Mission Engineering's
Switchable Expression Pedal
Tough Construction - Reliable Control
Reversible Polarity Switch Available (SP1-R)
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About This Item: This is the SP1 Expression pedal from Mission Engineering. This pedal is available as the SP1-R, with a built-in reversible polarity switch, from the "Select Model" drop down at the top of this listing. There is a small upcharge for the polarity switch option.

The SP1 (or SP1-R) is a unique switchable expression pedal. The switch is operated by pushing down on the front of the pedal with your foot. Thus, the pedal operates like a traditional wah pedal. The switch is used to turn a pedal driven effect such as a wah or vibrato on and off at the pedal itself! There are two 1/4” output jacks: one for the expression pedal, and one for the switch. The SP1-R option adds a polarity reversal capability.

The expression function is driven with a high quality sealed potentiometer. The SP1 (or SP1-R) expression is a full-range sweep expression pedal built to last with all metal construction.

Mission Engineering has created one great switchable expression pedal that meets the needs of most applications.

The SP1 and SP1-R Mission Engineering Switchable Expression Pedals work with a wide variety of MIDI controllers, processors, and stomp boxes.

  The Reverse Polarity Switch (-R models only)

The SP1-R features a mini toggle polarity reversal switch so you can flip the polarity of the potentiometer for compatibility with devices such as MIDI controllers and keyboards that require a reversed polarity. It's like getting two pedals in one!

The first thing you will notice about your new Mission Expression pedal is that it is built like a tank. Once plugged in you will agree that this pedal performs flawlessly, just the way you expect. The smooth travel arc gives you controllable response from 0 to 100% output. Expression pedals don't get any better than this.

The SP1 is compatible with a wide range of controllers, effects pedals, amplifiers, and more. The -R model, fitted with a polarity switch to reverse the polarity of the tip and ring connections on the pedal output, increase the chances of compatibility with various devices.

For modern control with a vintage vibe .... Get on a Mission.

Specifications:

Potentiometer:

• Internal resistance 20K Ohm
• Taper: custom, reverse logarithmic
• Connections: Clockwise(CW) to Sleeve, Counter Clockwise(CCW) to Ring, Wiper(SL) to Tip. Operating the polarity switch on the -R model changes the connections for Wiper (SL) to Ring, and Counter Clockwise (CCW) to Tip.
• Function: Voltage divider
• Usage Rating: 1,000,000 operations!

Switch

• Latching: 3PDT
• Momentary: 2PDT

External Power

Dimensions

• Base length at longest point: 9.9”
• Base width at widest point: 4.0”
• Height at highest point including feet: 3.25”
• Pedal length: 8.7”
• Pedal width at widest point: 3.0”
• Pedal width at narrowest point: 2.3”
• Weight: 3.5lbs

* We recommend you take time to read through the Mission Engineering Compatibility Matrix to ensure your equipment has been tested by Mission Engineering. The Compatibility Matrix can also be downloaded as a PDF file by clicking here.

Not All Expression Pedals Are Created Alike

When considered from the electronics perspective, expression pedals are fairly simple devices. One might imagine they would be fairly universal, but this turns out not to be the case. In fact, Mission Engineering was founded to make expression pedals that work with a variety of pedals.

Why is this so complicated?

The heart of an expression pedal is an electronic component called a potentiometer, or 'pot' for short. A pot is like water faucet, but for electrical flow. Open the pot up and more current flows, close it down and less flows. You open and close flow with your foot moving the expression pedal. This all has to do with changes in electrical resistance and voltages, but the key for now is that you control the flow based on how far you press the pedal forward (down) or back (up).

How does this control the pedal?

Once you connect your expression pedal to the expression-pedal input on an effects pedal, the effects pedal talks to the expression pedal using voltage (called the control voltage, usually about 5V, but that is not important to understand how it works).

The control voltage passes through the expression pedal pot and back to the effects pedal, which can tell when the voltage is changed, that is if the flow of current is increasing, decreasing, or remains the same. The effects pedal uses the change in flow (think about your faucet again) to change how it operates. If the effects pedal is a wah pedal, for example, then the wah effect will change accordingly. Make sense?

Again, so why is this all so complicated?

In theory this is pretty straight forward, but in practice there are many, many pots to choose from and each pedal, amp, MIDI, or other electronics manufacturer choose the best control voltage for their specific product. There is no agreed upon standard, as there is for filing library books or producing flashlight batteries. This is the source of most problems.

If you are interested in all the variables involved, I suggest you read more, for example on the Mission Engineering web-site. For simplicity, some of these variables are maximum resistance (measured in Ohms)the wiring to the pot itself, and the taper of the pot (the measurement of how far the pot is open or closed based on how the expression pedal is pressed forward or back).

Mission Engineering Solves These Problems!

As you can see, there are many reasons why you need to choose the right expression pedal. One that will give you the best performance with your equipment. This is the reason Mission Engineering got into the expression pedal business, and why you can have confidence that when you pick a compatible Mission Engineering expression pedal, you have a reliable pedal.