Voltage. AA and AAA are 1.5 volts. A 9volt has essentially 6 AAAA batteries in them ran together in series to provide 9-volts. It’s a common standard, and has the snap terminals which is good for things that are moving around instead of a spring loaded compartment.
https://upload.wikimedia.org/wikipedia/commons/e/ea/9V_innards_3_different_cells.jpg
Cool picture showing the various cells making up the typical 9v battery.
Thank you for your answer.
Is there some advantage to having 9 volts instead of 1.5?
Some of the components typically used (e.g. op-amps) in audio gear like active pickups & pedals typically need at least 5-10V to work.
If you used AA for those scenarios you’re either going to need a load of batteries or you’re gonna have a short battery life.
9V batteries are just a better fit for the use case basically and mean things like active pickups & pedals can be kept small
Honestly, if I were designing active guitar gear, I might just try to push 24v phantom power and XLR cables. Have a little power box at the amp or pedalboard and ditch the onboard battery entirely.
But I loathe alkaline batteries…
Fascinating. I had no idea, but this is starting to make sense.
Thank you.
+4dBu is 3.472 V peak to peak. You’d need 3 batteries to hit full line level, before you even get into the 0.7v silicon junction losses.
Remember that you’re making an AC signal from a DC power supply. The output is centered at half the battery voltage. It’s exactly the same as a class A amplifier.
People already use 9V for their pedals too.
Wait… Does this mean I might have to change a battery in my electric guitar someday? How would I know?
Only for a guitar that uses active pickups instead of passive ones. Look up the specs on your guitar and it should tell you which ones it came with. If you can’t tell from the spec page alone, then look up the specific pickups once you know what they’re called. Most electrics have passive pickups, so it’s fairly uncommon that you’d have active ones without knowing.
Not only that but if you do have active electronics you also most likely have a 9v shaped door on the back of the instrument for access to change said battery.
If you don’t see a door, you probably don’t have active electronics.
The AA cell typically provides 1.5V, so to get the equivalent output you’d need 6 of them which would add a noticeable amount of weight and bulk, plus cost more money and generate more waste.
Interesting stuff. Thanks for the explanation.
