Manley STEELHEAD RC - Manual (Page 7)

Each cartridge manufacturer’s product will work best in a laboratory sense when terminated
(loaded) with a certain amount of resistance and capacitance. By lab sense it is meant that the signal
developed by the cartridge is at maximum power transfer into the pre-amp, with minimum overshoot and
ringing, flattest frequency response and gentle roll-off characteristics. But it is those settings that create the
most musically satisfying results for you that are of uppermost importance. And your termination prefer-
ences may rightly deviate unpredictably from some lab-based norm. A good place to start is with those
values recommended by the cartridge manufacturer, less the interconnect cable capacitance. A good default
value, if the recommended cartridge load capacitance is unknown, is 150 pF, the sum of cable and termina-
tion capacitance switch settings. This value reflects a de facto standard as used by pre-amp manufacturers
past and present. From there we encourage you to scrutinize a range of switch settings until you find those
values which best suit you and your accompanying components.
Also notice that the audible affects of varying the termination capacitance can differ substantially
between cartridge types and brands. This is to be expected due to the greatly varying source impedance
characteristics of the cartridges available today. In general you may expect the termination capacitance
value to alter, at one extreme, subtle imaging and spatial cues, and at the other high-frequency content,
forwardness and speed of the reproduced sound. As with the load Z switch, feel free to tune the termination
capacitance switches for maximum sonic satisfaction even though the final setting differs from the car-
tridge manufacturer’s specs.
5. SWITCH-SELECTABLE AMPLIFIER GAIN
Cartridge output levels and downstream line-level interconnect drive voltage requirements can vary
greatly between manufacturers. Hence a four-step amplifier-block gain control has been included to ac-
commodate these differences, as well as differing cartridge sensitivities. You may select from 50 to 65 dB
of gain in 5 dB steps. The gain figure is referred to amplifier gain at 1 kHz. Notice that the pre-amp gain is
about 20 dB higher (10 times) at 20 Hz and about 20 dB lower (0.1 times) at 20,000 Hz. The MC step-up
autoformer may also provide approximately 2 to 12 dB of additional voltage gain depending on cartridge
source impedance and load switch setting.
6. PUSH-BUTTON SWITCH FUNCTIONS
Four feature switches have been provided for a variety of utility functions.
MUTE kills audio signals present at both the FIXED and VARIABLE outputs.
DIM reduces the output level by 20 dB, or about 1/4 previous volume. The DIM function is ef-
fective at the VARIable outputs only. Notice that preamp specifications at the VARIable output may be
slightly compromised with the DIM feature engaged. This feature should be treated as a convenience for
use when, for example, cueing up a record. System-menacing pops and thumps due to needle-drop are
held at bay yet sound from the pick-up may still be heard.
SUM combines the amplified audio into a binaural signal, present at the VARIable outputs only.
Monophonic or the lateral-only modulation content of your stereo records may now be heard. True mono
may be experienced if the feed to one of your two loudspeakers is cut.
SLEEP toggles the STEELHEAD between normal operating state and a near zero-power sleep
mode. No operating voltages are present when in sleep mode, except for some keep-alive CMOS system
control logic, energized by a separate small mains transformer in the power supply.
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