This is part one of a two-part post.
A high quality power supply (or supplies) is essential to any pedalboard build. If Khalil’s Ethos Overdrive Amp is the heart of his pedalboard, his Cioks DC10 power supply is the liver of the pedalboard. A good power supply will make sure your pedals are working at their optimum condition, minimise noise issues due to power, protect them from power surges in the mains electricity, and simplify the setup and teardown process, among many other things.
Basics - AC, DC, Voltage, Current, Power
So when we talk about power supplies, you’re bound to run into a few slightly technical terms. Just to make sure everyone’s on the same page, let’s cover the basics. (If you studied and remember anything from high school physics, you can skip to the next section)
AC - Alternating current. This is type of electricity that comes from mains power outlets, power strips and any unprocessed power source. Usually in 110V to 220V (approx.) depending on where you live. This type of power’s polarity is constantly flip-flopping either at 60Hz (Hz = Hertz = times per second) or 50Hz depending on where you live.
DC - Direct Current. This is the kind of power that most pedals like. Direct current is just like it sounds. The polarity does not change. To get DC power, you would need a device to process AC.
Voltage (V) - Measured in Volts. If electricity was compared to water flowing out of a hose, voltage would be equal to the size of the hose (thickness). Higher voltage, thicker hose. Lower voltage, thinner hose.
Current (A) - Measured in Amperes, or amps. Also mistakingly known as “Amperage” (which is not even a word). compared to water flowing out of a hose, current would be equal to the speed at which water flows out. Higher current, faster water flow. Lower current, slower water flow.
Power (W) - Measured in Watts. Power is the product of Voltage and Current. In the water hose world, it would be equivalent to how much water is actually flowing out. So the mathematical relationship between these three measurements is “Power = Voltage x Current”. So if you had a thicker hose, and faster water flow, more water would be flowing out, and vice versa. Although power is usually measured in watts (W), it is common to find it also measured in VA, voltage amps.
Power Supplies For Pedals - Since almost all pedals are powered off DC power (save a few reverbs and tube preamps), power supplies are essentially an AC to DC converter. On top of being a converter, they are also a step down adapter, as it would bring e.g. 220-240VAC (Volts AC), to 9VDC (Volts DC), making it suitable for most pedals in the market today. There are mainly a couple ways to do this. Either by using what is known as a ‘digital switching supply’ or by using a transformer.
High And Low Quality Power Supplies
So why shell out a lot more money for a high quality power supply over a standard wall wart AC/DC converter? Let’s take a small step back and look at AC power. Let’s take the example of 220V @ 50Hz. Since voltage is really all relative to what we ground it to, we can actually set the ground at 110V, which would give us +110V and -110V. Now let’s take a look at cheap power supplies. A lot of compact cheap power supplies for pedals are switching supplies. What that means is that the power supply sees the whole +110V -110V deal, and whenever the voltage is at -110V, it will flip the polarity to +110V. This happens 50 times a second. Since this is all happening digitally at a rapid pace, a lot of these cheap power supplies will leak a noise into the DC power going to the pedal, which would then leak into the audio signal. This is why a lot of cheaper power supplies cause noise! However, switching power supplies do have a place in this world because of their high efficiency, allowing them to have a compact design. As long as the piece of equipment is designed with power noise filtering, it should not pose a noise issue, but unfortunately, a lot of pedals out there are not. So how about high quality power supplies? They use transformers. Normal transformers aren’t that expensive, but like all things, good ones are. Transformers are basically a hunk of iron with wire wrapped around it. All passive, nothing fancy. Transformers have two basic design structures. The more common one, is like those that you would see in a tube amplifier. A square/rectangular shaped iron, with wire wrappings extruding on two sides. These are pretty common in basic high quality power supplies. Another transformer design is known as the toroidal transformer. These are often found in top-shelf power supplies, and in high-end HiFi audio systems. Toroidal transformers have a round shaped iron with the wire wrappings around it, following the circular shape. These transformers usually offer better isolation of noise, and a more stable stream of power, over their basic counterparts. Toroidal transformers are also usually larger, heavier, and of course, more expensive than standard transformers. That is why high-quality power supplies cost so much more. If you plan to build a professional pedalboard, that is flexible and reliable, a power supply with a toroidal transformer is essential.
Pedals Working Optimally
Almost all pedals we can get a hold of today, are built with power supply jacks, with the intention of them being primarily powered using power supplies, and secondarily powered by battery cells. In almost all professional pedalboards, though, we want things to run off a power supply so we don’t have to worry about batteries running dry. However, there are some pedals out there that like to be run off 9V batteries such as vintage fuzzes. A lot of musicians have power jacks installed in them but it is a highly debated topic that they do sound best when running off a battery as the internal properties of a battery play a part in the circuit. We won’t dive into that topic in this article. So pedals work the ‘best’ when they are powered by a stable and reliable source. That’s where high-end power supplies win over switching power supplies. Many switching power supplies have voltage ripple due to the way it works, which means that even if the power supply says that the output is 9VDC, chances are that it fluctuates slightly around 9VDC, causing the pedal to perform undesirably. Transformer-based power supplies are a lot more stable in their output voltages, and usually have ripple prevention circuits built into them.
Now that we've covered the basic advantages of high-quality power supplies, we will talk about other advantages of such power supplies in part two.