Avoid storing the amp in damp or dusty rooms to spare jacks, switches and
potentiometers. If you don't use the amp all the time, I recommend that you drape a
covering over it to prevent the intrusion of dust. Even better, keep it in a transport
cover or flight case.
Never use caustic or scouring detergents to clean the amp's housing, front or rear
panels. Use a soft, damp cloth or sponge with diluted soapsuds or a standard brand of
mild dishwashing liquid instead. Never use solvents they can corrode the amp's vinyl
skin and dissolve the front and rear panel labels. Keep liquids well away from the amp,
particularly the interior of the housing.
Make sure air can circulate at the front and top of the amp to allow for adequate
cooling, which increases component life.
Never operate the amp without an adequate load (a speaker, cabinet or suitable
terminating resistor).
High ambient temperatures place an additional strain on diverse components; so if at
all possible, avoid operating the amp at temperatures far higher than 30°C (86°F) for
longer periods. Running the amp at mains voltages exceeding the nominal mains input
voltage over longer periods can also shorten component life.
Replace tubes with selected tubes that satisfy ENGL selection criteria to forestall
microphonic properties, undesirable noise and unbalanced power amp signals.
Because power tubes' idle current (bias) must checked and possibly adjusted when
replacing tubes, this is a job best left to experienced and authorized specialists.
In this manual, MIDI programs are called presets and patches.
Though the MIDI standard defines program numbers 000 to 127, almost all MIDI
devices and foot boards indicate and control these programs using a 1-to-128
numbering scheme.
Glossary
MIDI Preset:
MIDI Channel:
MIDI specifications define 16 channels for sending and receiving MIDI data. The small
switches labeled 1, 2, 3, 4 and 5 on the larger piano-type DIP switch 46 on the back of
the amp determine the MIDI data receiving channel.
MIDI channels: 1 to 16, or OMNI (meaning that all 16 channels receive MIDI data).
MIDI Controllers:
The MIDI specification calls for 128 controllers numbered 000 to 127. The amp's built-in
MIDI system can process select MIDI controller data to switch certain functions off and
on as described on page 20 and 21.
If you wish to take advantage of this option, you will need a suitable MIDI foot board
such as the ENGL Z-15 that is able to send MIDI controller data with the specific
controller numbers assigned to the amp's functions (see the table on page 21). You will
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