Phasey-Q — a bad-ass stereo phaser

I was sifting through the late Jurgen Haible’s scattered treasure trove of DIY electronics and modular synthesizer explorations, when I stumbled upon mention of the EMS 8 Octave Filter Bank, a companion piece produced by EMS for its storied synthesizers. With a little more research, I found the frequency values of the filter bank, and I wondered what it might sound like in ZOIA’s hands….

I didn’t love it. It proved an interesting EQ option for ZOIA, but the shared resonance control made everything sound muddled, honestly. I put it aside and worked on other things for a while, but I returned to it sometime later, because I wondered what it would sound like modulated. In particular, I wanted to know if it would be an adequate foundation for a barberpole phaser, a sound I have been curious about for some time.

Modulating the filters sounded terrific! Rich and absorbing, it was the sort of phaser sound I really enjoy. But I ended up having trouble using the mixer module to create the right volume modulation for a barberpole phaser; something about it just seemed off. So, I pared it back, changed the volume control to VCAs, and made “Ed Crane Barber.”

Still, the phaser sound of the original formulation haunted me. Instead of setting up a barberpole configuration, I tried it with a run-of-the-mill sine LFO. Fantastic! Using the filter bank set up, where each frequency band could be boosted or cut allowed for an incredibly versatile sound, like a combination of phaser and eq.

Since I was working in stereo, I decided to see what would happen as I offset the LFO for each change, and it produced enormous stereo phasing. I was in love; I am in love.

The phaser module in ZOIA is fine, and this one is fiddly. There are a lot of parameters you might not be interested in. Using all of ZOIA’s CPU for a single-waveform phaser seems like an enormous waste, possibly madness. I get it; I am a lunatic. But this phaser… if you like phaser, this one… it’s really nice.

In order to get a mix control in, I had to sacrifice a filter (8k–which, while useful for adding “sparkle” to the top end, also tended to allow a lot more noise and hum pass), but it still sounds terrific.

The signal path is stereo throughout, although the effected signal shares outputs equally when the stereo control is below 1.000.

A special thanks to my patrons on Patreon for their support: Rob Flax, Stepan Grammatik, brockstar, Mats Unnerholm, D Sing, Will Scott, drew batchelor, Miguel, Steve Bragg, and Joab Eastley!

If you would like to support my work on ZOIA, please visit patreon.com/chmjacques

Controls:

Left stompswitch, momentary — tap tempo (the effect can also be controlled via MIDI clock)

Front panel:

Across the top is a row of controls representing each ZOIA color:

62.5, 125, etc. — these are the unmodulated frequencies of the filter bands; adjusting them will cut or boost the frequency band 20 dB; these can radically shape the sound of the phaser

Blinking white pixel — at the end of the row is a blinking white pixel that shows the rate of the LFO

Beneath this is a row of controls that deal predominantly with the phaser’s sound:

Depth — controls the depth of the frequency modulation; it can go from subtle and swirly to sea-sick warbles

Resonance — controls the resonance of the filters; the more resonance, the more pronounced the effect. As resonance is increased, the sound can take on a metallic quality. Gain also increases, and at highest resonances, you might need to attenuate your input volume to avoid distortion.

Freq shift — in order to compensate for the loss of the 8k band, I put in a frequency shift which adjusts the centerpoint of all the filter bands +/- 1 octave; you can think of it as a sort of “master tone” control, where values below 0 will darken the tone and values above 0 will brighten it

Beneath this are controls that allow you to tailor the sound more precisely

Swing — controls the swing of the sine LFO; swinging the LFO lightly in either direction can result in lop-sided sines; as this control increases, the waveform takes on a shape somewhere between a sine, square, and sawtooth wave

Stereo spread — offsets the left and right channel’s LFOs; at low amounts, it creates a rich, stereo image, at high amounts, the modulation ping-pongs from channel to channel

Mix — wet/dry mix; depending on the resonance and the cut/boost of certain frequencies, this control can get pretty unbalanced, so you may find that in order to create a 50/50 mix, you have to heavily favor the dry sound.

Beneath these are two pushbuttons that govern the behavior of the patch as a whole:

Modulation off (expression on) — switches the modulation on/off; when modulation is off, the patch can be used as an interesting, if limited, EQ; this is also directions a CPort module to the frequencies, allowing you to sweep them via expression pedal

Tap or clock — this button controls whether the patch accepts tap tempo or MIDI clock; when it is selected, MIDI clock is the clock source

Sound clip:

0:00-1:10 — I begin with very mild depth and resonance for a subtle movement, then increase the depth and resonance before finally increasing the stereo spread.

1:10-1:30 — I use the filter levels to give the phaser a “scooped” profile, then I push the resonance really high for some very extreme oscillation

1:30-1:55 — MF Drive engaged (I like running an overdrive before a phaser): I invert the previous profile, but much more subtly, bumping the mids and cutting the bottom and top end. The LFO is also pretty severely swung.

1:55-2:20 — Now the mix is set to 100% to show off a phase vibrato sound.

3 comments on “Phasey-Q — a bad-ass stereo phaser
  • Rob Flax on said:

    Extremely excited for this. I love phaser so much!

  • Christopher H. M. Jacques on said:

    Ha! Rob, I have to say, knowing your deep love of phaser helped me decide to publish this patch.

    Me: “It sounds great, but who is going to want a patch solely devoted to one admittedly awesome but still pretty conventional phaser sound? Maybe this is one doesn’t merit circulation.”

    Also me: “No, Rob Flax will like it, too! He loves phaser; there are at least two of us!”

    Edited for clarity, but that’s basically a real, internal debate.

  • tomikoo on said:

    Sounds sick! Can’t wait to try this.

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