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Connecting both channels of an amp

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Anonymous
April 20, 2004 2:10:50 PM

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

Is it possible to connect both channels of an amp separtely to a dual
voice coil subwoofer..what I mean is to connect the left channel to
one coil and the right channel to the other voice coil....the feed
signal will be comming off the LFE output of a home theater receiver?
Anonymous
April 20, 2004 11:18:48 PM

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

On 20 Apr 2004 10:10:50 -0700, kliamike@hotmail.com (conrad) wrote:

>Is it possible to connect both channels of an amp separtely to a dual
>voice coil subwoofer..what I mean is to connect the left channel to
>one coil and the right channel to the other voice coil....the feed
>signal will be comming off the LFE output of a home theater receiver?

I believe this is one of the recommended applications of a dual-coil
speaker. What does the maker say?
Anonymous
April 20, 2004 11:18:49 PM

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

The reason for dual voice coil speakers is to give added flexibility
on the loads of the amp..letting one adjust let's say from 4 ohms to 2
ohms..and the same for dual 8 ohms coils you can switch from 8 to
4....but as for connecting each voice coil separatly...I'm not
sure...i know it's an absolute no-no in stereo configuration where
each channel is getting diffrent signal..that is obviuos..
Related resources
April 21, 2004 2:28:20 AM

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

kliamike@hotmail.com (conrad) wrote in message news:<afb5a306.0404200910.3fe48c3c@posting.google.com>...
> Is it possible to connect both channels of an amp separtely to a dual
> voice coil subwoofer..what I mean is to connect the left channel to
> one coil and the right channel to the other voice coil....the feed
> signal will be comming off the LFE output of a home theater receiver?

Dual voice coil subwoofers have two coils so that you can connect
the left channel to one and the right channel to the other instead of
having to have two different sub-woofers in two different cabinets.
Of course you have to come up with some kind of cross-over (two,
actually, one for each channel) that sends the very low frequencies to
one of the dual voice coils and everything above those frequencies to
your regular stereo speaker for that channel (where the speaker's
internal crossover further divides things for its internal drivers).
Anonymous
April 21, 2004 4:17:53 AM

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

On 20 Apr 2004 15:46:18 -0700, kliamike@hotmail.com (conrad) wrote:

>The reason for dual voice coil speakers is to give added flexibility
>on the loads of the amp..letting one adjust let's say from 4 ohms to 2
>ohms..and the same for dual 8 ohms coils you can switch from 8 to
>4....but as for connecting each voice coil separatly...I'm not
>sure...i know it's an absolute no-no in stereo configuration where
>each channel is getting diffrent signal..that is obviuos..

If you Google "dual voice coil" you'll find:
http://www.crutchfieldadvisor.com/ISEO-rgbtcspd/learnin...


Your no-no seems to be a yes-yes :-)
Remember this is a sub unit. No (or little) directional information.
Anonymous
April 21, 2004 4:54:23 AM

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

> The reason for dual voice coil speakers is to give added flexibility
> on the loads of the amp..letting one adjust let's say from 4 ohms to 2
> ohms..and the same for dual 8 ohms coils you can switch from 8 to
> 4....but as for connecting each voice coil separatly...I'm not
> sure...i know it's an absolute no-no in stereo configuration where
> each channel is getting diffrent signal..that is obviuos..

Obvious? I'm not so sure. Doing so could have benefits, if for some reason
you want to sum the channels and don't mind giving up a little efficiency in
the process.
Anonymous
April 21, 2004 4:08:50 PM

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

Wiring the two channels in true stereo configuration where the
material in one channel differs from the material from the other
channel..could destroy your subwoofer...both channels have to have the
same exact signal going through them ....At least thats what I
beleive...does anybody dispute this?
Anonymous
April 21, 2004 7:11:14 PM

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

> Wiring the two channels in true stereo configuration where the
> material in one channel differs from the material from the other
> channel..could destroy your subwoofer...

Care to explain how?
Anonymous
April 21, 2004 11:13:05 PM

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

On 20 Apr 2004 15:46:18 -0700, kliamike@hotmail.com (conrad) wrote:

>The reason for dual voice coil speakers is to give added flexibility
>on the loads of the amp..letting one adjust let's say from 4 ohms to 2
>ohms..and the same for dual 8 ohms coils you can switch from 8 to
>4....but as for connecting each voice coil separatly...I'm not
>sure...i know it's an absolute no-no in stereo configuration where
>each channel is getting diffrent signal..that is obviuos..

Yes, yes. In fact, the original reason for dual voice-coils is to
permit them to reproduce both channels but yet keep them electrically
isolated. I used an old University CS12W way back in the the 50s in
exactly this way.

Kal
Anonymous
April 22, 2004 1:22:48 AM

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

"MZ" <zarellam@twcnyremove.rr.comspam> wrote in message news:<ysWdnRmLQYTPWhvdRVn-uQ@giganews.com>...
> > Wiring the two channels in true stereo configuration where the
> > material in one channel differs from the material from the other
> > channel..could destroy your subwoofer...
>
> Care to explain how?


If a speaker receives two diffrent signals on it two coils..which way
will the woofer move..to which sound..first....
Anonymous
April 22, 2004 3:38:05 AM

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

>> The reason for dual voice coil speakers is to give added flexibility
>> on the loads of the amp..letting one adjust let's say from 4 ohms to 2
>> ohms..and the same for dual 8 ohms coils you can switch from 8 to
>> 4....but as for connecting each voice coil separatly...I'm not
>> sure...i know it's an absolute no-no in stereo configuration where
>> each channel is getting diffrent signal..that is obviuos..

The first few posts are missing from my news feed, however, I must
correct the above.

While one could use the multiple coils for impedance matching, the most
compelling reason for two coils is to accept a stereo feed from the
amplifiers when you have only enough room for one speaker. For example,
in many small bathrooms there just isn't any space or budget for a
second speaker.

The two channel speaker allows one to use the same stereo amplifier
feed to operate stereo and mono rooms without going to a lot of fuss.
The most optomistic outcome of connecting two amplifier outputs in
parallel at a speaker is a mono result. Typically, the amplifier is
destroyed. If the amplifier somehow survived, all of the rooms would be
converted to mono.

If one wants to fuss about the last 0.00x percent of performance, the
dual voice coil approach is probably not the thing to do, but in
multi-room or subwoofer duty, it usually doesn't matter.

----

If you are using the dual voice coil speaker as a subwoofer, the line
level subwoofer output from an A/V receiver is usually mono, even if
there are two subwoofer output jacks. In this case, connecting both
coils will increase the output a bit. If you accidently connect the
voice coils out of phase, there will be very little or no output from
the speaker. (assuming the output from the amplifiers is identical)

-----------------------------------------------------------
spam: uce@ftc.gov
wordgame:123(abc):<14 9 20 5 2 9 18 4 at 22 15 9 3 5 14 5 20 dot 3 15
13> (Barry Mann)
[sorry about the puzzle, spammers are ruining my mailbox]
-----------------------------------------------------------
Anonymous
April 22, 2004 4:30:09 AM

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

> > > Wiring the two channels in true stereo configuration where the
> > > material in one channel differs from the material from the other
> > > channel..could destroy your subwoofer...
> >
> > Care to explain how?
>
>
> If a speaker receives two diffrent signals on it two coils..which way
> will the woofer move..to which sound..first....

The woofer will move in the direction that the magnetic interaction
specifies. The magnetic forces exerted by the coils are non-separable.
Since each coil sets up a magnetic field, the fields for the two will
basically sum, and the result is essentially the vector sum of the magnetic
forces. This resultant force will be applied to both coils. So I'm not
quite sure how your argument translates into blown speakers.
Anonymous
April 22, 2004 4:59:14 AM

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

On 21 Apr 2004 12:08:50 -0700, kliamike@hotmail.com (conrad) wrote:

>Wiring the two channels in true stereo configuration where the
>material in one channel differs from the material from the other
>channel..could destroy your subwoofer...both channels have to have the
>same exact signal going through them ....At least thats what I
>beleive...does anybody dispute this?

Sure. Why would this be so?
Anonymous
April 22, 2004 1:38:03 PM

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

In <afb5a306.0404212022.6ae4ea72@posting.google.com>, on 04/21/04
at 09:22 PM, kliamike@hotmail.com (conrad) said:

>"MZ" <zarellam@twcnyremove.rr.comspam> wrote in message
>news:<ysWdnRmLQYTPWhvdRVn-uQ@giganews.com>... > > Wiring the two
>channels in true stereo configuration where the > > material in one
>channel differs from the material from the other > > channel..could
>destroy your subwoofer...
>>
>> Care to explain how?
>
>
>If a speaker receives two diffrent signals on it two coils..which way
>will the woofer move..to which sound..first....

The forces developed by 2, 3, or 100 coils will add and the cone will
follow the sum. You could make a mild case that, if an individual coil
was driven differently than the others, there would be a tendency for
the coil form (all of the coils would be attached to a single form) to
be torn apart, but the forces involved are not high enough to hurt the
form.

Actually, there is a similar issue with the air. Ultimately, sound is
movement of air. We have an orchestra, an audience, airconditioning,
traffic, subways, airplanes, etc. all trying to pull air molecules this
way and that, but a given air molecule can only be at one place at a
given time.

At the micro level you can show that there is some interaction between
all the simultaneous signals in both the speaker and in air, but it is
more difficult to prove the significance of all this when our
perception processes the result.

-----------------------------------------------------------
spam: uce@ftc.gov
wordgame:123(abc):<14 9 20 5 2 9 18 4 at 22 15 9 3 5 14 5 20 dot 3 15
13> (Barry Mann)
[sorry about the puzzle, spammers are ruining my mailbox]
-----------------------------------------------------------
Anonymous
April 22, 2004 4:13:06 PM

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

> >If a speaker receives two diffrent signals on it two coils..which way
> >will the woofer move..to which sound..first....
>
> The forces developed by 2, 3, or 100 coils will add and the cone will
> follow the sum. You could make a mild case that, if an individual coil
> was driven differently than the others, there would be a tendency for
> the coil form (all of the coils would be attached to a single form) to
> be torn apart, but the forces involved are not high enough to hurt the
> form.

I'm not so sure this is accurate. If the two coils are setting up magnetic
fields, they will be influencing each other's magnetic flux. To a good
approximation, this would result in the same flux for each coil, and as such
they should both exert nearly the same force. This is especially true if
the coils are overlapping.
Anonymous
April 22, 2004 4:16:10 PM

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

On Wed, 21 Apr 2004 23:38:05 -0400, zzzz@zzzz.zzz (Barry Mann) wrote:

>If one wants to fuss about the last 0.00x percent of performance, the
>dual voice coil approach is probably not the thing to do, but in
>multi-room or subwoofer duty, it usually doesn't matter.

Indeed. A friend is in the audio supply trade. He say's the only
place there's money to be made today is in supplying and installing
"Lifestyle" systems, ranging from "Home Theatre" setups to completely
wiring a house for audio so there's no escape anywhere :-) (Rather
like the systems in pubs. They pride themselves in leaving no corner
uncovered by a speaker. Don't they realise many customers would
prefer a quiet spot?)

It seems possible to charge hi-fi prices for quite mediocre equipment.
Appearance is, apparently, paramount.
Anonymous
April 22, 2004 4:19:23 PM

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

On 21 Apr 2004 21:22:48 -0700, kliamike@hotmail.com (conrad) wrote:

>If a speaker receives two diffrent signals on it two coils..which way
>will the woofer move..to which sound..first....

Sit at a table next to a friend. On the table is a book. Both reach
out to hold the book. You are both going to randomly either pull it
towards you, or push it away. The book will move according to the
sum total of your actions. Nothing will break.
!