Hand-built in Richmond VA, the October Audio MNTNS is an analog, OTA-based, variable stage phaser with vibrato and gain modes inspired by the classic effects heard in the best records of the ’70s.

While the two large black knobs allow controlling the circuit’s Rate and Gain (i.e. a JFET op-amp gain stage), three toggle switches give access to a total of seven combinations delivering different tones. Here’s what they do:

  • FB: placed on the top left of the pedal, this is the Feedback toggle. When activated, it leaks the effect’s output signal to the input, causing a more intense phasing effect and LFO sweep.
  • 2/4: place right under the Rate control, this is the stage selector: 2 for a milder warble and 4 for a richer and warmer swirl.
  • G/P/V: placed under the 2/4 toggle, this switch selects the mode, which can be PhaserVibrato, or Gain only mode.

While the MNTNS, at low gain levels, sounds just as clean as the vintage phasers that inspired it, it can get gritty as some JFET phasers when that gain knob is turned towards its maximum setting.

The Gain-only mode, to quote the builder, isolates “the combination of the transistor input stage and the op amp output stage,” creating a “unique gain structure that provides an organic boost with a touch of breakup when cranked.”

Check it out in the video below, we added it to our article about the best phaser pedals.

October Audio MNTNS, Builder’s Notes


Pronounced “mountains”, mntns is a variable-stage phaser with vibrato and gain modes. Knobs control rate and amount of gain, and toggles allow 7 positions of options!

INSPIRATION: We love the clean, high headroom phasers from the 70s and have created a circuit that honors the sound of the originals, while utilizing modern technology and adding features for today’s players.

CIRCUIT SCIENCE: At its core, mntns is an OTA-based analog phase shifter. The knobs control LFO rate (phase speed) and a JFET op amp gain stage. There are two stages of filters available- 2 for a milder warble and 4 for a rich, warm swirl. The feedback (FB) toggle when engaged (to the left) introduces output signal to the input, sometimes called regeneration. This results in a more intense, wider sweep of the LFO and phaser effect. The mode toggle has 3 positions- G (Gain-only mode), P (Phaser mode), and V (Vibe). The feature toggles and unique gain structure control allow you to dial in several classic sounds, as well as new sonic explorations.

SOUND: mntns delivers clean, warm phaser tones suitable for a wide range of musical tastes.

-Dial in the Gain control to set mntns at unity or boost the signal if desired. You can also simulate grittier JFET phasers by turning the Gain control all the way up. The Rate control will vary in function depending on the toggle settings and can achieve anything from very slow sweeps to speedy, robotic ray guns.

-The feedback works best in the Phaser mode, sounding more intense for 4 stages and curiously more vocal in 2 stages.

-The Vibe mode allows true pitch vibrato and works best at faster rates. Try 4 stages for deeper pitch bending and 2 stages for a subtle shimmering effect.

-The combination of the transistor input stage and the op amp output stage can be isolated in the Gain-only mode. This creates a unique gain structure that provides an organic boost with a touch of breakup when cranked.

Note: The FB switch when on will mostly nullify the Vibe and Gain modes, rendering them slightly different phase shift tones.

Quick settings: Here are some ideas to get started!

  • Classic 70s sound: FB off, 4 stages, Phaser mode, set Rate to taste, adjust Gain to unity
  • Dramatic tone contrast: FB on, 2 stages, Phaser mode, set Rate slow, Gain to taste
  • Polite robot: FB off, 4 stages, Vibe mode, Rate all the way up, Gain to taste