March 2012 - about speaker polarity

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CeaSaR
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March 2012 - about speaker polarity

Post by CeaSaR » Wed Feb 29, 2012 10:08 pm

Hi Russ,
Just a quick comment.

The reason speakers have polarity is because of phasing. You had the idea, but didn't quite go far enough with it.

In order for the equivalent speaker drivers to work in harmony, they need to move in the same direction on the same
phase of the audio signal. They will produce full sound. If they move in opposite directions, they will tend to cancel
each other out, creating dead or muffled sound.

Now if you only have 1 pair of speakers in the house, it doesn't really matter what way they are hooked up as long
as they are hooked up the same. But if you have many speakers that overlap a soundfield, then you have to pay
attention to polarity or you run the risk of the dreaded dead spots.

Manufacturers make sure to follow standard polarity construction so that the drivers will work properly (all the same
phase) so that any driver can be used in any situation and not cause the aforementioned phasing problems.

There are other reasons too, but this is the most basic one you (the general populace) really need to know about.

CeaSaR
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Lenp
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Re: March 2012 - about speaker polarity

Post by Lenp » Fri May 04, 2012 8:38 am

About Phasing....
You can use a flashlight battery momentairly on the speaker terminals. Positive polarity on the positive terminal should cause the cone to move outwards. If the phasing is correct, sound from a pair of speakers will appear to be from in between them.
We used this test often in home systems. Mono mode, good bass, and a male voice. The sound seems to come from between the speakers when phasing is proper. Just reverse the polarity on one speaker and you can immediately hear the difference!
Len
Len

“To invent, you need a good imagination and a big pile of junk.” (T. Edison)
"I must be on the way to success since I already have the junk". (Me)

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Re: March 2012 - about speaker polarity

Post by CeaSaR » Fri May 04, 2012 11:47 am

Absolutely Len. If you cannot hear the difference, you have no business having more than 1 speaker. :mrgreen:

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Re: March 2012 - about speaker polarity

Post by Lenp » Fri Jan 02, 2015 1:06 pm

Just thinking...
When I hobby'd a lot, and was introduced to the Leslie speaker systems I cobbled together a surround(ing) speaker system. As I recall it was a bunch of small speakers in a large circle. The 'listener' sat in the center and a home brew motor driven switch mechanism rotated the audio around the circle. I believe it also flipped the phases The big problem was the switch failure so it was abandoned.
Someone with too much time on their hands might want to revisit this idea with solid state switching!
Len

“To invent, you need a good imagination and a big pile of junk.” (T. Edison)
"I must be on the way to success since I already have the junk". (Me)

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Re: March 2012 - about speaker polarity

Post by CeaSaR » Sun Jan 04, 2015 6:28 pm

Funny thing you mention that, Len. I happen to have a Leslie sitting right in front of me. Destined for a guitar project.

As for that effect, you could use a 555 astable low frequency, adjustable, into a counter, and feed the outputs to either a driver chip or discrete transistor drivers. Actually doesn't sound that complicated. It's all low speed so there shouldn't be any real problems with latency or saturation.

Darn you! Now I have another project. Hehe.

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Re: March 2012 - about speaker polarity

Post by Lenp » Mon Jan 05, 2015 7:53 am

Sad thing about it .....
You can't show it off with an MP3 file :sad:
Maybe you could call it a 'Whirl-it-zer'
Len

“To invent, you need a good imagination and a big pile of junk.” (T. Edison)
"I must be on the way to success since I already have the junk". (Me)

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