Luxman C-12 Schematic

Luxman C12 control amplifier & M12 power amplifier

General:

This pre-amplifier or control amplifier as Luxman likes to call it and power amplifier
set was produced in the early 1980’s.
They are part of the "Laboratory Standard Series" just as i.e. the T12 and the L10.

Special futures:

The pre-amp section of this set, the C12 was remarkable because of several features.
It employed no tone-control, it did however have a "Linear Equalizer". Below is
explained what it does:

All the program sources available are not always perfect.
Record discs, cd's and tapes, as a program source, are liable to have a
slight deviation of linear nature depending on the manufacturers.
For example, all recordings are equalized in accordance with RIAA standard,
but its quite common to encounter variations in overall tonal balance from
one recording to the other.
Also, differences in listening environment and room acoustics often require
a subtle degree of tonal compensation that conventional tone controls cannot
correct because of their wide range and overlapping characteristics.
The "Linear Equalizer" control provides a form of tonal compensation
especially intended for this sort of tendency.
With the control in its mids position, flat frequency response is achieved.
Switched to the "up--tilt" positions, the entire response curve is rotated
on a 1 kHz axis so as a linear increase treble response while simultaneously
decreasing bas response.
Conversely, selection of one of the "down-tilt" positions rotates the
response curve in a clockwise direction, providing a gradual decrease of
treble response and simultaneous increase of bass response.
Degree of slope for either positive or negative settings has been carefully
preset, and the overall response maintains complete linearity
from 50 Hz to above10 kHz, unlike the curvature in response normally
associated with ordinary tone controls.
Specifically, when the control is turned to the max "up-tilt" position, it
will decrease bass and increase treble by 2 dB at 100 Hz and 10 kHz
respectively.
Selection of the max "down-tilt" position will decrease treble and increase
bass by 2 dB at the same reference frequencies.
At the center of the rotation, components which consists the Linear

Equalizer are all by-passed to realize flat frequency response.
The control is inserted in the flat amp circuit and is effective on ALL
program sources.
It introduces no increase of harmonis distortion in any of his settings
because of the inherently linear nature of this circuit.

Schematic:

C12 schematic diagram: