Transconductance amplifiers & single-driver horns ~ by David
Wright, of Pure Music  Revisiting the SET text (why horns suit
SET amplifiers) after several years, I was struck by the clues
spread throughout that might have pointed me towards
transconductance amplifiers somewhat earlier. Unintentionally,
SETs are almost a halfway house between conventional voltage
amps and the subject of this article, current amplifiers (for
that is what TC amplifiers are).  Back in the earliest days of
audio, valves were the only amplifying devices available, so
amplifiers developed which exploited their greatest strength.
They were, and still are, the best voltage amplifiers, by which
I mean that their output voltage is a "magnified" version of
their input voltage, irrespective of load.  Loudspeakers.
however, use the magnetic field created by a current flowing
through the voice coil to make their sounds. It soon became
apparent that when the voltage from the amplifier went up, the
current through the voice coil didn't always