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

SiteTip IV : Doepfer Convergence Group on Soundcloud

If you are interested what kinds of sounds other Doepfer users make, or just want to be inspired, you can always go to the Doepfer Convergence Group on Soundcloud.

This site contains very interesting creative compositions made mainly on a Doepfer A-100 Analog Modular System.

The group is moderated by James Bragg (AKA HyperDust), a synthesizer player and producer from Bristol UK who has played in various bands since the early 1980's and who's musical styles have varied over the years from New Romantic, Rock, Rock/Dance, Trance and various electronica.

" I've been building up 2 suitcases of modules over the last 5 years. I love their immediacy but also their temporary nature.
There is a type of Japanese painting where you paint with water on a special stone. It can look beautiful but after a short time it dries and is gone forever. A Doepfer modular is a bit like that. I'll never get that sound again - you just have to live in the moment. Celebrate the now. We spend too much time worrying about the future, and regretting aspects of the past."

The group has 49 members, and 18 tracks already have been contributed by 10 different musicians.
Some of these are complete songs but it also includes long live-improvisations and weird soundscapes.

Definitely worth a listen, if you have some spare time... Here's a quick preview, just to give you an impression;

 biofeedback no.9 by cubistic microsonic 

Quick Tip VI : Theremin Antenna

By accident i learned that the same kind of thing that i advised for the A-198 Ribbon Controller (to remove the USB-cable from the controller after use, read the post HERE ) counts for the A-178 Theremin Controller's antennas as well...

If you, like i, have your A-100 system placed upright , the weight of the antennas is just a little bit too much for the mini jack connector.
The permanent sideways pressure, caused by the weight of the antenna can cause loose contacts of the connector. If you have your module installed on a flat (tabletop-like) surface the plugged-in antenna cause less sideways pressure and you'll probably be safe.

Although Doepfer uses a new type of jack sockets since 2003 with stronger springs and so-called "curly rear contacts",  loose contacts can hardly be prevented.
But don't worry, if this problem occurs it is not a huge problem because most of the times you can fix them yourself by following the instructions that you can find HERE.

In my humble opinion it is just better to unplug your antenna from your A-178 module when you are not using the Theremin functions.
Better be safe than sorry...

Timing Capacitors of the A-100 System

Okay... I did write a little about the Timing Capacitors of the A-100 modules in my latest post, but i found it so interesting that i thought i should do another short post about this.

Timing Capacitors of the A-118

If you want to modify a module yourself please read this document first: Timing capacitors of A-100 modules.
That document is intended for experienced A-100 users who want to modify the timing range of some modules (e.g. envelope generators, LFOs, slew limiters). 

To lengten the time or period the capacitor value has to be increased and vice versa. The capacitor value is proportional to the time or period (e.g. doubling the capacitor value even doubles the time or period, when the capacitor value is increased tenfold even the time or period increases tenfold). 

By request the time range of delay and/or length can be modified very easily by changing the value of a capacitor, e.g. 200 us...1 s or 20 us ... 100 ms or 2us ... 10ms. That way the module can be used also for audio applications.
If an electrolytic capacitor is used one has to pay attention to the polarity (minus and/or plus sign).

Timing Capacitors of the A-119

Although Doepfer has very clear pictures on their site on where to find the right capacitors i decided to make a library of my own as pictures with info for your comfort.
Here are two already, expect more in the coming next months.

Feel free to use and/or distribute... More promotion for the site is very much appreciated ;-)

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