With most stomp boxes you have the ability to power them in two ways: a power supply, or a 9v battery. Broadly, they perform the same function: powering your pedal. But they do this in different ways.
We can pretty easily look at the differences, both in application and function. But when it comes to tone, which one is better for pedals?
That’s the hard question to answer. Before we do, let’s look at the pros and cons for each option.
Powering Your Pedals With Power Supplies
There are a few pragmatic reasons I like to use power supplies. The first is you have sustained power as long as you have electricity. If you don’t have electricity, well, you don't have your amp so it doesn’t matter.
With this sustained power comes peace of mind in your set. You don’t have to worry about batteries dying or have to worry about changing them before shows. I did away with my Piezo pickup in my acoustic guitar in favor of a magnetic pickup for this very reason. I got tired of worrying about whether the battery was good, and always making sure I unplugged the cable from my guitar in between sets so the battery didn’t drain.
Not to mention, I don’t have many pedals that have a battery box I can clip out. Most, if not all, of the pedals I use regularly have the battery in the same area as the circuit board. Which means I have to unscrew the back to get to the battery.
I also like to use isolated power supplies, like the Voodoo Labs Pedal Power 2. They keep my pedals safe and I can adjust the voltage of each line as I need to (for larger Strymon type pedals, or pumping higher voltages into my overdrives, with 12v and 18v options typically).
Which is another good point: pedals that require 12v or 18v power rarely even take batteries. Many 9v pedals are starting to not accept batteries either. They’re being omitted from the circuits.
Batteries are expensive and contain hazardous materials. If the inconvenience of batteries weren’t enough to dis-sway me from using them, the price tag is. When I used them for wireless units and my acoustic pickup, I had a bunch of half used batteries laying around. Not wanting to risk the voltage sag from a battery losing life during the middle of a set, I would change them out frequently.
That left me with a dozen batteries that 1) I didn’t use fully (I don’t have anything else at home that uses 9v except smoke detectors, which should always have fresh batteries), and 2) that are hard to recycle.
Battery acid is awful for the environment, and there aren’t many good ways or places to recycle them.
Powering Your Pedals With 9v Batteries
With all of these reasons why batteries are bad options, why do so many people still use them, and why do pedal makers still provide that option?
If you were to ask Eric Johnson 20 years ago, he’d say 9v batteries (Duracell specifically) sound better. I think you have to have an amazing ear to hear the differences between fully charged batteries and a power supply. But maybe there’s something there.
Could a 9v battery sound better different than a power supply?
There is some basis for this. Guitar and bass effect pedals take DC (Direct Current) power. However, power like you have in your house or any commercial space is AC (Alternating Current) power. So the “AC Adapter” (power supply) adapts the AC power to our pedals....which require DC power...converting the AC to DC.
So AC power supplies (anything that plugs into the wall) takes the AC (Alternating Current) from the house/venue and converts it into DC power via a small rectifier for your pedals.
It uses capacitors to “smooth” the current. So just in the conversion the power has to go through several (albeit, instantaneous) steps. This happens in the wall wart part of the power supply (the box that plugs into the wall) on individual power supplies. And in the power bricks like the Voodoo Labs Pedal Power II it happens in the box itself.
In addition, since these power supplies are being fed by house/venue power, there is a chance for noise to enter your signal chain via ground loops. That's the 60 cycle hum (in the US) you get when you’re using bad (noisy) power.
Let’s contrast this with batteries. Batteries are a direct DC source for your pedals. There’s no conversion. No need to introduce any additional rectifiers and capacitors into your signal chain. When batteries are at 100% they’re pure clean consistent DC power.
The consistent part is appealing. You can go from venue to venue, studio to studio, rehearsal space to rehearsal space, and have consistent power with little to no noise. I think we’ve all played those crappy dive venues with awful power that created a ton of noise. You genuinely do need a $200+ power brick to mitigate that and provide clean power to you pedals.
And if you’re just using individual power supplies plugged into a power strip, which is plugged into the venue’s wall, you’re risking power surges that can damage your gear. Pedals don’t have fuses to protect themselves like amps do. Most of them anyway.
You’d need to buy the nicer AC Adapters to get the best current and protection. But like the power bricks they can get expensive.
Batteries, while more expensive in the long run, provide that consistent power and tone. And safety for your pedals.
Another battery benefit is that it doesn’t provide consistent voltage throughout its life cycle.
I know, I just went on a long spiel about how consistent batteries are (100% fully charged batteries, mind you). But when they start to get inconsistent (via losing their charge) they can create some really cool tones on some pedals.
This is mostly utilized on overdrive pedals. When a battery loses its charges it’s actually losing voltage. So it’ll dip from the 9v into 8v, 7v, etc. Your pedals have a power minimum, so you can’t just use a battery with 1v equivalent of a charge and expect it to work.
But in the 6-8v range you can use them with cool results. This is called sag, as in a power sag. It makes your overdrive sound a little loose and flappy. But in a good way. In fact, it’s so sought after that many power bricks and even amps have this feature.
It uses the same principle, dropping the voltage going to the pedal. I had a Mesa Boogie Stiletto Trident that had a sag switch on the gain channels. That was a sweet amp and I wish I hadn’t traded it. But that’s not why we’re here today.
The problem with using batteries for this purpose is that they won’t stay like that for long, and it takes time to get to that place.
Are Batteries Or Power Supplies Better For Guitar Pedals?
Most of the answer is subjective. We do have objective facts that can guide us, such as long term costs, signal integrity and sustainability, and convenience. But ultimately it comes down to the player and what they hear.
Battery users know how expensive batteries are, and complain about the costs. They know how inconvenient it is to have to change out batteries every gig, or every other gig. Yet they still buy their ration of batteries and throw them in their pedals.
So just like everything in guitar, it’s about preference. And in this case the pro-battery crowd suffers through the inconvenience for the sake of what their ears are hearing.
I’ve complained about this for years, but a lot of players use their eyes more than they use their ears. They choose (for example) a Klon Centaur or Dumble over another pedal or amp because they’re supposed to be better. Or a less hyped example, choosing a boutique pedal over a Boss pedal. Is that because the boutique pedal sounds better, or because it’s cooler to have a boutique or lesser known pedal?
As musicians (an aural experience), our ears should be our guide. So if batteries truly sound better to your ears, better enough to go through the hassle that comes with them, then batteries are better for you.
And if not, well, you know what to do.
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