2
Introduction _
The Mapletree Audio Design
L2X Stereo Line Preamplifier/Buffer
is a streamlined
version of the
Line 2B SE
line preamp without the dual heater voltage switch and balance
control. Nichicon polypropylene film capacitors and Alpha carbon volume control are
also employed. The
L2X
is matched to the compact
PSX
power supply that can be located
remotely from the preamp itself. The power supply features an all-solid-state full-wave
rectifier using high-speed diodes, and an unregulated dc heater supply. Other features
include:
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Compact chassis layout and separate power supply for low noise. Noise is less than
200
?
V.
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Exclusive use of NOS 12SN7GT octal tubes, known for low distortion and
musicality.
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Two switched inputs with user-specified gains of 0 or 10 dB. Unity gain (0 dB) is
available for buffer use, with the
L2X
inserted between the source and an integrated
or power amp where additional gain is not required.
Power Supply Connections______
The Mapletree
L2X
consists of a preamplifier chassis with provision for connection to the
separate
PSX
power supply. This allows separation between the two units and eliminates
induced hum originating from power supply circuitry and components. The Mapletree
PSX
power supply provides 12 VDC at 0.6 A for the heater supply and +250 VDC at full
load (12 mA) for the B+ plate supply. The power connections to the preamplifier chassis
are made through a special 3-conductor power cord that plugs into jacks located on the
rear panels of the power supply and preamplifier chassis.
CAUTION: Do not operate the power supply when it is not connected to the
preamp. Damage of components may result. Do not use the
PSX
power supply for
any other preamp. The current ratings are for the
L2X
preamp only.
Once the interconnecting power cord is securely attached between the two chassis and the
line cord is plugged in, the switch on the front panel of the
PSX
is used to activate the
power supply. The pilot lamp indicates that the unit is on. It takes about 30 seconds for
the tubes to reach operating temperature ready for use. During operation, is it normal for
the power supply chassis to become warm to the touch.
