HiFi Subjectivist ¦ Audio Forum ¦ NVA User Group

As I can adjust voltage by changing the secondary winding ratio to the primary it has dawned on me that this could be a boon to valve equipment users as often our voltage goes up to danger point for them in the UK as they are all built to EU regs at 220v. The one I have just built for Andy on my spot on 240v is giving 220v on the output, on his usual 244v he will get 224v well within tolerance for his valve gear. So a good additional benefit and protection, though it wont be standard, standard will be what goes in comes out, but balanced. So an ordered special. Valves are sensitive to this over voltage where as transistors are not unless it is grossly over voltage.

Another variation is I can build one to give 120v output if you have bought USA or Japanese gear, and obviously visa versa anyone in a 120v area can use this to power EU and UK units, just a different ratio transformer is fitted.

Would it be sensible to have a slight voltage drop as standard given most new equipment is rated 220-230v and not 240v? BTW I can't see Brexit changing this for practical manufacturing reasons.

Whilst on the BMU subject......
is there any reason NOT to use unused plugs on a BMU with items such as a NAS or Liner Power Supply (to a DAC) I suppose my question is based around is there any problem plugging (Dirty) computer based (read: noisey) mains in to it..... does it or can effect the other components being powered by the BMU?

I wouldnt have thought there would be any issue, the balanced mains unit I built is powering my amp, turntable, dac and phono stage.
However, mine is not the same as the docs, but i cant see it being a problem. I wouldnt bother plugging a nas ect into it, sources and amps yes, ancillaries probably not worth it

Plug only your hi-fi into it.

No normal need for voltage drop, only valve gear has a possible problem.

I certainly wouldn't connect a SMPS to the BMU that would defeat the purpose of having it in the first place.

Geoff.R.G wrote: ↑Fri Jan 05, 2018 10:39 pm I certainly wouldn't connect a SMPS to the BMU that would defeat the purpose of having it in the first place.

How so?

I thought the BMU ‘fed’ power to components? Not the other way round?

(Not disagreeing, but interested as to why)

I think what he means is the spew back into the ac voltage lines of distortion from SMPS supplies. That of course occurs on the secondary side of the BMU so will feed to the rest of your hi-fi, the BMU can't stop it.

Dr Bunsen Honeydew wrote: ↑Sat Jan 06, 2018 12:19 am I think what he means is the spew back into the ac voltage lines of distortion from SMPS supplies. That of course occurs on the secondary side of the BMU so will feed to the rest of your hi-fi, the BMU can't stop it.

Indeed, precisely what I meant.

Doc just a quickie is it ok to stand the Bmu on its end with plug sockets facing outwards and then sit the Phono 2 power supplies on top of the Bmu. Or does the Bmu have to sit on its feet the way you have designed it?