Way too much turkey over the holiday...
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Hi groovy guys and gals...
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Re: AB1, AB2, Audio and Radio Frequency Amplifiers.
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For the topic example, know there are two different
conventional layouts for grid driven AB1 operation, one
for audio, the other for RF.
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Classic guitar amplifier AB1 circuits are often push
pull layouts with phase inverters and high impedance
"grid circuits" (relative to RF amplifiers). Depending on
the method of bias, often a negative potential is
applied through the grid resistors which can be 100K
or more.
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We overdrive the tube guitar amplifier, it becomes
"AB2 as best possible", within the confines of the
circuit and its mix of contributing factors.
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You might assume AB2 to be the consumption of
drive power (grid current) , which is possible through
AC circuits. It does happen in audio circuits.
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Some of us pay big money for the end result
through Celestian Speakers.
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AB1 designed RF amplifiers often have a much lower
input (swamped) impedance, care and feeding issues
abound because the transition to AB2 operation is most
often unwanted. We do not see push pull RF
amplifiers much anymore.
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For the most part, both audio and radio frequency
AB1 amplifiers are AC coupled unless someone
is paying big money for true DC operation.
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My Krell 50watt output dc coupled stereo audio
amplifier makes a nice room heater... outputs
about 500+ watts of heat anytime the switch is
up. DC coupled amplifiers are not always "cool".
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cheers
skipp
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>> >> So an AB1 amp can be AB2 if it is over driven, and
>> >> an AB2 amp can be an
>> >> AB1 amp if it under driven?
>> >
>> >Nonsense.
>> >
>> ** please explain
>
>You can build an audio amp or modulator that is capacitively coupled
>to the grids of the output tube and there is nothing you can do to drive
>it into AB2 (grid current).
: How is DC grid bias applied to the grids?
>You have to DC couple it or use a transformer to
>drive it into grid current.
>Either the circuit supports AB2 or it doesn't.
>> >>
>> >> How would you design an AB1 amp that can not be over driven?
>> >>
>> >> - Rich...,
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