"Rich Grise" bravely wrote to "All" (03 Mar 05 23:00:40)
--- on the heady topic of " 1/4 vs 1/2 wavelength antenna"

RG From: Rich Grise
RG Xref: aeinews rec.radio.amateur.antenna:26329
RG sci.electronics.design:1386
RG On Thu, 03 Mar 2005 20:53:48 +0000, John Woodgate wrote:
I read in sci.electronics.design that gwhite 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. An output source impedance of 8 ohms would dramatically decrease
the electromagnetic damping on the loudspeaker voice-coil - by the huge
factor of .... two!(;-)

RG Yeah - isn't that why the TOOB amps had those taps? So you could get
RG that rich, full-bodied TOOB sound? ;-)

No, the taps are there to maximize the power output. If one uses the
8 ohm tap with a 4 ohm speaker the power is reduced and the same if
one uses a 16 ohm speaker. Audio output matching has little to do with
plate resistance in a beam tube or pentode. It has everything to do
with plate voltage swing and maximum plate current. The less plate
resistance the more power can get to the load. Beam tube curves look a
lot like a transistor's collector saturation curves.

However, some tube amplifiers had a current feedback control which
would increase the output impedance to equal the speaker's. Needless
to say it severely reduced the speaker damping resulting in exagerated
frequency response artifacts.

A*s*i*m*o*v

.... Without ignorance, knowledge is powerless.