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.

ValhallaUberMod: The MOD Parameters

ValhallaÜberMod allows the user to dial in different chorus, ensemble, and glitch shifting modulations through the use of the MOD controls. By clicking on the MOD button at the upper right of the GUI, the 5 modulation parameters can be viewed and adjusted:

The MOD parameters:

• MOD SlowRate controls the slower delay modulation LFOs, with the value represented in Hertz. Depending on the Mode being used, this will control the speed of anywhere from 1 to 16 LFOs.
  • In modes with multiple LFOs, the modulation rate varies for each LFO, so the SlowRate value maps to the cycle speed of the slow LFO with the highest frequency – all the other LFOs will be somewhat slower.
• MOD SlowDepth controls the modulation depth of the slow LFOs. This is more of a scale than an absolute value, and is used to balance the slow and fast LFO depths (which are both scaled by the high level DEPTH control).
  • The MOD SlowDepth also depends on the MOD OverMod setting, which acts as a control to set the slow LFO depth beyond reasonable bounds – see below.
• MOD VibRate controls the faster delay modulation LFOs, with the value represented in Hertz. Depending on the Mode being used, this will control the speed of anywhere from 1 to 32 LFOs.
  • In modes with multiple LFOs, the modulation rate varies for each LFO, so the VibRate value maps to the cycle speed of the fast/vibrato LFO with the highest frequency – all the other vibrato LFOs will be somewhat slower.
  •  For most applications, the MOD VibRate should be used to add vibrato to a chorus, with the main detuning generated by the MOD SlowRate and MOD SlowDepth controls. However, this is just a suggestion – the fast LFOs can generate cool chorus effects by themselves.
• MOD VibDepth controls the modulation depth of the faster LFOs. This is more of a scale than an absolute value, and is used to balance the slow and fast LFO depths (which are both scaled by the high level DEPTH control).
  • The MOD VibDepth setting doesn’t get as deep as the SlowDepth control, as LFOs running at faster frequencies cause more pitch change than slower LFOs.
  • In addition, the MOD VibDepth isn’t affected by the setting of MOD OverMod.
• MOD OverMod. Acts as a scale on MOD SlowDepth. At the default OverMod setting (1X), the slow LFOs are optimized for creating chorusing and detuning effects. For higher settings of OverMod, the detuning gets deeper and deeper, until it moves into the realm of pitch shifting and backwards delays.
  • The modulation depth established by MOD SlowDepth and MOD OverMod is also scaled by the high level DEPTH slider.
  • The pitch shifting is not the controlled type found in ValhallaShimmer. The amount of pitch bend depends on the interconnections between MOD SlowRate, MOD SlowDepth, MOD OverMod, and the DEPTH slider. A better name for this would be “glitch shifting.” I just threw up a little in my mouth as I typed this, but it is the most descriptive phrase I can think of for the OverMod artifacts.

Some more ValhallaShimmer examples

A few people have posted examples of ValhallaShimmer in action on Soundcloud. The first example, by Paul Mimlitsch, uses a greatbass recorder through Shimmer, set to a long reverb with no pitch shifting:

The next example, from Simon Stockhausen, uses a solo euphonium, automating the sends to 5 differently tuned instances of Shimmer. The results are very Wagnerian:

The final example, from Bronto Scorpio, uses a Wavestation through 2 instances of ValhallaShimmer:

Giving the gift of ValhallaShimmer this holiday season

I’ve had a few requests, asking how to buy ValhallaShimmer for a friend, loved one, etc. It’s really easy:

• Click on the PayPal button on the ValhallaShimmer page.
• Click the “Add special instructions to the seller” button, and write the first and last name (or user name, or company, or whatever) of the person you want to send the plugin to, as well as an email address for that person.
• Once I have that info, I can make out the keyfile to that person.

Hope y’all are having a happy holiday season. Here’s Drunk Orson Welles:

ValhallaShimmer Tips and Tricks: Shimmering

ValhallaShimmer was designed to get a variety of big reverb sounds, with the option of adding pitch shifted feedback to the decay. The “Shimmer” in the title refers to the classic shimmer effect, as used by U2, Brian Eno, Daniel Lanois, Coldplay, etc. There are a few presets that ship with ValhallaShimmer which reproduce this effect, but if you want to dial in your own version, here’s some tips:

• Use the mediumStereo or bigStereo reverb modes for the smoothest shimmer sounds. The mono reverb mode will have a stronger sense of pitch shifting in the feedback signal, while the other modes have a gentler onset of the pitch shifting.
• Set the Feedback control for the desired amount of pitch shift in the output signal, and then use the Size control to dial in the decay.
• The Pitch control should be at +12 semitones.
• Diffusion works best at around 0.9 for reverberant sounds. If you set Diffusion < 0.5, it will sound closer to a pitch shifted echo, which is another cool sound.
• The different pitch shift modes have different levels of “smoothness”:
  • The single and dual pitch shift modes have more noisiness in their decay. This is better for emulating the orchestral sounds as heard in “Deep Blue Day.”
  • The singleReverse and dualReverse pitch shift modes are much smoother, and are better for organ-esque sounds.
• colorMode should be set to dark. This produces a natural roll-off of high frequencies, which eliminates almost all of the aliasing noise in the feedback path of the pitch shifter.
• Set the modDepth control to a fairly low value at first, as the pitch shifting provides its own random modulation to the signal.

ValhallaShimmer: The Controls

At it’s heart, ValhallaShimmer consists of what I call “diffuse delay lines.” These are actually networks of diffusors, that act like a single delay line when the Diffusion control is turned down to zero, and generate clusters of reflections when the Diffusion control is turned up. By adjusting the Diffusion, Size and Feedback controls, the sound can be changed from short delays, to feedback echos that gradually turn into a gentle wash, to reverbs that decay away over several minutes. Add the pitch shifting, tone controls and modulation into the mix, and a huge variety of soundscapes can be generated.

ValhallaShimmer has 9 continuous parameters (“knobs”) to allow for coarse or fine adjustment of the reverb algorithm:

• Mix – controls the relative balance of the input (“dry”) signal and the reverbed/delayed (“wet”) signal. The Mix control uses a power-complementary crossfade technique, to ensure constant levels throughout the various settings.
• Pitch – controls the shift amount in the feedback loop, ranging from -12 to +12 semitones. The specific pitch shift characteristics also depend on the Pitch Mode, explaned below.
• Feedback – adjusts the amount of feedback applied around the diffusor delay / pitch shifter network. Note that the pitch shifting will only be audible with Feedback values greater than zero.
• Diffusion – controls the coefficients of the individual diffusor delays within the network.  A coefficient of 0.0 corresponds to no diffusion – i.e. a straight delay. A coefficient in the 0.5 to 0.618 range will result in a reverb sound that slowly fades in. A coefficient of 0.9 results in a fairly long decay (depending on the Size setting), even if Feedback is set to zero.
• Size – controls the delay lengths within the network. A small Size setting corresponds to short delays, which translates to a smaller room sound. A large Size corresponds to long delays, and a bigger room sound. The Size setting also effects the overall decay of the reverb: assuming all settings are the same, a larger setting of Size will correspond to a longer decay.
• Low Cut – controls the cutoff frequency of a highpass filter in the delay path, with the cutoff specified in Hertz. A higher setting of Low Cut will result in less low frequencies being passed through. The Low Cut filter is in the feedback path, so higher settings of Low Cut will result in the decay becoming brighter and brighter as it decays away.
• High Cut – controls the cutoff frequency of a lowpass filter in the delay path, with the cutoff specified in Hertz. A higher setting of High Cut will result in less high frequencies being passed through. The High Cut filter is in the feedback path, so higher settings of High Cut will result in the decay becoming darker and darker as it decays away.
• Mod Rate – adjusts the speed of the modulation, in Hertz. This is only a rough estimate of the actual modulation rate, as there are dozens of random modulators in the reverb algorithms, each with a slightly different base modulation rate.
• Mod Depth – controls the depth of the modulation. This translates to a constant value in samples, so it needs to be adjusted in conjunction with Mod Rate in order to get the amount of detuning desired.

In addition to the knobs, ValhallaShimmer has 3 mode selectors, which can be found under the knobs. The mode selectors are used to switch between different reverberation algorithms, pitch shifting types, and the overall tone of the plugin.

• Reverb Mode – selects the base algorithm type that is used. The Reverb Mode has a large impact on the perceived size of the reverb, and also impacts the reverb density, modulation depth, and the rate at which the pitch shifted feedback builds.
  • Mono – selects a mono-in, stereo-out reverberation algorithm. The Mono algorithm has a very large base size, and can take a long period of time to fade in This algorithm has a very high echo density with most settings of the Diffusion parameter.
  • Big Stereo – selects a stereo-in, stereo-out reverberation algorithm with a very large base size. This algorithm is the best for very large acoustic spaces, such as cathedrals and monumental spaces, as well as reverbs that slowly fade in and out. The Big Stereo algorithm has a very high echo density with most settings of the Diffusion parameter.
  • Medium Stereo – selects a stereo-in, stereo-out reverberation algorithm with a smaller base size than the Big Stereo mode. This algorithm, in conjunction with a reasonable amount of feedback, is the best choice for traditional “hall” reverbs. It is also a good choice for pitch shifted feedback with a fairly fast build of harmonics. The echo density is lower than the Mono and Big Stereo algorithms, but is still fairly high.
  • Small Stereo – selects a stereo-in, stereo-out reverb algorithm with a small base size. This algorithm can be useful in achieving small room sizes, chorused short ambiences, and other smaller reverb sounds. It can be more strongly colored than the other reverb modes, and has a noticeably lower echo density than the other modes.
• Pitch Mode – selects the type of pitch shifting used in the feedback loop of the reverberator:
  • Single – the signal within the feedback loop is shifted upwards or downwards, with the pitch ratio determined by the Shift control. This is the “classic” mode used for recreating the Shimmer sound found in many of the Eno/Lanois productions. The randomization used in the pitch shifting will create noisy sidebands in the feedback loop, which results in a sound that is reminiscent of a large orchestra
  • Dual – the signal within the feedback loop is shifted both upwards and downwards simultaneously, with up/down pitch ratios determined by the Shift control. This is a good setting for getting a rich, symphonic harmonic texture.
  • SingleReverse – the signal within the feedback loop is shifted upwards or downwards, where the signal within each pitch shifted “grain” is reversed in time. This results in a smoother pitch shifting sound than the Single or Dual modes – less orchestral, more organ-like.
  • DualReverse – the signal within the feedback loop is shifted both upwards and downwards simultaneously, where each pitch shifted “grain” is reversed in time. This mode is well suited for producing a pipe organ sound.
  • Bypass – the signal within the feedback loop is not pitch shifted, and is passed straight through without alteration. This is useful in created more conventional reverb sounds, where turning up the Feedback parameter increases the decay time.
• Color Mode – controls the overall “tone” of the algorithm:
  • Bright – the reverberated signal can be “full-bandwidth,” depending on the setting of the High Cut control. There is no inherent high frequency lost in this algorithm. The resulting sound is more “hi-fi” or modern than the Dark color mode.
  • Dark – the reverberated signal has a large amount of high frequency loss, with the exact amount of high frequency loss varying depending on the Reverb Mode selected. The resulting sound is reminiscent of the classic digital reverbs of the 1970′s and early 1980′s, with steep cutoffs above 10 kHz.

ValhallaShimmer: a bit of history

ValhallaShimmer has its roots in the earliest digital reverberation algorithms, as described by Mannfred Schroeder in 1961. Schroeder, in his earliest AES paper on the subject, described a “colorless” reverberator, based upon cascaded diffusor (allpass) delays. At the time, the computation power available on the mainframe computers Schroeder was using limited the complexity of his algorithms.

In 2006, I experimented with extending Schroeder’s early reverberator structure to much higher orders. I was expecting that using much larger numbers of cascading diffusors would increase the echo density of the algorithm. It did, but it had a really weird effect: As the number of diffusors increased, the reverb decay started to sound less and less like a “real” acoustic space, and more and more like some weird spooky backwards thing.

It turned out that I had run into an artifact of what is known as the Central Limit Theorem. Without getting into the messy scientific details, the effective result was that, as the number N of cascaded diffusors increased, the attack and decay characteristics of the reverb changed from an exponential decay towards a bell, or Gaussian, curve. In other words, the reverb would slowly fade in, and then slowly fade out.

This wasn’t what I was expecting. More importantly, it sounded cool. Add some randomized modulation to each of the diffusors, and the result was an ethereal, ghostly soundscape.

The pitch shifting Eno trick was one that I had first tried back in 2004. The pitch shifter I used at the time produced decent results. Later on, I conducted research into early pitch shifting techniques (as detailed in earlier blog posts) and developed a simple yet effective algorithm for pitch shifting. The goal was to generate similar artifacts to what a “de-glitched” pitch shifter would produce in a feedback loop with a reverberator, but without performing the costly autocorrelation analysis that the deglitching pitch shifters used. The result was a pitch shifting algorithm that added noise and texture to the feedback loop. It was an attempt to avoid metallic colorations (and emulate what a deglitching pitch shifter sounds like when it is freaking out), but it also sounded like a huge orchestra warming up.

When I started work on ValhallaShimmer in the spring of 2010, I knew that I wanted to combine the results of the cascaded diffusor experiments with the pitch shifted feedback as used by Brian Eno, Daniel Lanois, U2 et al. In order to put these into plugin form, I had to perform extensive optimization on the basic building blocks, as my early experiments used up far too much of the CPU. After a few months of work, I had a framework that brought the CPU consumption down by a factor of 10 to 20 from my 2006 experiments.

The original version of ValhallaShimmer had a single reverb algorithm, the one currently labeled as “mono.” Testing the plugin with material recorded with stereo miking techniques quickly pointed out that true stereo algorithms were necessary. The resulting algorithms (bigStereo, mediumStereo, smallStereo) were designed to get different perceived room “sizes,” although most of the sounds fall in the range between pretty big and huge.

During the optimization process, I found that one of my CPU-reducing tricks resulting in a lot of high frequency loss. Instead of looking at this as a technical shortcoming, I listened to the results. The optimized code sounded “warm,” and much closer to an ancient digital reverb with a low sampling rate and steep anti-aliasing filters. So I left it in as the “color” mode, so the user can choose between the original “bright” mode for modern reverb sounds, and the “dark” mode for that warm vintage sound.

Looking back at the history of ValhallaShimmer, it just struck me that most of what makes this an original algorithm was embracing the weird little artifacts that I came across while experimenting with various digital signal processing techniques. The cascaded diffusors didn’t behave in the manner I was expecting, but they sounded great. The pitch shifting artifacts added some grainy texture to the reverb decay, that sounded like a string orchestra section, even though the original goal was to get rid of metallic coloration. My optimization techniques darkened the overall tone, and helped me to realize that dark is often a good thing for a reverb. Happy accidents.

ValhallaShimmer released for Windows RTAS

I just released the Windows RTAS version of ValhallaShimmer. Set your browsers to

http://www.valhalladsp.com/shimmer.html

and check it out. Demo versions available at that link.

To sum up (as there has been several updates in the last few days): ValhallaShimmer is now released for:

OSX VST
OSX Audio Unit (32-bits)
OSX Audio Unit (64-bits)
OSX RTAS

Windows VST (32-bit)
Windows VST (64-bit)
Windows RTAS

I’m going to go out and enjoy the snow with the kids for the rest of the day (it’s snowing here in Seattle, which doesn’t happen in November that much). After that, I will put up a few blog entries about ValhallaShimmer, explaining the history of it, how it works, tips and tricks, that sort of thing. I also have a few generic topics that I want to cover, although coding has taken priority over happy creative thoughts for the past several months.

ValhallaShimmer updated to version 1.0.2. 64 bit AU, 64 bit Win VST available.

I’ve just updated ValhallaShimmer to version 1.0.2. The new features:

• 64 bit Audio Unit (in addition to the 32 bit AU)
• 64 bit Windows Vista/7 VST (in addition to the 32 bit VST)
• Improved saving/recall for OSX DAWs
• Internal presets now included in the Windows VSTs

Check it out at http://www.valhalladsp.com/shimmer.html

Next up, finishing the Windows RTAS port. After this is done, I hope to get back to blogging every now and then.

ValhallaShimmer released for OSX AU, VST, RTAS. $50. Demo versions online.

After far too much work, ValhallaShimmer is finally available for sale and demoing:

ValhallaShimmer

OSX users, grab yerself a demo copy and see how you like it. Windows folks, I estimate another week of work and beta testing until the Windows VST/RTAS release.

Some thanks are in order:

• Beta testers. You’ve dealt with far too many revisions, and your input has been invaluable.
• The Audio Damage guys. You gave me credit for my work on Eos, at a time when I had never received any public credit for my consulting gigs.
• My old co-workers at Staccato Systems / Analog Devices. It was like going to school, just getting paid.
• My teachers at University of Washington and CCRMA. It was exactly like going to school, except I was learning really cool stuff. You helped me start off on this crazy journey.
• Bram Wessel and David Hopper, for encouraging me to keep going on Shimmer even when I was ready to walk away from the project.
• All of you who have been following this blog and the forums, and giving me words of encouragement.
• Last and by no means least, my lovely wife Kristin has given me emotional and financial support, time, and has been an awesome web designer. Plus, you’ve heard me rant about allpass filters and modulated delays for the past 13 years, which makes you a freaking hero.