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Copper plated poles
Copper plated poles
As an electrical ignoramus, i have long been puzzled by a throw away
comment often seen in loudspeaker reviews along the lines of...
"the copper plated pole piece acts as a shorted turn", the implication
being that this is a good thing.
Can anyone explain in simple terms why copper plating would have this
effect?
And if it is such a good thing, why don't they just short one of the turns
deliberately?
Ken
As an electrical ignoramus, i have long been puzzled by a throw away
comment often seen in loudspeaker reviews along the lines of...
"the copper plated pole piece acts as a shorted turn", the implication
being that this is a good thing.
Can anyone explain in simple terms why copper plating would have this
effect?
And if it is such a good thing, why don't they just short one of the turns
deliberately?
Ken
Re: Copper plated poles
On Wed, 26 Mar 2008 15:30:34 -0000, UnsteadyKen
<unsteadyken@gmail . com > wrote:
>As an electrical ignoramus, i have long been puzzled by a throw away
> comment often seen in loudspeaker reviews along the lines of...
>"the copper plated pole piece acts as a shorted turn", the implication
>being that this is a good thing.
>
>Can anyone explain in simple terms why copper plating would have this
>effect?
>And if it is such a good thing, why don't they just short one of the turns
>deliberately?
>
It is a way of controlling the damping of the motion of the cone. The
shorted turn has signal induced into it, and heats up, dissipating
power. By adjusting the thickness of the plating the amount of damping
it provides can be adjusted to achieve some desired value. You
wouldn't want to short one of the actual turns, because that would
cause too much loss of signal power.
d
--
Pearce Consulting
* w w w .pearce.uk . com
On Wed, 26 Mar 2008 15:30:34 -0000, UnsteadyKen
<unsteadyken@gmail . com > wrote:
>As an electrical ignoramus, i have long been puzzled by a throw away
> comment often seen in loudspeaker reviews along the lines of...
>"the copper plated pole piece acts as a shorted turn", the implication
>being that this is a good thing.
>
>Can anyone explain in simple terms why copper plating would have this
>effect?
>And if it is such a good thing, why don't they just short one of the turns
>deliberately?
>
It is a way of controlling the damping of the motion of the cone. The
shorted turn has signal induced into it, and heats up, dissipating
power. By adjusting the thickness of the plating the amount of damping
it provides can be adjusted to achieve some desired value. You
wouldn't want to short one of the actual turns, because that would
cause too much loss of signal power.
d
--
Pearce Consulting
* w w w .pearce.uk . com
Re: Copper plated poles
Don Pearce said...
> he
> shorted turn has signal induced into it, and heats up, dissipating
> power.
>
Thanks Don. A bit like regenerative braking at the end of the voice
coils travel. Now it makes sense.
--
Ken
Don Pearce said...
> he
> shorted turn has signal induced into it, and heats up, dissipating
> power.
>
Thanks Don. A bit like regenerative braking at the end of the voice
coils travel. Now it makes sense.
--
Ken
Re: Copper plated poles
"UnsteadyKen" <unsteadyken@gmail . com > wrote in message
news:MPG.22547c44450511ed98969c@news.btinternet . com
> As an electrical ignoramus, i have long been puzzled by a
> throw away comment often seen in loudspeaker reviews
> along the lines of... "the copper plated pole piece acts
> as a shorted turn", the implication being that this is a
> good thing.
The problem being addressed is eddy currents induced into the pole piece by
the voice coil.
This is problematical because the voice coil's relationship with the fixed
pole piece is changing when the speaker is driven. It creates nonlinear
distortion. It makes the performance of the speaker harder to predict.
> Can anyone explain in simple terms why copper plating
> would have this effect?
The copper plating has lower resistance than the usual iron or steel that is
used to make pole pieces. Sometimes a copper cap or ring is used for the
same purpose. Sometimes aluminum parts are used.
> And if it is such a good thing, why don't they just short
> one of the turns deliberately?
The shorted turn would be part of the voice coil, not part of the pole
piece. It's the relative motion that causes problems.
"UnsteadyKen" <unsteadyken@gmail . com > wrote in message
news:MPG.22547c44450511ed98969c@news.btinternet . com
> As an electrical ignoramus, i have long been puzzled by a
> throw away comment often seen in loudspeaker reviews
> along the lines of... "the copper plated pole piece acts
> as a shorted turn", the implication being that this is a
> good thing.
The problem being addressed is eddy currents induced into the pole piece by
the voice coil.
This is problematical because the voice coil's relationship with the fixed
pole piece is changing when the speaker is driven. It creates nonlinear
distortion. It makes the performance of the speaker harder to predict.
> Can anyone explain in simple terms why copper plating
> would have this effect?
The copper plating has lower resistance than the usual iron or steel that is
used to make pole pieces. Sometimes a copper cap or ring is used for the
same purpose. Sometimes aluminum parts are used.
> And if it is such a good thing, why don't they just short
> one of the turns deliberately?
The shorted turn would be part of the voice coil, not part of the pole
piece. It's the relative motion that causes problems.
Re: Copper plated poles
Arny Krueger said...
> The shorted turn would be part of the voice coil, not part of the pole
> piece. It's the relative motion that causes problems.
>
Thank you Arny the light dimly dawns.
--
Ken
Arny Krueger said...
> The shorted turn would be part of the voice coil, not part of the pole
> piece. It's the relative motion that causes problems.
>
Thank you Arny the light dimly dawns.
--
Ken
Re: Copper plated poles
"UnsteadyKen" wrote ...
> Arny Krueger said...
>> The shorted turn would be part of the voice coil, not part of the pole
>> piece. It's the relative motion that causes problems.
>>
> Thank you Arny the light dimly dawns.
Speaking of copper....
* w w w .youtube . com /watch?v=cVkZZsS-66c
"UnsteadyKen" wrote ...
> Arny Krueger said...
>> The shorted turn would be part of the voice coil, not part of the pole
>> piece. It's the relative motion that causes problems.
>>
> Thank you Arny the light dimly dawns.
Speaking of copper....
* w w w .youtube . com /watch?v=cVkZZsS-66c
Re: Copper plated poles
On Wed, 26 Mar 2008 10:14:52 -0700, "Richard Crowley"
<rcrowley@xp7rt . net > wrote:
>"UnsteadyKen" wrote ...
>> Arny Krueger said...
>>> The shorted turn would be part of the voice coil, not part of the pole
>>> piece. It's the relative motion that causes problems.
>>>
>> Thank you Arny the light dimly dawns.
>
>Speaking of copper....
> * w w w .youtube . com /watch?v=cVkZZsS-66c
>
>
Thank you - that's a keeper.
d
--
Pearce Consulting
* w w w .pearce.uk . com
On Wed, 26 Mar 2008 10:14:52 -0700, "Richard Crowley"
<rcrowley@xp7rt . net > wrote:
>"UnsteadyKen" wrote ...
>> Arny Krueger said...
>>> The shorted turn would be part of the voice coil, not part of the pole
>>> piece. It's the relative motion that causes problems.
>>>
>> Thank you Arny the light dimly dawns.
>
>Speaking of copper....
> * w w w .youtube . com /watch?v=cVkZZsS-66c
>
>
Thank you - that's a keeper.
d
--
Pearce Consulting
* w w w .pearce.uk . com
Re: Copper plated poles
"Richard Crowley" <rcrowley@xp7rt . net > wrote in message
news:64vekdF2df11mU1@mid.individual . net ...
> Speaking of copper....
> * w w w .youtube . com /watch?v=cVkZZsS-66c
>
That's a hoot. For anyone who wants the video file, it's on my site at
* w w w .smokeylake . com /Fun%20Stuff/Fun_Stuff.htm
It's a 2 MB wmv file.
--
Regards from Virginia Beach,
Earl Kiosterud
"Richard Crowley" <rcrowley@xp7rt . net > wrote in message
news:64vekdF2df11mU1@mid.individual . net ...
> Speaking of copper....
> * w w w .youtube . com /watch?v=cVkZZsS-66c
>
That's a hoot. For anyone who wants the video file, it's on my site at
* w w w .smokeylake . com /Fun%20Stuff/Fun_Stuff.htm
It's a 2 MB wmv file.
--
Regards from Virginia Beach,
Earl Kiosterud
