what causes background huming noise in audio when playing through tv or amplifier?

Answer 1

Usually one of two things:

1) Poor earth (ground). One of the connections isn't sitting right and the interference is causing the hum. Check all the connections are tight and the problem should be solved.

2) Poor quality equipment. This is one of the problems with cheap audio and TV equipment, especially from Argos or supermarkets. You can't do anything about it, except buy new kit.

Answer 2

CAUTION: Do not defeat polarized plugs they are polarized for a reason. Doing so may result in damage to the equipment or the user (that is you).

1. Non polarized power plug needs to be turned around and plugged in the other way (110 volt AC American outlets).

2. Audio source and TV/Amplifier are not plugged into the same outlet or power strip. Or one is plugged into a different level of filtered power than the other is plugged into. Or one is in a battery backup power supply and the other is not.

CAUTION: Do not place high current drain devices on a battery backup supply it will damage the battery backup unit for most consumer models.

3. Audio source and TV/Amplifier are not in the same outlet and worse the outlets are 180 degrees out of phase with each other (fundamental aspect of 110 volt circuits in a home where 220 volts is also available for the air conditioner and the large appliances that use it).

Line 1 -- 110 volts --- Phase 0 degrees ---- Point A

Neutral --- 0 volts --------------------------------- Point B

Line 2 -- 110 volts -- Phase 180 degrees -- Point C

Ground -- 0 volts --- Grounded at Building - Ground

Some of your outlets have 110 volts coming from Point A with connection to Point B for the return to Neutral. The other outlets have 110 volts coming from Point C with the return to Point B for Neutral. Your 220 volt power comes from Point A and Point C with no return to Neutral. The hum is hard to explain in lay person's terms but it goes away if both devices are on the A-B or the A-C power lines and not mismatched with one device on A-B and the other on A-C.

Also hum can come from the audio source if the music or voices are really soft (not loud) and the amplifier is turned up a lot (almost full volume).

I helps to properly record the levels.

Answer 3

This doesn't usually occur with more modern televisions, (i.e Plasma or TFT Screens), but if yours is CRT, (tube), driven then this is an unfortunate norm.
CRTs need a lot of power. this is usually generated by a component called a HTR, High tension rectifier. the EM Field generated by this unit will definately be heard through any additional amplification circuit.
Try to put as much distance between your TV and amplification, (including Loudspeakers and Tape-decks) as possible. This can often make a great deal of difference.

Hope this helps!

Take care. C.J.

Answer 4

This is almost certainly a bad earth connection. Check that all audio plugs and sockets are fitted tightly, especially the SCART ones..