Manley JUMBO SHRIMP - Manual (Page 8)

2. VOLUME AND BALANCE ATTENUATORS
The JUMBO SHRIMP’s volume attenuator features two conventional logarithmic-taper resistance tracks, with
the notable exception that the matching of these two tracks is especially good over the rotational range of the
control. Invariably a headache with cheap dual potentiometers, this enticing attribute of the ALPS attenuator set
translates into very good level balance between channels as the control is adjusted.
Before the volume and balance attenuators lives a White-Follower buffer stage - a perennial favorite of ours.
This not only reduces the output impedance of the first stage (thus effortless driving the rest of the unit), but also
decreases distortion and increases headroom as an added bonus.
As an added measure of level matching insurance, the gain profile of the JUMBO SHRIMP’s gain blocks have
been purposely arranged so that setting the volume attenuator at the “12 o’clock” position will result in unity volt-
age gain through the preamp. A hairy judgement about the overall relative level of any given source, as compared
to its neighbors, may then be drawn from the volume control’s position.
The balance attenuator features a special track whose resistance is zero either side of center when the attenuator
set at the center-detent position. This helps ease the voltage amplification burden of the first gain stage, as there is
no parasitic balance-control resistance to overcome when driving the attenuator network.
Use of these controls is self-explanatory, but caution is advised if it is found that extreme control settings are
necessary when operating the JUMBO SHRIMP with associated signal sources and power amplifiers. Under
normal conditions the balance control should be very close or in the center-detent position. Balance control set-
tings below “10 o’clock” or above “2 o’clock” are indicative of trouble elsewhere in the system that should be
investigated. The volume control can then be put to conventional use, to throttle back louder sources, such as a
CD player, or boost quieter ones, such as older tube tuners or tape decks.
Both the volume and balance attenuator output signals are buffered by the White-follower output amplifier stage
before being routed to the output jacks. This prevents the output loads from interacting unpredictably with the
attenuators, and lowers the preamp’s output impedance.
3. PUSH-BUTTON MUTE SWITCH AND MUTE INDICATOR
A specially illuminated push-button feature switch has been provided to permit invocation of the ever-handy out-
put MUTE function. The switch’s built-in lamp shows the status of the mute circuit during warm-up cycles and
normal operation and as we all know, BLUE LED’s make gear sound better. The mute circuit controls the mute
relay whose contacts are arranged to quench signals present at the output of the preamp.
A flashing lamp at power up indicates the beginning of a 30-second warm-up delay, during which time the mute
relay is closed; no sound will be heard from the preamp. A steady lamp indication means that the manual mute
circuit is engaged, cutting signals from the outputs (shorting them to ground, to be more precise). To unmute
the preamp, press the MUTE button. The mute relay will relax, the mute lamp will darken and signals will be
restored to the output. The MUTE button features an alternating toggle action, or “press-on, press-off” type of
behavior.
Note that the entire 30-second warm-up cycle will not fully recycle unless the preamp has been deprived of mains
power for more than a few seconds.
4. MANLEY REMORA REMOTE CONTROLLED VOLUME
The Remora is a radio-frequency based remote control that allows command of the silicon-free, high-quality
motorized VOLUME attenuator set, for infinitely resolvable control of listening levels. No need to “point” the
remote in any direction - the Jumbo Shrimp’s attenuator can be controlled from another nearby room, through
walls, through floors, through doors, and through opaque closet or cabinet doors! Please, no need to get up. Sit
back. Relax. Enjoy.
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