The pilot lamp on the front of the Phono 3C chassis indicates that the preamp is active. 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 quite warm to the touch.
The PSX power supply is protected by a 20mm, 1 A, 250 V fast-acting fuse that can be
accessed by removing the fuse drawer from the ac receptacle after disconnecting the ac
line cord. 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. A
spare fuse is also located within the fuse drawer. 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______
12SC7
(R)
12SN7
Power In Line 2
GndOut Ph 2
Ph 1
ON
OFF
Phono input selector switch
Power out to Line 2C preamp
(if sharing PS 2C power supply)
Power in from PSX power supply
Power cutoff switch
(normally left in ON position)
RCA jacks are provided for two stereo phono inputs, selectable using the toggle switch
located between them, and one stereo output. The same ground binding post is used for
both inputs. Left channel jacks (white) are uppermost.
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. Some listeners enjoy trying different brands and
variants of tubes. The highly regarded 12SX7GT is equivalent to the 12SN7GT.
Warranty___
Mapletree Audio Design warrants the materials and workmanship (parts and labor) for a period of 2 years
to the original purchaser. Tubes are warranted for 90 days. Electrolytic capacitors are heat sensitive with
lifetimes that vary with usage and are not covered by the warranty. Warranty service does not include
shipping costs.
