LABOGA – The Beast 30 Plus
TUBES
Tube placement in the chassis
V1
– 12AX7 preamp tube. It's the very first tube stages of the preamplifier. Therefore it might
produce an effect called microphonic. It's a normal effect varying on the tube. First half of this
tube works only for drive channel and the second one works for both.
V2
– 12AX7 preamp tube. It's next stage of the preamplifier. First half of this tube amplifies the
signal, adding quite a bit of distortion, but only for the drive channel and the second half is the
inverter. Between those two stages the Effects Loop is located.
V3
÷
V6
– EL84M power pentodes working in push-pull circuit. They work with self biasing, so it's
not possible to adjust it after tube replacing. All four power tubes work, no matter which
output power mode is chosen, because lower output power is achieved by reducing supply
voltages.
Replacing tubes in the head version, is rather not possible without taking the chassis out of the
housing. You need then to unscrew four screws, take the chassis out a bit and then unplug the wire
connecting screen on the housing with the chassis – the
connector
is inside the chassis.
Preamp tubes are covered with metal shield. To take it of you need to twist it until it will pop out.
Power tubes are holed just by spring retainers.
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