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12.4 INTERFERENCE: HUM, BUZZ, HISS & RADIO etc.
Keep your EDB-2 and signal cables away from devices with strong
magnetic fields. These include large AC mains transformers,
generators, lighting control systems, fluorescent and unearthed neon
lighting. If possible, switch off equipment which is causing interference.
Keep signal cables away from mains and speaker leads. Uncoil mains
power leads!
Use highly screened instrument cables, shorter, uncoiled cable runs
and metal shielded jack covers with good solder connections.
When using the XLR DI outputs on the EDB-2 set the GND LIFT
button to cut earth loop hums if required.
AC Mains Filters are useful to stop an impure mains power source
affecting your amplifier.
If lighting is causing you hum and/or buzz try to power your amplifier
from a different AC mains ring which is not used for stage lights.
Hum and buzz can be generated in stringed instruments where there is
no earth connection between the output jack ground and strings or any
tail piece.
Cut externally generated hum via notch filter by cutting with Notch-Q
on minimum at around 50-60 Hz
Excessive hiss will normally be produced by a faulty device or poor
quality noisy device in the chain or by imbalances between different
gear. To reduce hiss, identify gear responsible and increase levels into
it while reducing its own gain or removing it. Also, turn down unused
channels and turn off EDB-2 XLR Switch if un-used.
Alternatively, reduce treble or use notch filter at Sharp "Q", at 6 kHz
(high frequencies) or use "Noise Filter" Rack Unit.
Radio interference within the signal may be caused by the use of poor
quality leads such as curly leads, especially where High Impedance
and low output passive pickups are used.
To avoid, use highly screened jack leads into inputs and use active
pickups.
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