On 11/12/2020 11:29 pm, Peter Wieck wrote:
The Dynaco PAT-5 biFet makes 15V @ 50MA +/- 5%
**Umm, not quite. The specs for the LF357 indicates significantly lower
numbers than that. At 25 degrees C:
* Maximum output Voltage (god, I forgot just how primitive that old
things was - zener regulation!?), with a +/- 15 Volt supply - 25 Volts
p-p = 8.8 Volts RMS (theoretically).
* Maximum output current @ 25 V p-p (dunno what the value of the output
series resistor is, as that will change the final figure somewhat) - +ve
20ma and (wait for it) -ve 5ma.
There is an Aktika (sp?) pre-amp that makes 20V @ 50MA +/- 5%
And there is a mod for the PAT-5 to get it to 42V @ 20MA +/- 5%
The reasoning for those superficially absurd voltages is headroom. And that is a long, difficult, and very nearly futile discussion mostly based on revealed religion.
**Well, once the input Voltage limits of the power amp are exceeded,
it's all over red rover.
And, that is AC voltage. Not DC - so those electrons are flying back and forth at whatever the audio frequency might be. Not departing for parts-unknown and in only one direction.
**Of course.
--
Trevor Wilson
www.rageaudio.com.au
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