Filters III : A-124 Wasp Filter

The A-124 is a special 12dB multimode filter using the filter circuit of the EDP Wasp, a monophonic black and yellow analog synthesizer, that was built around the end of the seventies and manufactured by the UK company Electronic Dream Plant.

I totally love the sound of the A-124 Wasp Filter module. It does have it's own special sound due to the special circuits in it which makes the module sound a little dirty and distorted. This can sound very nice with extreme filtersweeps, i often control the cut-off frequency with the pressure CV from the A-198 Ribbon Controller.

The module has 2 audio outputs; a band-pass and a combined low/notch/high pass output that can be controlled with the 'mix' knob that defines the relative amounts of low and high pass signals.
( middle position is notch )

One downside of the module is the lack of a QCV input like most A-100 filters have, so sadly the Resonance cannot be controlled via an external voltage. You can only adjust this manually.
It would have been nice if the Mix could also be controlled by CV...   IMHO

Out of the box this filter can't go into self oscillation, in contrast to most of the other filters in the A-100 system, but modifying  for self-oscillation is quite easy;

Soldering a 10k resistor in parallel to R13 (27k) leads to self-oscillation of the filter at the max. resonance setting of the resonance control.*

 More info on this modification can be found HERE

100th PatchPierre Post

Woooooot! ...again. :-)

My 100th post already (the 50th was on December 7, 2010), and the blog is still going strong.
With fewer posts though, but the viewing rates are still slightly growing every month.
Thank you all again for regularly visiting this site and for your valuable feedback.
I hope my blog can still please the people who just got into analog (modular) synthesizers, and also provide the more advanced users with interesting links and different insights.

In this post i would like to take a quick look into the most popular of my first hundred posts.
Although i cannot exactly tell how many people read each post (many of the visitors land on the main page, where they might read multiple posts at once), i can tell by the individual clicks what the most popular posts were and tell a bit about their traffic sources.

By far the most popular post was my Busboard Access post from November 17, 2010.
I guess struggling for hours through the manuals for a complete overview of all modules that are capable to read or write to the A-100's busboard was worth it.

Also still very popular is my PatchPierre Mobile App for Symbian post from December 8, 2010.
I am still very proud with the almost 5000 installs of the application on Nokia Symbian and selected S40 devices. I do hope Nokia will find a way to port these kind of self-made apps to the Windows Mobile platform and Market too. The more installs, the better... :-)
I did get an email from OVI that my App will soon be updated with some new extra features and an 'enhanced user experience'. A blogpost about that will follow...  (meanwhile the app is still available HERE)

The A-101-2 Vactrol Low Pass Gate and  A-156 Quantizer Follow Modification posts were also quite popular, together with the various other DIY and Modifications posts that i did.
The Book-tips and the CD-tips also seem to be of your interest. I still have a few book-tips on the shelve, and i will try to post some interesting (synthesizer-related) CD-reviews in the near future too.

And... where did all this traffic come from?
Well, Google's search in all its varieties ( .com /.co.uk /.fr / .de / .nl ) was by far the #1 top referring site, but that is hardly a surprise.
Social Media-sites like Twitter (#2) and Facebook (#4) also proved to be very useful to attract readers to the site, and  a lot of viewers came from the Nokia/Symbian mobile application referrals ( #5, but not as much visits as i expected, a lot of people still seem to only read my blog in-app, thus still missing out on a lot of the links ).
More surprisingly was the #3 spot, because Tony Steventon's Synovatron.blogspot.com seems to have been a true link-farm for links to my blog. Thanks for that Tony ;-) Keep up the good work with your interesting projects!
The link to my site on the Doepfer A-127 webpage has also attracted quite a few (new) readers, i'm pretty proud with that one and it looks like the MuffWigglers have (re-)discovered/ finally found this blog too. ( thanks to THIS post ) I have seen a lot of traffic coming from there in the last month... Welcome!

I hope i can serve all of you with at least 100 more posts in the future, but it might take bit longer than the first 100...

Saving Patches

One of the downsides of a modular synthesizer is the lack of memory banks.
There are times when you have finally found that perfect sound, but need some modules for other patches...
A good (photographic) memory will often do the job in the more simple cases for anyone, but for bigger patches you might need a little reminder sometimes.

To 'store' patches you have a few options;
First, always try to sample the sound you made with a (hard- or software) sampler. Although that often does not catch every aspect of your sound, it is always good to keep what you made in some audio-way. Try sampling it in all its varieties, with your favorite settings and or knob-twists.

Okay... you now have the sound , but not the list of modules that were used to make that sound.
Doepfer came up with the nice idea of patch-sheets in the last page of every module's manual.
You can print out these modules, stick them on a bigger sheet (i've even seen some on pinboards) and draw in your knob-settings and patchcables.
The idea is/was nice, but i hardly ever used these sheets. But it can be handy for some...

I also like the online Eurorack Modular Synth Planner. With hundreds of modules from 52 different manufacturers (!) you will be able to configure your patch including a variety of colored patch-cables and save it as a screenshot.
This great site is regularly updated with the latest eurorack modules, but still has a few (small) bugs and imperfections. Follow them on Twitter to get their latest updates.
Another online planner is Stefan Breitenfeld's Modular Planner, also very neat but with much less manufacturers/modules.

My personal favorite way to store my favorite patches is the modern way.
Thanks to my smartphone i always have a digital camera in my pocket.
One or two quick snapshots of my patches is often enough, and only takes a few seconds.

LFO's A-145 and A-147

Low Frequency Oscillators or LFO's produce periodic control voltages that can be used as a modulation source for all kinds of other modules.

The A-145 LFO1 was the first and one the most basic single Low Frequency Oscillators that Doepfer sold.
It provides 5 different waveforms; sine,sawtooth, triangle, pulse and inverted sawtooth ,and each waveform has their individual (and simultaneous) output.
With the Frequency-knob and the 3-way switch you can select a wide range of frequencies, from on cycle every minute up to audio frequency at the highest.
A reset input allows you to synchronize the LFO signal to an external trigger signal and each trigger will re-start the waveform from its zero-point.

The most obvious use for an LFO is to do some pitch modulation on a VCO to create a vibrato and to modulate amplifiers (VCA's) for a tremolo effect, but with a creative mind you can use these two modules for all kinds of sound manipulating.

The A-147 Voltage Controlled LFO is basically the same LFO as the A-145.
It doesn't have one of the A-145's sawtooth waves, but does have an extra Control Voltage input that is very useful.
Think of an A-174-2 Wheels Module or A-174-1 Joystick Controller as the most used control voltages, but dare to think further... how about controlling the A-147 frequency with noise or perhaps another LFO for example?
My personal favorite use is to put a voltage of an A-198 Ribbon Controller or Theremin Voltage though the CV input and send it to an VCA to get a tremolo effect, but at a higher frequency in the higher notes.

I will discuss the A-146 LFO2 in a future post because it is a slightly different module with different features and uses.