[andyr]

Mains polarity, for those ignorant of this arcane subject, is concerned with getting the "right" connection of mains "Active" and "Neutral" vis-a-vis your power transformer.

It sounds like wank but many people report hearing a major improvement when their system is correctly polarised.  

Ginger ... R U out there??    Can U hexplain the theory behind this??

For those who have not come across this topic before, I invite U to read the article at: www.boundforsound.com/tweak.htm

For those of U in the know, could U possibly do a measurement and report back?  It will be interesting to get results both from 240v countries and those benighted souls who make do with 110v!  

What U need to do is:
1.  disconnect all ICs from the component under test
2.  temporarily disconnect the earth pin in your power cord from making contact with the wall-socket earth slot (2-pin US folk have no problem here!)

What I did (in Oz, a 3-pin country) was take apart a double-adaptor and remove the brass earth pin connectors.  Then I plugged this into the wall-socket and my AKSA 3-pin plug into it.

Then switch your DVM to "AC volts", plug the black probe into the earth slot of another wall-socket and the red probe onto a convenient chassis screw-hole or earth bolt, and measure.

Then you reverse the "Active" & "Neutral" wires (I made up a 6" extension cord which reversed these wires) and repeat the measurement.

The orientation which gives the LOWER reading is the "correct" one ... don't ask me why!     Giiingggeeeerrrr!!

I was expecting to read a few volts, max, but I was gob-smacked to measure up to 70v AC on my meter when the component was switched off and 110v when it was switched on!  

Does anyone else get these enormous readings??

(Of course, in the "real world" when the component is in use, the earth pin of the power cord IS connected to wall-socket earth (and your case is attached to the IEC socket earth pin), so there's no safety issue!)

Regards,

Andy

[Tinker]

I had a class A amp I rigged up with a DP4T switch (didn't need 4 throws but couldn't find a 3T with the current rating) so that the input to the tranformer could be reversed without rewiring.

Have you tried your ground lift experiment in other houses? I thought Aussie mains supplies are meant to have the earth and neutral bonded together. See AS 3000 under "multiple earthed neutral."  

T.

[andyr]

Have you tried your ground lift experiment in other houses? I thought Aussie mains supplies are meant to have the earth and neutral bonded together. See AS 3000 under "multiple earthed neutral."  

T.

Hi, Tinker,

I am going to repeat the measurements with an AKSA 55 in another house next weekend.

Regards,

Andy

[andyr]

... I thought Aussie mains supplies are meant to have the earth and neutral bonded together. See AS 3000 under "multiple earthed neutral."  

T.

Tinker, I don't think this mains "polarity" issue has got anything to do with AS3000 and neutral being bonded to earth.

As I understand it, it's simply a matter of how the power transformer is oriented wrt mains active and neutral - ie. is the "input" end of the primary wire (lets assume this is the end which you first place against the core of a transformer, then you wind the primary wire next to the first loop on the core until you've covered the core with one layer of windings, then over to a second level on top of the first ... and a third ... etc ...) ... is this end connected to active or is the "output" end connected to active?

For some reason that I don't understand, these two alternative orientations generate different case-earth voltage differences and make the sound better or worse.

Regards,

Andy

[Tinker]

FWIW the polarity on my old amp was audibly different, although it weas never blind tested.

I did understand what you meant by polarity. As to souding different, possible sources of difference for AC "polarity" are all to do with how they interact with the transformer and come from
- waveform asymmetry
- hysteresis
- core grain orientation and magnetisation (and the effect this has on hysteresis)
- DC offset

Incidentally, as long ago as high school I remember plugging a CRO into the mains and the waveform was hideously asymmetric. Anyone tried a UPS?  

T.

[DSK]

Hi Ben, you have a PM on a non-related issue.

[Johnny]

I've been thinking about power conditioning lately, and tempted to try balanced power, since I have access to a "spare" isolation xfmr at work- all 5kv and 102 lbs. of it!

I was wondering if balanced power gets around this "polarity" issue, at least to some extent, since the power is applied evenly to both sides of the component power supply xfmr?

If there are any transformer experts out there, I have some other questions too    I'd appreciate some advice...

[kyrill]

I've been thinking about power conditioning lately, and tempted to try balanced power, since I have access to a "spare" isolation xfmr at work- all 5kv and 102 lbs. of it!

I was wondering if balanced power gets around this "polarity" issue, at least to some extent, since the power is applied evenly to both sides of the component power supply xfmr?

If there are any transformer experts out there, I have some other questions too    I'd appreciate some advice...

Hi Johny
See http://www.equitech.com/faq/faq.html
one of the many resources on the web

I have balanced power and now my neighbour as well  

Nice as well is to see the effect on TV or on my D-ILA lcd [projection system (1365x1024) The image is much sharper because of less "noise"

The polarity issue shouldn't be there..

also :
Clean AC Power

The benefits of balanced AC power delivery to your home theater or audiophile two-channel system lies in the broad-band elimination of a wide range of noise:

    * From your air conditioner/furnace/refrigerator motors
    * florescent lighting
    * dimmer switches
    * personal computers
    * and radio frequency signals picked up by the power lines/cords acting as antennae.

This garbage invades your entire audio/video system through their power supplies and raises the noise floor of your entire system.

The solution is the cancellation of unwanted noise by CMR [Common Mode Rejection] only possible via balanced AC power. A balanced isolation transformer (what's used inside our conditioners) splits the standard incoming +120/240V (hot) / +0V (neutral) AC into +60/120V (hot) / -60/120V (neutral) components and cancels anything but the pure AC power sinewave when these out-of-phase signals are summed. Your equipment sees a summed 120/240V source, but the result of CMR is a dramatically lowered noise floor, an improvement in system performance you can see and hear"

I must say easily if you have a transparent system