Problem with home theater speakers (connect, system, outlet, HD)

[KaiserD2]

I have a 2-year old pair of Sony home theater speakers which I am still using with a tv and also with a DVD player. One of them is the "master speaker" in effect. It has two separate RCA cable inputs, one of which is now coming from my cable box, one from the DVD player. It also has an "out to tv" RCA outlet which I using to run the sound into the TV as well. (The first HD tv I bought after buying this system had output jacks for audio, and I ran sound from the DVD player and from the cable box into the TV, and out of it to the speakers, but the new HD TVS don't have that feature, it seems. Digression there, sorry.)

Now the problem is that the speakers have developed a pronounced hum. It is coming and going, but it's bad enough to make them unusable. Can some one suggest how I might troubleshoot this? Thanks.

DK

[gguerra]

As far as troubleshooting, just plug in one device at a time to see what is causing the hum.

Now that you have a new TV you should have at least 3 HDMI inputs to use.

Your cable box should already have HDMI if it's less than 10 years old.

You DVD player may also have it.

Your TV probably has some type of digital output which your speaker probably does not support, you can use the RCA's for that, from TV to Speaker.

Time to go digital and switch to HDMI.

Cables can be found for cheap, they start about $5 each.

[harry chickpea]

Start by unplugging and replugging every connection.

Hum can be caused in various ways, such as a failing bridge rectifier, but more commonly the issue is ground continuity.

To make a complex subject simple, with some obvious errors in the pursuit of simplicity, your incoming powerlines have three wires going to your system - hot, neutral, and ground. Both the neutral and ground go not only to the power lines, but to a rod in the ground that acts as protection against a bunch of electric problems.

Your entertainment system also has a "ground." This is supposed to be connected to the main electrical ground - on all components. This is the reason why electric plugs are polarized or three prong. The most prominent connector is the neutral or ground.

When everything is working right, the ground system acts like an impervious shield around all the inner workings. If there is an electrically noisy appliance, such as a drill or saw motor, the noise cannot penetrate but immediately gets shunted to the ground rod outside your home.

When one plug is inserted backwards, or the outer shield on one cable or RCA connector fails, the system fails. With stereo RCA cables, since there are two, and the outer shield with ground is redundant, the system will "work" with one cable not connecting the grounds between the components.

Any break in the system can introduce hum. The place most noticed used to be from the tonearm of a record player to the preamp, where the signal strength was so small that any noise was amplified.

Intermittent hum generally indicates a bad connection somewhere. Most of the time the cabling is at fault, but it can be inside a component or power supply.

[grampaTom]

If your new tv has an HDMI outlet also labelled ARC be sure to use that outlet for your speakers.