A Mains Conditioner, of sorts, by  Don Lodge

I think I suffer from what the high-priests of hifi call sour mains.  We live in a city, so I expect there are a lot of locally induced noise and surges.  A few years ago I checked our mains voltage with a volt meter as I was using a valve amplifier designed for 220 volts, which got rather hot after an hour's use.   The mains measured over 250 volts.  Subsequent measurement has shown it sometimes goes down to 245V.  There seems to be a bit of a debate about what the official tolerance of mains voltage supplied in the UK, but we seem to be at the high end of the spectrum, to say the least.

To prevent my valve amplifier going into an early grave, I dug out a large mains transformer, that seems to have accompanied me throughout adult life, “just in case.”  It has mains (primary) taps for 210V, 220V, 230V, 240V, and a number of high amperage low voltage secondaries.  It is very heavy, needing two hands to hold it. I stood the transformer in a small thick cardboard box, and soldered an in-coming mains lead across the 0 – 240  volt terminals.  I then soldered another piece of mains cable across the 0 – 220 volt terminals and connected the other end to a 13 amp mains socket.  So in effect I was just using the primary winding of this transformer as an auto-transformer.  The valve amplifier lived on, much cooler to touch, and sounded much sweeter.

 Then a couple of years ago, I put the valve amplifier out to grass, and bought Linn amplification.  A few weeks ago I came across the large old mains transformer in the loft, still in its cardboard box, with mains leads still attached.  I checked the mains voltage – still around 245V.  I succumbed to temptation: I plugged my Linn amplifier and pre-amplifier into the 220 volt socket of the transformer and plugged it into the mains.  Sat back.  Listened.  Amazingly better – every hifi journal's adjectives – quieter, sweeter, deeper, better sound-stage, the lot!

I had to have this improvement on a permanent basis.  I could not live without it, but I could no longer live with a large dangerous mains transformer in a cardboard box.  My wife, my friends, the insurance man would all have views on this.

Where to get and affordable metal box to house an old transformer and some mains plugs and sockets.  A quick look on the web revealed nothing affordable.  Likewise a trawl round local builders' merchants produced nothing, although I was tempted by a neat ceramic square plant pot, but thought it might shatter on drilling. I finally found what I wanted in the kitchen section of Home Base – a smallish black mild steel bread bin.  Rather lugubrious for bread, but great for a transformer.  Being black it would more easily radiate any heat, being steel it would offer magnetic screening à la Faraday. It would also be fire-proof, and I would be able to fully earth the case.

I mounted the IEC socket and a double 13 amp mains socket on one end of the box, the transformer inside at the opposite end, and a couple more 13 amp double sockets on the back – using these at normal mains voltage.  My black bread bin should also serve as a mains distribution board I decided.  I used unswitched sockets because the hifi fraternity claim they sound better – designing out switch contact resistance can only be an improvement.  The project took about four hours – from initial drilling, filing, bolting, wire preparing, soldering, and testing with an ohm meter.  A good day – no hitches, no swearing, nothing stamped on or thrown out of the window.  Four self-tapping screws to seal the box up against any guests looking for bread in unlikely places.  Finished.

Just in time for plugging in, and enjoying a cup of afternoon tea by the hifi.  And the magic sound is still there.  Sounded even better the next day.

What is going on?  I think it is difficult to say.  Certainly it could be argued that as the Linn amplifiers have switch-mode power supplies, they would not notice a 10% reduction in voltage.  But they do.  Perhaps the issue is not just one of voltage.  Perhaps
 the transformer windings offer a more inductive source which in some way pleases the amplifier circuitry.  Undoubtedly the impedence of the mains as it reaches the amplifiers is different to the straight mains.  Perhaps the transformer offers some level of mains regulation as maybe transients are limited by core saturation, and high frequency rubbish is similarly absorbed.  Any thoughts?

I have tried to look around on line for some sort of commercial equivalent to my bread bin conditioner.  Russ Andrews, who is at the forefront of all manner of hifi improving products produces the nearest thing I can find.  He, however, perhaps goes the whole hog and makes the mains output balanced - inviting the amplifier in effect to see a mains potential which oscillates around earth.  120V - 0 - 120V in effect.  No doubt this has other curative benefits.  See Russ Andrews Balanced Mains Transformers

ON NO ACCOUNT EXPERIMENT WITH OR CONSTRUCT EQUIPMENT WHICH HANDLES MAINS VOLTAGES UNLESS YOU ARE QUALIFIED TO DO SO. THANATOS IS ALIVE AND WELL.

 ©  Don Lodge             December 2011