Octave HP 300 SE, Owner'S Manual

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11. TROUBLESHOOTING
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Hum and crackling
Hum in an audio system is often caused by several system components being earthed
individually. It is particularly common with tuners, VCRs or satellite receivers, where the earthed
antenna cables cause a hum loop with other earthed units. Power amplifiers are normally earthed
too. Removing the earth connection on your mains plugs is not a permitted solution. You can
isolate the antenna ground connection with a special signal isolator. Such a device has no
adverse effect on the sound or picture quality of tuners or TVs.
The HP 300 SE is not direct earthed and therefore cannot cause ground loops.

Clicks and pops
Older fridges and 12 V halogen lamps can cause cracking through the loudspeakers when they
are switched on and off.
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 a tight fit. Bend the outer ground contact inwards slightly if
necessary. Sometimes the internal pin in a RCA plug may not be a tight enough fit, in which case
you should change either the interconnect or the socket.
1. Damaged cables and poorly fitting RCA 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. Although a
rare occurrence, the heater inside the particular tube may be the cause of the problem.
Solution: Replace the tube.

Increased hiss on one channel
Hiss that varies in level is a sign of a faulty or worn driver tube.
Solution: Replace the worn tube.