One PSU, two units

Hello,

Obviously (but then again probably not all that obvious) when building high-end mixing consoles (hi-fi systems with lots of controls) we used the same power supply for multiple stages.

The power supply was a remote one.

However, the power distribution was within the mixing console.

Putting power distribution outside a bunch of equipment does represent a major difference: that of ground loop potential.

To offer a single PSU1 option for multiple devices has often crossed my mind - but how to make it "bullet proof" for non-technical or semi-technical users has, I must admit, been eluding me.

For a power supply to be just a power supply and not to interfere with the equipment's performance requires that all grounds terminate at the source or input.

Where a phono stage is used in conjunction with a headphone amplifier the input is at the phono stage - all grounds when the equipment is suitably connected with an interconnect - an interconnect complying with the protocols of proper and low impedance shielding (as the shield is the ground of the power supply) - point at the phono stage input ground.

That's OK but with a simple Y adaptor cable from the PSU1 there is another ground: the negative or 0 volt wire, which in effect places a direct connection between the headphone amp ground and phono stage ground with a potential somewhere along that connection (the PSU1).

The potential also has to obey the rule of termination to the input (only). By being part way along the connection, the power demands of the headphone amplifier tries to "lift" the ground to a higher potential. Masked by the music, the effect of introducing inaccuracies due to the ground fluctuation may not manifest itself to the listener, but technically it's there.

Therefore, the proper solution should be that the headphone amplifier only gets the positive feed from the PSU1 and not the 0 V feed.

It would pick up its 0 V feed from the interconnect ground which is terminated to the phono stage input (getting complicated and possibly counter-intuitive?) - this being why the interconnect shield has to be the lowest possible impedance - and its ground is coming from the PSU1 via the input ground of the phono stage.

Why would the positive feed not require the same treatment? It would if not for the equipment having its own local voltage regulators terminated to the respective input grounds.

If Jon would like to isolate the ground wire of his Y-cable and give the above a try?

Graham

Hi Graham I see what you have in mind and would try it, except I no longer have that setup.

OK, if no-one is in a position to do this I could give it a go when the time comes. So if I understand correctly, I could take a single wire from +ve of the PSU1 plug (at the Reflex power in) and take it to the +ve of a similar plug going to the Novo - and that's it?