Carl Martin Ottawa

The Carl Martin Ottawa is a compact, fully analog envelope filter pedal, an auto-wah that sweeps a wah-like filter in response to how hard you pick instead of a treadle under your foot¹. At the center of the circuit is an optical envelope filter with three selectable modes, High Pass, Band Pass and Low Pass, and Carl Martin designed it to be usable with both guitar and bass¹². It is a redesign of the Danish maker's earlier optical envelope filter, arriving in the lineup Carl Martin refreshed in 2018 with anodized enclosures and top-mounted jacks¹³.

What it does to your sound

An envelope filter reads the level of your signal, your picking dynamics, and uses it to sweep a filter up and down. Carl Martin describes the Ottawa as giving "classic wah-like movement without a treadle," with the sweep following your attack rather than your foot¹. The optical part means the circuit uses a light-dependent element to do the sweeping, and Premier Guitar's review of Carl Martin's earlier optical envelope filter noted that "you can manipulate the wave envelope with an analog optical circuit," the principle the Ottawa carries on⁴.

Compared with a standard wah pedal, the hands-free approach has a practical advantage. Reviewing Carl Martin's optical envelope design at MusicRadar, the reviewer made the case that "an optical filter can react more quickly (and accurately) to your playing technique than rocking your foot back and forth"⁵. The trade-off is control: there is no treadle to place the filter exactly where you want it, so the Attack and Q knobs do that shaping instead.

The three filter modes set the character of the sweep:

• High Pass: the filter emphasizes the high end as it opens, the familiar quacky auto-wah voice.
• Band Pass: a focused peak that moves through the midrange.
• Low Pass: the filter works downward from the top of the spectrum, retaining low frequencies, which Carl Martin says "specifically allows it to function great as a bass envelope filter"¹.

Guitar World's news coverage of the pedal placed its tonal range "from '60s psych sounds to '70s disco tones"⁶.

The controls

The Ottawa has four knobs and a three-way switch, plus a bypass footswitch¹⁶. Carl Martin's own support article explains what each control does²:

One thing to know before dialing it in: Guitar World noted that the Tone, Attack and Q knobs "are said to be closely linked, and so some off-the-cuff changes may be required to maintain an optimum tone"⁶. In practice that means a change to the Q or Attack may call for a small Tone or Level adjustment to rebalance the sound.

Power and setup

The Ottawa runs on a 9V DC center-negative power input and draws around 14 mA, which Carl Martin calls "super low" and easy on a pedalboard supply¹.

The input jack accepts the guitar (or bass) signal and the output jack sends it on to the next device or amp, both top-mounted to save pedalboard space¹³. With the effect off, the pedal is true bypass¹.

Where it came from

The Ottawa is a redesign of Carl Martin's earlier optical envelope filter, which the company announced in 2011 alongside the Blue Ranger overdrive¹⁷. That earlier pedal, the Classic Optical Envelope, was described by No Treble at its release as a "Classic Auto-Wah with Opto-Technology" for bass or guitar, running on a 9V battery or regulated supply, and built, in Carl Martin's words, using "the same high-quality optical technology as Carl Martin's renowned Opto-Compressor"⁸⁷.

The Ottawa arrived as part of the lineup refresh Carl Martin carried out in 2018, which brought the anodized enclosures and top-mounted jacks the Ottawa wears³. When the pedal reached the press in September 2021, Guitar World called it "a beefed-up version of the brand's pre-existing Optical Envelope Filter," and Delicious Audio described it simply as "a redesign of the company's previous auto-wah"⁶⁹. Gearnews reported its three presets for High, Band and Low Pass filters on a three-way mini-toggle¹⁰.

The main practical differences from the Classic Optical Envelope are the compact enclosure, the Low Pass mode that makes bass use straightforward, and the power arrangement: the Classic could run on a battery, the Ottawa cannot¹⁸⁷.

What reviewers said

Guitar World's review of the Ottawa listed its origin as China and its dimensions as 60 x 115 x 50 mm, and summed up the pedal's sound in two words: "Superb sounds"³. The same review credited the refreshed enclosure style, noting that "slick-looking anodized enclosures were the order of the day, with pedalboard placement made easier via top-mounted input and output jacks"³.

On Carl Martin's artist page, Phil Soussan is listed as a user of the Ottawa¹¹.

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