Mapletree Mellow Boy 6SL7 User Manual

Power supply unit should be plugged into the amplifier unit with the tubes in
the correct sockets BEFORE POWERING UP. 6SL7/5691 goes in front socket and
the 6336/6AS7G/6080 goes in back socket of the headphone amplifier unit.
Please allow at least 12 hours for the tubes to burn in since they are new. It is
not uncommon to hear crackling and metal expanding for new tubes. They
require settling in, especially the 6336 which can be particularly noisy in the
beginning since it is trying to remove impurities due to the manufacturing
process from the plate and cathode. It is recommended not to have the
headphones plugged in for about 3 hours when installing a new 6336.
Do Not plug in headphones immediately after the high voltage LED, second
LED, goes ON. One has to allow the output capacitors to be charged up first. It
is OK if the headphones are constantly plugged in to the headphone amplifier
since the high voltage power supply ramps up slowly.
Stacking amplifier as shown on manual cover will increased hum. The
6336/6AS7G/6080 are more microphonic than usual. With some headphones
this may not be an issue. Low sensitivity headphones will produce less
audible hum. A magnetic shielding plate, 1/8" - 1/4 " steel plate, with acoustic
dampening, felt/rubber, can be used between the amplifier and power supply
to reduce the hum. If this is still an issue separate the power supply unit from
the amplifier unit.
For super sensitive headphones the 6SL7/5691 might require shielding. Just
place a metallic cylinder/ shield over the tube and allow the cylinder to touch
the mounting screws of the socket for the 6SL7/5691.
Do not clean with alcohol or paint thinner. Water damp cloth is sufficient or
dust off.
MapleTree Audio Design
100 Cliff Cres
Kingston, ON
CANADA K7M 1A8
al@mapletreeaudio.com
www.mapletreeaudio.com
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