A Guide To Powering Your Guitar Pedals. 

Powering your pedals.  Where do we even begin? 

This is a topic that sounds simple, but as you will soon find out is anything but.  I think, as with all great pedal power related topics, we need to start with a haiku. 

Power your pedals

Yes, you needn’t rush this part

Or, POP! Your gear’s gone. 

Alright.  I think that about sums it up. 

If we are going to do this topic justice, we need to start at the beginning… 

What power supply should I use? 

There are two main types of power supplies: Switch Mode and Toroidal (or Linear). 

Switch Mode supplies, like your typical Wall Wart (on the left), get a bad rap for adding unwanted noise into your signal path.  This is 100% true - sort of.  If you buy a cheap, poorly built Switch Mode supply, you will get noise.  If you buy something like a Strymon Zuma which is built with high quality components and quiet power in mind, you will be hard pressed to find any unwanted, power related noise in your signal path. 

Toroidal supplies (like the Voodoo Labs Pedal Power 2+ on the right), use isolation transformers (pictured below) - shaped like delicious doughnuts (also pictured below for your reference) - typically do a great job of delivering clean quiet power.  Why not just stop here and say, “Always buy toroidal and stay away from Switch Mode”? Because you would be missing out on some great gear that might be the perfect fit for your rig! 

Toroidal power supplies (PSUs) are a solid choice, but they are also heavy and can’t deliver the same specs that a Switch Mode supply can.  There is no right answer here other than knowing what specs to look for and deciding which will best suit your individual needs. 

The other thing to consider is input voltage.  Can your power supply be used anywhere in the world? Some power supplies allow an input voltage of 100-240V (you can use it in any country) and others are voltage specific (120v only as an example).  You may not need multiple input voltages now, but when you do, you will wish you had the option. 

Isolated vs. Daisy Chain

There is another note here around power supply types.  Should you daisy chain your effects or isolate? 

Yes. 

Both are acceptable.  If you have a couple of analog effects - a couple of simple overdrives into a Boss DD5 out to your amp - you can get away with a wall wart and a daisy chain (pictured below).  This essentially means you are going to use one power outlet to power multiple pedals.  

If, however, you are using digital effects that require isolated power - like a Line6 HX Stomp or a Strymon TimeLine you will need isolated power.  This essentially means you will need a power supply with multiple, isolated outputs.  For any pedal that needs isolated power, you will need to dedicate a power tap on your PSU to that one pedal - No daisies here! 

If you dare to ignore my warning you will be greeted with a noise so ugly it is sure to be met with screams of horror from on-listeners.  

In short - Daisy chain your analog effects if needed, and isolate everything else.  Or as the famous saying goes, “If you need to ask a mate, isolate.” 

Final note - Not all power supplies with multiple outlets are isolated.  Check the manual before buying! Some multi-outlet supplies are simply trying to look the part but are masquerading as a daisy chain! If you’re absolutely at a loss, get in touch with the manufacturer or e-mail me and I’ll take a look.

Volts (V), Milliamps (mA) and The Hulk. 

We have established that isolating your pedals is the preferred method of delivering that soon-to-be-quiet-power.  Now we can talk about power specs.

On each isolated output of your power supply you will see at least two symbols (V and mA) preceded by a number.  Something like, 9V and 250mA.  Volts (V) and Milliamps (mA).  Not to be confused with a herd of 1000 amps.  

Volts are referring to the amount of voltage the pedal requires - make sure the voltage supplied from your PSU and the voltage needed from your pedal match. Milliamps are referring to the maximum amount of amperage/current that outlet can deliver.  Make sure to at least match mA, but to be safe, try to have more mA on the tap than needed.   

This is best described with a metaphor.  

You just finished a gruelling shift at Bed Bath and Beyond.  Judy wanted King Single sheet sets stocked in three different areas in the store at the same time as John wanting his piping hot mocha frappuccino.  You’re glad to have this day behind you. You walk to your car and drive home.  Luckily it's school holidays so traffic isn’t too bad - you might just make it home in time for Wheel of Fortune. 

You finally pull into your driveway and see an olive green envelope sticking out of your mailbox.  Intrigued, you grab the letter, being careful not to damage it.  Upon opening this personalised piece of prose, you soon realise it’s an invitation - To cook dinner for the best avenger; The Hulk. 

Excited and terrified, you RSVP before noticing that this monstrous event is actually at your house - your only house, which isn’t yours; it's rented.  You aren’t flakey, so you keep your promise and start making preparations to cook the Avenger known for destroying property, a delicious dinner. 

You know from all the popular forums that The Hulk has a specific eating regime and prefers to consume his meals at 9 spoonfuls per minute and will keep going until he has eaten approximately 300lbs of food.  If he eats too quickly or too slowly or if there isn’t enough food for him to consume, he will most likely lose his temper.  Not something you, or your land-lord can afford. 

You get to work and finish cooking this feat of culinary mastery - Soup de Jour - with only minutes to spare before you hear your front door CRACK to the ground.  The Hulk, trying to be polite, knocked a little too hard and entered your abode, albeit a bit bashful and very hungry. 

Dinner starts promptly at 7pm.  You make sure to ask The Hulk a question when he’s eating a little too quick, slowing him down. When he starts talking a bit too much you tell him a story so he can focus on eating.  It's a science that you master quickly thanks to reruns of Bill Nye.

You started the evening by putting 400lbs of soup on the table and by your calculations there are about 115lbs left when The Hulk finally puts his spoon on your table - actually through your table, but he tried - you never liked this table anyway.  

After a short lived arm wrestle, suggested by The Hulk, the big green guy leans your shattered front door against the frame and runs home.  

Overall this evening was a great success. Ever the optimist, you feel thankful that you won’t have to do groceries for the next 6 months with a cool 115 pounds of delicous De Jour sitting in your kitchen. 

Tired, you go to bed dreaming of joining The Avengers as Soup Man - The most soothing avenger. 

In this long-winded example, The Hulk is your guitar pedal, Voltage is the rate at which he eats and the amount of food on the table is the current, or milliamps. 

1. 9 spoonfuls of food per minute - Give exact voltage (9V to a pedal that requires 9V) 
2. 400lbs of food served - Oversupply Current (mA) - Put a pedal that requires 50mA to run on a power tap that can supply 50mA or more! You can put a 50mA pedal on a 500mA power tap without issue, although this is an extreme example.  
3. If you decide to daisy chain pedals on one outlet, make sure they require the voltage that outlet is set to (all need 9V on a 9V outlet for example) and the sum of their current draw does not exceed that isolated power outlet.  3 pedals that all require 100mA each need to be on a tap that can supply a minimum of 300mA. 

Could I have said all of that without a lengthy, semi-redundant story? 

Absolutely. 

Current and Voltage Doublers

There are often times your power supply doesn’t have the required specs to power your pedals.  A common example of this would be a pedal that requires 18v.  If your power supply doesn’t have an 18v outlet, do you need to sell your pedal or worse yet, stop playing guitar all-together? 

No.  

You can use a voltage doubler.  This is a DC cable that - yes, you guessed it - doubles the voltage.  It does this by taking two 9V outlets and adding their voltage together! You can check these out on our DC Cable Designer for more info.

A note on voltage doublers.  The voltage doubles, the current does not! This is kind of like The Hulks brother - Bulk - who eats the same amount of food as Hulk, but at twice the speed. 

In a similar way, you might have a pedal that requires more current than any of your individual outlets can supply, let's take the Line6 HX Stomp for example.  This pedal needs 1000mA or 1A of current to run properly.  Yes, you can use the Line6 provided wall wart with great success, but who has the time to plug in two power cables when you’re getting ready for a gig.  Not me.  

With a current doubler (another simple DC cable) you can use two 9V, 500mA outlets on your supply and double the current - in this case, voltage will stay the same (9V).  Now your 1000mA of current is flowing generously to your HX Stomp at 9V. 

Polarity 

Every DC pedal requires two power rails, a positive and a negative.  Just like the two terminals on a typical battery, you need to properly assign the correct rails to your pedals.  

The most common polarity for guitar pedals is center negative (-).  This means that the middle pin on your DC plug is the negative rail (or ground) and assumes that the outside of the barrel plug is positive (+).  

If only we could stop there and keep this simple.  

Not all pedals require center negative power.  Certain pedals require center positive power like the Eventide H9.  

No fancy, over the top stories for you here, just make sure you check your owners manual before plugging power into your newest pedal purchase! The wrong polarity can damage guitar pedals!

DC Plug Types 

There are three main DC Plug types you will come across as a guitar player.  

1. 2.1mm barrels 
2. 2.5mm barrels 
3. 3.5mm jacks 

The most common DC plug you will come across as I'm sure you’re aware is the 2.1mm barrel plug.  Often this plug is also center negative, but not always, so always check your owners manual! 

The 2.5mm barrel is often (but not always) center positive.  The Eventide H9 is center positive, the Line6 HX stomp is center negative.  Just in case it hasn’t sunken in - Check your owners manual BEFORE you plug in power. 

Lastly the 3.5mm jack. You will find these in old ProCo Rats, Klons and TS808s (among others).  These are often tip positive, BUT …. You know what to do (check your owners manual).

You can often find adapters (shown above on the right) that go from 2.1mm to the plug type you need but just check polarity on these adapters as well.  Some will invert to center positive, others won’t. 

Find your pedals power requirements

I know I keep harping on about checking your user manual.  You’re sick of hearing it and I'm sick of saying it.  I’ve gotten too many emails saying, “I plugged in the wrong power to my pedal and now it won’t turn on” to leave you without fair warning.  Do me a favour.  Grab a hot cup of coffee, sit in your favourite leather armchair, kick your feet up, and read some manuals.  Your bank account will thank me later. 

What happens when you check your manual, find the specifications section and it says something like: 

Power Requirements: Use supplied power supply only!

Well, you can do a couple things.

1. Take a wild guess and just plug in the first power tap you have available - NOT recommended.
2. Pick your favourite search engine and type in something like, “What voltage does my EHX POG need?” and start reading. 
3. Do the same for current, “H9 Current draw.” 

Another handy tool, one I use often is the TrueTone 1Spot Milliamp Meter.  You can plug in your basic guitar pedals and it will tell you how many mA they need to run.

There you have it.  A little bit of research and you have all the power info you could ask for.  Thank you internet! 

I know this little guide has been long winded.  I know we could have made this short and boring, but then it would have been short and boring rather than long and less boring.  

If you’re ever stuck, send us an e-mail and we will do our best to help.  You are not in this pedal powering game alone.  Ask questions early, not after you’ve over-supplied your dads vintage Klon.  

If you got something out of this, leave a comment and let me know.  We love hearing from you and still have plenty to learn, so add to this article in the comments! 

May your pedals always have clean power and your milliamps stay abundant. 

Until next time.