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

[JazzMan]

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]

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

 

[JazzMan]

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

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
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[Michael Black]

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.

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

 

[JazzMan]

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

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

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"Rats and roaches live by competition under the laws of
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live under the laws of justice and mercy." - Wendell Berry
**********************************************************

 

[Michael A. Terrell]

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

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

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Michael A. Terrell
Central Florida

 

[kinyo]

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.