Loudspeaker design question

Archived from groups: rec.audio.tech (More info?)

On Wed, 26 May 2004 22:10:50 GMT, "Richard Tomkins"
<tomkinsr@istop.com> wrote:

>Has any manufacturer ever designed/built a loudspeaker that reversed the
>functions of the voicecoil and permanent magnet, such that the permanent
>magnet was attached to the speaker cone and the electromagnet was the
>stationary magnet?

Would add substantial moving mass which is usually unwanted.

>What about having the voicecoil on the outside rim of the speaker rather
>than on the inside? Has this ever been done?

Most dome tweeters. Some have attempted this with larger drivers.

>Instead of using a single voicecoil in the center, how about one on the edge
>and one in the middle?

If you could control the drive in a coordinated way.

>How about a dual voice coil, one being driven and the second providing
>feedback like a closed servo loop?

Old hat.

Kal

Archived from groups: rec.audio.tech (More info?)

On Thu, 27 May 2004 02:23:28 GMT, "Richard Tomkins"
<tomkinsr@istop.com> wrote:

>Great. Any examples or URL's to reference?

No. Have none off hand and no time for such research.

Kal


>
>
>"Kalman Rubinson" <kr4@nyu.edu> wrote in message
>news:s86ab0tije4vo4qk5gr3dfam49b5ui83gi@4ax.com...
>> On Wed, 26 May 2004 22:10:50 GMT, "Richard Tomkins"
>> <tomkinsr@istop.com> wrote:
>>
>> >Has any manufacturer ever designed/built a loudspeaker that reversed the
>> >functions of the voicecoil and permanent magnet, such that the permanent
>> >magnet was attached to the speaker cone and the electromagnet was the
>> >stationary magnet?
>>
>> Would add substantial moving mass which is usually unwanted.
>>
>> >What about having the voicecoil on the outside rim of the speaker rather
>> >than on the inside? Has this ever been done?
>>
>> Most dome tweeters. Some have attempted this with larger drivers.
>>
>> >Instead of using a single voicecoil in the center, how about one on the
>edge
>> >and one in the middle?
>>
>> If you could control the drive in a coordinated way.
>>
>> >How about a dual voice coil, one being driven and the second providing
>> >feedback like a closed servo loop?
>>
>> Old hat.
>>
>> Kal
>

Archived from groups: rec.audio.tech (More info?)

"Richard Tomkins" <tomkinsr@istop.com> wrote in message news:<1ed4fca729895c10541ebd08b44ee484@news.teranews.com>...
> Has any manufacturer ever designed/built a loudspeaker that reversed the
> functions of the voicecoil and permanent magnet, such that the permanent
> magnet was attached to the speaker cone and the electromagnet was the
> stationary magnet?
>
> What about having the voicecoil on the outside rim of the speaker rather
> than on the inside? Has this ever been done?
>
> Instead of using a single voicecoil in the center, how about one on the edge
> and one in the middle?
>
> How about a dual voice coil, one being driven and the second providing
> feedback like a closed servo loop?
>
> Regards, rtt


Way back in the day there were speakers with conventional voice
coils but that used a stationary electro-magnet instead of a permanent
magnet. In order to energize that stationary coil it was also used as
the filter inductor in the power supply.