Power Up! A Guide To Powering Your Effects Pedals

Power to the pedal...but you have to do it right

by Ara Ajizian

Volts, amps, current, polarity, regulated, unregulated...these are some of the terms you've undoubtedly encountered (and probably been confused by) when it comes to powering your effects pedals with anything other than a 9V battery. It seems complicated, but in this article we’ll tackle the essentials you need to know.

Before we dive in, let me remind you of the Golden Rule about powering your effects pedals:

If the manufacturer includes or recommends a specific power supply, use it!

An included power supply is designed to match the pedal's requirements and is always the best choice for powering your pedal in lieu of a battery. However, not all pedals include a power supply, and batteries aren't cheap, so let's look at what you need to know before buying an aftermarket power supply or power brick.

Volts and Polarity

Typical stompboxes require 9 volts of DC power and use a center-negative plug scheme. How can you tell if yours has these requirements? First off, if it also runs on a 9V battery, that's a good clue it's a 9V pedal. Second, most pedals print the voltage requirement and the tip polarity around or near the power supply input jack. With the TC Electronic Arena (Fig. 1), the jack is labeled clearly—you can see it's a 9V pedal, negative tip, and also that it draws 100mA of current.

Fig. 1: The Arena pedal from TC Electronic is totally unambiguous about what kind of power it wants.

Although most compact stompbox effects are 9V, there are plenty of exceptions—some pedals require 12V, 18V, or 24V, however there are all sorts of variations. The main benefit of a higher-voltage pedal is typically more headroom, and therefore, more dynamics as well as more level before distortion. For example if your guitar has high-output pickups, consider experimenting with higher-voltage pedals to determine if they have a positive impact on your sound.

Milliamps

The other important effects pedal power spec is the current draw in milliamps, often expressed as a number followed by mA. Regardless of the voltage an adapter produces, if it doesn't provide enough current, the pedal won't work or will under-perform. Additionally, if you're using a power supply for multiple pedals (like a Visual Sound 1 Spot or one of the Voodoo Lab Pedal Power models; see Fig. 2), you need to make sure that the total draw of all the pedals you're powering doesn't exceed the mA rating of the power supply, or you'll run into trouble.

Fig. 2: The Voodoo Lab Pedal Power 4 x 4 has four 9V isolated high-current 400mA output sections (2 with 12V option), and four 9V isolated 100mA output sections.

You may hear conflicting advice about current draw. Some say, "As long as the adapter's rating is at least what the pedal requires, it will work." In other words, if you have a pedal with a 40mA draw, and a voltage-matched adapter that has an output of 100mA, it will be fine because the pedal will only take what it needs. That's only true of a regulated power supply—one that maintains the right voltage regardless of draw. An unregulated power supply will not, so if it's rated at 9V of output at 100mA but the pedal draws only 40mA, the voltage output can actually increase—which is bad news for your pedal.

Types of Current

We all love AC/DC...the unstoppable riffage, the blazing solos, the double entendre-laden lyrics. Your pedals, however, can only love AC (alternating current) or DC (direct current), but not both. Most of the time it's direct current they want, which is why you hear the term "power adapter" used a lot—a wall outlet produces alternating current, and the power supply "adapts" it to direct current. In the case that your effect needs AC power, you'll want to make sure you use an appropriate power supply, but the rules for voltage and current draw still apply.

Go Forth And Acquire Power!

So there you have powering pedals, in a nutshell. Whether you're shopping for a new pedal and want to know if your power brick will work with it, trying to find an aftermarket adapter for one of your favorite pedals, or simply looking to stop dropping so much coin on batteries, having this knowledge will ensure your prized pedals won't go out in a puff of smoke. Remember that Golden Rule from the beginning? I'm going to say it again: If the manufacturer includes a power supply or recommends a specific one, use it! In fact, some effects makers like Electro-Harmonix specify that using a power supply other than the included/recommended one will void the warranty. When in doubt, stick with batteries or contact the manufacturer directly for a recommendation.