As multi-effect modeling pedals become more realistic in both sound and responsiveness, the interfaces through which we control them become even more important. Digital processing is ironically making the analog aspects of the guitar — nuanced tone, feel, touch — more important, because the accuracy of how each aspect is translated now matters.
The same goes for expression pedals. My go-to floor box is the Boss GT-1000CORE — stay tuned for an upcoming review in TapeOp. These new generation of ultra-portable modelers benefit greatly from outboard controllers: instead of just controlling volume or wah, we can now assign expression pedals to organically tweak any function in real time — drive, tremolo, EQ, delay, pitch, or combinations simultaneously.
An expression pedal is now an integral part of making unique sounds. And the addition of the classic toe-switch found in wah pedals is key in compact modelers with understandably limited switches.
As of this writing, two options incorporate toe switches at this price point — Mission Engineering SP1-RB and HeadRush — both at $149. I ranked each through four essential categories, summarized in the scoring tables at the end.
Form Factor and Build Quality
Mission Engineering SP1-RB
L: 253mm | W: 100mm | H: 73mm (toe down) | 1.44kg Score: 2 out of 5
The familiar Crybaby form factor was initially appealing — until I remembered my old Crybaby through rose-colored glasses. The SP1 doesn’t just look like it; it repeats its original flawed details. One of its rubber feet had fallen off straight out of the box. Sure, removing a screw to pop it back on is easy, but it triggered a vivid flashback to losing a Crybaby foot right before a gig 25 years ago. Everything in the SP1 — the rubber feet, the finish, the construction — is old-skool off-the-shelf components that were mediocre then and badly in need of an update now.
The SP1 is heavy but doesn’t balance its center of mass well — it’s also narrow, making it easy to tip over when miss-stepped. Mission could have kept a vintage design vibe while meeting modern performance standards. They chose not to.
HeadRush Expression Pedal
L: 257mm | W: 123mm | H: 64mm (toe down) | 1.58kg
Score: 4 out of 5
To treat the ‘vintage PTSD’ from the Mission, I purchased the decidedly un-vintage HeadRush. Its bad-arse coffin-like footprint is not all show — its weight is distributed to give a wicked-low center of gravity, augmented by getting significantly wider under the ball of your foot. The result is a tank-like pedal that stays put and can’t be tipped over.
The precisely machined aluminum body instills confidence and durability. There’s an architectural logic to its form: where the SP1 is a re-hashing of old mistakes, the HeadRush is a studied evolution. Two small gripes: the skateboard-grip-tape pedal surface wears through socks quickly, and there’s no easy way to open it for servicing without ripping off the rubber base pads.
Pedal Action
Mission SP1-RB
Score: 2 out of 5
The SP1’s fulcrum is far too far back toward the heel — you basically have to stand on top of it for fluid, detailed action. This is a problem for players who sit or place their pedal on a second tier. The moving part is heavy with lots of inertia — fine for wah-style playing, but assign it to a subtle delay speed or pitch parameter and the action becomes frustrating, leading to small-muscle fatigue.
Tightening the friction fit (via an extra-long allen wrench — supplied, but do you really want to carry that around?) only holds for a while. After a long session the action loosens again. The SP1 is designed for an era when wah-wahing was the norm, not subtle expression tweaking.
HeadRush
Score: 5 out of 5
The pivot point is 85mm from the heel versus 55mm on the SP1 — 30mm doesn’t sound like much, but in ergonomic terms it’s a world apart. The moving pedal portion is light with no momentum of its own, becoming an extension of your foot for comfortable, detailed tweaking. The easy-to-reach hex bolt adjusts resistance with a standard allen key.
Where the SP1 uses old gear-against-potentiometer action that jams with gunk over time, the HeadRush has a sealed lever arm that disappears into the body. Smoother, more precise, and maintenance-free. Works from any posture — standing, seated, second tier.
Toe Switch
Mission SP1-RB Score: 1 out of 5
Upon plugging in, the SP1’s toe switch was immediately glitchy — causing parameters to blink on and off even with a firm stomp. The culprit: a sticky-back felt bumper that pushes down on the switch from the underside. Felt is an incredible material, but it’s not designed for repeated compression — it doesn’t spring back. Mission even ships an extra felt pad, which is an implicit acknowledgment of the issue.
Replacing the felt with silicone improved things, but the glitch was still there 1 out of 5 times. Opening the SP1 revealed the reason: a cheap ‘radio shack’ hobbyist switch. The foot switches on the GT1000CORE, by contrast, merely look like classic analog buttons — they are actually highly engineered momentary switches with precision click action that pairs with the unit’s ultra-fast processor. The SP1’s cheapo switch causes the GT1000’s computer to read rapid-fire jitter. Mission’s regressive analog thinking in a digital ecosystem is a complete fail.
HeadRush Score: 5 out of 5
Hallelujah. The HeadRush toe switch works flawlessly — no moving parts, just a heavy-duty metal pin contacting a heavy-duty metal surface. The precisely engineered rubber bumpers produce a satisfying, tactile thud-like click. Flush-mounted to the top of the metal body, the entire action of pedal and switch is unified. The HeadRush feels like an instrument itself — a visceral extension of the body.
Jack Location
Mission SP1-RB Score: 2 out of 5
The original Crybaby has jacks on its side because effects connect in-line. But an expression pedal is not an inline effect. Side jacks on an expression pedal mean the cables run forward, where you step on them while operating the pedal. Mission’s workaround requires specialty TRS L-cables — common in TS but not TRS format — adding cost and inconvenience to accommodate a lazy design decision upstream.
Even Dunlop, the manufacturer of the Crybaby, puts the jacks at the front on their DVP4 mini expression pedal. If it can be done in that compact format, Mission can find a way. Either that, or drop ‘Engineering’ from their name.
HeadRush Score: 5 out of 5
Jacks at the front. That’s it. Easy to wire directly to the modeler, spaced far enough apart that L-cables can be used without them crashing into each other. This is what integrated design looks like — the toe switch placement, the lever arm, and the jack location were considered as one piece of gear. In the Mission version, the components compromise each other.
Final Tally
| Headrush Expression Pedal | score (1-5) |
|---|---|
| Form factor and build quality | 4 |
| Pedal action | 5 |
| Toe switch | 5 |
| Jack location | 5 |
| Total | 4.75 |
| Mission Expression Pedal | score (1-5) |
|---|---|
| Form factor and build quality | 2 |
| Pedal action | 2 |
| Toe switch | 1 |
| Jack location | 2 |
| Total | 1.75 |
Conclusion
Long story short: buy the HeadRush Expression Pedal.
The HeadRush is a piece of engineering — construction quality easily worth its price. At first it’s a joy to use, and then you forget about it. That’s the best compliment for any interface: it becomes a seamless part of your playing.
The Mission SP1 is a backwards-gazing piece of gear that’s not up to par with the new generation of modelers. At $149 it is totally overpriced compared to the HeadRush. Upon contacting their tech support, they replied with a statement that revealed both regressive thinking and a stuck-up attitude toward their customers:
“Sorry to hear that you had problems. We have shipped hundreds of thousands of units over more than ten years that use the exact same switch and felt pad assembly. We have not had this reported by anyone else for any of the models so far. It’s also the same part as used in countless wah pedals from other manufacturers… We do test and measure the switch function on each pedal before it’s shipped. This includes an experienced player actually operating the switch.”
An expression pedal is not a wah. That’s the whole point — and Mission fails to understand it. The fact that they’ve been doing this for ‘over ten years’ is testament to not keeping up with the times. And the reference to ‘experienced players’ testing their gear is basically telling their average customer to shut up.
HeadRush is the actual innovator here — they make the modelers themselves, so their expression pedal is a natural extension of their advanced technology, designed from the ground up for a new digital ecosystem. When making broader choices, I’d much rather support a company with the future in mind than one that dumpster-dives into the past.
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