Date: Fri, 29 Apr 2011 07:53:00

Author: Zani, Gerald

Subject: Re: speakers

Post:

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More questions.

I guess it is a history of audio technology question.

When was it that an audio amplifier output used an audio transformer to
bridge to a loudspeaker? 1950?
And what was the impedance choice for the two transformers?


The original link:
http://hyperphysics.phy-astr.gsu.edu/hbase/audio/imped.html#c2
(posted and discussed on tap-l) is labeled "Impedance Matching" and models
the amplifier output impedance with an 8 Ohm resistor to match the 8 Ohm
speaker. It is my belief that this may be a wrong model? It does not show
an audio transformer, it shows resistors.

The second link (you referred) is labeled "Matching Amplifier to
Loudspeaker"
http://hyperphysics.phy-astr.gsu.edu/hbase/audio/imped.html#c2
and has a different model for the amp output impedance called a "Dynamically
controlled low impedance". That is a little better explanation because it
does mention low impedance, which implies an impedance mismatch which I
think is correct. But it does not give a measure of what low means. How
low? And the point about being dynamically controlled is not defined. So
it is still unclear at best.

I find the different Hyperphysics pages that discuss the issue of impedance
matching with audio amplifiers and speakers to be unclear.

I am trying to learn what is right. And what is printed.
- Jerry Z.

On Thu, Apr 28, 2011 at 4:14 PM, Jerry DiMarco
wrote:

> To see the HyperPhysics page I referred to in my previous post, click
> on the maximum power transfer link...
>
> Jerry D
>
> <><><><><><><><><><><><><><><><><><><><><><><><><><><><><>
>
> Jerry DiMarco
> Manager of Lecture Demonstrations and Instructional Labs
> Montana State Univ., Physics Dept.
>
> Bozeman, MT
>
> Our Motto: "A demo a day helps learning to stay"
>
>


--
Gerald Zani
Demonstration Manager
Physics
Brown University
(401) 863-3964

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More questions.I guess it is a history of audio technology question=
. When was it that an audio amplifier output used an audio transfor=
mer to bridge to a loudspeaker?=A0 1950?And what was the impedance choi=
ce for the two transformers?

The original link:http://hyperphysics.phy-astr.gsu.edu/hbase/au=
dio/imped.html#c2=A0(posted and discussed on tap-l) is labeled &quo=
t;Impedance Matching" and models the amplifier output impedance with a=
n 8 Ohm resistor to match the 8 Ohm speaker.=A0 It is my belief that this m=
ay be a wrong model?=A0 It does not show an audio transformer, it shows res=
istors.

The second link (you referred) is labeled "Matching Amplifier to L=
oudspeaker" http://hyperphysics.phy-astr.gsu.edu/hbase/audio/imped=
.html#c2

and has a different model for the amp output impedance called a "Dynam=
ically controlled low impedance".=A0 That is a little better explanati=
on because it does mention low impedance, which implies an impedance mismat=
ch which I think is correct.=A0 But it does not give a measure of what low =
means.=A0 How low?=A0 And the point about being dynamically controlled is n=
ot defined.=A0 So it is still unclear at best.

I find the different Hyperphysics pages that discuss the issue of imped=
ance matching with audio amplifiers and speakers to be unclear.I am=
trying to learn what is right.=A0 And what is printed.- Jerry Z.

On Thu, Apr 28, 2011 at 4:14 PM, Jerry DiMar=
co arco@physics.montana.edu> wrote:

=A0 =A0 To see the HyperPhysics page I referred to in my previous post, cl=
ick on the maximum power transfer link...

=A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =
=A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0Jerry D

<><><><><><><><><><=
;><><><><><><><><><&g=
t;<><><><><><><><><>&=
lt;>



=A0Jerry DiMarco
=A0Manager of Lecture Demonstrations and Instructional Labs
=A0Montana State Univ., Physics Dept. =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =
=A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0
=A0Bozeman, MT

Our Motto: "A demo a day helps learning to stay"

-- Gerald ZaniDemonstr=
ation ManagerPhysicsBrown University(401) 863-3964

--0016e6d99c7b04755904a20d5205--

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