Converting mon amplified audio out to lstereo line input (line level?) in

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JazzMan 20 years ago

I want to use my TV's built in speakers as the center channel for my old ProLogic surround. My TV has stereo audio inputs, my ProLogic receiver/amp has only amplified center outputs in mono. I had thought about trying to take my TV apart and cutting the speaker wires loose from the main board and then running them to a jack (added by me) on the back panel, but the TV is just too heavy for me to work with due to a blown disk.

So, I thought about just making a cable that went from the amplified center out on the receiver to the audio input jacks on the TV, turn the receiver center volume way down, the TV volume way down, and then hope for the best, but I think there will be a problem with the linearity of the volume control this way, plus it just seems like an inelegant hack job.

My question is, is there a simple, easy way to convert the amplified audio in mono from the receiver/amp to a line level source in stereo? I have a center channel speaker but can't use it because it physically won't fit within 5' of the TV where I've got it mounted now.

Thanks!

JazzMan

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PeteS 20 years ago

Well, if you are trying to make a mono input (on stereo outputs), then simply sum the channels.

Take your left and right channels, from now on L and R

Now use a simple summing amplifier to yield L+R. There's your mono output. You may want to buffer each of the inputs to the summing amp.

Cheers

PeteS

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JazzMan 20 years ago

I need to go the other way. I have a mono amplified output from a receiver/amplifier, this output is designed to run a center speaker. The TV has stereo line-level inputs to run the stereo speakers in the front of the TV.

The only reason I want to convert mono to stereo is so that both TV speakers are being used, otherwise the center channel audio will be off center. The TV doesn't have a mono input.

JazzMan

********************************************************** Please reply to jsavage"at"airmail.net. Curse those darned bulk e-mailers! ********************************************************** "Rats and roaches live by competition under the laws of supply and demand. It is the privilege of human beings to live under the laws of justice and mercy." - Wendell Berry **********************************************************

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JazzMan 20 years ago

Yes, I was aware my original question was not clear enough, but I'm glad I got my though across on the second try. :)

For attenuation, is a resistor enough? What about issues of scaling, i.e. small changes in amplifier output produce wide changes of volume on the TV speakers?

JazzMan

********************************************************** Please reply to jsavage"at"airmail.net. Curse those darned bulk e-mailers! ********************************************************** "Rats and roaches live by competition under the laws of supply and demand. It is the privilege of human beings to live under the laws of justice and mercy." - Wendell Berry **********************************************************

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Michael Black 20 years ago

Then your original question wasn't clear. At the very least it was too cluttered.

Take the mono signal, and feed it into both audio channels of the tv set. You can get y-adaptors that will do this, or just get a cable that fits into your receiver and splice it to a cable that will fit into your tv set. Wire the two tv set end plugs in parallel __________left jack of tv set | signal--------| |__________right jack of tv set

ground--------ground of tv set

If you're fussy about signal levels, then add an attenuator at the output of the receiver, a pair of resistors.

Michael

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Michael A. Terrell 20 years ago

Use a pot instead of two fixed resistors so you can adjust the level.

Link to my "Computers for disabled Veterans" project website deleted after threats were telephoned to my church. Michael A. Terrell Central Florida

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kinyo 20 years ago

JazzMan, You do need to attenuate the amplified outputs using resistors and/or capacitors. The attenuator circuit would depend on the ratings of the output amplifier ... how many watts into what ohms ... and it is also important to know whether the (-) terminal of center speaker is ground.

If the (-) terminal is not ground, the circuit will require some sort of dc isolation, hence some capacitors or isolation transformer is necessary.

If the (-) terminal is ground, the attenuation circuit would only consist of two resistors as voltage divider. If say the center amplifier is typically rated 25 watts into 8 ohms, it wouldn't hurt to start with 100 ohms and 10 ohms resistors.

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Converting mon amplified audio out to lstereo line input (line level?) in

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