Mapletree Ultra 4B SE User Manual

Volume

Ultra 4B SE Stereo Preamplifier

Modular Series

Ultra 4B SE Special Edition

Stereo Phono/Line Preamplifier

User’s Manual

Phono Line1 Line2

Mapletree Audio Design

Balance

Rev. Feb. 22/13

Mapletree Audio Design

Lloyd Peppard

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

[phone]

www.mapletreeaudio.com

[e-mail]

© Copyright Lloyd Peppard 2002-2013

-Specifications are subject to change without notice-

2

Introduction _

The Mapletree Audio Design Ultra 4B SE Stereo Phono/Line Preamplifier offers the
audiophile a number of desirable features:

? ? Compact chassis layout for use with separate power supply for low noise.
? ? Exclusive use of NOS octal tubes, known for low distortion and musicality.
? ? Switchable for use with 12SN7GT or 6SN7GT tubes.
? ? Precise RIAA equalization (±0.5 dB) using non-interacting passive and active filters.
? ? High input impedance and low output impedance.
? ? Parallel output jacks for bi-amp or headphone amplifier applications.
? ? Phono gain of 48 dB suitable for all moving magnet (MM) and high-output moving

coil (MC) phono cartridges.

? ? Audio grade polypropylene and polystyrene film capacitors in signal path.

Power Supply Connections______

The Mapletree Audio Design PS 2 power supply provides +12 VDC (regulated) heater
supply voltage and +200 VDC B+ plate supply voltage at a current of 15 mA (see
specifications). It utilizes a slow start cathode type rectifier tube (6X5GT) in conjunction
with low-noise ultra high-speed diodes to achieve all the advantages of tube rectification
(low noise, soft startup) with the high efficiency of a bridge rectifier topology.
The separate power supply eliminates induced hum originating from power supply
circuitry and components. 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.

Once the interconnecting power cord is securely attached between the two chassis and the
line cord is plugged in, the power supply can be turned on. The pilot lamp on the power
supply chassis indicates that the unit is on. It takes about 30 seconds for the tubes to reach

3

operating temperature ready for use. During operation, is it normal for the power supply

1

1

L

R

chassis to become warm to the touch.

The power supply is protected by a 1 A/250 V fast-acting fuse, which can be accessed by
removing the bottom chassis cover after the unit has been unplugged for at least 60 sec.
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. If the fuse blows a
second time, you should not try to operate the unit. Contact Mapletree Audio Design for
information regarding service.

Signal I/O Connections______

12SN7

6SN7

1

Out

Gnd Phono

2

Line

2

The signal input/output jacks are located on the rear panel of the preamplifier chassis.
RCA jacks are provided for phono input, two line inputs, and two line outputs. Left
channel jacks are at the top and right channel jacks are at the bottom. A binding post is
provided for phono ground. The phono input resistance is 47 k?? which matches standard
MM phono cartridge loading requirements. The input capacitance is approximately 50
pF. The line input impedance is 470 k???which provides minimal loading of any line
source such as CD/DVD player, tape deck, tuner, or PC sound card. 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 ground wire from the turntable should be
connected to the ground binding post to minimize hum pickup.

The heater voltage switch located next to the power input jack allows you to
accommodate either 12SN7GT (supplied) or 6SN7GT tubes in your Ultra 4A. Note that
the switch does not affect the heater voltage for the 12SC7 tubes. While it will do no

damage to switch to 6SN7 position with 12SN7 tubes installed, operation in the 12SN7
position with 6SN7 tubes may damage the tubes.