I read in sci.electronics.design that gwhite wrote
(in ) about '1/4 vs 1/2 wavelength
antenna', on Thu, 3 Mar 2005:
By definition, conj-match insists RL = Ri = 110 ohms. Again we are
limited in our clipping constraint by static drain current, and supply
voltage, specifically 10 V.

Our negative swing limit is, as ever, 10 V (the drain voltage).

positive swing = Id*rL = 1*55 = 55 V

This would breakdown the device, but the lower negative swing will force
us to back down the drive to meet the design defined clipping
constraint.

Pload = 10^2/(2*110) = 0.455 W

And the power dissipated in the device is also 0.445 W. Matching
according to the 'maximum power theorem' or conjugate matching, results
in equal power in the PA and load. That's why it isn't useful for power
amplifiers.

Doesn't everyone know that an audio amplifier that id designed to feed
an 8 ohm load MUST have an output source impedance of 0.0000001 ohms or
less. An output source impedance of 8 ohms would dramatically decrease
the electromagnetic damping on the loudspeaker voice-coil - by the huge
factor of .... two!(;-)
--
Regards, John Woodgate, OOO - Own Opinions Only.
The good news is that nothing is compulsory.
The bad news is that everything is prohibited.
http://www.jmwa.demon.co.uk Also see http://www.isce.org.uk

On Thu, 3 Mar 2005 20:53:48 +0000, John Woodgate
wrote:

Doesn't everyone know that an audio amplifier that id designed to feed
an 8 ohm load MUST have an output source impedance of 0.0000001 ohms or
less.

Hi John,

I hope that was a joke.

73's
Richard Clark, KB7QHC

On Thu, 03 Mar 2005 13:44:06 -0800, Richard Clark wrote:

On Thu, 3 Mar 2005 20:53:48 +0000, John Woodgate
wrote:

Doesn't everyone know that an audio amplifier that id designed to feed
an 8 ohm load MUST have an output source impedance of 0.0000001 ohms or
less.

Hi John,

I hope that was a joke.

Please! You know Mr. Woodgate _hates_ explaining his jokes:

"Doesn't everyone know that an audio amplifier that [is] designed to feed
an 8 ohm load MUST have an output source impedance of 0.0000001 ohms or
less[?] An output source impedance of 8 ohms would dramatically decrease
the electromagnetic damping on the loudspeaker voice-coil - by the huge
factor of .... two! (;-)
[^^^^]

Please notice the last sentence in that paragraph. ;-)

73's

Best regardses? ;-)

Cheers!
Rich

Rich Grise wrote:

On Thu, 03 Mar 2005 13:44:06 -0800, Richard Clark wrote:

On Thu, 3 Mar 2005 20:53:48 +0000, John Woodgate
wrote:

Doesn't everyone know that an audio amplifier that id designed to feed
an 8 ohm load MUST have an output source impedance of 0.0000001 ohms or
less.

Hi John,

I hope that was a joke.

Please! You know Mr. Woodgate _hates_ explaining his jokes:

Mr. Clark _hates_ reading and comprehending. I forsee a clash royal.

On Thu, 03 Mar 2005 23:07:14 GMT, Rich Grise
wrote:

Please! You know Mr. Woodgate _hates_ explaining his jokes:

Hi Rich,

Some love explaining their jokes. I've gotten quite a bit of
correspondence to that matter already.

73's
Richard Clark, KB7QHC

Richard Clark wrote:

On Thu, 3 Mar 2005 20:53:48 +0000, John Woodgate
wrote:


Doesn't everyone know that an audio amplifier that id designed to feed
an 8 ohm load MUST have an output source impedance of 0.0000001 ohms or
less.


Hi John,

I hope that was a joke.

73's
Richard Clark, KB7QHC

I think he just meant that damping factor is important in an audio amp.

At least I hope that's what he meant.

He forgot to mention that for that output impedance to be relevant, you
need superconducting wire to the speakers as well as superconducting
voice coils.

tom
K0TAR

I read in sci.electronics.design that Tom Ring
wrote (in ) about '1/4 vs
1/2 wavelength antenna', on Thu, 3 Mar 2005:

He forgot to mention that for that output impedance to be relevant, you
need superconducting wire to the speakers as well as superconducting
voice coils.

See the last sentence, about the effect of an **8 ohm** source impedance
on damping.
--
Regards, John Woodgate, OOO - Own Opinions Only.
The good news is that nothing is compulsory.
The bad news is that everything is prohibited.
http://www.jmwa.demon.co.uk Also see http://www.isce.org.uk

John Woodgate wrote:

I read in sci.electronics.design that Tom Ring
wrote (in ) about '1/4 vs
1/2 wavelength antenna', on Thu, 3 Mar 2005:


He forgot to mention that for that output impedance to be relevant, you
need superconducting wire to the speakers as well as superconducting
voice coils.


See the last sentence, about the effect of an **8 ohm** source impedance
on damping.

Get a sense of humor. Or maybe more ice and mixer.

tom
K0TAR

John Woodgate wrote:

I read in sci.electronics.design that Tom Ring
wrote (in ) about '1/4 vs
1/2 wavelength antenna', on Thu, 3 Mar 2005:


He forgot to mention that for that output impedance to be relevant, you
need superconducting wire to the speakers as well as superconducting
voice coils.


See the last sentence, about the effect of an **8 ohm** source impedance
on damping.

Oh, and going from 8 ohms output impedance to 10e-7 (unless I
miscounted) would take the damping factor from 1 to 8e7, which is a bit
more than 2. Ignoring the speaker wires of course.

tom
K0TAR

I read in sci.electronics.design that Tom Ring
wrote (in ) about '1/4 vs
1/2 wavelength antenna', on Fri, 4 Mar 2005:
John Woodgate wrote:

I read in sci.electronics.design that Tom Ring
wrote (in ) about '1/4 vs
1/2 wavelength antenna', on Thu, 3 Mar 2005:


He forgot to mention that for that output impedance to be relevant, you
need superconducting wire to the speakers as well as superconducting
voice coils.


See the last sentence, about the effect of an **8 ohm** source impedance
on damping.

Oh, and going from 8 ohms output impedance to 10e-7 (unless I
miscounted) would take the damping factor from 1 to 8e7, which is a bit
more than 2. Ignoring the speaker wires of course.

Also ignoring the ***voice-coil resistance***. If that is included, as
it must be for a correct analysis, you get 2.

F Langford-Smith 'invented' the concept of damping factor, and around
1949 accepted the point made by James Moir that, by not properly taking
into account the effect of the voice-coil resistance, it was a seriously
misleading concept. Yes, 60 years later, people are still being misled.
--
Regards, John Woodgate, OOO - Own Opinions Only.
The good news is that nothing is compulsory.
The bad news is that everything is prohibited.
http://www.jmwa.demon.co.uk Also see http://www.isce.org.uk