LEEDS WORLD HIZ PRE User Manual - page 11
OPERATION____________________
3.5
Output Level
For ideal signal-to-noise ratio (clean signal with lowest noise),
it is recommended that the output level of the HiZ Pre is set as
high as possible without overdriving the mixer, console, or
amplifier while keeping the input level on the mixer, console, or
amplifier at a minimum.
3.6
Vacuum Tubes
The HiZ Pre comes supplied with a 12AX7 vacuum tube. Tube
life and performance are affected by how often a tube is used
and by how hard the tube is driven when in use. Signs of wear
may be exhibited by poor performance or by the tube
becoming “microphonic”. Periodic replacement of vacuum
tubes is recommended. The time between the suggested
replacement varies greatly with the amount of the nature of
use of the vacuum tube. A good rule to follow: If you notice
deterioration in sound quality, then it’s time to change the tube.
Tube replacement can be accomplished by following these
steps:
1.
Unplug the unit from the electrical outlet
2.
Remove the (3) knobs on the front panel by loosening (not
removing) the screws on the side of each knob
3.
Remove the (3) nuts and washers from the potentiometers
(posts under knobs)
4.
Remove the plastic nut on the front panel input jack
5.
Remove the (8) screws which attach the front/top to the
chassis.
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