F1 Power Amplifier

The F1 is a 10 watt per channel stereo amplifier operating in balanced single-ended Class A without feedback. Each channel has only one gain stage and draws a constant 100 watts.

It is a power trans-conductance amplifier (or power current source, if you like), replicating an input voltage into an output current. A regular amplifier sends output voltage to the loudspeaker. This is not that kind of amplifier.

This amplifier ignores the elements in series with the load circuit, including back-emf, wire resistance, inductance and such, and creates voice coil acceleration in direct proportion to the input signal.

It is well suited to sensitive full-range drivers such as Lowther or Fostex, and allows easy use of parallel loading networks to tailor the driver response.

It has both balanced and single-ended inputs. The input impedance is nominally 80 Kohm, and the output impedance is 80 ohms. The output noise is around 100 picowatts (100 trillionths of a watt).

The simplified schematic of the F1 looks like this:

At this time, F1's are only available used, but there are a very few copies of new F1's which are updated using the new power Jfets as found in the J2 amplifier. See the F1J product page.

Download F1 Manual and the F1 Service Manual

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