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11. TROUBLESHOOTING
11.1. Troubleshooting
Hum and crackling
Hum in an audio system is often caused by several system components being grounded
individually. It is particularly common with tuners, VCRs, or satellite receivers, where the grounded
aerial cables cause a ground loop via the aerial input.
Power amplifiers are normally also
grounded. Removing the ground wire on your safety plugs is not a solution. You can isolate the
aerial earth connection with a special signal isolator. This device has no adverse effect on the sound
or picture quality of tuners or TVs.
The HP 700 SE is not grounded
and therefore cannot cause ground loops.
Solution
The XLR output on the HP 700 SE can be connected without ground connection to
interrupt a ground loop in the power amplifier with a grounded source device.
Alternatively, the IN 8 line input module can be used. This transformer-coupled XLR
input module also allows for ground separation.
Clicks and pops
Older refrigerators and 12 V halogen lamps can generate strong radio interference, and when they
are switched on and off, audible clicks and pops in the system’s loudspeakers may occur.
Solution
The only solution is to use a single-power socket board for your entire system and to
use a different power outlet in your listening room.
Channels are not balanced
Check that the RCA plugs are plugged in properly. Bend the outer ground contacts inward if
necessary. Sometimes the internal pin in an RCA plug may not be a tight enough fit, in which case
you should either replace the cable or the socket.
1) Damaged cables and poorly fitting RCI plugs can create resistance in the signal path, enough to
reduce the output level of one channel.
Solution
Try new cables or clean plugs and sockets with isopropyl alcohol. You could also try
cleaning or contact fluid.
2) A faulty tube can cause a drop in output in one channel and generate distortion. This is a rare
occurrence, the heater inside the particular tube may also be the cause of the problem.
Solution
Replace the tube.
Increased Noise on one channel
Noise that varies in level is a sign of a faulty or worn driver tube.
Solution
Replace the worn tube.
Tubes with this type of error can generally still be used in power amplifiers. The
increased noise here is rarely a issue.
