Oh no! Mismatched Audio Levels in Analog Phone Patch :(

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#1 21660836 22 Jan 2012 23:09

Drake Anubis Drake Anubis

Anonymous

Post #1
21660836 22 Jan 2012 23:09

I'm trying to play audio from a cd-player into a phone line using a 600 ohm 1:1 transformer taken from an old modem. It works, however the audio is almost twice as loud on my end than it is on the receiving end. Any ideas why?

Any help would be appreciated!
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#2 21660837 23 Jan 2012 06:49

Calinoaia Valentin Calinoaia Valentin

Anonymous

Post #2
21660837 23 Jan 2012 06:49

What is the output impedance of your CD player ?

And I don't understand exactly what you're trying to do: you want to play music on a CD and hear it on a telephone ?
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#3 21660838 23 Jan 2012 06:56

Drake Anubis Drake Anubis

Anonymous

Post #3
21660838 23 Jan 2012 06:56

It doesn't say; is there a way I can measure it?

And sort of. I would like to play sounds from the cd player into the phone line so that they can be hear on the remote end of the call. Although the cd player was just for testing, in the long run I wanted to use it for radio phone patches and other applications. Will the circuit have to be tuned for each device?
#4 21660839 23 Jan 2012 14:37

Calinoaia Valentin Calinoaia Valentin

Anonymous

Post #4
21660839 23 Jan 2012 14:37

You can't measure the output impedance ...

It seems that you need to attenuate the output level of the CD-player.

Try using a 50 K potentiometer between the CD out and the 1:1 transformer like this:
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Oh no! Mismatched Audio Levels in Analog Phone Patch :(

Oh no! Mismatched Audio Levels in Analog Phone Patch :(

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