Mapletree Ultra 4C User Manual page 6

currently manufactured 6SN7 tubes may work well in the series configuration but this
should be verified by measuring the voltage across each tube heater (pins 7-8).
Care of your Ultra 4_____
The chassis finish is lacquer-based. Both the chassis and labels/logos are moisture resistant but
you should avoid cleaning with water, alcohol, or other strong chemical. A soft 1" paintbrush is
recommended to dust the chassis periodically.
Heat is the most troublesome enemy of electronic components, especially capacitors. Heat can be
properly dissipated by ensuring free air circulation around the preamp and power supply chassis.
It is not recommended that you leave the power on when not in use.
Warranty___
Assembled components are warranted for 2 years to the original purchaser for failure of parts
(excluding tubes) and workmanship. Tubes are warranted for 90 days exclusive of shipping cost.
Service, including parts and labor (but excluding shipping), is free within the warranty period.
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