Sunfire Classic Vacuum Tube Preamplifier - Manual (Page 7)

7
User's Manual
Front Panel Features
7. Contour On/Off
In the OFF position, the contour circuits are bypassed
and the two contour controls (11) will have no effect.
In the ON position, the signal frequency response can
be adjusted by the contour controls to suit your taste.
8. Input Program Selector
This rotary switch selects the program source which
will be heard. The same program source is also
presented to the Tape outputs for recording. Note that
there is no Tape selection, you should engage the
Tape Monitor switch to listen to your tape deck.
If you have the optional Phono input, select either MM
or MC using the rear panel switch (depending upon
your phono cartridge), and then select CD/Phono.
To minimize bleedthrough, or an audible signal when
you select an unused input, it is recommended that
“shorting plugs” be inserted in all unused inputs. Do
Not install shorting plugs in any OUTPUT jacks, as
this would short-circuit the preamplifier output. If you
do not use shorting plugs, that is perfectly OK., and
you can prevent bleedthrough by turning off or muting
all signal sources not being listened to.
9. Volume Control
This is the master level control for the stereo system.
The control is a continuous taper potentiometer to
allow smooth transition from one level to another.
The taper rate of the potentiometer was chosen to
provide maximum flexibility and compatibility with
other components. Input signal levels will vary from
one source to the next, as well as from one disc, tape,
or FM station to the next, so it is normal to notice that
your preferred volume control setting varies.
Note: The remote control’s Volume Up function is
disabled when the system is muted or warming up.
This is to prevent causing damage to your speakers
due to accidentally high volume levels. The remote’s
Volume Down function is available at all times, and
you can still set the volume at any time using the front
panel control (but make sure it is turned down while
the preamp is warming up).
10. Balance Control
This adjusts the relative levels of the two stereo
channels. In its center position, the levels are exactly
equal. Clockwise rotation reduces the Left channel
level, while counterclockwise rotation reduces Right
channel level. Small movements off-center produce
smaller shifts in the stereo image per degree of
rotation than near the extreme left and right position.
This makes slight trimming of levels more convenient.
11. Contour Controls
The Sunfire Classic is equipped with a tone-control
stage in the signal path after all input selection and
tape switching. These controls are switches which
select a variety of precise contour curves. In opera-
tion, a muted click or pop may be heard when chang-
ing switch positions. The controls may be switched in
or out of circuit by the contour switch (7), allowing the
contoured signal to be quickly compared with the
preamplifier’s laboratory-flat frequency response.
The contour controls are asymmetrical in boost and
cut. They have been designed to be very appropriate
for real music listening situations. The boost exhibits
no shelving, and reaches a maximum of +6 dB at full
clockwise rotation. Bass may thus be boosted without
the boom associated with shelving, in order to in-
crease deep punch without mid-bass fatness. Treble
boost will field greater definition, without the shrillness
which results from treble-boost shelving.
In the cut (counterclockwise) position, treble and bass
are not rolled-off, as with most tone controls, rather
energy output in the upper and lower ranges is
reduced while maintaining flat frequency response in
those ranges. Cut does not exceed -10 dB, since
frequency response attenuation beyond this yields a
dead sound character which is not musically advanta-
geous. Cut is not substantially affected by the tone-
turnover frequency switches. This shelving character-
istic for the cut mode is very useful, for example, if a
recording sounds too bright. The relative harmonic
energy can be reduced without affecting the balance
of the harmonic content. Thus, a violin will still sound
like a violin, retaining its air, sheen and openness,
while reducing excessive brightness.
Note: We encourage the routine use of the contour
controls as this will significantly enhance your listening
pleasure.