Finding the right power supply for your board can be a daunting task. They all look the same and have very similar product descriptions, so how to choose. Well, here are a few terms and tips that will help you choose.
Before we dive in, this is going to be a long post, so if you don't feel like nerding out completely, just follow these 8 basic rules and you'll be good:
Below you will find the following subjects:
Isolated outputs vs daisy chaining
Voltage (V)
Current (mA)
Reverse Polarity
Linear Power Supply vs Switching or Switched Mode Power Supply
AC power
Isolated outputs vs daisy chaining:
There are two basic ways of powering your pedalboard, daisy chain or isolated power.
A daisy chain is basically a cable that allows you to split the power of one outlet to multiple pedals. The technical explanation is that a daisy chain is a parallel connection, with the hot running from each pedal to the power outlet and the ground running from pedal to pedal and finally to the outlet. The pros of a daisy chain is that it's cheap and easy to set up. The cons include: the shared ground creating ground loops, mismatched current draw can introduce noise, you can only run pedals with the same voltage requirements and you can never be 100 percent sure that it will run noise free.
By now you're probably thinking that daisy chains don't sound like a good solution for a pedalboard and you are absolutely right... like 95 percent of the time. Low current drive pedals can almost always run off of a daisy chain, without issues, so if you run out of outlets on your power supply, consider daisy chaining your drives, instead of just buying a new expensive power supply.
The only way to ensure a noise free setup is by using an isolated power supply. An isolated power supply provides separate power to each pedal, even though they are all powered by the same IEC cable (standard cable that connects to the outlet in your wall). The main thing isolated power does, is it eliminates ground loops and it allows you to run digital pedals, without weird digital noise. The noise is often caused by some of the signal that is sent to ground by the digital pedals. When daisy chaining the ground is shared and so that signal is sent into the circuit of the other pedals.
Unless specifically stated in the description, never assume that a power supply is fully isolated. Look for power supplies that say FULLY ISOLATED or state that each outlet is INDIVIDUALLY ISOLATED. Some companies will deliberately be vague about it, if it's not properly isolated and some will even say that it's isolated, but still have some of the outlets being daisy chained. Cioks, Strymon and Voodoo Lab are some of the safe choices. If they say that it's isolated, it's isolated. Read the manual if you are in doubt. FULLY isolated is usually something companies are proud of.
Voltage (V):
Let's move on to voltage, as voltage can potentially damage your pedals. Always make sure you use the correct voltage for your pedals. Lower and the pedal wont function properly (some people like the sound of drives being starved of voltage. This is known as sagging). If you feed your pedals too much voltage, the pedals will most likely take damage. Maybe not right away, but the circuit isn't built to handle it and it will over time overload the components.
Voltage affects the overall headroom in pedals, meaning that it sets the threshold for when the circuit starts clipping. A lot of drive pedals are built to handle more than the standard 9 volts. If you increase the voltage, you will increase the headroom and thereby making the pedal cleaner and less compressed. Disclaimer… some pedals take 9-18 volts, but will adjust the voltage internally. In these cases increasing the voltage will have no effect.
Current (mA):
There are 2 things you can get wrong with current. 1. You don't feed your pedals enough. In that case, they simply won't work properly. Digital pedals often take a lot of current, so keep that in mind. 2. You exceed the total power rating of your power supply, meaning that your pedals collective power consumption is greater than what your power supply can provide. I highly recommend you do the math before buying power supply or setting up a new board. Look up the current draw of your pedals and simply add them. That's your total power consumption.
Feeding a pedal more current than it needs won't damage it. It will only draw what it needs.
Reverse Polarity:
Reverse polarity or center positive pedals refer to pedals that need the polarity of their power cables flipped and so use different cables than the standard center negative. They are very uncommon and chances are, you'll never have one on your board, but if you do have a pedal that takes center positive power, you need to be careful to use the right power cables for it. Otherwise you will damage the pedal… same goes the other way around. A center negative pedal cant handle a center positive cable.
New Boss, TC Electronic, Behringer, Wampler, MXR and JHS pedals all take center negative power. Check the manual of the pedal if you are in doubt.
Often a center positive power cable will have a red plug, so you can tell the difference, but always read up on how the cables are labelled on your specific power supply.
Linear Power Supply vs Switching or Switched Mode Power Supply:
I'm not going to go in depth with how these work, but a linear power supply is the “old” type of power supply and it relies on a bigger transformer, than the newer switching power supplies.
Linear power supplies are immune to noise coming from the mains connection and are very robust, but because they produce more magnetic interference, due to the larger transformer and some pedals, like wahs, are vulnerable to interference, you have to watch where you place your pedals. They are also quite a bit larger than switching and very ineffective compared to switching power supplies.
Switching or switched mode power supplies are the new kids on the block. For a long time, they have had the reputation of being too noisy for audio equipment, but lately they have been gaining popularity, because manufacturers have found ways to filter out the noise and make them even more quiet than the linear ones.
Switching power supplies can produce a lot more power than the linear ones, due to the design being far more effective and because they use smaller transformers, they are also greatly reduced in size. Switching power supplies often also have the advantage of being very flexible and a lot of them have extensions, so you can expand your pedalboard, without having to buy a new powers supply.
Pricewise, the linear power supplies are quite a lot cheaper than the switching power supplies, though there are cheap versions of the switching once on the market, they are still in the expensive end of the spectrum. I recommend you check out a switching power supply, if you are looking for a new one. If you already have a good quality linear power supply, with isolated outputs, that fulfils your needs and isn't noisy, there's no need to change that.
AC power:
AC stands for alternating current and is what comes out of your wall sockets. In the olden days, there was no industry standard for powering pedals and so you can run into vintage pedals that take AC power. Modern pedals almost exclusively take DC power and with good reason. AC power really isn't very well suited for pedals, as the cables have to run perpendicular to the audio cables to not introduce noise. Those of us who have set up a lot of boards know what a hassle that is and to be completely honest, i've never tried an AC powered pedal, that was worth said hassle.
Using AC power on a pedal that takes DC power will likely damage it, so watch out for that, if you have an AC power cable on your board. Feeding an AC powered pedal with DC power won't have any effect. The pedal wont work, but it wont get fried either.
Some pedal manufacturers provide a power supply with their pedals. These often say AC adapter... They do not provide AC power, but convert AC power to DC power! If you need AC power, something like the Truetone 1spot Pro CS12 is a good option, as it has both AC and DC power.
