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

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:

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
http://bastamusic.com
Volume 1 2CD: Cat. Nr.: 3091 822 / More info HERE
Volume 2 2CD: Cat. Nr.: 3091 832 / More info HERE

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!

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 )

Quotes X : Bernie Worrell

" I talk by playing, not by words..."

Bernie Worrell  Musician, Keyboardist, Composer, Producer, best known as a founding member of Parliament-Funkadelic

Doepfer Usergroup Poll: Analog Shift Register

Another new Poll at the  Doepfer A100 Modular System Users Group is up.
This time it is about the idea of realizing a Doepfer Analog Shift Register A-100 module.

A few days ago this was posted:
" ...It has been a while again, so I'll bring it up again. I believe it is time for a Doepfer analogue shift register... Does anyone agree with me?... " (*edited)

To be honest, i had never heard of an Analog (or digital) Shift Register, but a quick search on the web provided some hugely interesting information.
For the basic theory on what a Shift Register does i'd advice you to read the Wikipedia page first.

Shift register working principle  (Source)

For the musical use and a brief history on Analog Shift Register modules there is an excellent post at http://hardsync.blogspot.com, describing most of the known Shift Register modules.

" Ok, so what is an ASR? An ASR module is a sophisticated S&H. It will, at every clock pulse, sample the CV value of the input and makes it available at the first output. So far, it's a basic S&H. The thing is, a ASR has many outputs, and what it does is that at every clock pulse, it shifts the value of output 1 to output 2, and likewise, value of output 2 gets to output 3. So at every clock pulse, the CV values gets' shifted to the next output with the exception of output 1 that samples a new value at every clock. " *

Doepfer does call it's own multifunctional A-152 a "Voltage Addressed Track&Hold / Analog Shift Register (ASR)/ Octal Switch (Multiplexer) ",
but Hardsync writes " I own a Doepfer A-152, and my opinion is that the claimed ASR function of the A-152 will not get you the true ASR results you might expect. The A-152 is a switch. A very powerful and sophisticated one, but it will not push the value of one output into the next. Therefore, not a ASR as we defined."

Dieter Doepfer himself replied to the new poll very quickly;
" Though the A-152 is not a real ASR you can do similar things with this module. The most frequently mentioned application is to distribute a control voltage to the CV inputs of several VCOs.
At the rising edge of the clock signal of the incoming CV is sampled and routed to the next VCO. For this function an ASR is not essential as the VCOs are equivalent.
But there may be applications that require a "real" ASR (I'd be interested in applications where an ASR is required and that cannot be realized with the A-152).
In case that we will develop an ASR we'll go the digital way, i.e. ADC - processor - multiple DAC.
This has a lot of advantages, e.g. no voltage loss of the analog S&H capacitors, included quantizer for VCO pitch applications and some more.
But I'm not sure if the expected sales will justify the development of such a module (especially as we have already the A-152 available).

Update August 3 / Dieter continued;
" We already discussed the chance of multiple functions in the company.

One could treat the ASR as kind of a ring memory that could be "filled" in different ways. E.g. from a CV source via AD conversion (the usual ASR) but also via Midi or USB. The ring memory could be looped or not by means of a simple switch. 

One could combine the module with arpeggiator functions, e.g. fill the memory by playing a chord on a keyboard and then use only one of the CV outputs. 

One may also fill it with several analog CV's and the filling could be triggered by a gate signal (i.e. output of a sequencer or a CV/gate keyboard). That way one could combine several similar functions in one module. From my point of view this would make more sense than a pure ASR. 

One could combine the functions of an ASR, arpeggiator and and a rudimental digital sequencer. For ASR the number of steps could be limited e.g. to 3 or 4, for the arpeggiator and sequencer more steps make sense. A lot of ideas for the long evenings of the upcoming

fall and winter .... :-) "

Find the poll and vote HERE / Please join the Doepfer A100 Modular System Users Group by registering first.

The question in the poll is plain and simple;

Would you want and buy a Doepfer Analogue Shift Register module?

O - Yes!

O - Maybe...

O - No

* Source: http://hardsync.blogspot.com