In most (er, many, some, a few?) circles, "no feedback" in
the context of audio product description implies ac negative loop
feedback. I assume "ac negative loop" gets dropped for brevity at the
risk of sloppy terminology, although "loop feedback" is mentioned in
the text - I'll talk to Marketing. Anyway, the Gordon uses two
variable-gain, open-loop (again, ac loop) amplifier stages with the
second stage switched out at the lower gain settings. Loop feedback
is used throughout the pre, but only dc loop and local feedback are
used around the audio path.
There are only two stages, each with six steps from 10-35dB, for
thirteen steps from 10-70dB, with the second stage cutting in at 40dB.
Each step can be calibrated and is "gain staged" to optimize dynamic
range and distortion. Most of the circuitry in the photo is for
support functions, primarily: closed-loop voltage and current
regulators for each stage, ten discrete closed-loop supply regulators
per channel, output load compensation, and gain control.
Grant Carpenter
Gordon Instruments
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