Balanced Power

[mcandmar]

Has anybody tried it, or have any opinions or theorys as to its pros/cons?

I recently picked up a 1KVA isolation transformer so i'm curious to know if anybody has found any tangible benefits powering audio amplifiers with them.

[Paul Birkeland]

The late Bottlehead sage John Buddha Cammille (one of the 4 C's in C4S) strongly advocated for balanced power.  It isn't an inexpensive adventure, but at least pretty straightforward. 

A 1KVA isolation transformer is a bit big for BH gear, but if it has several taps, it should be usable.

-PB

[Skip Pack]

If you happen to have a 240 VAC outlet or can have an electrician repurpose a 120V circuit near your equipment to 240 VAC, a 230 to 120 stepdown isolation tranformer works very nicely as you use naturally balanced 240 on the primary.

Skip
 

[Grainger49]

In the states balanced power is +/- 60V.  The ground is between them.  Without that ground the equipment is not safe.

I can't speak for current PS Audio regenerators, or the Power Plant Premier but the early ones were all balanced around ground.

[mcandmar]

That's good enough for me, going to have to try it

They are currently listed on eBay for £35 each so i couldn't pass it up at that price.  I got it with the thought of making an isolation transformer for tinkering with amp circuits from a safety point of view.  Already have a variac and a light bulb limiter, this completes the set if you like.  While researching that i found a lot of discussions on audio forums singing their praises, hence i thought i would ask the opinions from people i trust.

The transformer itself has two 115v primarys, and two 115v secondarys so i am going to wire both primarys in series (240v mains), and wire the two secondary windings in series with the center point connected to mains earth. Hence creating a 120v-0-120v balanced winding.  If anything it will be another fun project..

P.S. Bonus points if anybody can tell me what the two yellow wires are for?

[Grainger49]

Grab your meter and see if the yellow wires are connected to the windings.  If not they might be internal shields.  Ground them.

[caffeinator]

There is a lot of info on the web on balanced power - should be enough to devise one's own setup.

In a conversation on this forum, I was reminded that since the neutral becomes hot with balanced power, and Bottlehead kits usually switch only the hot lead, that one might consider replacing power switches to switch hot & neutral (or employ other means) to ensure that equipment isn't powered when it is switched off.

Here's a few links to check out, though I'm sure you've probably turned them up in your research:

http://www.audioasylum.com/audio/tweaks/messages/103826.html
http://www.equitech.com/articles/origin.html

Good luck, and Happy New Year!

david

[mcandmar]

Thanks for the links, i'll have a good read through those.  I measured all the windings and got 1.9r for each primary and secondary, and 2.2r across the two yellow wires.  There is no continuity between the yellows and any other winding so its on its own.  Powered it up and everything looks good, but the two yellow wires have zero volts across them so i really dont know what these are.  There is a dedicated wire for the internal shield (Green/Yellow) which only adds to the mystery. Do i ground the yellows or leave them floating?