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The above values are a guideline but should be OK for most brands of valves, although
the bias point for any amplifier is somewhat subjective. Increasing the values shown may
improve the tone but will make the valves run hotter, whereas lower values will increase
valve life and reliability.
9. Now insert black probe into V2. The other BIAS ADJUST control should now be
adjusted to give a reading on the voltmeter as close to 0mV as possible (+/-1mV).
10. Repeat steps 7, 8 & 9 until no more adjustment is required.
For more advice on this please contact the Service Dept. or distributor in your territory.
The output valves on the GA-30 do not require biasing to be manually set due to the
CATHODE SELF BIAS design of the output stage. Therefore to change valves simply
follow points 1, 2 and 3 immediately above.
IEC Socket/Mains Fuse
This is for connection to universally used IEC mains leads to connect to appropriate
domestic mains supply.
In the event of having to replace the mains fuse always use the same fuse rating and type
as marked on the unit's rear panel. Using one of a higher rating will invalidate the
warranty.
If after replacement the mains fuse should blow a second time, immediately refer the unit
to an approved service engineer for checking.
Super "Goldtone" Cabinet Instructions
The Super "Goldtone" speaker cabinet incorporates a sealed (infinite baffle) 2x12"
bottom, with two Celestion Vintage 30 speakers, and an open backed 2x10" top, with
two Celestion Vintage 10's.
The power rating of these individually is 60 watts RMS, therefore the power rating of the
whole cab will be 240 watts RMS.
The rear panel sockets and switch allow the cabinet to be configured as either a 4Ω
mono cab, a 16Ω mono cab or a 2 x 8Ω stereo cab. To prevent serious damage check
that the correct impedance is set on both amplifier and the speaker cabinet each time
that they are used. Also make sure that any cables used to connect to the cabinet are
proper speaker cables (NOT GUITAR/INSTRUMENT CABLES) and that they are in good
working order.
When set to 8Ω stereo, a separate amplifier can drive into each of the sockets, however,
when set to mono, either 4Ω or 16Ω, only one of the two sockets should be used at
once. The likely result of driving two amplifiers into the cabinet when set to this
configuration could be the destruction of both the amplifiers and speakers.
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