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    A+ PRISM-9


    The A+ Prism-9 is a truly inspiring stompbox for any musician looking for new ideas. With this pedal, even the most ordinary sound can turn into an outlandish chorus of awesomeness!

    The Prism-9 is a unique, complex, fully-featured effect that embraces analog synthesis techniques — particularly modulation and filtering. The pedal has two switchable global modes — “classic” and “modern” — which are comprised of the same elements but in a different order.

    The Prism-9 combines:
    1. 5 low frequency oscillators (LFOs) to modulate the incoming signal;
    2. 3 transposition modules + clean blend;
    3. a 4-pole resonant low-pass filter (LPF);
    4. a room/hall reverb algorithm.

    The pedal splits the incoming signal and, via its complex pitch shifter, adds to it an octave up, an octave down, and a fifth. All the parts are then mixed back together and sent through the 4-pole (24 dB/Oct) filter, which is controlled by the sum of two LFOs. The first LFO is a sine wave running at a fixed rate. The second one is a trapezoid wave; its rate and depth are controlled by the RATE and RANGE knobs, respectively.
    After pitch shifting and filtering, the signal gets smoothed out by the room reverb and finally goes to the output jack.

    All in all, this complex effect is controlled by just two knobs: RATE (LFO rate) and RANGE (LFO depth). The third knob controls the reverb. Think of it as “three Rs”: RATE, RANGE, and REVERB.

    Having started out as a VA synth prototype and gradually transformed into its current form, the Prism-9 combines many different elements, which are all fine-tuned to play well together and provide easy control over the resulting sound.

    The pedal has 3 main modes:
    1. Manual — a static mode in which the parameters are controlled manually;
    2. Auto — a mode in which filter sweeps are automated by the trapezoid LFO;
    3. Auto Fat — same as above, but the sound is “fatter” due to extra harmonics.

    • The RATE | DRIPS knob (in Classic mode):
      • In the Manual mode, the trapezoid LFO is disengaged, and the RATE knob controls the depth of the sine LFO (this is called the DRIPS mode). The knob’s range is split into two halves:
      • 7 — 12 o′clock: regular mode, LFO depth increases from 0 to max;
      • 12 — 5 o′clock: “fat” mode, LFO depth decreases from max to 0.
    • The RATE | DRIPS knob (in Modern mode):
      • In the Manual mode, the LFO is disengaged, and the RATE knob controls filter resonance. The filter goes from mild operation to self-oscillation, with maximum Q at 12 the o’clock position. The knob’s range is split into two halves:
      • 7 — 12 o′clock: regular mode;
      • 12 — 5 o′clock: “fat” mode with added octaves.
    • In the Auto and Auto Fat modes, the RATE knob controls LFO rate, creating a kind of a chorus effect when turned clockwise.
    • The RANGE knob determines the filter cutoff frequency.
    • The REVERB knob controls reverb amount & decay.
    • The MIX knob controls wet signal volume. Dry signal volume is constant and has no control knobs.
    • The MODE switch selects among the pedal’s three modes: Manual, Auto, or Auto Fat.

    Global modes: Classic and Modern
    • In Classic mode, the filter is fixed at 24 dB/Oct and is placed before the reverb.
    • In Modern mode, the filter is placed after the reverb, and its slope varies depending on the mode:
      • Auto Fat: 24 dB/Oct;
      • Auto: 12 dB/Oct;
      • Manual: 12 dB/Oct, with the RATE | DRIPS knob controlling the resonance.
    • In Modern mode, there are fewer octave sounds, and max LFO speed in Auto modes is higher.

    Switching between Classic and Modern modes
    1. Bypass the effect. Power the pedal off for at least 5 seconds;
    2. Power the pedal back on. Over the first 10 seconds, flick the switch up and down 8 times in total.

    The global mode will change, and the preference will be stored in the power-independent memory. There is no indication of the active global mode; the easiest way to check is to set the mode switch to the up position and set the RATE knob fully clockwise. If the sound resembles a helicopter, the pedal is in Modern mode.

    • The Prism-9 is an original design supposed to contribute to the world of existing modulation effects (phaser, chorus, tremolo, etc.);
    • The pedal works great for creating ambient pads and backgrounds in slower styles of music;
    • The Prism-9 boasts a variety of timbres. It enhances the guitar signal in a way similar to analog synth processing techniques of the late 70s and early 80s;
    • The pedal is built on a new platform, which provides a sound that is very sensitive to your playing style, as well as to your guitar’s pickup configuration and preceding effects in the signal chain;
    • The controls work in a straightforward manner:
      • The REVERB knob always controls reverb amount. The reverb can be cut out almost completely;
      • The MIX knob always controls wet signal volume (dry signal volume is constant);
      • The RATE | DRIPS and RANGE knobs control the actual effect (their function depends on the selected mode).
    • The Prism-9 is not a reverb in its pure sense: to get a noticeable effect from knob tweaks, you have to play notes;
    • The pedal utilizes resonant filters which have certain (highly musical) artifacts such as phasing and pitched noise. This contributes to the complexity of the resulting sound;
    • The Modern mode seems to work better with bass guitar (although you might like the Classic one, too);
    • The bypass is active: this prevents the click of the footswitch from getting into the reverb space;
    • The Prism-9 has switchable tails. To switch tails on or off, cycle the power and press the footswitch 10 times over the first 10 seconds upon power-up. The LED will flash to indicate the selected mode. 2 long flashes indicate that tails are on, while 8 short flashes indicate that tails are off;
    • The pedal’s current draw may reach 100mA, so a battery might only last for several hours and should be viewed strictly as an emergency option. For best results, use a corresponding PSU.

    Dimensions — 111 х 60 х 50 mm (4.37 x 2.36 x 1.97”)
    Power supply — 9V, regulated.
    Current draw — 70mA.


Demo videos