Digital TV, poor sound

[Derryanna]

Paul, my dear, there is no way your wife would not love you and I hope you never suffer any scarring from a fry pan. Chuckle!

Be aware at this point much of what I read of your information is 'over my head' as I am not an electrician nor highly versed in electronics. Years ago, friends and neighbors would ask me to come to their homes and explain what their Manuals were trying to convey, and, hopefully, ask would I assist in wiring some of their speaker systems and adjust their sounds. I have since always handled any new equipment that we purchase and do the connections of all. We have the various 5 TV's of all ages and Makes, three hooked to decent receivers and speakers.

The first thing I did when this Sound problem arrived was delete the internal TV speakers and revert to only Receiver speakers. Still, the bad sound came through only in a larger quantity.

The common link of all our TV's is, of course, they are all plugged into our house electricity. On one of my messages way above this one, you will read I wanted to disconnect ALL items in our home from ALL the walls. It seemed to me to be a smart way to achieve some proof. But, Cornucopia , as you will read, thought I was a bit out of my head, so to speak.

I also pictured in my mind the electronics had I purchased at the time we heard the bad audio. I wondered if when I plugged one of them in, did it in someway, affect the electricity and carry the problem to other TV's.

Our new purchases were a Panasonic Plasma TV, a Yamaha Receiver, and, I had an older set of 5 speakers, a change of Comcast Cable DVR, (we have two DVR's in our house plus one old Comcast Cable Converter Box). and lastly, a new digital tuner Panasonic LCD TV. The purchase of the LCD was for its' modern tuner and the ability of that Tuner to bring in digital channels WITHOUT paying the Cable Company for another Converter Box.

Now, and think about this, the Cable Company soon realized what the Public was doing and so started deleting from the cable all the better digital channels we were getting free. In order to obey the Laws, the Cable Company had to, free of charge, deliver to anyone wanting it, free analog converter boxes. These are small, simple, devices, we hook to our TV and the box converts the digital sound back to analog sound, but then, though we could only receive about 76 channels, that was better than the junk channels with which Comcast Cable company had left us.

Where my mind is now, is that little analog converter. I have delayed in unplugging it as then I have to contact Comcast Cable, wait and wait, to have a Cable company employee reset the box when I again replug it to the wall. There is that slight possibility that little conversion box is messing with our house. Far reaching, I am sure, but, I am grabbing any train of lucid thought I can.

Anyway, my new Friend, I will pounce on my sometimes errant Husband who understands electricity, interference, etc., better than I, and maybe he can read your advice and act upon it. In the meantime, that little analog box hooked to the Panasonic LCD digital TV, is going to be unplugged today. We will see if it has any association with the other TV's. If one of our TV's was small enough to carry, (none are), it would be a good idea to try it out at one of our Neighbor's homes just to cover all our bases. Your idea is good.

I keep thinking of your fellow with the Hearing Aide and how you were able to track down the interference bothering his Aide. I have even thought of Neighboring electronic garage openers bothering our TV's, but, of course, they would have to be using the Openers constantly. Laugh!

By the way, my Mother's side of our family has the surname of, "Chamberlin". The family story is he was a close relative of your Prime Minister Chamberlin of long ago. The "Pond" is shrinking, huh?

Dee

[Derryanna]

Paul, I am now on page 3 of this thread.

Dee

[Derryanna]

Paul, I almost forgot. If you and yours ever are here in America, we would love to meet with you. As to understanding each other, our Country is amassed with accents of all kinds. My problem with understanding is when I listen to an Australian. Laugh!

Dee

[jagabo]

What I've done to improve the sound on some of my TVs is open them up and disconnect the internal speakers. Then run those speaker wires to external speakers. Our main HDTV has a pair of Polk Audio R300 towers connected this way. Fry's sells those speakers for about US$100 per pair. Those aren't the greatest speakers in the world but they're far better than the internal speakers.

If you don't want to open up your TV you can run a pair of powered speakers off the headphone or line-out jack. One of your TVs has a pair of M-Audio AV-30 speakers connected this way. Beware, a lot of computers speakers sound really bad too!

TV manufacturers don't care about sound. They just toss some crappy speakers in the cabinet and call it done. LED backlight TVs are the worst. There's no room for decent sized speakers in the case so there's no bass or even lower midrange.

[Derryanna]

Hello, jagabo! Well, the first thing I did when all this sound business started, was to eliminate my TV speakers and only use my Polk speakers and Sony receiver. The same thing in the other rooms where I was connected to my full Yamaha and Kenwood sound systems. But, it makes no difference and they all still sound the same. Something I connected a couple or so years ago is the culprit. Also, the Comcast Cable is a possibility with their analog converter. I will disconnect that today and see if there is any improvement.

Speaking of computer speakers, my son flew from Atlanta, Ga., after he had ordered a specially made Dell computer system for me, and, he wired the computer room with a full 5 speaker system. It was nice of him, but, jagabo, I really do not need all the speakers. Still, the Dell speakers are quite wonderful, but, being I am in a 10 by 10 room, probably anything would sound good.

You are right, though, as I listened to loads of speakers some years ago and at that time Polk did quite well. Other highly named Brands were not as good. I did pay quite a bit more than $100 per each.

When my DVD Player, which was hooked to a TV that had NO Cable connection, had the same audio distortion, I knew at that point the Cable Company was not involved. The movie DVD still had that over amplified stereo sound. Now, as I mentioned, I am suspicious of the little analog converter box though it was not connected to that TV, but, still connected to an electrical room plug. All of you have been thinking there might be a chance of adulteration through the electrical wiring in our house.

Did you read Paulyvee and his experiences of odd happenings with vibrations/signals/ electricity? This era of micro waves, cell phone waves, TV signals, etc., is still putting us in unknown territories of what these traveling signals can do.

Dee

[paulyvee]

Dee
Yes I know that i talk techno - speak and also sometimes suffer from verbal diorea. However I have a good excuse - I am a technician.

Let me see if I can Translate what I think the problem is - in fact what the problem is on my own kit - almost an identical effect.

Assume one of your kids is playing on a trampoline set up in the house.
He is jumping up and down quite fast about 4 feet high - representing mid frequency sound and your trampoline is 1 foot high with a 8 feet ceiling.

Absolutely no problen

Now - introduce a very slow jack under the trampoline - so slow he doesn't notice - the bass sounds you can't hear because the speaker system is too small
Jack the trampoline up and down with the same amplitude signal - 4 feet.

Now do the maths.
No jack - all is good.
Jack set to 1 -2 feet - things are getting a bit hairy.
Jack up - 3 feet
Now your kid is bouncing off the ceiling
Jack fully up - 4 feet
Now he has either decreased the height of his jump or his head ends up 1 foot through the ceiling.

This hopefully demonstrates the interaction - cross-modulation caused by the two signals.

Now if you look at the transmission spectrum.
Same kind of effect BUT in an analogue world the television stations tended to reduce the bass amplitude to perhaps a 2 foot high jack.

No matter how much you mixed it up he was always 1 foot clear of the ceiling.

Analogue systems inherently have a narrower bandwidth that digital systems. - the coupling components between the various stages in an amplifier are frequency concious. Capacitors for instance couple a high frequency better than a low and these introduce a low frequency roll off

Now lets digitise the signal.
Take your jack and a tape measure.
Measure the height every second and write down the result. It doesn't matter how fast or slow you send those measurements to someone they do not change - it just takes longer to receive them. .
The quicker you measure the height - digitising rate - the more accurately you can reproduce the movement. If you are too slow the jack may have reached its maximum and started dropping for example and you would miss the maximum.

Analogue systems have a bandwidth of 50hz to perhaps 18khz.

Digital systems - providing the digitising rate is fast enough have a bandwidth from DC to wider than the audio band. If you keep measuring the jack even if it does not move you still have a string of data to send. It just doesn't change.

The major difference between the two is if the analogue signal is small inherent circuit noise is a large factor and if video you get a noisy signal. If the digital signal is small it just don't work - the screen isn't updated and the picture freezes.
BUT - if the signal is large enough they both work well.

The digital signal frequency of update - the rate of sending the messages is fixed so bandwidth is less of a problem. We are now more concerned with high frequency performance so that the digital signal is not distorted - bandwidth needs to be at least 10 times the digitising rate or the square on-off signals start having their edges rolled off - they start becoming analogue.

One of the selling points of the conversion to a digital world is the better performance of systems bandwidth wise but only providing the rest of the system is able to handle it.

I hope this is a bit clearer.
See - i warned you about the verbal excess

All the best - Paulyvee

[Derryanna]

Paul, I have read all your comments, as well as the comments of others, to my husband, and, between us, we are going to start our search. I will let you know the results in a few days.

I have been very, very, blessed by the help of all of you. Thank you.

Dee