Clean AC power

You will need an oscilloscope to see the sinusoidal waveform of your AC coming into your home. If you're dead keen on seeing it, that's what you want to use.

What you use in your house / stereo system will introduce noise into the supply, especially localised noise.

What I liked that sold me on the idea of the Puritan PSM 156 power conditioner is the no nonsense approach. Twin transformers to allow for good current flow with no bottleneck, DC (direct current) removal (also can been seen using an oscilloscope) and each receptacle is isolated from each other by using a high pass shunt of electrical energy to ground, from both neutral and active, individually. It also has circuit protection.

And it's one of the least expensive, with the most features.
I'll admit it, I am a performance buyer, with limited budget - so it had better perform!

Household Circuitry: 101

All household circuits are tied together at the circuit breaker panel. Kind of like a train switchyard. The rumbling of a train will be most severe on the track it’s traveling. But, the other tracks will still suffer the effects of milder rumbling since they’re all connected.

Most residential houses in the U.S. have a circuit breaker panel with two hot buss bars and one neutral buss bar - along with a ground connection. Each hot buss bar is tied (connected) to the one neutral buss bar via the circuit breakers. In other words, no matter how many circuits you have in your house, they all meet at the two buss bars and the one neutral. The one neutral is shared by every circuit in the house. Here’s how Bob Vila explains it.

A dedicated circuit for audio that is properly installed will help isolate it from the noise on other circuits caused by various household appliances. A dedicated circuit is definitely a major improvement. Yet, a high resolution audio system will still reveal noise (distortion) that’s polluting other circuits – such as a hairdryer that’s being used in the upstairs bathroom. Many dedicated listening rooms that have multiple dedicated circuits – also have power conditioners behind the equipment rack.

Most audio systems sound best after midnight during the week - or on Sundays - when the town’s electrical grid is less taxed. Apartments in apartment buildings share the noise from their neighbors. Houses in housing developments share the noise from their neighbors.

Much depends on how resolving the audio system is – and one’s hearing sensitivity. Curiously, the cleaner the power supply, the easier it is to hear anomalies. Imagine looking a white wall that is randomly speckled all over with black dots. Your eye will wander around the wall. There’s plenty to look at, but specific areas are ignored. Now, imagine looking at a white wall with only one black dot. Your eye will zero in on that one black dot. A low resolving system is like the first wall. A high resolving system is like the 2nd one. The black dots would be points of distortion. (nota bene, Christo).

Safety warning: Do not poke around a circuit breaker box - if you don’t know what your doing. Instant death may occur.

jea48: My panel is a Challenger SB40. The buss material is hard to determine; it is clearly not raw copper, but has a shiny metallic finish. The contacts in the breaker are copper.

I cleaned the load wire with a fine metal brush until the copper was shiny, then sprayed Deoxit: same for the the load end. Didn't touch the buss connector.

Thanks for your detailed response to my last question.

vgizzi, steakster has a great overview above. The only quibble I have is the main improvement we get with a dedicated line is nothing to do with isolation, it is all from the wire running continuous. Most circuits are run outlet to outlet, with each outlet adding a number of connections and each connection adding a lot of micro-arcing and noise. So that is the main benefit, and they should be called direct instead of dedicated. But whatever. 

People talk about noise in terms of obvious stuff like a blow dryer. The number one thing to keep in mind is every wire is an antenna. RFI is everywhere. So every wire is an antenna bringing RFI into the system. The AC can be somehow perfectly clean, yet the first inch of wire coming out of it starts picking up RFI. This is probably one reason power cords make such a difference, but whatever. Not the point. Point is noise is everywhere, so the fixes must be everywhere, there is no one silver bullet. 

Transformers work primarily because of the way they are designed. The alternating current in the primary creates a rising and falling magnetic field that induces a current in the secondary. There is no electrical connection, just the alternating field. The same happens by the way with the output transformers in an amplifier, or a SUT for MC cartridges.  

Ever notice the difference high quality transformers make in these cases? It is huge. Why? Because it is hard to design one to work across a wide range of frequency. The alternating field in a AC isolation transformer is designed to very efficiently pass 60 Hz AC. But higher frequencies not so much. Most of the line noise we are trying to eliminate is RFI, radio frequency, very high. Any old transformer will filter RFI just fine. It is just not that hard. Once you understand the principles on which transformers work it is pretty easy to understand why they are used all over the place.  

That answers your transformer questions. And your dedicated circuit question.  

As for the stuff you tried, the proof is in the pudding. It does no good to ask what if. Who cares what the transformer at the end of your street is doing? To know you would have to move your stereo to the house up the street. Or run a line from before that transformer. To what end? Why? Such questions are academic.  

What really works is to deal with what really works. Sorry, but if you try something and hear no difference then by definition it doesn't really work. All the stuff I am talking about, it really works. You will hear it, and not just barely either. 

vgizzi OP7 posts

07-05-2021
12:59pmjea48:

My panel is a Challenger SB40. The buss material is hard to determine; it is clearly not raw copper, but has a shiny metallic finish. The contacts in the breaker are copper.

@ vgizzi

Approximately what year was the house built?