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Sharing an audio output between 2 amps

Discussion in 'Audio' started by TTL, May 25, 2015.

  1. TTL

    TTL

    182
    5
    Oct 24, 2013
    I would like to add an amplifier/speaker to an audio output which already goes to another amplifier/speaker. Can I simply connect my new amp's input to that output line or would I need to use some additional circuitry in-between so as not to negatively affect the existing audio?

    The project involves a computer with stereo line-level outputs and a mono output (not sure which level) which goes to its computer display output connector (as the monitor has a built-in speaker). I want to put a small (1-2W should suffice) mono amp and speaker inside the computer as well and assume I can use the same output pin which goes to the display output connector.

    Computer's audio generating & output section:
    Audio_out.png

    Computer's video display output connector (with audio output for the monitor's internal speaker):
    DIN13_audio.png
     
  2. ramussons

    ramussons

    342
    61
    Jun 10, 2014
  3. TTL

    TTL

    182
    5
    Oct 24, 2013
    I was afraid this would affect the impedance or something. Perhaps I'm confusing this with mixing two audio outputs into one input, and not the other way round (one output split into two inputs)?
    Does it seem the "AUDIO" labelled output (mono) in the first schematic is a line-level signal? I was thinking of using this low cost 2W mono amp or this even cheaper mono amp. Do they seem to be suitable?
     
  4. ramussons

    ramussons

    342
    61
    Jun 10, 2014
    The input impedance of the amplifiers, will normally not be an issue. But in your case, you will need to convert the stereo to mono to feed the mono amplifier. You can connect the display amp without any problem.

    Connect 2 pieces of 47 K resistors to the input of the mono amp and connect the stereo sources to the free end of the 2 resistors.

    Technically, you will be introducing what we term as "cross talk" between the left and right channels, but in your setup, this is of purely academic interest.
     
  5. TTL

    TTL

    182
    5
    Oct 24, 2013
    So you're saying that I can't tap into the already mono signal (which goes to the display's speaker) but I need to use the line outputs instead? I intend to be using those stereo line-level outputs for situations when I want to attach an external amplifier, so attaching this new mono amp shouldn't affect that audio.

    Here's a drawing of what I first thought would be possible:
    direct_mono.png


    And here's a drawing of what I believe you're suggesting instead:
    stereo_mono.png
     
  6. ramussons

    ramussons

    342
    61
    Jun 10, 2014
    You are mentioning a "mono" output in your computer. I have not seen a computer that gives a "mono" output.

    That aside, from what your schematic shows, connecting the mono amp parallely to the monitor as you have shown is okay.

    My suggestion was presuming that the computer has a stereo output feeding stereo speakers on the monitor and an addition of a mono amp.
     
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