Mapletree L2X Stereo Line User Manual

Modular Series

L2X Stereo Line Preamplifier/Buffer

PSX Power Supply

User’s Manual

Revised Feb. 23/14

Mapletree Audio Design

Lloyd Peppard

R. R. 1, Seeley's Bay, Ontario, Canada, K0H 2N0

[phone]
www.mapletreeaudio.com
[e-mail]

© Copyright Lloyd Peppard 2002-2014

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:

? ? Compact chassis layout and separate power supply for low noise. Noise is less than

200 ?V.

? ? Exclusive use of NOS 12SN7GT octal tubes, known for low distortion and

musicality.

? ? 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.