Guitar effects pedals need power to work. Most pedals are designed to run on a 9-volt battery and don’t use a lot of power.
Some (mostly) digital pedals consume more power and cannot be powered by a 9 volt battery. When you have several pedals, it is often useful and sometimes even necessary to use a so-called multi-power supply. But which one do you choose? And what should you pay attention to? In short, what is the best power supply for my effects pedal?
Electric current basic course
To answer these questions, we first go back to the basics of electricity, and more specifically the difference between voltage and current.
What is voltage?
Voltage is expressed in volt(age) and is the amount of energy it takes electrons to move from one point in a circuit to another. A socket in the Netherlands has a voltage between 220 and 240 volts and a block battery supplies 9 volts.
There are two types of voltage namely AC voltage and DC voltage. With alternating voltage, the voltage varies with a certain frequency between positive and negative values. In Europe, this frequency is 50 Hz, ie the voltage changes from negative to positive 50 times per second. With DC voltage there is no voltage change.
What is current?
Current is expressed in Amperes and is the number of electrons moving from one point to another every second. With direct current (DC – Direct Current) they always move in the same direction (from plus to minus) and with alternating current (AC – Alternating Current) the current changes direction periodically.
You also have resistance and power, but I’ll leave them out of consideration here so as not to make it too complicated.
Polarity – center negative
Most guitar pedals require direct current (DC) with a voltage of 9 volts. The connection for this to the pedal is in 99% of the cases via a 2.1 mm plug. The polarity of the connection plays an important role here. You may have heard the term center negative. Almost all pedals use a center negative connection with the power on the outside of the plug. Make sure that you do not exchange these, you can damage the pedal irreparably!
Incidentally, it is remarkable that the power is on the outside of the plug. It would make more sense to run the current inside the plug. One of the reasons for this is the way batteries are connected in pedals. Connecting a power supply to a pedal disables the battery’s circuitry and can only do that if the power is on the outside. In this article from Neunaber you can read more about that.
Warning: never connect a higher voltage!
While we’re warning, also be careful never to connect a 9V pedal to a power supply with a voltage higher than 9 volts. The chance that the pedal will break is quite high. That said, some pedals can handle a higher voltage. The manufacturer will always indicate this in the manual of the pedal. Please contact us if you are in any doubt about this. The advantage of this is that the pedal then gets more headroom and/or less compression.
Higher current is not a problem and even recommended
You can safely connect a pedal that needs 10mA (mA stands for milli-ampere – 1/1000th of an ampere) to an adapter that supplies 500mA of current. The pedal, as it were, draws the current required from the power supply and will not draw more than is necessary. It is therefore no problem and even recommended to use a power supply with more current than necessary, in this way you can connect several pedals to the same power point (daisy-chaining, more about that later).
Why should you want isolated outputs?
Isolated outputs may also be a term you’ve seen. A power supply with five isolated outputs actually has five adapters in the box, each of which ensures the correct current and voltage of that output. The current and voltage that goes into it is first tapped off and then converted to the correct current and voltage. The big advantage of this is that the power supply is never the cause of hum or other unwanted noises caused by ground loops. Furthermore, isolated outputs are also safer for your pedals because no other voltage can come to your output.
Is that the same as a regulated power supply?
No, that’s not it. A regulated power supply ensures that the voltage remains the same regardless of the amount of current drawn. So whether you need 10 or 1,000 mA of current, the voltage always stays the same. If you demand more current than the power supply can handle, so if you connect pedals that require 2,000 mA and the power supply is maximized at 1,500 mA, the voltage will decrease.
Daisy chaining effect pedals
You can also daisy chain your pedals, in other words connect multiple pedals to the same output. You use a special daisy chain cable where the different plugs are looped through. You can probably guess the big advantage of this, you only need one output that supplies the desired amount of power. That means fewer cables, less space and it is an extremely cheap solution of a few tens. However, there are also important drawbacks. With a daisy chain you connect all the electronics of your pedals together and very often you introduce unwanted hum due to ground loops. A daisy chain is not recommended, especially with digital pedals.
One of the causes of a ground loop is that the ground of pedals is never exactly 0 volts, but a few millivolts. By linking effect pedals together, you add these small voltages together and a larger voltage is created. This causes a current to flow, which can be heard in your audio signal. This is often a 50Hz hum or a derivative thereof (100Hz, 200Hz, 400Hz etc.). You can easily remove this ground loop by using an isolated multi-power supply or battery-powering all pedals.
A battery or a power supply?
Pedals that do not require a lot of power can be powered by a battery. A Duracell 9V battery delivers about 500mA for an hour and then runs out. If you have a pedal that requires 10 mA of current, you can basically play for 50 hours with a battery. In practice, however, when the battery is 70% empty, you will no longer get the desired voltage from a battery. There are also guitarists who find this an advantage (especially with certain fuzz pedals). Make sure you remove your audio cables from your pedal when using a battery. When a cable is connected, the pedal consumes power (even if it isn’t much).
What is the best power supply for my effects pedal(s)?
That’s all nice, but which power supply should I choose? If you stick to the step-by-step plan below, you can’t go wrong and you will automatically choose the best power supply for your guitar effect pedal.
- Determine the number of different voltages you need.
If you only have 9V pedals, you’ll be ready quickly, but also keep in mind any future expansions. - Consider if you want to daisy chain pedals.
My advice is not to do this, it can go well, but you won’t know until you do it. You cannot assume that this will always work without any problems. - If you are going to daisy chain: add the number of mA of the pedals in that group for each group for example: you have two 9V pedals that each require 100mA of current and you have two 18V pedals that each require 200mA of current. Then you need at least 2 outputs, one of 200mA/9V and one of 400mA/18V.
- If you are not going to daisy chain: then you need at least as many isolated outputs as you have pedals.
In the example above, there are four. Note: 8 outputs on a power supply does not mean that these are also 8 isolated outputs. Some power supplies have isolated sections within which they group outputs. In fact, this is a daisy chain (but in the power supply). - Check whether each pedal requires a center negative polarity and whether the pedal can indeed be connected with a 2.1 mm plug.
- View the range of power supplies/cables and make your choice.
Cioks and Strymon power supplies are modular and can be retrofitted. This is very useful if you plan to expand your pedal arsenal in the future. Don’t forget to check whether the power supply (in terms of thickness) fits under your pedal board.
Reputable brands of power supplies include Strymon, Cioks, Truetone and Voodoo Lab.
Brands in the cheaper segment include Mooer, Foxgear and Xvive.