Octave RE 320, Owner'S Manual

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7. TUBES
7.4. Replacing the tubes
 Driver tubes
Replacement driver tubes require no adjustment.
 Output tubes
:
General procedure
1.
Switch off the amplifier and allow it to cool down for 10 minutes. Remove the
old tubes and fit the new ones.
2.
Before you switch the amplifier back on, turn all BIAS adjustment screws (see
chapter 7) counter clockwise (this greatly reduces the anode current). These
screws are ten-turn potentiometers, i.e. it takes ten revolutions to go from the
maximum to the minimum setting.
3.
Switch on the amplifier and turn the BIAS selector switch to the BIAS position.
Following the Soft-Start phase, the "minus" LED (yellow) will illuminate at every
of the four Output tubes. If from this point of time any of the LEDs are green or
red, this indicates a faulty tube that must be replaced. After a 10-minute warm-
up period, set the BIAS as explained in chapter 7.
3.1
Original Octave tubes.
There is no need to break in original Octave replacement tubes, as they are
factory tested and passed a 24-hour endurance test. Allow the tubes 10
minutes to warm up and adjust them to the appropriate setting for the tube
type.
3.2
New, untested output tubes should be allowed a longer warm up period. You
should adjust these tubes after about 20 minutes and control the setting in the
first days of operation
7.5. Running in
All OCTAVE equipment is subject to a 48-hour performance test at the factory to break in the tubes.
The tubes are preselected for use in each particular model.
New tubes can take up to three months to run in and start sounding their best.
Daily use is beneficial in speeding up this process but is not mandatory. Continuous operation does
very little to help reduce the running-in time and is therefore
not
recommended.
7.6. Tube service life

Thanks to the protection circuits and soft-start electronics, the output tubes in your amplifier can
achieve a service life of up to 3 - 5 years.

Driver tubes can be used for 10 years or even longer.

Because tubes have different service lives, you will never have to renew the entire tube
complement at the same time. The facility for setting the BIAS for each output tube individually
makes it unnecessary to use matched sets of output tubes. You can replace output tubes
individually if you wish.

Some tubes require a long time (up to 300 hours) to achieve their optimum sound quality.
Depending on how long the tubes have been stored, it may be necessary to adjust the BIAS
several times in the first two to three weeks after installing them.