Hi

To power my self-built guitar amp, I'm using a TalentCell PB240A1. This has 3 outputs: 24V, 12V, and 5V (USB). The 24V and 12V outputs are centre positive. I'm using the 24V output to power the amplifier (which requires centre positive), and I'm hoping to be able to simultaneously use the 12V supply for my effects pedals. These pedals run on 9V and require centre negative. So I bought a small voltage reducer to step the 12V output down to 9V (checked out okay on multimeter), and I've wired my pedal cable to deliver centre negative (again checked with multimeter).

With the TC battery just supplying the amp, that works fine. And with the TC battery just powering the effects pedals, but with a separate power supply for the amp, both work fine. However, when I power both the amp and the pedals from the TC, I get a high pitch whirring noise. So I'm assuming there's some kind of interference/problem with running these two battery outputs simultaneously. Any advice would be very welcome.

 

Without having a Schematic-Diagram for any of this,
the best solution would be to use your fancy ~24-Volt Supply only for the Amplifier,
and purchase a separate ~9-Volt-Supply specifically designed for powering multiple Effects-Pedals.

What You probably have is called a "Ground-Loop",
and they can be a real headache to solve,
especially with the really cheezy design-practices used in most Effects-Pedals.
.
.
.

 

Without having a Schematic-Diagram for any of this,
the best solution would be to use your fancy ~24-Volt Supply only for the Amplifier,
and purchase a separate ~9-Volt-Supply specifically designed for powering multiple Effects-Pedals.

What You probably have is called a "Ground-Loop",
and they can be a real headache to solve,
especially with the really cheezy design-practices used in most Effects-Pedals.
.
.
.

Thanks very much LowQCab -- I'll follow your advice.

 

If you are trying to power the various devices with a single supply, you will first need to know if the "common" side of the connection is tied to the supply positive or the supply negative. From the description it seems like that may be the case.
Unless the voltage reducer you have provides a totally isolated output the connection may be causing a shorted circuit.

I am very seriously opposed to any coaxial power connector having the center negative, because it is intended to provide instant damage when a standard supply is connected.