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Showing posts from June, 2011

Modifying the A-124 Wasp Filter for self-oscillation

Out of the box the A-124 Wasp filter can not go into self oscillation, in contrast to most of the other filters in the A-100 system.
Lucky for us modifying the module for self-oscillation is quite easy;
Doepfer's DIY page tells us that;

"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."

Locating the R13 resistor was perhaps the most difficult part of the job. Because the resistors are all soldered on the PCB very tightly it is hard to read what the printing on the board says about the mounted resistors... but i found it!
R13 is located in the gap between IC1 (CD4069) and IC2 (i.e. the upper CA3080, close to C4/100pF). See picture above.

I did have a few spare parts lying around, including a 10k resistor. Soldering in parallel in this case was very simple. I did this on the backside of the PCB.After locating the correct resistor you can simply solder the new resistor on the othe…

A-175 Dual Voltage Inverter

The A-175 (Dual) Voltage Inverter simply does what the name says; it contains 2 separate inverters that invert the voltage of incoming signals; an input of +4 V will be output as -4 V, an input of -3 V will be output as +3 V, and so on.Two LEDs give a visual indication of the (positive or negative) output signal for each inverter.
I use this module a lot, as i blogged before, most of the time both inverters are constantly attached to my A-174-1 Joystick module. I am thinking of buying another one soon, because this module is just so useful.I love the fact that each inverter has 2 inputs, so they can be used as a (mini) multiplier.
In this way you don't have to 'lose' the original signal.
As input source you can use almost any CV source, not just the ones that produce both positive and negative voltages. 

A simple LFO will do, and the Joystick and Modulation Wheels are also very handy basic controllers.The A-175 manual has some interesting user-examples, including a basic panni…

Quotes IX : Jean-Michel Jarre

" I think that you have to seriously have fun, or taking serious things in a light way... and obviously for me before all, music is made of fun and pleasure and excitement. "

Jean-Michel Jarre  Composer, musician, artist, producer
(from WikiQuotes)

How To Hide an Arpeggiator

An arpeggiator is a feature available on some synthesizers that automatically steps through a sequence of notes based on an input chord, thus creating an arpeggio.

One of my biggest personal complaints about the 'original' A-190 MIDI-CV Interface was the fact that the front-plate had the text 'arpeg.' on it while an arpeggiator function wasn't even implemented (and still not) in this module.

Doepfer recently stated that "...there were plans to add an arpeggiator when the module was designed about 15 years ago. But we found that the processor power is not sufficient to add this feature..."
He also stated that the new A-190-3 USB/Midi-to-CV module does have an arpeggiator available. ( the A-190-3 is the modular version of the Dark Link and Dark Energy USB/Midi interface, watch an 8-minute video about the Dark Energy's arpeggiator functions below ).

The same functions should work on the A-190-3 ( and Dark Link ) too, but i haven't had any hands-on tim…

Black, The New Silver

Like it or not; It looks like Doepfer is slowly changing the main colors of their products into the new black and white color-scheme.
It all started with the Dark Energy synthesizer and the Dark Time sequencer, and recently they changed the case-colors of their USB/MIDI interfaces MSY2, MCV4 and Dark Link.

The first (and probably only) A-100-related new black thing is Doepfer's Ribbon Controller ( The R2M control box and the manual, not the A-198 module itself )
As of June 2011 the cases of this Ribbon Controller will be black with white printing instead of the old silver-grey look.

I like this move towards black from Doepfer because it does make these instruments and boxes look slick(er).
It is probably cheaper too for them to produce, but i'm not sure of that ( and doesn't really matter to me).

But what will be next..? Will they also change the A-100's front-plates?
I guess (and hope) not... that will seriously mess up the overall view in my opinion, although i do l…