ValhallaRoom Released for Windows (32/64-bit VST)

I am happy to announce that the 32-bit and 64-bit VSTs of ValhallaRoom have just been released for Windows. Check out the demo at

Thanks to my beta testers for helping me sort out installer issues and the like.

ValhallaShimmer now available for Windows VST

I just posted ValhallaShimmer for Windows VST. A demo version is available, which mutes the sound every 45 seconds (just like the OSX versions), but is in all other aspects identical to the full version. Check it out at

Thanks to everyone who has bought ValhallaShimmer so far. I appreciate your support.

ValhallaShimmer, Meet Korg Monotron. Korg Monotron, Meet ValhallaShimmer.

My old friend David Hopper gave me a Korg Monotron yesterday. I’ve had an insane amount of fun getting R2D2 noises, FM drones, and rhythmic beats out of this little battery operated analog synth.

Today, I recorded a few short Monotron drones through ValhallaShimmer. I’m using 4 series instances of Shimmer, with 2 of the instances pitch shifting the feedback by +/- 12 semitones and +/- semitones. Here’s what came out:

For reference, here is the original Monotron track with no instances of ValhallaShimmer enabled:

ValhallaShimmer was designed to create a huge amount of sonic complexity out of any sound source. By using a simple sound source such as the Monotron and controlling only a few parameters (Pitch, VCF Cutoff, VCF Peak), you can make big sounds that are responsive to subtle sonic gestures.

In other ValhallaShimmer news, I ported the plugin to Windows VST and RTAS late last week. I need to add some optimizations to the Windows code, but this should allow me to release the Windows and OS X versions of the plugin at the same time. (UPDATE: Windows VST, and OSX VST/AU/RTAS released. Go to to get yourself a copy.)

ValhallaFreqEcho MkI Released: GUI. Tempo Delay. VST/AU/RTAS. Mac/Windows. Free.

I am pleased to announce the MkI release of ValhallaFreqEcho:

The plugin now features a custom GUI, as seen above. I have added the ability to sync the delay time to tempo. ValhallaFreqEcho MkI is available for Windows and Mac, in VST, AU, and RTAS formats.

ValhallaFreqEcho MkI has been under development for quite some time, and I am rather proud of the results. I invite you to download it and check it out. Keep checking this blog in the next few days for tutorials, tips and tricks, and a bunch of theoretical musings.

ValhallaFreqEcho updated: new controls, VST+AU

I just posted some updates to ValhallaFreqEcho, my free frequency shifter + analog echo plugin. You can download the plugin here. The new stuff:

  • New parameters: Low Cut and High Cut. These control the gain of shelving filters in the feedback path of the echo (the direct and initial echo signal are not filtered). These controls are very useful in getting different type of analog sounding echos, as well as harsher or flubbier echos, plus a variety of strange chaotic oscillations.
  • An Audio Unit version of the plugin is available, in addition to the VST plugins for Windows and OSX.

I’ll be posting some usage tips soon. I have spent a lot of time setting up runaway oscillations with the plugin, using no input (it self-oscillates like the old analog echos). Some very trance-y sounds can be coaxed out of this thing – not the dance music type of trance, but the “staring into space and drooling for awhile” type of trance.

Eos tips and tricks

Eos has been out for a month and a half now, and the reception seems pretty positive. I thought I would share some tricks that came up during the development of the algorithms, as well as some more recent ideas.

  • Gated reverb. The Attack control in Superhall allows you to approximate a gated reverb sounds Set Attack to around 50, Decay to a low value (<1 second), Diffusion to 100, and play around with Size to get the gate time. If the sound is too grainy, turn up Decay a little higher.
  • Reverse reverb. Same settings as above, but set Attack closer to zero.
  • “Shape.” The late 80′s Lexicon reverbs had “Shape” and “Spread” controls to control the initial onset of reverb energy, with high Shape settings resulting in a reverb that fades in slowly. The Superhall Attack control has a similar function, in that the first few hundred milliseconds can have an exponential decay (for high settings of Attack), a relatively flat response (Attack=50) or fade in slowly (Attack=0).
  • Using an external chorus to simulate the EMT-250. I recently heard sound examples of the EMT-250, and that thing had TONS of modulation. In Eos, the Superhall algorithm can get similar levels of modulation right out of the box, but the plate algorithms have a somewhat drier sound for the first few hundred milliseconds. By running a decent chorus or ensemble plugin in front of Eos, and using the Plate 1 or Plate 2 algorithms, you can get a sound that is closer to the EMT-250 (the Plate algorithms are closer in concept to the EMT-250 than Superhall). Set the Low Crossover and High Crossover frequencies at 1000 Hz, set the Size to 30 meters, Mod Freq to 0.5 Hz or so, and Mod Depth at max, and then tweak your chorus until the initial sound is as “wet” as you like. Obviously, this works better on a bus send. The internal modulation of Eos will give you spreading sidebands as the sound decays, that you just can’t get out of a convolution reverb.
  • Ethereal vocals. Use Plate 1 or Plate 2, set the Low Cut frequency to a fairly high value (800 Hz to 1200+ Hz), and the High Cut frequency to a similarly high value (8000 Hz or higher). Set the mix to a fairly subtle level. The fundamental frequencies of the vocals will not be reverberated to a great extent, but the syllabants and consonants will have a fair amount of reverb. This type of sound can be heard all over Simon and Garfunkel albums – I’m not sure if this was due to the 7-story staircase reverb chamber at Columbia studios, or over enunciation of consonants, but it is definitely a good sound for those choirboy things.
  • Emulating older reverbs by backing off on the diffusion. The Superhall algorithm took some of its sonic inspiration from the Lexicon Concert Hall algorithms, but Superhall can have a much higher initial echo density. By turning the Diffusion parameter down to 50% or so, the more “spacious” or “grainy” sound of the older algorithms can be achieved.
  • Longer reverb time. In your host’s default parameter view, move the Low Crossover to a high frequency (>8000 Hz), and set the Low Multiplier to 2.0. This should increase your maximum Decay time to 20 seconds.

If you have any Eos tricks that you would like to share, feel free to post them in the comments.

Eos is released

After 10+ years in this business, my first commercial plugin work has been released. Eos is an algorithmic reverb, available in VST and AU format for OS X and PC.

I developed the three reverb algorithms used in this product, under contract to the good folks at Audio Damage. The AD guys spec’d out the algorithms, and designed the GUI and all the interface code, while I contributed the DSP.

Go take a listen. Today is a good day.

The frequency shifter and Dr. Who

Like all semi-trendy electronic music nerds, I became obsessed with the BBC Radiophonic Workshop, Delia Derbyshire, the Putney, the Delaware, and all that good stuff back around the turn of the century. At one point, my coworker Tim Stilson fired up Cool Edit 2000 (state of the art waveform editor at the time) and looked at the Dr. Who theme in the spectrogram view. The spectrogram confirmed what we had suspected: the echos at the end of the theme were shifting upwards in pitch.

I soon found out that these shifting echos were the product of a frequency shifter with a tape echo in its feedback loop. Apparently this combination was a popular effect in Delia Derbyshire’s toolkit, and was used most notably to create the electronic scream that was played before the end credits:

The following description is from Mark Ayres’ most excellent history of the Doctor Who theme:

The sound consists of two elements, a rising bubbling sound and a descending scream effect. First of all, let’s deal with the rising bubbling sound. The process used to create this was very simple. The first couple of notes of the closing titles (as the theme melody enters) were copied onto a new piece of audio tape. This was leadered, then flipped over so that it played backwards. The output of the tape deck was then fed into a frequency shifter set for a downwards shift at a short delay, and fed back into itself. When the tape was played into the shifter, it came out the other end milliseconds later with its pitch shifted down slightly. This output was fed back to the input and so on, creating a downwards cascade of ever more distorted sound. This was copied onto a new tape, and when this piece of tape was in turn flipped over, Delia was left with a rising flood of sound starting very distorted and slowly resolving into the opening couple of notes – this was then spliced onto the beginning of the theme.

The downwards scream was created in similar fashion. The source sound is a downwards-sliding hard-edged tone produced using an audio oscillator. Again, this was fed into the pitch shifter with very short delay, a downwards shift, and heavy feedback. Aliasing distortion within the shifter added to the overall effect. The result was mixed with the rising echoes to give the sound we are all familiar with.

I have been working on recreating these sounds with my VST frequency shifter / echo plugin, with some degrees of success. The overdrive in my analog echo simulator sounds a bit soft, but the harsh edged “scream” is also dependent on having a more edgy tone being fed into it. The process would be easier if I exposed tone controls for the internal filters, so I think that will be my next step. I find myself enjoying the sounds that the plugin makes on its own, without emulating any particular existing sounds. However, the Dr. Who sounds are so archetypal, it would be good to have a tool that can make similar sounds, so I will keep working towards that.

Frequency Shifting, 10 years later

Back in the spring of 1999, I was taking a yearlong computer music course at the University of Washington. I wasn’t a matriculated student at the time. I talked my way into the course, as I was obsessed with getting the sounds in my head out into the world.

One of my obsessions at the time was creating a digital emulation of the Bode Frequency Shifter. A frequency shifter is basically one half of a ring modulator. While a ring modulator takes an input signal and a modulation signal, and produces the sum and difference frequencies, a frequency shifter will produce just the sum frequencies, or just the difference frequencies. It turns out that separating the frequencies is actually fairly complicated, and involves some fancy filtering, as well as working with complex numbers. I hadn’t dealt with complex numbers since high school, so I rolled up my sleves and set to work.

After a lot of dead ends and swearing, I created a high quality Hilbert network, which is the heart of the Bode frequency shifter. My Hilbert network had all of the nice artifacts of the original analog phase differencing network, which allowed me to get the barberpole phasing sounds I always wanted to hear. I implemented the Hilbert filter in Csound, which was very powerful for the time, but seems amazingly primitive to me today. My code would take several minutes to render, but when I heard the results, I was a happy man.

A lot of experimentation followed. I put the frequency shifter in feedback loops, using delay lines and other processing blocks, to get Risset endless glissandos out of any source material. I used the frequency shifter to FM input signals, and fed the output back to the modulation inputs, for some weird phase locked loop tricks (I need to track that work down again). Finally, I tried out my newly acquired C skills, and implemented the Hilbert network as a Csound unit generator.

This spring marks 10 years that I have been working with frequency shifting. I have implemented versions of the frequency shifter for a lot of platforms, from Reaktor and Supercollider to the original Xbox audio DSP.  After all these years, I have finally created a version of my frequency shifter code in VST form (with AU code to follow). You can get it here. I have added some new tricks: the frequency shifter is in series with an analog echo emulation. Turn up the feedback, and you can get screeching endless glissandos, barberpole flanging, or soft echos that rotate around and through your skull. It’s a work in progress, but it sounds pretty nice right now.