Tuesday, November 30, 2010

Polarity matters

There has been some debate going on as to whether polarity of the power supply affects sound quality.

Previously I was skeptical that polarity matters.

However, when I reviewed the MIT Z Strip (230V model), I felt that  it sounded better with a UK-plugged power cord connected to the wall socket compared with the US-plugged power cord that came with the power filter/distributor.

Like all homes in Malaysia, the electrical wiring in my house is based on British standards and the plugs used are the BS 1363 standard which is a three-pin plug with rectangular pins with ground and a 13-amp fuse on the live pin. This  is simply because Malaysia is a former British colony and the BS 1363 standard is followed in many other former British colonies including Cyprus, Hong Kong, Ireland, Malta and Singapore. UK itself uses similar plugs and sockets.

The problem is that in the United States, the Nema (National Electrical Manufacturers Association) 5-15 standard plugs and sockets, which are also three-pin with ground, have the live and neutral pins in the reverse positions of the BS 1363 plugs.

Since most audiophile power cords come with US plugs, the issue of reversed polarity arises when audiophiles in Malaysia plug them into the UK sockets with normal US/UK adapters.

Audiophile US plug and IEC connector from Oyaide.

There are US/UK adapters in the market which correct polarity and if these are used, then there is no problem arising at all.

Some Malaysian audiophiles have changed their UK sockets to US Nema 5-15 ones and they would not face polarity problems when using US-plugged power cords.

But most would use normal US/UK adapters and they would suffer from polarity problems. But is there a problem in the first place?

Some people say there is no issue because the power supply is AC (Alternating Current) and the stereo system will still function with the live and neutral connections reversed.

It’s true that the system will function, but there is the safety issue - this is because when the live and neutral connections are reversed, the power supply section in the component is still live even though the component’s power supply switch is turned off (with the power cord still attached to the wall socket which is still switched on).

This is due to the fact that the power supply switch is fitted on the live wire. Also, the fuse is fitted to the live wire.

So if you somehow touch the wires inside the component thinking that it would be safe since the component is switched off, you may suffer an electric shock.

Sonically, there seems to be a difference too.

As I said earlier, the MIT Z strip sounded better with the UK-plugged power cord.

Initially I thought the change in sound quality was due to the EMI/RFI passive circuitry and Power Factor correction network in the MIT component and the reversed polarity somehow affected the circuitry.

So I decided to check out the effects of polarity with the resident Furutech eTP60/20 power distributor which has no circuitry at all and uses just a layer of special compound to absorb EMI/RFI. the eTP60/20 comes with its own power cord with US plug. The Roksan Caspian CD player (used as transport), the Benchmark DAC1 Pre and Bryston 4B SST power amp were all plugged to the Furutech with US plugs.

I used a normal US/UK adapter to connect the Furutech’s power cord to the wall socket which meant the live and neutral were reversed for the entire stereo system.

The BS 1363 UK plug commonly used in Malaysia.

It was a simple matter of listening to the system with the live and neutral reversed and then switching the live and neutral wires on the Furutech power cord’s US plug connected to the wall socket to correct the polarity.

There are differences - with reversed polarity, the soundstage becomes narrower, the images are diffused, there is less transparency and the bass is softer.

With polarity corrected, the soundstage widens, the images are more ‘solid’ and have more ‘body’, transparency improves and the bass sounds stronger.

After a few songs I was convinced that polarity matters.

Reversed polarity may not affect other electrical components like fridges and kettles, but for stereo systems, it is a major degrading factor.

So, audiophiles in Malaysia (and other ex-British colonies using the BS 1363 standard) must ensure that polarity is correct when using power cords with US plugs.

Update 6/12/2010

I noticed that there was static build-up when the polarity was reversed and I got zapped when I touched any part of the components.

I did not know why it happened and I posted it in a Malaysian hi-fi forum called www.hifi4sale.net and the best answer was from an expert forumer:

"All transformers (in the equipment) have an optimal polarity of operation.

With the correct polarity, the earth leakage is much less compared to the wrong polarity.

This is because the coils in a transformer are never really perfectly symmetrically wound.

The polarity where u get zapped less, or don't feel zapped, is the correct one.

And the transformer would operate at higher efficiency as well. Less eddy-current losses."

No comments:

Post a Comment