Gitaar effectpedalen hebben stroom nodig om te kunnen werken. De meeste pedalen zijn ontworpen om met een 9 volt batterij te werken en verbruiken niet heel veel stroom.
Some (mostly) digital pedals consume more and cannot be powered by a 9 volt battery. When you have multiple 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 effect pedal?
Basic course on electric current
To answer those questions, we first go back to the basics of electricity—specifically, the difference between voltage and current.
What is voltage?
Voltage is expressed in volts and represents the amount of energy required for electrons to move from one point to another in an electrical circuit. A wall outlet in the Netherlands has a voltage between 220 and 240 volts, while a rectangular 9-volt battery supplies 9 volts.
There are two types of voltage: alternating voltage and direct voltage. With alternating voltage, the voltage varies between positive and negative values at a specific frequency. In Europe, this frequency is 50 Hz, meaning the voltage switches from negative to positive 50 times per second. With direct voltage, there is no fluctuation in voltage.
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 periodically reverses direction.
You also have resistance and power, but I will ignore these 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 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 before. Almost all pedals use a center negative connection with the power on the outside of the plug. Be careful not to exchange these, as you could irreparably damage the pedal!
Incidentally, it is noteworthy that the power connection is on the outside of the plug; it would seem more logical to route the power through the inside. One of the reasons for this lies in how batteries are wired within pedals. When an external power supply is connected, the battery circuit is disconnected—a process that is only possible if the power connection is located on the outside. You can read more about this in this article by Neunaber.
Warning: never connect a higher voltage!
While we’re on the subject of warnings, make sure never to connect a 9V pedal to a power supply with a voltage higher than 9 volts; there is a high risk of damaging the pedal. That said, some pedals can handle higher voltages—something the manufacturer will always specify in the pedal’s manual. Feel free to get in touch if you have any doubts about this. The advantage of using a higher voltage is that the pedal gains more headroom and/or exhibits less compression.
Higher current is not a problem and is even recommended.
Furthermore, you can safely connect a pedal that requires, for example, 10mA (mA stands for milli-ampere – 1/1000th ampere) of current to an adapter that supplies 500mA of current. The pedal, as it were, draws the current needed from the power supply and will not draw more than necessary. So it is not a problem and even recommended to use a power supply with more current than necessary, this way you can connect multiple pedals to the same power point (daisy chaining, more about that later).
Why do you want isolated outputs?
“Isolated outputs” is another term you may have come across. A power supply with five isolated outputs essentially houses five separate adapters within the unit, each ensuring the correct current and voltage for its specific output. The incoming power is tapped off and then converted to the appropriate current and voltage levels. The major advantage of this design is that the power supply never causes the hum or other unwanted noise associated with ground loops. Furthermore, isolated outputs are safer for your pedals, as there is no risk of stray voltage reaching the output.
Is that the same as a regulated power supply?
No, that’s not it. A regulated power supply ensures that the voltage remains constant regardless of the amount of current being drawn. So, whether you need 10 mA or 1,000 mA of current, the voltage stays the same. However, if you demand more current than the power supply can handle—for instance, if you connect pedals requiring 2,000 mA while the supply is capped at 1,500 mA—then the voltage will drop.
Daisy chaining effects 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 for this in which the various 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 for just a few tens of euros. However, there are also important disadvantages. 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 connecting effects pedals together, you add up these small voltages and create a larger voltage. This causes a current to flow and is audible in your audio signal. It 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 by providing all pedals with batteries.
A Battery or a Power Supply?
Pedals that do not require much power can easily be powered by a battery. A Duracell 9V battery delivers approximately 500 mA for one hour before running out. If you have a pedal that draws 10 mA of current, you can theoretically play for 50 hours on a single battery. In practice, however, once the battery is 70% depleted, it will no longer provide the desired voltage. Some guitarists actually consider this an advantage (particularly with certain fuzz pedals). Do remember to unplug your audio cables from the pedal when using a battery; as soon as a cable is connected, the pedal draws power (even if only a small amount).
What is the best power supply for my effects pedal?
That’s all well and good, I hear you think, but which food should I choose now? If you follow 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’re all set, but keep potential future expansions in mind as well. - Consider whether you want to daisy-chain your pedals.
My advice is not to do this, it may go well, but you won’t know until you do it. You cannot assume that this will always work without problems. - If you are daisy-chaining: for each group, add up the current draw (in mA) of the pedals in that group.
For example: suppose you have two 9V pedals requiring 100mA each and two 18V pedals requiring 200mA each. You would then need at least two outputs: one rated at 200mA/9V and one at 400mA/18V. - If you’re not going to daisy chain, you’ll need at least as many isolated outputs as you have pedals.
In the example above there are four. Please 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 food). - Check carefully whether each pedal requires center-negative polarity and can indeed be connected using a 2.1 mm plug.
- Browse the selection of power supplies and cables, and make your choice.
Power supplies from Cioks and Strymon are modular and can be expanded afterwards. This is very useful if you plan to expand your pedal arsenal in the future. Don’t forget to check whether the power supply fits (in terms of thickness) under your pedal board.
Reputable power supply brands include Strymon, Cioks, Truetone and Voodoo Lab.
Brands in the cheaper segment include Mooer, Foxgear and Xvive.
Leon Keemer is gitarist, gear-nerd en vaste schrijver bij Pedaltown.nl. Met een voorliefde voor alles wat je geluid kan vormen, verbuigen of verbeteren, test hij regelmatig nieuwe effectpedalen—van boutique fuzzes tot moderne multi-FX. Leon staat bekend om zijn heldere uitleg en eerlijke reviews die zowel beginners als doorgewinterde gitaristen verder helpen. Als hij niet achter zijn pedalboard zit, experimenteert hij in de studio of speurt hij naar obscure effecten die muziekmakerij nét een beetje spannender maken.