Skip to main content


Showing posts from November, 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

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.

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…

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 …

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/…

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 …

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

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

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…

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. A…

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 …