MXR MC404 CAE

The MXR MC404 CAE is a wah pedal from MXR, developed with Bob Bradshaw of Custom Audio Electronics and the Cry Baby design team and released in 2009¹². Its defining feature is a pair of switchable Fasel inductors, giving the player two distinct wah voices in one housing: one with high-end emphasis, the other with low to mid resonance¹.

Alongside the two inductors, the pedal carries a built-in boost circuit borrowed from the CAE MC401, internal Q and gain trimmers, and true hardwire bypass³. .

A wah with two Fasel inductors

The inductor is the component at the heart of a wah's voice, and the MC404 CAE carries two Fasel inductors that the player can switch between. Dunlop describes the two voices as high-end emphasis on one side and low to mid resonance on the other¹. The company's buying guide frames the same choice as "two switchable inductors for a warm, vintage vibe or bright transparency"⁵.

For a player, that means one pedal covers ground that would otherwise take two. The high-end voice cuts through a busy mix, while the low-to-mid voice sits rounder and thicker underneath a riff. Pedal of the Day's reviewer found the switching itself to be the pedal's standout feature⁶³¹:

The controls: two kickswitches and internal trimmers

The MC404 CAE is operated from the top and the sides. The treadle sweeps the wah as on any Cry Baby-style pedal, while two small kickswitches mounted on the sides of the housing handle everything else, and both are reachable with your foot mid-performance⁶¹.

The internal pots are set with a screwdriver rather than on the fly, which suits the Q and gain adjustments they control: those are voicing decisions a player tends to make once and leave alone. Premier Guitar's review also notes a custom-designed CTS extended-life low-noise potentiometer for the treadle among the pedal's top-grade components⁶.

The boost

One of the two kickswitches engages a built-in MXR MC-401 Boost/LineDriver, a clean boost circuit that delivers up to 18 dB of extra level³⁶. Premier Guitar's reviewer put its purpose plainly: "A built-in MXR MC-401 Boost/LineDriver gives you an extra kick in your tone if you need one"⁶.

Because the boost is inside the wah rather than on the board as a separate boost pedal, a player can stomp it in during a solo without moving to another pedal, and it can also push the front end of an amp harder when the wah is engaged⁶³.

Designed by Bob Bradshaw and the Cry Baby team

The MC404 CAE came out of a collaboration between Dunlop and Custom Audio Electronics, the rig-design company founded by Bob Bradshaw. Dunlop credits the pedal to Bradshaw and the Cry Baby design team¹, and JHS Pedals' account adds that the collaboration was initiated by Jimmy Dunlop, with head of engineering Sam McRae as lead engineer². Bradshaw had already built a reputation before the project; JHS Pedals calls him "an industry legend"².

The pedal was released in 2009 as the MXR MC404², and Custom Audio Electronics announced it as "the MC404 CAE Wah developed in conjunction with Bob Bradshaw"³.

What reviewers said

Published reviews were positive. Premier Guitar's reviewer wrote that "Dunlop takes another big step forward with the MC-404 CAE, with more features and added versatility" over the 535 and GCB-95 Cry Baby models⁶. Pedal of the Day's review echoed the maker's own description of the dual inductors and highlighted the on-the-fly switching as a feature that "opens up twice as many soundscapes" as a single-inductor wah⁴.

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