Inspired by the Shepard Tone first described by Roger Shepard in 1964, Spira uses a bank of resonant bandpass filters to create the illusion of a never-ending, layered, overlapping glissando. The glissando effect is produced using the resonance of the filters, and can be applied to any instrument.

Spira sounds as if it is continually and infinitely sweeping either up or down, creating musical tension and energy. Its texture and sweeping motion are perfect for psychedelic, drone, and ambient styles, and anywhere else you want to add movement to your sound.

“This thing… is quite awesome. The swirl effect is amazing, and I see massive potential with multiple instruments. If you’re into modulation, this is your guy.” effectsbay.com

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Spira receives the Premier Gear Award

“Spira can produce near-subliminal modulation, shrieking freakouts, and everything in between. The build quality is excellent. The results are inspiring.”

Read the full review.


Up to 24 parallel high-performance resonant filters

A high performance parallel resonant filter bank is at the heart of Spira. Spira’s filters can be selected to operate at 6, 12, or 18 dB per octave and the Q factor can be set from flat to near oscillation.

Selectable density

Set Spira’s filters for an octave spacing to get the classic Shepard effect. Set the filters for tritone spacing to double the density, or select the middle mode of alternating octave and tritone intervals for a spacy and unique effect.

Control the rate of the sweep from glacially slow through tremolo range

When turned fully to the left, the filter sweep freezes, producing an effect similar to a comb filter or formant filter. Turn it up a bit and the classic, slow sweeping Shepard effect is produced. As you go further clockwise, a warbling tremolo effect is produced.

Sweep up or sweep down

The illusion of the filters infinitely moving in one direction can create a strong tension and mood. Reversing the direction from sweeping up or down offers even more control over the sound, and can have an impact at all settings of the rate control.  

Volume and blend controls to strike just the right balance

Use blend to have total control over the balance and intensity of the effect. The volume control helps ensure just the right level when you punch in the effect.


  • Power supply included

  • Standard 9v, center ground power jack

  • 180 mA required current

  • Soft Touch True Bypass

  • Top mounted jacks

Internal DIP switches

Remove the back cover to access additional customizations.

  1. OFF: Default to bypass at power on, ON: Default to effect on at power on.

  2. OFF: Default to ramp down at power on, ON: Default to ramp up at power on.

  3. OFF: Pulsing LEDs, ON: Non-pulsing LEDs.


Check out a demo of the features and settings of the Spira pedal.