For the last 20 years our electricity has been supplied by an cable from an overhead pylon across the road. The local government have decided to bury new cables underground and have been digging up the road for months. Last week they connect us to these new cables by cutting the cable at the pylon end and running the cable down to the underground cables on our side of the road.
Amazingly the sound of my hi-fi has improved significantly (no I can’t do double blind testing to prove it obviously) but there are things I haven’t hear before and notes seem clearer. Of course it could be that the houses on the street that produce electrical noise have not yet been connected to the new cable but has anyone else experienced this? Note I do not yet have a dedicated connexion to the fuse box (of course it has jumpers rather than fuses).
I’m not surprised you have a better SQ with the new power supply.
Depending on how the old overhead supply was; the really old separate three individual wires carrying 3-phase, one neutral & one earth, if thats what you had, thats as bad as it gets. The individual separated wires do not reject interference & it will typically have degraded connections with age.
If the overhead was a single cable or twisted 3-phase & N/E, that’s a lot better & as the twist in the cable(s) rejects interference noise & as it’s newer would most likely have less connection degradation.
Your new underground cable will be the latest in construction/materials, & most probably higher current carrying capacity as overhead cable weight can be a problem & typically have less or no reserve. And being underground its not affected by outside interference.
The pylon part has 4 uninsulated wires between the concrete pylons. The part that crosses the road seems to be two insulated wires twisted together. I noticed the person doing the connection had to scrap the oxidation of the uninsulated wires to get a good reading for his meter.