200W mezclador-amplificador /
mixer-ampliifier Manual del usuario / User's manual
14
PROBLEM
CAUSE
SOLUTION
Hum or buzz when a CD, cassette,
VCR or keyboard is connected to the
unit.
1 - The equipment and powered
speaker are not plugged into the
same mains outlet.
2 - The audio signal cable is too long
or too close to an AC cable.
3 - The mains cable has only two
conductors and therefore has not a
ground terminal and the chassis is
not grounded adequately.
4 - The cable is defective and has an
open shield.
1 - To determine if the hum is coming
from the equipment connected to the
powered speaker set the main
LEVEL
control to minimum and check if the
hum goes away. If that is the case,
connect the mixer and the powered
speaker to the same mains outlet.
2 - Use a cable that is as short as
possible and/or move the audio signal
cable away from mains cables.
3 - Replace the mains cord with one
that has a ground conductor.
4 - Replace the cable.
Hum or buzz when using lighting
controls in the same building.
1 – The audio signal cable is too long
or too close to the lighting cable.
2 – On a sound system with three-
phase AC, the lighting equipment and
the unit are connected to the same
phase.
1 – Move the audio signal cable
away from lighting cables. Try to find
out at what point the noise is leaking
into the system.
2 – Connect the sound system to a
different phase than the lights. You
may need the help of an electrician.
When speaking into a microphone,
voices are heavy.
1 – Microphone proximity effects.
Bass gets dramatically louder when
speaking too close to the
microphone.
1 – Speak a little further away from
the microphone and /or turn down the
low frequency equalisation if
available.
Feedback and howling appears when
the microphone level is turned up.
1 – The microphone is pointing
towards the speakers.
2 – The microphone is not directional
enough or the talker/performer is too
far from the microphone.
3 – Incorrect EQ.
1 – Place the speakers in front of the
microphones.
2 – Use quality directional
microphones such as cardioid, super-
cardioid or hyper-cardioid and/or
nicely (this is very important!) ask
the talker/performer to talk or sing
closer to the microphone explaining
why.
3 – Avoid high gain settings on the
equaliser.
