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Zen Variations 9:
by Nelson Pass.
In
ZV8 we dipped our toes into the waters of power JFET transistors using
the new Lovoltech LU1014D in a simple circuit.
The focus of the project was on the JFET itself, and except for a
cascode transistor the rest of the amplifier used only passive
components.
Here in four installments we will increase the complexity of the
circuitry around the JFET with an eye toward distortion performance
surpassing any of the Zen projects to date.......
First,
we will put in an active supply filter to reduce power supply noise and
turn-on thump.
Then we will replace the light bulbs with a 2 amp constant
current source.
It will not glow warmly on cold winter evenings, but it will draw
less current, deliver about 50% more power, and has lower distortion and
noise......
There
are few other changes to the circuit of Figure 1, but you will note the
addition of an audiophile-approved bypass capacitor on the
output, and variability in the value of R3.
Later we will see that that this value can be used to optimize
the performance around the characteristics of individual JFETs......
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