Doepfer A-188-1X BBD (128 Stages)

The Doepfer A-188 module is an exciting BBD module for delay, flanging and Karplus-Strong synthesis, which is available in various configurations.

The BBD circuit established itself in the 1970s as an inexpensive, more compact alternative to tape-based delays, which were also much more maintenance-intensive. When digital delays appeared, pedals such as the legendary Electro Harmonix Memory Man temporarily fell out of fashion again, only to enjoy a resurgence in popularity that continues to this day.

A BBD circuit consists of a chain of sample & hold units, the so-called stages (capacitors). These pass on their voltage to the next stage before they are filled with new "memory content" by the previous stage. The clock of the oscillator determines the speed of the transfer and thus the corresponding delay time.

The name Bucket Brigade Delay was coined because the way it works is reminiscent of a classic bucket brigade, in which liquids are passed on by human hands using buckets. The first bucket in the chain can be seen as the audio input, while the last one symbolizes the audio output. Of course, a few drops of "water" (in this case voltage) are lost here and there along the way. If too much/too little arrives at the next BBD element, there will be small inaccuracies in the way it works. The greater the number of stages, the longer/greater the delay time. The higher the clock rate, the shorter the delay time.

Typical applications for the A-188-1 are: Flanger, Chorus, Analog Delay or Karplus/Strong synthesis. However, the clock rate can also move outside the "recommended" ranges, which causes the aforementioned inaccuracies (underclocking/overclocking). Like the delay time, it can be CV-controlled and, like the polarity switch of the CV inputs (BBC Radiophonic Workshop anyone?), can provide extremely experimental sound experiences. There are also feedback and BBD out/mix, clock and CV output of the high-speed VCO, BBD clock input and a feedback insert. The feedback can also be driven into self-oscillation madness. This can be used to realize many creative applications (e.g. ADSR-controlled delay, random, envelope follower or sequencer with positive or negative effect).

A special feature is the lack of an anti-aliasing filter so as not to limit the creative possibilities of the module from the outset; this can be realized via the CV output if necessary. Whether in the 128-stage or the 4096-stage version, the Doepfer A-188 offers plenty of scope for (CV-)controlled or free-rotating sound experiments and adds a heavy deal of character to your Eurorack.

Features:

• Classic bucket brigade delay module
• 128 to 4096 stages (depending on chosen module)
• Provides Delay, chorus, flanging/ensemble or Karplus-Strong synthesis
• High-speed VCO
• Delay clock out and external delay clock in for under- or overclocking
• CV and feedback polarity switchable
• Sum CV Out
• Mix and BBD outputs
• External feedback input (processing of individual delays possible)

The versions with 128 and 256 stages are well suited for Karplus Strong and flanging.