Balanced AC possible without isolation transformer?

Thanks for the link G.

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FWIW: Your question is quite appropriate based on my experience. My Equicore 1800 (recent Underwood model) is “feeding” my 200 watt amp (plus 65" tv, plus all remaining audio kit) to maximum reasonable current demands with excellent results…quite improved over previous wall outlet to vintage/dated conditioner (via custom direct line from breaker box, now feeding the Equicore, of course).

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Thanks @jedi1.

It’s based on Paul’s advice. He stated that Equitech makes fine products but that the surplus impedance introduced by the transformer would be detrimental if the goal is to drive a power plant ideally. (Not the P3 specifically but I trust he knows best what his power plants like to eat in general)

Of course Paul agreed that a big enough transformer negates concern but he sees little point in balanced mains. I see a lot of point in it, especially in terms of whole-house solutions because having the house NOT act as a huge antenna seems like a huge benefit. There’s enough radio pollution already, I don’t want it running along my length of copper. I see balanced mains as equally important as balanced audio.

I have two P20s and was wondering whether it would be OK to connect balanced toroidal isolation transformers between the P20 and a source component. Please post your comments, if any - thanks!

You can do that but I would question the need and would also be concerned you’re taking a step backwards in sound quality.

The only benefit to balancing the power after the regenerator would be to gain a small amount of common mode rejection of what’s in the connecting power cable. It’s unlikely, if you have a decent power cable, that it’s picking up anything worth worrying about unless it’s a very long power cable.

I’d not do it if it were me.

Got it. Thanks for the follow up. I ended up replacing my P10 with a Torus AVR2 20. I still intend to replace the panel that supplies the power to that part of the house with a balanced box, also likely a Torus.

Hey Paul, thanks for your response. While the P20 is an amazing piece of technology, it’s abundantly clear to me that it’s still extremely sensitive to the input AC power cable (I’ve auditioned/compared many different ones myself, and heard significant differences), hence not invariant to even minute differences in the quality of the incoming AC. While the P20’s regenerated AC is darn-near perfect, it still has meaningful amounts of noise - perhaps not so much common-mode type (alluded in your reply above), but mostly high-frequency spectral noise. It is the latter, plus AC offset noise, and ground-pin DC noise which can all be removed by a high-quality balanced toroidal isolation transformer; a power-capacity rated at 3-5x the component’s power draw for extra headroom will ensure that there will be negligible current constraints for the power supply of source components (not power amps).

BTW, why aren’t there more objective noise measurements (of the P20) published in the public domain? I would be thrilled to see detailed spectra graphs of the amplitude and frequency of the noise in both the post-regeneration AC line noise, and on the ground pin. Surely, it can’t be that difficult, with an oscilloscope interface?

Big fan of balanced power here.

Had my entire system powered by it for the last 7 years, really big improvement over straight from the wall.

All started when a friend (Electrical Site engineer) of mine brought over his DIY balanced mains box at a bake off at mine and the improvement was night and day - my mains were officially terrible.
Got me thinking and I decided to get balanced mains in my system,.
Went a step further and hard wired my BMU unit (2KVA rating) into mains, and from that a hardwired “hydra” block Feeding iec power to all my bits of kit.

The impedance concern was always at the back of my mind though, and on my next major upgrade (when I got my PS Audio gear) I looked again and improving the mains if I could.

Decided to take the nuclear option to set and forget.
All power cables upgraded to silver Wireworld and to eliminate any possible impedance niggles, I swapped out the 2KVA rated balanced mains unit for a FAR lower Impedance 10KVA one.
My friend is an electrical engineer and Site Mgr who installs Multi KVA power substations, so took my advice from him on safety aspects, as the install was quite hardcore.
We fitted twin pole RCBO circuit breakers on both primary and secondary windings and the install was signed off by an electrician.
So all good.

Nowadays have lost the “Hydra” and have a single tail coming from the BMU feeding a double socket, from that have a Wireworld mains block.
Simpler and better than good enough.

The BMU has multi taps for different incoming voltages, so tried a regen unit (not a PSA Unit) to test the value and stability of voltage so I could use the correct tap for my mains.
I’d considered a P20 when buying my DS and BHK, Didn’t find the regen unit made anywhere near as much of an improvement.
P20 would have been different of course, but it was that or my BHK Pre, which I felt would have made more of an improvement.

It’s a Big mother!
Stored away out of sight and not in the listening room happily.

To get the 10KVA rating, two massive toroidal Transformers inside.


This is the balanced toroidal isolation transformer I’m considering - two units, connected after the P20, for the two mono powerbases powering my MSB Technology Select II DAC:

The PLiXiR Elite BAC400 is good for powering components adding up to 250W (total), according to the guidelines from this 2017 German review:

The caveat (I’ve learned) is to make sure they’re plugged into the High Current duplex of the P20, because their power draw upon turn-on can be so immense that they may pop fuses and breakers.

Looks well designed John,
Like everything in audio, all about what it’s used with.

Will improve rather than take away from sound quality, so a good investment.