Isolating The Amps Power Supply Or Audio Signals?

[DarthTangYang]

Hello!

I'm building a W/D/W rig and right now I'm trying to work out the whole isolation issue with using 3 amps. All along this project I've heard I need to isolate 2 of the amps by running the audio cables through some kind of isolation box/boxes before connecting them to the amps inputs. However, someone recently told me it's "better" to isolate the power to 2 of the amps and that the only reason you would isolate the audio cables would be because you for some reason can't isolate the power.

I'm not sure whether or not this is correct and I sure don't know what to look for here in Europe (Sweden specifically) that will allow me to isolate the power to 2 of my amps. I am planning to get a Cioks DC7 power supply for everything on my pedalboard but I was simply planning to hook up the amps to my wall outlets.

The guy who told me this (on another forum) told me a common and reasonably priced device used in the US is the "Ebtech Hum-X". Does anyone know of a similar device designed for Europe, with either Type C Plug (Europlug) or Type F Plug (Schuko), made for circuits with 230 V, 50 Hz, and currents up to 16 A?

Or perhaps this information isn't even correct?

Any help on this is more than welcome

[R.G.]

someone" recently told me it's "better" to isolate the power to 2 of the amps and that the only reason you would isolate the audio cables would be because you for some reason can't isolate the power.

The word "better" always seems to set me off. My reply to someone telling me that something is "better" or "best" is nearly always to ask "how exactly do you measure that "better"-ness?

As a practical matter, isolating power to different amps is difficult and expensive. Pretty much, you stick an isolation transformer between the mains and two out of the three amps, and hope the quality of the isolation transformers is good enough to cut any capacitive and/or magnetic coupling between them down enough. It seems to me that it's more practical to transformer isolate the signal than the power. At least it's smaller and might be cheaper.
I've rolled my own transformer isolators, with good (as in, close to acceptable for high-fidelity good) results for guitar amps, and there are pro products that are possibly much better. My initial response to this situation would be to pick the dry amp to get the un-isolated signal and to put an isolator in front of each of the other amps.

But I'm always willing and eager to learn. I'd love it if you could get the person who told you to isolate the power to tell you why that would be so. Please...

[pdf64]

The HumX is a horrid thing that shouldn’t be allowed within 100km of a guitar rig, they’re only available in regions with lax consumer safety regulation.

Many modern guitar amps include a simple circuit to break hum loops via the mains earth of different items of interconnected mains powered equipment.
All that’s required is a couple of diodes, resistor and capacitor, wired in parallel between the amp’s 0V circuit common and its connection to the chassis.
Unfortunately many vintage amps were built with several / multiple connections between circuit common and the chassis, using the chassis as an 0V common conductor.