Design and Philosophy
Introduction
You may recall that nearly four years ago I introduced the model F3, an amplifier
using the Lovoltech JFET power transistors. The F3 remains one of my favorite
pieces, a 15 watt single stage / single-ended Class A power amplifier which
achieves very low distortion and exceptional subjective quality for such a simple
amplifier. Until now, it has been the only power JFET amplifier that you could buy,
excepting the efforts of Sony and Yamaha from more than 30 years ago.
The details of the First Watt F3 are found in the owner's manual (and the DIY
articles Zen Variations #8 and #9), and the charms of the amplifier's sound can be
found in the many reviews.
First Watt is nothing if not a moving target, so:
Meet the New FETs
Not the same as the old FETs. Advances in semiconductor technology have
resulted in new Silicon Carbide (SiC) JFET transistors with much greater voltage,
current, and power capabilities. How much more? How about 1200 volts, 30
amps, and 273 watts?
Offered by a new company in Missouri, SemiSouth, these parts are designed for
fast high power switching in solar power and electric car applications. They
achieve that last little bit more energy efficiency from conversion processes, and
that justifies a sampling price as high as $60 or so.
Tomorrow's transistors at tomorrow's prices!
Don't worry, I get a volume discount.
Given the manufacturer's intended use, there is a certain irony in making Class A
amplifiers with them. Obviously there are plenty of alternatives for power devices
if we simply want to make an regular amplifier.
So you have to ask, aside from the novelty such a new unique part, what makes it
special for audio? In two words:
Lower Distortion.
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