Haunting pseudo-reverb with descending or ascending spiraling pitch shifting, roaring momentary feedback-oscillation, and dynamic depth/feedback controls.

Using the Delay Line module’s linear modulation to achieve consistent pitch shifting, this patch can create a creepy downward (or upward) spiral of pitch shifting by alternating between two modulated delay lines, and with some feedback it diffuses them into a washy reverb sound. There’s a momentary feedback button to create noisy, destructive self-oscillation (reminiscent of WWII-era aircraft passing overhead! Or perhaps magic rainbow wizards?), and an envelope follower to duck the feedback or pitch depth, allowing the pitch shifting effect to only occur in reverb tails without muddying up regular playing.

Some big-brand reverbs offer a similar mode (Mercury7, NightSky, etc) but those are horribly over-the-top – at least to my ears – so this patch is MUCH more subtle/usable (especially with the Envelopes enabled). Of course it CAN also go completely nuts and get extremely freaky; it reminds me of what my Rainbow Machine can do with the pitch just above/below unity and with the Magic turned up (and it is, in fact, very similar at the core of the patch).

There’s also a simple little sequencer plus synth in there that I used to test the patch while building it, but that sad little melody fits the mood quite well, so I left it in.

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[OVERVIEW]
-Input/Output: Stereo in/Stereo out (or Mono in/Stereo out)
-CPU load: Around 80%
-Build: Initial version built with firmware 2.0
-MIDI: Controls are set to CCs (I use channels 21/36, see CONTROLS section for details).

[REVISIONS]
1.0: Initial patch.

[PATCH STRUCTURE]
There are 2 delay lines, each going into their own channel of an audio switch. The channels (=the delays) are being switched between via a sequencer, which also does the delay time modulation; when delay A is heard, its delay time is modulated via a Slew Limiter, creating a fixed pitch shifting effect. When the delay time returns to its original delay time (causing an inverted pitch-shift effect; what goes up must come down!) we’re not hearing it because we already switched to delay B. This neat little trick lets us do pitch shifting in one direction and ‘increasing/decreasing’ the perceived delay time, while at the same time keeping the SAME delay time; it’s a pretty interesting effect!

There are 2 diffusers after the audio switch to smear things out, then into a Reverb Lite (set to short decay time and medium mix) to the output. The diffusers also go to a VCA for feedback; it’s at 0dB when FBCK is at 1, but with the momentary BURST button you’ll go as high as +1dB, really building up the noise quickly, and it offers a surprisingly unique and pleasant breakdown (I think cause of the diffusers?). I did add a “LO CUT” toggle (technically incorrectly named) that sliiiightly reduces the lowest frequencies via a Low Shelf Multifilter, to prevent runaway oscillations from muddying up too fast.

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[CONTROLS]
All the main controls are on PAGE0 and are labeled and starred (see below for a “Picture Manual” in the comments). The Stereo Output module with gain parameter and the Reverb Lite module are found on PAGE1.

TIME (sets the delay time; acts similar to a reverb pre-delay; cc21)
FBCK (sets the feedback; acts similar to a reverb decay setting; will verge on self-oscillation at maximum; cc22)
DEPTH (sets the pitch vector depth; from a very mild ascend/descend to approximately full-note increments; cc23)
MIX (sets the balance between dry and wet sound; goes fully wet; cc28)
SMEAR (sets the diffusion and reverb mix; goes fully wet; cc24)

ASCEND / DESCEND (activates upwards/downwards pitch vector)
ENV FBCK ON / ENV FBCK (toggles envelope ducking to the FBCK control; louder input decreases feedback depth; ENV FBCK sets amount of ducking; cc26)
ENV DEPTH ON / ENV DEPTH (toggles envelope ducking to the DEPTH control; louder input decreases pitch shift depth; ENV DEPTH sets amount of ducking; cc27)
BURST (momentary feedback-oscillation; highly interactive with TIME, DEPTH and SMEAR)

Additional controls on PAGE1:
LO CUT (toggles a high-pass shelve filter to reduce low-end rumble; default is on, but can create a variation in feedback oscillation)
PLAY TUNE (toggles a creepy little self-playing synth)

LEFT stomp = same as BURST
MID stomp = unused
RIGHT stomp = unused

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[TIPS/TRICKS]
>>> Good settings for a ‘subtle’ pitch vector: low TIME, DEPTH, medium FBCK and high SMEAR settings.
You can safely increase the FBCK or DEPTH settings pretty high, as long as you enable the FBCK ENV or DEPTH ENV, it will still duck the intensity of the pitch diving according to your input dynamics.

>>> This patch works great on vocals; it’s like singing into the pits of hell!

>>> Reduce the SMEAR value for more audible delay taps and more Rainbow-machine-like weirdness.

>>> You can ‘play’ the feedback by holding/releasing the momentary BURST button for anything from sea-sickening pitch dives to absolute audio destruction.

[THOUGHTS/IDEAS/PLANS]
This patch turned out pretty good I think, it’s a very unique style of reverb. No future plans for this one yet.

If there’s any bugs/questions/remarks/requests or suggestions for improvement, please let me know!
Enjoy!

(Image: Levi Van Veluw)