillators.
In a typical setup, one oscillator (master) restarts the cycle-period of the other one (slave) , what results in equal base frequencies on both oscillators. This is called Hard Sync.

The result is an irregular waveform with it's own harmonic spectrum, completely different from 'standard' waveforms

Soft Sync is a more general name for all kinds of oscillator synchronisation.
This form is very similar to Hard Sync, but here the slave oscillator is forced to reset to zero with every cycle of the master regardless of position or direction of the slave waveform, which often generates asymmetrical shapes.

In Soft Sync, rather than resetting to zero, the wave is inverted;  its direction is reversed.
Further variations to the sound can be made by comparing the sounds with different comparison tresholds. For more info see the Wikipedia page on Oscillator Synchronisation
Soft Sync sounds smoother  and distinctly different from hard-sync.
It is difficult to replicate this effect on digital synths, due to aliasing problems.

Soft Sync-like effects can also be created with other modules, for example a phaser or a Phase Locked Loop (PLL) Module.

Thursday, October 28, 2010

Quick Tip III : Vocoder testing

Ideal for ( Doepfer ) vocoder testing;

Try feeding an audio-book or a recording of your favorite radioshow through your system while tweaking your vocoder settings.

Speech-only programmes are perfect for this purpose.

Short demo:
  In the Morning Vocoder test by NetPierre
* original audioclip from: /

Quotes I : Edgar Varèse

"I dream of instruments obedient to my thought and which with their contribution of a whole new world of unsuspected sounds, will lend themselves to the exigencies of my inner rhythm."

Edgard Varèse 

Tuesday, October 26, 2010


A filter is a device for eliminating selected frequencies from the soundspectrum, and in some cases to emphasize the level of other frequencies.

Lowpass filter: Removes frequencies above its cutoff frequency

Highpass filter: Removes frequencies below its cutoff frequency

Bandpass filter: Only allows frequencies to pass through above and below a specified range

Notch filter: Allows frequencies to pass between specified ranges ( = Band-Reject filter )

Sunday, October 24, 2010

CD-Tip II : Popular Electronics by Philips Research Lab

This 4-CD Boxset with the subtitle  " Early Dutch Electronic Music from Philips Research Laboratories 1956 - 1963 " is a collection of great (restored) works from the Dutch pioneers in electronic sound.

These four CD's contain hard-to-find compositions and sound-examples from the groundbreaking Philips NatLab studios in Eindhoven, the Netherlands.
Pioneers from that time like Dick Raaijmakers,Henk Badings and Tom Disseveld were already working on electronic sounds in the late 1950's, and this collection of Dutch electronic and tapeloop-music is the most complete one ever compiled.

The boxset includes 7 booklets (180 pages) and a few mini-posters, full with background information on the history of Philips NatLab and the composers and technicians of that time. You will also find all the CD details in these books, as well as lots of pictures, scores, schematics and other related documents.

 Popular Electronics: Early Dutch electronic music from Philips Research Laboratories, 1956-1963 by Basta Music

Additional info on this  Popular Electronics  4CD Boxset
BastaMusic: Cat. Nr.: 3091 412

Friday, October 22, 2010

A Question of Cables

Doepfer sells  patch-cables for the A-100 system (3.5 mm plug mono jack) in many different colors and sizes.
The latest addition to the Doepfer assortiment are the orange 50 centimeter patchcables with angled plug on one side. 

The prices are fairly acceptable, and the more you buy ( at once ) the cheaper they get each...
Sizes vary from 15 (yellow), 30 (black) , 50 (grey), 80 (red) , 120 (blue) to 200 (green) centimetres, but i wish they also had other lengths. (...and colors)

Let me know in the comments if you know a place where they sell patch-cables in other colors or lenghts, it will be appreciated.
Purple ones would be nice... but not too long... ;-)

Tuesday, October 19, 2010

Never Enough VCO's

The engines or hearts of all modular synthesizers are definetely the VCO's. As main sound source for your patches it seems you never have enough of them.

I own 5 VCO's at the moment, One A-111 High End VCO plus four A-110 Standard VCO's. Ideal for stacking layers of waveforms to make extra- fat sounds, and also very useable for multiple A-100 melodylines

The A-111 is the one i use most because of its extended possibilities. 
This VCO has an extended frequency range, improved waveforms, FM and Soft Sync inputs plus an extra fine-tune-controller. Ideal for controllerfreaks like me. 
It produces sine, triangle, pulse and sawtooth waveforms, which are all derived from the triangle oscillator, what does make it hard to produce perfect sine-waves ( but a little better as the A-110's sine wave )
One of the best things is that all 4 waveforms are all simultanously available at the outputs for your mixing pleasure.

The much cheaper A-110  has less controls and is based on a sawtooth oscillator. All outcoming waveforms of this module are derived from this sawtooth by internal waveform converters. This module also generates sinewaves that are not completely perfect, but to 'normal' ears this is hardly audible

I never noticed, and i guess most of us don't care and never noticed the imperfect-ness of the sinewaves of both modules.
Even on an oscilloscope it is hardly visible that the sinewaves are nothing more than rounded sawtooth-waves.
For a perfect sine wave Doepfer recommends the A-143-9 Quadrature LFO/VCO, another interesting module, that i will highlight in a future blogpost.

Note: As the special circuit CEM3340 used in the A-111 High End VCO module is no longer available the module has to be discontinued. Sales at Doepfer while stocks last !

Sunday, October 17, 2010

A-100 Module Circuit Board (Picture)

Most of the Doepfer A-100 modules' circuit boards are really pretty. It is almost a shame to build them into a case...

They almost look like a well-architected mini-city on a tiny Doepfer-board, almost like LEGO- miniature-city.

Patchpierre MiniQuiz:    What A-100 Module is this?*

* Answer is HERE - feel free to take the short Poll; "  Analogue or Analog?  "

Friday, October 15, 2010

Analog Noise vs. Digital Noise

My Doepfer A-100 system includes 2 Noise different generators, the A-118 Noise/Random Voltage Generator, and the A-117 Digital Noise Generator.

A noise generator is an oscillator that produces an internal noise signal, typically white or pink noise.
Noise Generators produce random signals, containing harmonics on all frequencies, and can be modified into the desired tone. 

The A-118 produces white and colored noise. The white noise is the well-known 'hiss'.
The spectrum for the white noise has the same amount of energy in every section. 
The colored noise output of the module is a mix of blue noise ( high frequency component ) and red noise ( low frequency component )

Noise in the audio spectrum can be used in many ways, most commonly in wind-effects, or in cymbal crashes and hi-hat -sounds.

The A-117 Digital Noise sounds very different and has less control possibillities.
This module has 2 outputs, consisting of mixes of multiple oscillators to re-create vintage Roland TR-808 and TR-606 sounds like the hi-hat, cymbals and cowbell.
One output has a mix of 2 fixed digital oscillators, that can be used as a basis for the distinctive 808 cowbell-sound, the outher output has 6 oscillators to form cymbal and hi-hat sounds.

The Random outputs of both modules can be used as a Control Voltage for all kinds of stuff. I prefer the Analog Noise for that, simply because it has more controllers.
I often use it as a modulation source to add subtle changes in a filter (check out a short example HERE), but these modules can also provide interesing effects in combination with the A-148 Sample and Hold module. More on that in a later post...

Video: A-118 Demo 

A118 Noise and Random voltage generator demo made by @Hawklord2112