Product Profile: Korora Audio Spira and Merlo Pedals

The Merlo and Spira effect pedals from Korora Audio offer high quality “classic” Tremolo and Phase effects as well as some really interesting and unique Tremolo and Phase and Modulation effects drawn from the early days of analog additive synthesizer technology. Both pedals are designed to be stage and pedalboard ready and are powered by the included standard nine-volt power supplies. While Spira is designed to be primarily designed to be used with electric Guitar or Bass it can be used effectively with any amplified instrument. Sound Designers and Composers as well as performing musicians will be right at home with Spira and Merlo.

You can quickly and easily dial in usable effects on both pedals however Spira and Merlo are deceptively simple to operate and it would be a mistake to categorize Spira and Merlo as “just another Tremolo and Phaser pedal”. There really is a lot more science going on with both pedals then is first apparent. If you take some time to learn how the controls interact with each other you will discover that Spira and Merlo go much further both as performance and sound design tools then you would at first think possible.

The Spira effect pedal is inspired by the Richard Shepard’s ‘Shepard tone” effect first used in the 1970s and which was used in films and by artists such as Pink Floyd. The Shepard Tone is an audio illusion created by super imposing Sine waves over octaves the combined effect of which creates the illusion of a tone that to the ear seems to continually ascend or descend in pitch or tone but in reality gets no higher or lower than the original pitch. Using Spira in conjunction with a Looper will help you to fully experience Spira’s Shepard tone effect.

There are four rotary controls on Sipra. A Rate control that adjusts the speed of the filter sweeps, A Resonance control which sets the resonance of the filters, a Blend control which adjust the level of the effect against your dry input and a Volume control which sets the overall output of the effect.

The heart of Spira is a parallel resonant filter bank that can be selected via a three-position toggle switch set to operate at 6, 12 of 18 dB per octave. There are three positions on each toggle switch. The filter slope toggle switch allows you to select Spira’s filter roll off of 6, 12 or 24 dB from a steep to a gradual slope. The Density slope toggle switch enables 12,18 or 24 parallel filters. The lowest position on the Density toggle switch enables filters tuned an octave apart, the middle position alternators the filters between octave and tritone intervals and the lowest position enables the three filters tuned an octave apart throughput the audible range. The left Footswitch changes the direction of the filter sweep and allows the direction of the effect to be reversed in real time. The right foot switch enables or bypasses the overall effect.

Merlo is a unique harmonic tremolo effect pedal which can be used to generate classic to experimental tremolo effects, unique modulation effects and much more. Merlo’s front panel has four rotary controls that adjust Rate, Depth, Shape and Color. The Shape and Color controls work in conjunction with Merlo’s two toggle switches that allows you dial in three oscillator shapes Sine, Triangle or Square and three different tone shaping curves.

The top position of Merlo’s top toggle switch helps dial in classic tremolo effects. The Middle position gives you two additional frequency band and the bottom position gives you higher end roll off and lower frequency emphasis for warmer tone. Merlo’s bottom toggle switch also has three positions, and which work in conjunction with the shape control to adjust the overall LFO (Low Frequency Oscillation) of Merlo’s overall effect. The bottom three-position toggle switch selects from three waveforms, Sine Triangle and a Shark Fin shape. The three waveforms work in conjunction with the rotary Color, Shape controls. The Depth control will allow to fine tune the overall effect against your dry signal.

Adjusting Merlo’s Shape and Color controls in conjunction with the two toggle switches allows you adjust the overall character and tone shape of the effects. Adjusting the Rate and Depth controls helps you dial in classic Tremolo controls slow to fast from minimum to maximum dynamic range. The tremolo rate can be set either with the Rate control or the front left Tempo footswitch. The front right footswitch will activate or bypass Merlo’s overall effect.

Both Spira and Merlo have a set of internal DIP switches that allow for selecting on or off the Pulsing LEDs of the front panel of each effect as well as a selectable Boost control from 0 to 3 dB when the pedal bypass switch is turned on and which is great for dialing in Spira and Merlo’s effects during solos.

For stage you can use Spira and Merlo to dial subtle or “over the top” rhythm and lead effects that will be right at home on your pedalboard. For recording, both pedals are almost “a plug-in in a box” giving you manual real time control over the effects.

Korora Audio has done great job dialing in some serious additive synthesis capability into two relatively simple and easy to use effect pedals Spira and Merlo are available for purchase now on the Korora audio website for $249 each.

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