Solving Effect Pedal Power Issues

The most common questions I hear revolve around powering effect pedals. In fact, any time someone contacts me about a strange issue they are having with a pedal, the first question I ask is “How are you powering it?” Choosing the right power supply for your rig can easily become the cause, or the solution, to random electrical “gremlins.” With numerous choices available in a variety of prices, let’s see if we can decode the mystery to find the right choice for you.

The first thing to consider will be the number of pedals you wish to power and their current draw. Effects, such as distortion and overdrive, typically require less power than modulation effects, such as delays. Each power supply, whether isolated or not — more on this later — will have a maximum-rated current output, measured in milliamps (mA). It is important to choose a power supply that can handle the number of pedals, and their required current. You can often find this information in your owner’s manual or by contacting the manufacturer.

Visual Sound One Spot 9V Adapter

Visual Sound One Spot 9V Adapter

When you power an effect with a 9-volt battery or a dedicated power supply, also known as a “wall wart,” you are supplying one path of current and ground to the individual pedal. In other words, the power is isolated. This is an important term to remember when shopping for a power supply. An isolated power supply contains outputs that do not share current and ground with other outputs.

A non-isolated power supply, commonly referred to as a “daisy chain,” is a string of plugs that share a common current and ground. These are less expensive than an isolated power supply. Beware, certain “brick” models may appear to be isolated but, in reality, are just glorified “daisy chain” power supplies.

On occasion, a simple non-isolated power supply will function fine with a particular rig. Other times, noise and hiss can be introduced — and amplified — due to the shared ground. Some pedals are notorious for not “playing nice” with other pedals when powered together by a non-isolated power supply.

Some effects have unique power needs:

  • All early made-in-Japan, and some made-in-Taiwan Boss pedals, require 9-volt battery or 12-volt ACA power.
  • Some vintage fuzz pedals with PNP transistors, which have a positive, rather than negative, ground. If you power them with a traditional power supply, the polarity will be reversed and you could damage the pedal.
  • Some vintage Electro-Harmonix units require 18 or 24 volts.
  • Some Fulltone pedals, including the Octafuzz, Soulbender and ’69, have reverse (center positive) polarity.
  • Some Line 6 and the Digitech Whammy require 9-volt AC (not DC) power.
  • The Boss DD-20 draws more power (up to 200 mA) than your average pedal and is notorious for not working well with a daisy chain power supply.
Voodoo Lab Pedal Power ISO 5

Voodoo Lab Pedal Power ISO 5

When in doubt, consult with the manufacturer. And, for the love of all things holy, don’t even think about powering your precious pedals with a random wall wart from a cordless telephone or electric toothbrush. Serious damage can occur.

If you are experiencing excessive noise, hum or ticks in your rig, try rearranging the order of your pedals. Also, supply isolated power, in the form of a fresh 9-volt battery when possible, or a dedicated power supply. If the problem disappears, you would likely benefit from investing in a high-quality isolated power supply. Which one? The choices can be overwhelming. Personally, I like Voodoo Lab. They make a variety of products with different features and their customer service is top notch. Other great options include the T-Rex and Cioks. Even Truetone / Visual Sound — long known for manufacturing the non-isolated 1 Spot daisy chain power supply — now offers a high-end isolated model.

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Johnny Balmer is the owner of Alchemy Audio, where he builds, repairs and modifies guitar effect pedals.

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