#1
OK, since this sort of queston comes up at least once a week, here is all you need to know about powering your pedals...

(For most of this "Article" we will be using 9 volts as the standard voltage rating since that is what the majority of pedals operate at)

Pedals require a certain voltage to run properly, and also require a certain current to operate properly.
Voltage will usually be abbreviated as "V" or "vDC", or "vAC".
In the pedal world, its most often vDC (though not always).
DC is the abbreviation for Direct Current
AC is the abbreviation for Alternating Current
These two types of power ARE NOT interchangeable.
If you use one type to power a pedal (or any other electronic device), when it calls for the other, you will break it.
Pedals that require AC or Alternating Current type voltage generally come with their own power supply. Though not always.

Current, or Amps, Amperage, or Milliamps (Milliamps is generally abbreviated as "mA").

When a Pedal calls for 9vDC is means it needs 9 Volts Direct Current to operate, abbreviated as 9vDC, or sometimes just "9v".
Running a pedal that calls for 9 volts at anything more than 9 volts can damage it.
However, there are some pedals that can run at higher voltages.
Analog Overdrives are a prime example of this. (I run my Fulltone Fulldrive 2 MOSFET at 18 Volts)
BUT, ALWAYS CHECK WITH THE PEDAL MANUFACTURER BEFORE TRYING A HIGHER VOLTAGE.

Now we get to Negative Voltage and Positive Voltage as well as polarity.
We have +9vDC" and "-9vDC".
The only time you are likely to come across "-9vDC" is with older pedals, particularly older fuzz pedals.
DO NOT CONFUSE THESE TWO, THEY ARE NOT INTERCHANGEABLE.
We have what is called Positive Ground and Negative Ground.
Negative Ground is more or less the standard for today's pedals.
Positive Ground pedals will generally only run on batteries or come with a special adapter.

Another Polarity issue is with the power adapter.
With the power adapter, as well as the pedals themselves, the polarity is generally referred to by the center pin or connection on the adapter plug or jack (Center Negative or Center Positive).


On some pedals, there will be a small graphic showing which type it is.
The same images will often also be on the power adapter.

The center part of the image is a graphical representation of the plug or jack.
Sometimes the image will be reversed but pay attention to what is in the center of the image and which element connects to the "+" and which one connects to the "-"

This is the most common, Negative Polarity, Or Negative Ground, often referred to as "Boss Standard":



This one is Positive Polarity. Or Positive Ground:


REMEMBER THIS NEXT PART, THERE WILL BE A TEST (OK A HISTORY LESSON) LATER.
A little more detail on Positive Ground and Negative Ground.
Go grab a 9 Volt Battery.
Go on, I'll wait..................
Back? OK good.
Look at the side of the battery neat the terminals.
You will see a Plus and a Minus symbol, one on each side.
Positive ground means that the battery terminal marked with the Plus symbol, will be connected to ground. This type is most often found on older pedals.
Negative ground means that the battery terminal marked with the Minus symbol, will be connected to ground.
Negative Ground is the most common way with most modern pedals.


If a pedal list its power requirements as : "9vDC 100mA" that mean it needs 9 Volts Direct Current (9vDC), and 100 Milliamps (100mA) to operate properly.
You will generally find this in the user manual or on the manufacturers web site. Sites that sell these pedals (such as Sweetwater, Guitar Center, Musicians Friend, etc. will sometimes also list this information).
You can also check the stinkfoot power list : http://stinkfoot.se/power-list
Not all pedals are listed there, but it also has instructions on how to check your pedals yourself.
Here is another resource for pedal current draw (thanks to trashedlostfdup for the link) : http://custompedalchainsystem.com/CPCS/ACCUEIL_files/EFFECT%20CURRENT%20DRAW%20BASE%202013%20CUSTOM%20PEDAL%20CHAIN%20SYSTEM.pdf

mA rating on a pedal indicates how much power (in mA) that pedal needs to operate properly.
The mA rating on a power supply indicates the maximum amount of power/current it is capable of supplying.

Supplying less than the manufacturers stated current draw (mA) will generally cause no problems for the effect, it just won't operate properly.
It can however cause problem for the power supply.
A pedal will try to draw the current it needs to operate properly, if the power supply can't supply enough current, it could overheat.

If you plug a pedal into a power supply that has a max current output rating of less than the pedal needs, you could damage the power supply.
For example, if the power supply is only capable of supplying 100 mA and the pedal draws 150 mA, that could cause problems for the power supply.
The pedal won't work properly and you may overheat the power supply.

On the other hand, if the power supply is capable of putting out 150mA, and the pedal needs less than that, you are good.

Digital tends to be pickier than analog with regards to voltage and current levels.
Digital can sometimes do some weird shit without the proper power levels.

And I will repeat this again...
mA rating on a pedal indicates how much power (in mA) that pedal needs to operate properly.
The mA rating on a power supply indicates the maximum amount of power/current it is capable of supplying.

So technically, if you have a power supply outlet that is rated at 400mA, you can put 4 pedals that draw 100mA each (or 1 at 400mA).
Although, I consider it good practice to keep the current draw below the maximum rating of the power supply (usually around 75% - 80% or so).
If your car produces the most power and redlines at 6,000 RPM, you aren't going to run it at 6,000 RPM all the time are you?

Daisy Chaining Versus Isolated Power.
An example of a Daisy chaining power supply would be the Visual Sound (Now TrueTone) 1 Spot.
There are many others as well.
Look around.
Chances are if it doesn't say it has isolated output, it probably doesn't.
Daisy Chaining the power can work great most of the time.
However, some pedals don't play well together when you daisy chain the power.
This problem usually lets itself be known in the form of unwanted noise.
An Isolated power supply is like each power outlet is on its own power line, isolated from the rest.
This, IMO is a far superior way to power your pedals.
An example of an Isolated Power supply would be the Voodoo Labs Pedal Power Plus 2 (there are others, such as the new TrueTone One Spot Pro).
Do some research on both types to see what suits best suits your needs.

One final note on Voltage.
There are cases, where running a pedal at a LOWER voltage can be desirable.
This is done often with Fuzz pedals.
Some pedal power supplies will have an adjustment on some of their power outlets to let you adjust the voltage output level.

And I will repeat this again...
NEVER RUN A PEDAL AT A HIGHER VOLTAGE THAN STATED ON THE PEDAL, THE MANUAL, OR THE MANUFACTURERS WEB SITE.
IF YOU HEAR OR READ SOMEONE SAYING THAT THEY RUN THEIR XYZ SUPEDUPER SEXY OVERDRIVE ON 18 VOLTS, ALWAYS CHECK WITH THE MANUFACTURER FIRST!

NEVER RUN A PEDAL WITH AN ADAPTER WHERE THE ADAPTER HAS A CURRENT (mA) OUTPUT LOWER THAN THE MANUFACTURER STATES THAT THE PEDAL NEEDS.


Quote by Will Lane
Good that someone made this un. Might want to include the ac/dc symbols as well.
Good point.
Here we go:



HERE IS THE TEST (I.E. HISTORY LESSON):
You remember me saying that Positive ground pedals are most often found on older pedals. Not so much on newer ones, unless they are period correct clones of older pedals.
Now I'll tell you why.
In a nutshell, PNP transistors were easier and cheaper to make.
Much of the easily available electronic components could only be run (or ran better) on a Positive Ground type of power source.
Like may of the early fuzz pedal ran with what are called PNP Transistors.
PNP transistors run primarily on Positive Ground power signals.
There are exceptions, like the Jordan Bosstone which uses an NPN AND a PNP type transistor, but this is the exception rather than the rule.
PNP generally doesn't like to be run on a Negative Ground power source.
Pedals are an incredibly tiny segment of the electronics world, and our needs don't mean squat to the manufacturers of electronic components.
I would get into the difference between PNP and NPN, or even Ge (Germanium) versus Si (Silicon), and the reasons one type was used rather than the other, but that's best suited for a more in depth article, or even a book.
But there is tons of information out there (Literally. if you were to print out the info on paper, all that paper would weigh over ton) if you want to learn.
Go hit up Google if you want more details.


NOTE:
I may update this from time to time when I remember some things I have forgotten (I've been working with electronics since 1981 and have probably forgotten more things than many people will ever know), or if someone thinks of something I didn't or information they think should be included.

MODS, feel free to edit any incorrect info or add anything I have missed.
Just let me know what was changed.


If you have an idea that you feel should be included in the above information, don't be shy, speak up.
Last edited by CodeMonk at Oct 21, 2015,
#3
good idea
I'm an idiot and I accidentally clicked the "Remove all subscriptions" button. If it seems like I'm ignoring you, I'm not, I'm just no longer subscribed to the thread. If you quote me or do the @user thing at me, hopefully it'll notify me through my notifications and I'll get back to you.
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#4
From a pedal builder on another forum:
Quote by RambleFX;7309865
Good thread - I just have a few things to add.
  • If an adapter is not well regulated (most general purpose adapters), don't believe it's rated voltage.
  • Bypassed pedals are still drawing current.
  • Reverse polarity protection in 99% of pedals consists of 1 diode that provides almost no polarity protection.
  • Not all amp effect loops attenuate the signal to battery levels, which can overload or damage a pedal not designed for line level voltages.
#5
I've repaired too many pedals in my time due to some moron plugging in whatever AC/DC adapter they have around. I've learnt whenever you buy used pedals don't just trust that it works and to always bring the appropriate power adapter with you.

Thrift stores are great for getting power adapters. Thought that might be good to know.
..I was watching my death.
#6
Quote by timbit2006
I've repaired too many pedals in my time due to some moron plugging in whatever AC/DC adapter they have around. I've learnt whenever you buy used pedals don't just trust that it works and to always bring the appropriate power adapter with you.

Thrift stores are great for getting power adapters. Thought that might be good to know.
Quote by RambleFX;7309865

Good thread - I just have a few things to add.

If an adapter is not well regulated (most general purpose adapters), don't believe it's rated voltage.
Bypassed pedals are still drawing current.
Reverse polarity protection in 99% of pedals consists of 1 diode that provides almost no polarity protection.
Not all amp effect loops attenuate the signal to battery levels, which can overload or damage a pedal not designed for line level voltages.
#8
Never run a pedal with higher than stated voltage...
Ive always thought that dc electronics will only pull the necessary voltage. So running a 9v pedal from an 18v power supply would be ok. I must be wrong. Now im curious as to why its not ok to run a 9v pedal on 18v and why it is ok to run a 100ma pedal on a 150ma power supply
#9
Because the current rating is the maximum current that the supply can source. It won't supply more than the pedal draws. The voltage is the potential to do work. Therefore a higher supply voltage will cause more current to be drawn.
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#10
Quote by timbit2006
So like... What's with the winky face?
General purpose adapters (like what you might find at a thrift store) are not well regulated and or can be noisy. 1-Spot or die.
Last edited by Will Lane at May 25, 2016,
#11
Quote by timbit2006
I've repaired too many pedals in my time due to some moron plugging in whatever AC/DC adapter they have around. I've learnt whenever you buy used pedals don't just trust that it works and to always bring the appropriate power adapter with you.

Thrift stores are great for getting power adapters.
Thought that might be good to know.


i disagree. one mismatched or bad one can take out a $100 pedal (or whatever it costs), that would buy you three 1 spot packs (that come with the daisy chain and adapters) or a dozen decent 9v adapters.
WTLT 2014 GG&A

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youre just being a jerk man.



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