Power supplies are voltage sources, which means they supply a voltage. A 9V power supply will always supply 9V, no matter what you connect to it. On the other hand, the current can change freely. Consider this: when nothing is connected to a 9V power supply, the voltage is 9V, but the current is zero, because there is nothing the current can flow into. As soon as you connect a pedal to the power supply, current begins to flow, and the value of the current actually depends on the pedal (how much does the pedals require), not the power supply.

Every power supply has a limit however, some maximal amount of current that - if exceeded - will cause the power supply to overheat, go into protection, fail, or even be destroyed. The actual result depends on how well the power supply is designed, but the bottom line is: this value should not be exceeded.

What this means from the pedal's perspective is:

1. The voltage value of the power supply should exactly match the voltage required by the pedal
   
2. The current value of the power supply should be equal or higher than the current required by the pedal.

If you connect several pedals to the same power supply, you should add the current requirements of all the pedals. This sum should be equal or less than what the power supply can output.

Now, let's go into more detail about all of this:

If you know a little about electronics, or if you are a little bit curious and maybe made a current measurement on your pedal, you may know that a pedal rarely actually draws the exact current that it says it requires. This is because current is highly dependent on many factors that vary - sometimes widely - like ambient temperature, or the fact that the exact values of the components can't be controlled to an infinite degree of precision. In particular, tubes are known for varying largely, and if some tubes are sorted, only a few characteristics are actually selected (usually gain), while the others remain unmeasured (like heater current, which has no effect on audio). When it comes to digital products, any firmware change can have a slight effect on current draw, which is virtually un predictable.

 How all this is taken into account may differ among manufacturers. Here is how it goes for us here at Two notes Audio Engineering:

1. Indicated current draws are indeed always a little higher than current draws measured in real situations. This is because we always take into account the worst case scenario: every function used at maximum power, every input and output connected, extreme temperature, small variations of the values of every electronic component, and so on. The final step of this is to round up - such has the advantage of presenting a nice and simple figure, but is also a safety margin.
   
2. Please note, a manufacturer of a power supply may or may not include a safety margin. Our safety margin also takes that into account in some respect.
   
3. All of this insures that, if you respect the current draw indicated on our products, you will never have a problem.
   

So does this mean you can actually power your Two notes product with less current than indicated? Maybe using a 400mA power supply while Le Clean requires 500mA? Well, the short answer is obviously "no, you shouldn't", but let's say it like this:

1. You can always try to bite the margin, and because it is a margin, maybe everything will be fine. But maybe at some point it won't, because these margins are stated for no reason at all. So it's basically up to you to use caution and common sense. We can ensure that if you keep within the margins, everything will be fine, but we can't ensure anything if you bite them. It might work, but you'll have to test it to be sure - even then, it might work one day and stop working the next; or it might work 1 hour and fail the next; Or it can work at home, but not on stage; Or it can work on a fresh day but not on a sunny day.
   

So if you want to try, our advice is as follows: you can, but keep in mind that it may not work, and it may even destroy the power supply! Even if it does, keep in mind it may not work in every situation. Maybe monitor the temperature of the power supply, and stop if it begins to get really hot. Definitively keep the original power supply somewhere as a backup, and if something doesn't work as expected, don't insist, use the original power supply instead!

Having issues?

Our support team is here to assist you! For any enquiries, please head over to our Help Desk and submit a ticket to speak directly to one of our in-house specialists.