Mapletree Line 2B SE User Manual

Modular Series

Line 2B SE Stereo Line Preamplifier

User’s Manual

Revised Nov 18/13

Mapletree Audio Design

Lloyd Peppard

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

[phone]

www.mapletreeaudio.com

[e-mail]

© Copyr ight Lloyd Peppard 2002-2013

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Introduction _

The Mapletree Audio Design Line 2B SE Stereo Line Preamplifier is part of the MAD
Modular Series of preamp/power supply components. It offers the audiophile a number of
desirable features:

? ? Compact chassis layout for use with separate power supply for low noise.
? ? Exclusive use of NOS 12SN7GT octal tubes, known for low distortion and

musicality.

? ? Heater voltage switch for use of 6SN7GT tubes if desired.
? ? Low output impedance (less than 500 Ohms).
? ? Parallel output jacks.
? ? User-specified gains of from 0 to 22 dB.
? ? Premium Auricap polypropylene film signal coupling capacitors.
? ? Alps volume control.

Power Supply Connections______

The Mapletree Line 2B SE consists of a preamplifier chassis with a separate power
supply. This allows separation between the two units and eliminates induced hum
originating from power supply circuitry and components. The Mapletree PS 2 or PS 2a
power supplies provide 12 VDC (regulated) at 0.6 A for the heater supply and +200 VDC
at full load (12 mA) for the B+ plate supply. The PS 2a has dual power outputs that allow
the Phono 3 phono preamp to share the power supply with the Line 2B. The power
connections to the preamplifier chassis are made through a special power cord that plugs
into jacks located on the rear panels of the power supply and preamplifier chassis. This
manual refers to the PS 2 power supply. Operation with the PS 2a is identical.

CAUTION: Do not operate the power supply when it is not connected to the
preamp. Damage of components may result.

Once the interconnecting power cord is securely attached between the two chassis and the
line cord is plugged in, the toggle switch on the front panel of the PS 2 is used to activate
the power supply. The pilot lamp indicates that the unit is on. It takes about 30 seconds

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for the tubes to reach operating temperature ready for use. During operation, is it normal

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for the power supply chassis to become warm to the touch.

The power supply is protected by a 1 A/250 V fast-acting fuse located inside the power
supply chassis. Under normal conditions, it should not be necessary to replace the fuse. If
power fails to come on, you can check the fuse and replace with a spare if necessary.
Wait 60 sec with the unit unplugged before removing the bottom cover. If the fuse blows
a second time, you should not try to operate the unit. Contact Mapletree Audio Design for
information regarding service.

Input/Output Connections______

The signal input/output jacks are located on the rear panel of the preamplifier chassis.
RCA jacks are provided for three stereo line inputs, and two stereo line outputs.
Depending on how you ordered your Line 2B SE, the line input gains may be different.
The standard configuration is 10 dB for all inputs. Consult the invoice included with your
shipment to verify the gains for your unit. The upper jacks are the left channel. The line
input impedance (resistance) is normally 100 k? , which provides minimal loading of any
line source such as CD/DVD player, tape deck, tuner, or PC sound card. If one or more
inputs have been configured for other than the 10 dB standard gain, the input impedance
will be affected. See the schematic diagram for details. The line output impedance is less
than 500 ?? which is suitable for connection to a power amplifier through cables up to 10
ft in length.

The heater voltage switch located next to the power input jack allows you to
accommodate either 12SN7GT (supplied) or 6SN7GT tubes in your Line 2B. Note that

operation in the 12SN7 position with 6SN7 tubes installed will most certainly damage
the tubes.

12SN7

6SN7

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