VC – Digital Signal Processor
The Z-DSP is an open-source, cartridge-based, digital sound processing and generating platform for your modular synthesizer. The Z-DSP has a stereo DSP processor with 24-bit sampling, 15kHz of bandwidth, smooth voltage-controlled parameters, and the ability to be programmed, all in Eurorack format. While the Z-DSP cannot compete with the processing power found on personal computer, it does provide direct control of the DSP hardware and has a unique set of features aimed at the manipulation of digital effects. With the Z-DSP, digital audio can be bent, stretched, deformed, and distorted by interacting with your modules; something personal computers just can’t do.
The Z-DSP interface provides VC digital parameters, VC Wet/Dry mix, manual and sequential program switching, and a pair of VC feedback loop paths with exposed patch points that let you insert the rest of your modular into the DSP process. The Z-DSP lets you go far beyond ordinary processing, breaking the rules and allowing you to patch right into the heart of the DSP chip trough the clock input, allowing for some digital madness and creative sound design.
Size: 28HP – Depth: 59mm – Power: +12V 130ma / -12V 36ma
Dragonfly MKII is a set of eight voltage-controlled, time-based delay effects for the Z-DSP. MKII features advanced delay programs with added filters and additional taps spicing up the original set of Dragonfly programs.
With up to 1000ms of delay time and feedback control on each program, the Dragonfly MKII is perfect for deep, stereophonic, spacey washes of sound covering all delay effect duties within a modular and more.
The external feedback loop on the Z-DSP let you feedback through other modules like filters, VCAs or just about any other module to further process the Dragonfly repeats.
Hook up a Z3000 for a variable clock of the DSP processor chip to mess up the algorithm’s processing speed, shifting from clear digital repeats to grungy lo-fi warbles, this is where binary DSP bits meet up with the organic analog circuity of the Z-DSP.
The Dragonfly Delay contains the following algorithms:
– Mono in Stereo out L/R Tap: Two taps on a mono delay time.
– Mono in Stereo out Lowpass + Feedback: Two delay taps with LPF in feedback.
– Mono in Stereo out Highpass + Feedback: Two delay taps with HPF in feedback.
– Mono in Stereo out Right Ratio: Selector for ratio of Right delay time to Left.
– Mono in Stereo out Ping Pong: Two tap delay from Left to Right with LPF.
– Stereo in Stereo out L/R Delay: Independent delay lines on Left and Right.
– Stereo in Stereo out Highpass + Feedback: Two delay lines with HPF in feedback.
– Stereo in Stereo out Lowpass + Feedback: Tow delay lines with LPF in feedback.
Grain De Folie
Granular Synthesis uses small slices of sounds (grains) to compose new sounds from existing material. By combining multiple grains of differing lengths, amplitude, pitch, and speed, new sounds are created which are often very different from the original sound recorded in. Xenakis claims to have invented the technique and, indeed, his “Analogique A-B”, composed of tiny tape splices of pure tones, is credited as the first piece of granular music back in 1959.
In the context of the Z-DSP, a block of memory is set to hold digital samples for playback: the Z-DSP has one second of memory for the audio used in processing. From this audio buffer, the grains will be sampled and modified for playback with the number of grains determining how dense the overall output sounds. These programs have 3, 4 or 6 grains for playback. Each grain plays from a random point in the audio buffer and have an independent envelope controlling their duration. The envelope time is the “grain size” parameter in many of the programs.
The French phrase for the cartridge is “Grain de Folie”, which could be translated as “seeds of madness”, but in French “grain” also translates to “grain” and “madness” evokes the strange disassembling/reassembling granular process. Also, “avoir un grain de folie” is a typically expression to describe people behaving in a non-conventional way, thus a fitting play on words that quite nicely describes the unpredictable nature of this set of algorithms.
Pitch shifting in the Z-DSP uses a technique called “rotating tape head” delay lines named after pioneering tape based experiments in Germany in the 1960s. The tape heads move at speeds independent of the tape playback path and two heads are crossfaded to make a continuous output capable of beautiful pitched delay effects, harmonization, and smooth reverbs.
These pitch shifting algorithms are much like the earliest digital pitch shifters released. Sounds similar to the eventide H910, AMS 15-80 (with pitch board) and Publison DHM 89 can be achieved. These programs are intended more for pure effects rather than the complex, multiple harmony lines later devices and plugins became known for producing. Chords can easily be made from single VCOs using the “Interval” programs on the card, though.
Using a Z3000 to clock the Z-DSP, complete chaos from the delay lines and pitch shifting emerges, creating great and unexpected new sounds. Modulating the stereo pair of analog VC-Feedbacks animated the times and distance of the pitch shift opening up these algorithms for additional control from CV and audio signal alike.
Chorus effects for the Z-DSP thicken incoming sound and create animation within the sound’s harmonic structure. In addition, they provide an excellent tool for mono to stereo processing of any incoming sound, or even a whole mix, producing a stereo widening effect.
The card contains eight digital algorithms inspired by a set of the most classic analog chorus effect ever made, hardware like the Dimension D, Solina String Ensemble, and other very rare devices. True to the modular spirit, the control parameters offer a wide range from subtle and smooth to fast LFO modulation and sea sick wobbles, with a lot of sweet spots in between.
Using the Z-DSP’s own stereo analog feedback path to apply feedback to the effects results in beautiful, lush, and organic animated drones. Using those feedback inputs as an additional 2 input channels of direct injection into the DSP chip, the Z-DSP can take up to 4 external sources for generating impressive stereo drones with a classic chorus touch. The end result is a great tool for the design of atmospheric sounds completely contained in the modular environment.
Clocked Delays are a collection of eight stereo delay programs that let you sync the delay time of the Z-DSP to an external clock input.
With a quick set up, the clock input easily and exactly synchronizes the delay repeats to external rhythms generated by the Trigger Riot, Circadian Rhythms, or other clock sources. A Divide parameter is included with each program to switch between different divisions of the stereo ratios, creating a spatial audio clock divider which automatically matches the repeats to a beat. Feeding the clock input odd clock divisions from a module like the Trigger Riot has the interesting effect of moving the repeats in relation to the beat.
When it comes to their sound, some of the programs feature a pristine classic delay lines, while other programs insert a colored band-pass, low-pass or high-pass filter into the feedback loop, imparting a beautiful harmonic transition to the repeats as they feedback through the filter and slowly decay away. Using the Z- DSP’s analog feedback path adds an additional voltage-controlled stereo feedback which can slightly drift the repeats out of their tight sync to the incoming clock, due to the DSP chip latency, and also extend the delay tail intensity up to self-oscillation. Controlling the Z-DSP’s DSP chip speed externally via the Clock jack can even devolve everything into glitchy out-of-sync binary chaos.
Spring Waves brings a set of physical behavior modeling algorithms to the Z-DSP. It dives deep into experimental digital sound design techniques known as waveguide synthesis, which was first developed in 1998 by Julius O. Smith III of Stanford University by building off of Karplus-Strong synthesis. In addition, there are two spring models and space synthesis: making real Newtonian physics calculations at sample rate.
The principle behind these algorithms is a mathematical feedback formula excited by external signals which self-oscillate as a damped tone. The type and harmonic content of the external signals these algorithms can react to is extremely wide and so are the tones that they can impart to a sound.
The card contains six Karplus-Strong and two spring models. When fed with an external pulse or bursts of noise they self-oscillate, creating synthetic sounds similar to glass, springs, bells, and a variety of string tones. When structured sounds like high pitched FM tones, drones, drum sounds, and vocals pass through they get a harmonized-type effect, frequently with unexpected results. This card is anything but standard as it takes the natural “springy” artifacts of digital audio, and, instead of fighting to eliminate it, actually makes use of it as a new source of sound inside the modular.
Numberz is a USB device that communicates with a software front-end (for PC) and can be used to download DSP programs and display text to blank, non-volatile cartridges for use with the Z-DSP. Numberz can also feed directly into the Z-DSP’s cartridge socket for real-time programming.
With Numberz you can:
– Download free Z-DSP programs from the web and “burn” them into cartridge.
– Modify programs for new and interesting effects.
– Write and Debug Z-DSP programs in a real-time environment.
– Share your programs online with other Numberz users.
– Share your programs on Z-DSP Cartridges with other Z-DSP users.
– Create your own text for the Z-DSP LCD display.
The Z-DSP blank cartridges are rewritable memory cards for use with Numberz and the Z-DSP with up to 1 million erase/write cycles. These cards are made of printed circuit board with two (2) memory chips soldered on their bottom side providing low-cost, non- volatile memory for Z-DSP programs and display data.