No. Type and Brand Function
V1 12AX7 A (Chan A input) B (Chan B input)
V2 12AX7 A/B 2
nd
gain stage/Cathode Follower
V3 12AX7 A/B Phase Inverter
V4-V5 EL-34 Output Tubes
V6 5AR4/GZ-34 High Voltage Rectifier
The version of output tube this amplifier is designed for is a matched pair of EL-34.
When replacing a pair of output tubes, it’s usually required to have the bias adjusted
for its proper output. There is an internal bias control and bias test points. Bias
adjustments should be made by a qualified service technician.
This amplifier is designed for 3 x 12AX7 or the proper equivalent preamp tubes. There
are several manufactures of preamp tubes. Each manufactures preamp tube will have
its own sonic properties. It’s up to the user to decide their own sonic preference.
The 5AR4, GZ-34 is the rectifier for the high voltage power supply for this amplifier. It is
recommended to use only this version tube in this amplifier for proper results.
Tubes must be installed in the correct orientation. The smaller, all-glass tubes have a
blank space in the ring of pins which must line up with the blank space in the ring of
tube pins in the tube socket, located on the chassis. The larger, bakelite-base tubes
have a small cylinder with an indexing key in the center of the ring of tube pins, and
this indexing key must match up with the corresponding slot in the socket on the
chassis.
The output stage of the Royalist is a class A/B (grid bias circuit). Bias adjustment is
necessary when changing output tubes unless the replacement tubes are the same
matching group as the tubes in the amplifier. There is an internal bias adjust trim
potentiometer and bias test points for bias adjustments. We suggest this procedure is
done by a qualified service technician.
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