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Clipped 15th January 2009 02:30 PM

magnetic poles of a speaker motor
can a speaker operate if the voice coil interacts with only one pole of the magnet?

Vaughan 15th January 2009 06:30 PM

Wouldn't that mean that the cone only moves in one direction ? I mean both north and south poles are required for both positive and negative wave cycles (and polarity changes based on the AC wave cycle or how far along the wave cycle is)

So then I take it that the waveform wouldn't be reproduced. But I'm sure someone more knowledgeable will tear my words down.


ABJensen 15th January 2009 07:09 PM

No a magnet always have two poles.So the the voicecoil will interact with both.

Clipped 16th January 2009 01:25 AM

you only need 1 pole for the voice coil to move.

HK26147 16th January 2009 01:34 AM

you answered your own question.
Audio is AC and does the change of attraction/repulsion in the voice coil.

Clipped 16th January 2009 10:04 AM

just wanted to double check before i drop $200 on NEO bars to make a sub.

Steerpike 16th January 2009 10:19 PM


No a magnet always have two poles.So the the voicecoil will interact with both.
Exactly so.

But you may be planning to have the coil only near one pole; the other pole far away - which in effect give you a really HUMONGOUS air gap, compared to conventional driver construction.
Result = low magnetic flux = poor effieciency & low power handling.

HK26147 16th January 2009 11:15 PM

There are a variety of transducers that use only 1 pole of a bar magnet such as the ribbon tweeter on this page:
Audio Magazine had a construction article ( 70's ) orienting neo bars magnets in V's on both sides of the membrane.

Perhaps an unconventional design is in mind?

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