What is UberMod?

ValhallaÜberMod, at its heart, is a stereo modulated multitap delay line. The signal is written into parallel delay lines (1 for left, 1 for right), and is read out by one or more delay taps. The taps can be moved back and forth in time, by low frequency oscillators or user controls, in order to produce pitch changes via the Doppler effect. The plugin also incorporates diffusion delays, soft saturation, low and high cut filters, and a variety of other controls to shape the delay tap amplitudes, spacing, tone and movement.

So, what can you do with a stereo modulated multitap delay line?

• Chorus. ValhallaÜberMod contains elements inspired by the Roland Dimension choruses, but vastly expanded in order and with fully parametric controls. The classic “Dimension D” sound can be emulated, but ÜberMod can also emulate the multi-voice choruses previously limited to high end rack gear.
• Ensembles. The modulation section of ÜberMod contains slow and fast LFOs, that can be mixed in together. In addition, some of the Modes are based around the specific modulation schemes of vintage string ensemble units, such as the 3-phase LFOs found in the Solina and Crumar Performer, and the dual triangle LFOs of the Roland VP330/RS505. This allows ÜberMod to dial in a variety of “classic” ensemble effects, as well as more realistic emulations of orchestral sounds.
• Flanging. By using one of the multitap modes, and keeping the delays short and grouped closely together, ÜberMod can create huge flanging sounds, that incorporate the through-zero effects of tape flanging, while adding random motion and complexity to produce an effect that is remarkably similar to a jet flying overhead.
• Delays. ÜberMod allows the user to sync the delays to the DAW tempo, as well as dialing in specific delay times in milliseconds.
• Multitap Delays. With up to 32 taps, ÜberMod can create dense clusters of delays, rhythmic tapped delays, strongly pitched comb filtering effects, and all sorts of multitap sounds. The TAPS controls allow the user to shape the spacing and amplitude of the delay taps via intuitive high-level controls.
• Ping-Pong Delays. The new WARP InputPan control (introduced in the 1.0.1 ÜberMod release) allows for any of the delay Modes to be turned into a ping pong mode. This goes well beyond the standard ping pong delays, and can produce ping ponging delay clusters, ping pong delays with strange rhythmic divisions, ping ponged multitap clusters, and tons of other effects that bounce back and forth between speakers.
• Tape and BBD delay emulations. ValhallaÜberMod has a flexible overdrive section, including pre and post gain, as well as noise that can be mixed into the signal. The delay time changes can also be slewed, using the WARP Smoothing control, to produce the slow delay transitions and pitch changes that are typical of analog delays. By dialing in overdrive, noise, and feedback, and adjusting the flexible EQ section, the user can get low-bandwidth BBD emulations, wobbly tape delays, and long echos that degenerate into shrieking oscillation.
• Diffuse delays. Many of the high-end Lexicon and Eventide rack units combined diffusion delays with longer delay lines, to soften the attacks of echos. ValhallaÜberMod has a flexible diffusion section, to create smeared echos, clusters of delays, and all sorts of diffuse effects.
• Reverbs. The diffusion section in ÜberMod has variable size and modulation parameters, similar to ValhallaShimmer, but more optimized for generic delay effects. Crank up the diffusion size and turn up the feedback, and all sorts of reverb effects can be produced: short ambiences, large rooms, huge halls.
• Nonlinear and reverse reverbs. Combine the diffusion section with a Mode that has a larger number of delay taps (8/16/32 taps) to generate short gated reverbs, “reverse” reverbs that fade in slowly over time, room reverbs with a truncated decay, etc.
• “Glitch Shifting.” The triangle oscillators in ÜberMod were designed to create “detuned” choruses, without an obvious sense of pitch wobble. Crank up the OverMod control, however, and all sorts of unpredictable pitch shifted and reversed sounds can be produced. I call this “glitch shifting,” although I still feel dirty whenever I type that phrase.
• Oscillations. Turn on the DRIVE, and crank up the feedback, and ÜberMod will start making sounds on its own. By adjusting the delay and modulation settings, all sorts of crazy burbling whirling machine noises can be generated.
• Stereo Widening. Use short Diffusion settings to widen the stereo image. Add a bit of modulation to create stereo choruses. Crank up the DEPTH control to create super-stereo effects.
• Chimeras. This is the term I use for sounds that combine aspects of several effects to create sounds that are new, weird, and in many cases defy easy categorization:
  • Reverbs with ensemble modulation
  • Ping-Pong Reverbs
  • Tape Reverbs, where the sound gets more distorted as it decays away
  • Sounds that don’t have names yet

So, why create a single plugin that covers all of these sounds, instead of several plugins where each plugin is tailored to a specific application? I’m not exactly sure. In many ways, I feel that ValhallaÜberMod was a plugin that designed itself, instead of me creating something that did exactly what I wanted it to do. At each stage during the development process, I uncovered new and exciting sounds that defied easy categorization. I decided to create a plugin that allowed for those sounds to be dialed in, as well as sounds that as yet remained undiscovered.

ValhallaÜberMod is “close to the metal.” There are a lot of controls, that have been grouped according to logical function. In some ways, ÜberMod is like a Swiss Army Knife for modulated delays, but this doesn’t really describe the chimera effects that are neither fish nor fowl. The oddball possibilities are what I find most interesting about ÜberMod. It explores the spaces, the shared commonalities, that lie underneath the common modulated delay effects, while making room for other effects that don’t fit within the standardized categories. I nearly went crazy designing ÜberMod, and I think that some of that over-caffeinated energy was captured within the plugin, in the context of a logical structure that allows the user to control the sanity/insanity ratio.

Cave Paintings, Wabi-Sabi, and Plugins

The other night, the wife and I saw Werner Herzog’s latest film, “Cave of Forgotten Dreams”:

The movie was a 3D documentary about the paintings found in Chauvet Cave. These paintings are believed to date from up to 32,000 years ago, and are of an artistic standard that is stunning to this day:

The entrance to the cave is believed to have collapsed around 20,000 years ago, essentially sealing in the art until the cave was rediscovered by explorers in 1994.

After the film, my wife and I had some deep discussions about art and impermanence. Right now, my main artistic outlet is the development of plugins. And plugins (and software in general) tends to be very ephemeral. A plugin or music software program that runs on a general purpose computer will be lucky if it runs 10 years from now. Windows machines tend to be better in this respect, as an audio app that ran in Windows 98 could conceivably run today. However, the more useful audio applications from the 1990′s tended to run on the original Macintosh OS, and it is difficult to find a computer that can run these applications today. I have several friends that spent years creating work in Supercollider 2, and that work will no longer run on modern Macintoshes. Turbosynth is another “classic” Mac OS application that will no longer run.

The impermanence of digital audio software is obviously not limited to plugins and Mac/Windows apps. Most of the “canonical” computer music pieces were created for systems that no longer exist. In order to get the maximum performance out of limited hardware, the majority of the “classic” computer music languages from the 1960′s through the 1980′s were created using the assembly language of the machine they were run on, and will not function outside of that environment. For example, Music 11 only runs on a PDP-11; Music 360 only ran on an IBM360; Music Kit was designed for the NeXT cubes with built-in Motorola DSPs; the Samson box compositions only ran on the Samson box.

A few of the older computer music languages were written in Fortran (Music 4F and Music V) and still have a fighting chance of being compiled today. Unfortunately, the compositions written for these programs are also hard to get up and running – good luck finding a working punch card reader today. For that matter, many of the optical and magnetic drives from the 1990′s are no longer functional.

In some ways, the impermanence of software brings to mind the Japanese concept of Wabi-Sabi. This is the idea of finding beauty in transience, and that beauty that is “imperfect, impermanent and incomplete.” In the traditional Japanese conception of this idea, wabi-sabi can be found in rustic items such as the simple clay bowls used in the tea ceremony. The cracks and chips of such bowls, and the changing color of the glaze over time as it is chemically altered by hot water, are believed to embody the idea that “nothing lasts, nothing is finished, and nothing is perfect.”

It is tempting to explain away the short lifespan of audio software as wabi-sabi. This perspective would allow me to explain away bugs as “imperfections to reflect upon,” and would carry on the grand tradition of appropriating Eastern religious concepts into a Western philosophical framework without bothering to truly understand those Eastern concepts. However, I’m not able to make the comparison stick.

One could argue that analog musical instruments and equipment decay gracefully with age. The yellowing grillcloths of a Fender amp, the crackle on the lacquer finish of an older guitar, the small tuning instabilities of an older analog synth, the strange electronic howls of a fuzz box as its battery dies…all of these would allow the user to reflect upon the passage of time.

Software does not age gracefully. It works, and then it doesn’t. The life of software is nasty, brutish and short, and death comes quickly via a hard drive crash, or painfully via the bloat of a Windows registry. When it is gone, nothing useful is left behind, except for a box full of toxic metals.

So, how do I, as a software developer and digital artist, respond to the impermanence of software?

For starters, I keep my prices reasonable. Charging several hundred dollars for something that won’t work 20 years from now feels weird. I’ll keep things running as long as I can, but there will come a day when I am no longer alive, and these plugins won’t keep working.

I can also look into embedding my algorithms into hardware. The long term longevity of digital signal processors has yet to be seen, but I have several digital reverb boxes that are 20 to 25 years old, and are still running strong.

Finally, there is source code as a way of survival. My algorithms from my Csound days are still being integrated into open source projects today, and those algorithms are from 1999. I am not working on any open source projects presently, but it something to consider for several years down the road.

Nevertheless, the odds that any of my algorithms will survive 100 years, let alone 32,000 years, are slim at best. At Chauvet Cave, we are seeing the work of a very few artists, and we have no true way of estimating the scope of art in the ancient world, but it is probably save to assume that the vast majority of ancient art has been lost forever to the processes of decay and weather. Life is fleeting, and all turns to dust in the end, so having art that is a reflection of this truth is probably the most honest response.

Shimmer: Modulation, auto-correlation, and decorrelation

In my previous post, I discussed the Eno/Lanois shimmer sound, and how it is based around a pitch shifter and a digital reverb placed in a global feedback loop. It is worth exploring what is going on in this signal chain at the micro level, and how a fairly simple signal routing can create such a complex sound.

The AMS pitch shifter used by Eno and Lanois used a de-glitching board in its architecture, to find the ideal points for splicing together the time-scaled waveform chunks. This presumably worked in a similar manner to the H949 de-glitching card, in that autocorrelation was used to find the most similar segments of the waveform, and the delay time of one of the channels was adjusted for an ideal splice. It is also possible that the auto-correlation would trigger a new splice, such that the rate between splices was a function of the periodicity of the input signal.

Auto-correlation works well for determining splicing points, assuming that the input signal has a certain degree of correlation. A single sustained guitar note, for example, can have a high auto-correlation factor after the initial attack. But what happens when the signal to be shifted has a very low auto-correlation factor? Such a signal is said to be decorrelated; that is, the auto-correlation or cross-correlation is said to be greatly reduced compared to the original signal.

In the audio world, decorrelation often refers to randomization of the phases of the signal while preserving the frequencies, or to a time-varying process to slightly shift the frequencies of a signal to prevent feedback. Both of these processes are present, to a large extent, within time varying reverbs such as the Lexicon 224 and EMT250 used by Eno and Lanois.

The Lexicon 224 Concert Hall algorithm is made up of a number of allpass delays, which preserve the input frequencies while completely scrambling the phase response. In addition, the Concert Hall algorithm uses time varying delays inside of the recursive delay network, which increased the perceived modal density of the reverb, and also impart a beautiful chorusing to the reverb decay. This lushness from time-varying delay lines is very prominent in 1980′s Eno/Lanois productions – in addition to the Concert Hall algorithm and EMT250, they made use of the multi-voice chorus algorithms in the Lexicon units, as well as the Symphonic preset in the Yamaha SPX-90.

So, what happens when a pitch shifter that uses auto-correlation to find the ideal splicing points is put into a feedback loop with a reverb that is highly decorrelated and time-varying? The answer: chaos. The pitch shifter will NOT be able to find ideal splicing points, as the phase of the reverb output is continually being scrambled.

The pitch shifter HAS to splice, whether or not it is a perfect situation, so it will pick the best possible match, but this will probably be a fairly random location each time. The result will be random delays for each new splicing point, or random sizing of the grain windows, depending on how the auto-correlation is used within the pitch shifter. This randomization will cause the sidebands of the input signal to be spread out, such that an individual sinusoid would be turned into a band of frequencies centered around the original (that has been shifted up by an octave).

Add in the additional octaves produced by the feedback, the random sideband spread caused by the modulation within the reverb, and harmonics that are created by analog nonlinearities in the feedback path, and the result is a HUGE amount of sonic complexity generated from a simple system. Put a sine wave into this type of feedback system, and the output can approach near orchestral levels of thickness.

In this light, it is interesting to think about Eno’s use of the DX7 around this time. The DX7 can produce chaotic sounds through the use of cascaded FM, but it can also produce gentle, minimalist textures through the use of parallel operators (sine oscillators). A simple DX7 patch with several parallel sine oscillators and a low FM index may produce a fairly boring sound on its own, but would create an enormous yet controllable sound when fed into a complex feedback loop of digital processing.

Coming up: more on the topic of generating complexity through simple systems with feedback applied to them, both from a technical and creative perspective.

Modulation in reverbs: reality and unreality

The use of modulation in digital reverbs dates back to the first commercial digital reverberators. The EMT250 used an enormous amount of modulation, to the point where it sounded like a chorus unit. Lexicon’s 224 reverberator incorporated what they called “chorus” into the algorithms, working along principles not dissimilar to the string ensembles in use at the time. The Ursa Major Space Station was based around an unstable feedback arrangement, that relied upon randomization to achieve longer decay times without self-oscillating.

Recently, Barry Blesser has written about randomization in his book, “Spaces Speak: Are You Listening?” Blesser argues that thermal variations in most real-world acoustic spaces results in small variations of the speed of sound within those spaces. Multiply this by several orders of reflections, and the result is an acoustic space that is naturally time varying. Blesser goes on to argue that random time variation in algorithmic reverbs emulates the realities of an acoustic space more accurately than time-invariant convolution reverbs.

Blesser makes a convincing argument, but I am not convinced that the heavy amounts of delay modulation used in the older reverbs makes for a more “realistic” space. The randomization in the older algorithms does a nice job in masking the periodic artifacts that can be found when using a small amount of delay memory. However, the depth of modulation used in the old units goes far beyond what can be heard in any “real world” acoustic space. The thermal currents in a symphony hall will result in a slight spread of frequencies as the sound decays, but will not create the extreme chorusing and detuning found in the EMT250, or in the Lexicon algorithms with high levels of Chorus.

Having said that, I would argue that the strengths of algorithmic reverbs is not in emulating “real” acoustic spaces, but in creating new acoustic spaces that never existed before. Blesser recently said that the marketing angle of the EMT250 was to reproduce the sound of a concert hall, but later describes the EMT250 in terms of a “pure effect world.” The early digital reverbs, in the hands of sonic innovators such as Brian Eno and Daniel Lanois, were quickly put towards the goal of generating an unreal ambience, where sounds hang in space, slowly evolving and modulating. Listen to Brian Eno’s work with Harold Budd, on “The Plateaux of Mirror,” to hear the long ambiences and heavy chorusing of the EMT250 in action. A later generation of ambient artists made heavy use of the modulated reverb algorithms in such boxes as the Alesis Quadraverb to create sheets of sound, that bear little resemblance to any acoustic space found on earth.

Creating these washy, chorused, “spacey” reverbs has been a pursuit of mine since 1999. My early Csound work explored relatively simple feedback delay networks, with randomly modulated delay lengths, in order to achieve huge reverb decays that turn any input signal into “spectral plasma” (a term lifted from Christopher Moore, the Ursa Major reverb designer). With my more recent work, I have tried to strike a balance between realistic reverberation, and the unrealistic sounds of the early digital units. The plate algorithms in Eos are an attempt to emulate the natural exponential decay of a metal plate, but were also inspired by my understanding of the EMT250. The Superhall algorithm in Eos was not attempting to emulate any “natural” space, but rather the classic early digital hall algorithms, with heavy randomization, nonlinear build of the initial reverberation decay, and the possibility of obtaining near infinite decays. The “real” world continues to be a source of inspriation for my algorithms, but I find myself more attracted to the unreal side.