Beyerdynamic MA 212 User Manual

9. Slowly turn up the source equipment input gain controls until you begin to hear

the sound source from the loudspeakers connected to the amplifier. If the sound
is clear and undistorted, adjust the system level to the desired listening levels.

10. If you want the ducking function of the microphone inputs 1 and 2, it has to be

activated (refer to chapter “4.1.1 Priority switching”).

• The power switch is not switched to the 

ON position

• The AC plug is not connected
• The AC power source is defective

• Defective fuse

• Switch the power switch to the ON 

position

• Connect the AC plug properly
• Locate and correct the AC mains 

problem

• Check and exchange the fuse

• Turn the volume control up
• Locate and correct the short circuit

• Reduce output level of the sound 

source (for sound carriers)

• Make sure that the impedance is not 

below 4 

Ω

• Check the loudspeakers, disconnect 

one if necessary

• The source itself has a hum

• The input wiring passes near AC mains 

wiring

• Defect in the unbalanced wiring

• Determine  if the source is defective 

or wired incorrectly and correct

• Reroute the input wiring

• Balanced connection to the input
source

Hum in the output

No or distorted sound

No reproduction

• Volume control is set to “0”
• There is a short circuit on the loudspeaker 

output

• Input level is too high

• The loudspeaker impedance is too low

• There is too much loudspeaker load on the

output

• The source itself has a hum

• The input wiring passes near AC mains 

wiring or wiring to lighting dimmers

• There is pickup of RFI (radio frequency 

interferences) from TV transmissions. This
kind of interference sounds like power 
line related buzz, but tends to change in 
character every few seconds due to 
changes in the video image.

• Determine if the source is defective 

or wired incorrectly and correct.

• Reroute the input wiring

• Try different cabling or grounding 

techniques. Try to solve the problem 
by using the 0.1 µF capacitor connected
to bypass the shield. Try different 
routing of input and power cables.

• The source output is set too high and the 

gain control of the amplifier is turned way
down to compensate

• The source itself is distorted

• Reduce the source output level and 

increase the setting of the gain 
control of the amplifier

• Try a different source and/or have the

source repaired

Distortion in the
output

Buzz in the output