Preamp Controls; Tubes - Mapletree Line 2B SE User Manual

Preamp Controls____

The front panel controls of the preamplifier include a three-position source selector
switch to select between one of the three line inputs, balance control, and volume control
that acts on both channels.

Tubes____

The vacuum tubes supplied are new-old stock (NOS) and have been pre-tested. A burn-in
period of several hours may be needed to achieve the best sonic performance. Tube life
should be thousands of hours. Aging tubes may result in a reduced gain in one or both
channels or an increase in noise levels. Infrequently, a heater may burn out which is
indicated by total loss of sound. Replacement tubes can be obtained from several
suppliers in the U. S. and Canada. Mapletree Audio Design will attempt to provide
replacement tubes to customers at cost plus shipping. Some listeners enjoy trying
different brands and variants of tubes. The highly regarded 12SX7GT is equivalent to the
12SN7GT. The heater voltage switch permits the use of 6SN7GT tubes including the
5692 variant and currently manufactured types.
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