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 http://raulsworldofsynths.com/) took the time and recently made some very interesting tutorial-video's explaining the whole A-188 in detail. 
This set of YouTube video's show you all the secrets of the module, with clear narration and pro sound-examples. Make sure you have some time, because in total this 4-part tutorial is longer than an hour (!)

Video 1: Doepfer A-188-1 BBD basics
"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 Whatis.com

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 www.reichelt.de (order no. 3GP-60), in USA from www.mouser.com (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: