Mutable Instruments Warps

onimpulse schrieb:

Gibt es dazu eigentlich schon mehr Infos?

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Programmed Warps’ factory testing GUI tool.
Inspected defective Warps from beta tester #1. Just a solder residue blob that got trapped between the pins of a potentiometer!
Rewrote from scratch Warps’ sample rate reduction code. The dirty secret is that if we were to judge by CPU use, Warps would primarily be a sample rate conversion module smile emoticon The DSP code works internally at four sample rates – 96kHz (native rate of the AD/DA, internal oscillator, digital VCA), 576kHz (cross-modulations, non-linear operations), 32kHz (filter-bank middle bands), and 8kHz (filter-bank lowest bands), and to do this, there are various polyphase FIR upsamplers/downsamplers ticking inside. I started a tedious process of fine-tuning the original “naive” resampling code by unrolling loops, reordering computations, trying various ways of storing the coefficients (arrays in flash or in RAM, in order or in polyphase decompositions) and found that the code was a mess to unroll by hand! I ended up using the same approach as in some of my other Mutable or-pre Mutable projects – code generators in the form of C++ templates unrolling, pre-computing and inlining at compile-time everything that can be pre-computed. The new upsampling/downsampling code was 60% faster and all gains were reinvested in increasing the length of the filters.
Optimized Warps’ filter bank code and used the CPU gains to add more bands (from 16 to 20).
Implemented several variations of Warps’ vocoder operations, including a nice “formant sweep” that warps/shifts/pinches the vector of gains from the analysis filter bank.
Did a bunch of performance optimisations to Warps’ code, in particular replacing lookup tables by the actual computations in a few places! All gains reinvested in faster reaction to CV changes.
Started working on Warps’ easter egg.

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Researched several ideas centered around formant processing for Warps easter egg. After two days, the results were still glitchy under heavy modulations and worked on a fairly limited range of input material, so I decided to put this bit of code to rest for now.
Implemented easter egg take #2 for Warps. Took three hours to get a proof of concept, instant fun, worthy of a stand-alone module. Keeper!
Dug deeper into one ingredient used in Warps’ easter egg. Rather than re-using the same implementation as everybody else, redid the maths from scratch and came up with something that had better performance and still fit my computational budget.
Did yet another pass of polishing for Warps – a few more code optimizations, added the Yahtzee secret handshake for enabling the easter egg…

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Wrote draft of user manual for Warps.
Spent a lot of time troubleshooting an ADC noise issue on the Warps prototypes.
Did yet another pass of code tweaks on Warps – so that the spectral/vocoding FX blends well with the other modulations.
Ordered a few boards of what I hope will be the final hardware revision of Warps.

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Evolved from the oscillator mixing section of Mutable Instruments’ desktop hybrid synths, Warps is designed to blend and combine two audio signals. A variety of cross-modulation methods – some of them emulating classic analog circuits, some of them purely digital – are provided by the module. With Warps, the cross-modulated sound can be sculpted with control voltages along 4 dimensions: by controlling the amplitude and distorting the input signals, by smoothly scanning through the collection of modulation algorithms, and by adjusting a timbre parameter controlling the brightness/harshness of the modulated signal.

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Crossfade. The carrier and modulator are crossfaded into each other, using a constant-power law. TIMBRE controls the crossfading position – both signals are equally mixed at 12 o’clock.

Crossfolding. The carrier and modulator are summed, a tiny bit of cross-modulation product is added to spice things up, and the resulting signal is sent to a wavefolder the amount of which is controlled by TIMBRE.

Diode ring-modulation. The carrier and modulator are crudely multiplied, using a digital model of a diode ring-modulator. TIMBRE post-processes the resulting signal with a variable amount of gain (and emulated diode clipping).

Digital ring-modulation. A gentler version of the previous algorithm which uses a proper multiplication operation in the digital domain, which will sound more similar to all the AD633-based analog ring-modulators out there! TIMBRE post-processes the signal with a gain boost and soft-clipping.

XOR modulation. Both carrier and modulator are converted to 16-bit integers, and the two resulting numbers are XOR’ed bit by bit. TIMBRE controls which bits are XOR’ed together.

Comparison and rectification. A handful of signals are synthesized through comparison operations (“replace the negative portion of the carrier’s signal by the modulator”, “if the absolute value of the carrier is greater than the absolute value of the modulator, output the modulator else the carrier”…). TIMBRE morphs through these signals (some of which having an octave pedal flavor).

Vocoder. A classic implementation of an analog vocoder, with a bank of 20 analysis and 20 synthesis third-octave 48dB filters. The modulator sub-band signals are processed by envelope followers from which are derived the gains of each of the carrier sub-band signals. TIMBRE warps the connections between the modulator’s envelope followers and the carrier’s gain elements – effectively shifting up or down the formants extracted from the modulator signal.
As the ALGORITHM knob is turned clockwise, the release time of the envelope followers is increased.
By turning the knob fully clockwise, the modulator signal is frozen. The carrier is filtered by whichever formants were present in the modulator signal before the knob reached this position.

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adam schrieb:

Das scheint mir sogar vergleichsweise eingängig, da hier nicht 1000 Funktionen unter einen Hut gebracht werden mussten.

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adam schrieb:

Man weiß auch immer genau, was man gerade macht

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Zotterl schrieb:

Warps: Die Luxusnutte unter den Ringmodulatoren

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Shipped several hundred of these to various dealers today. More to come around mid december! http://mutable-instruments.net/modules/warps

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To enable the frequency shifter...

First, set the timbre and the two VCA knobs to their minimal position.

The 9 icons around the big knob are numbered 0 (crossfade), 1, 2, 3,
4, 5, 6, 7, 8 (vocoder freeze). You have do dial a combination by
getting the big knob to point to a "number", and then pressing the INT
OSC button. The combination is 2 4 3 6 1 5.

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pichenettes schrieb:

Here's a little explanation about the easter egg...

With INT. OSC enabled, the module works as a frequency shifter.

ALGORITHM knob and ALGO CV input: frequency shift. No shifting at 12 o'clock, positive frequencies when turning CW, negative frequencies when turning CCW. The control curve is linear until 50 Hz then becomes exponential. The response of the ALGO CV input (which modulates shifting amount) depends on the position of the big knob - it is linear when the big knob is near its central position, and 1V/Octave-ish when the big knob is above 50 Hz or below -50Hz.

INT. OSC: carrier waveform. Available waveforms: sine, three harmonics, "random" signal created by summing 7 harmonics with random amplitudes/phases. With a low frequency shifting amount, you can think of this as the tremolo/delay/phasing modulation waveform. Another way to think about this parameter is that there will be one shifted "copy" of the input signal per harmonic of the carrier waveform.

LEVEL 1 CV/knob: feedback amount.

LEVEL 2 CV/knob: dry/wet amount.

TIMBRE: balance between the lower and upper sidebands. Both sidebands are present (ring-modulation) when the knob is at 12 o'clock.

AUDIO IN 1 & 2: two audio inputs, summed together.

AUDIO OUT 1+2 / AUX: the two audio outputs react reversely to the TIMBRE knob. For example, if TIMBRE is fully CCW, 1+2 will output the lower sideband, and AUX will output the upper sideband. Great for generating a wide stereo image!


Now what happens when you disable INT. OSC? The module becomes a kind of "quadrature cross-modulator". Mathematically, it computes the product of the analytic signals obtained from inputs 1 and 2, and another complex exponential - then the real and imaginary parts of the result are dispatched to the two outputs. This one is tricky to explain! You can think of it as frequency shifting, except that instead of dialing the shifting frequency with the big knob, you directly feed a sinewave at this frequency on input 1 to shift input 2. Obviously, feeding a waveform more complex than a sinewave on input 1 will cause multiple shifts of the signal on input 2 - creating very complex inharmonic tones! When INT. OSC is disabled, ALGORITHM controls the amount of phase shifting on the result of the modulation. You won't hear much difference when you move it very slowly - the magic happens when it is modulated.

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This firmware adds the following features to the module:

An easy interface to switch between 9 modes, each determining a different function for the module. The stock mode (morph between algorithms) is now called Meta-mode, and is only one of 9. The easter egg (frequency-shifter) is another.
Most modes take the stock algorithms and go deeper into them, with two dimensions of control instead of one; some are completely new functionalities.
New features include: a dual chorus/flanger/slapback, a binaural panner with doppler-effect simulation, a dual bit-mangler, a Chebyschev waveshaper.

Consequently, all features of the official firmware are left untouched and still accessible (with a few exceptions mentioned in the documentation).

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