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Balance Audo Circuit

Discussion in 'Electronic Design' started by Astro, Apr 4, 2007.

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  1. Astro

    Astro Guest

    I need help with a circuit design.

    I am using RS232 4-wire audio output and need to bridge into another
    piece of equipment.

    I would like to used and build an audio bridge with matching impedance
    between the input of the bridge in the output of the bridge to other

    The output of the balance circuit would also be 4-wire audio. I need a
    circuit that will match impedance of 600 ohms both both input & the
    out put.

    I have had trouble finding what size resistors to used in the bridge
    to match the impedance.


  2. Eeyore

    Eeyore Guest

    What exactly do you mean by 4 wire audio ?

    Telecoms ? 600 ohms is no longer used for audio outside of that specific area.

  3. Astro

    Astro Guest

    RS232 will be used for the line which of course os 600 ohm. This is
    not being used with telco equipment but with LMR (Land Mobile Radio)
  4. Eeyore

    Eeyore Guest

    Is it ? That's news to me ! I think you'll find it's not actually.

    RS232 is a digital serial data protocol.

    It seems to me you're confusing hardware with communications standards.

  5. Don Bowey

    Don Bowey Guest

    RS232 is not an audio spec; it's for digital signals.

    Are you trying to build a "phone patch."

  6. Tam/WB2TT

    Tam/WB2TT Guest

    So you want to use existing RS232 wires for audio? The short answer is
    forget the whole thing. RS232 wires may be 600 Ohms. They may also be
    anything else, including 50 and 900. To put audio on unshielded wires, you
    want twisted pairs, but RS232 may or may not be. Your wires are probably
    less than 50 feet long, and don't require matching if you drive them from a
    low impedance source. You don't match speaker wires. If you insist on doing
    it, one way is to use transformers, and pick the 8 or 16 Ohm tap.

  7. Robert Baer

    Robert Baer Guest

    RS-232 is a bi-directional *data* communication specification and is
    not related to audio.
    So your info is incorrect and incomplete, making for no answer.
  8. Robert Baer

    Robert Baer Guest

    I have seen 500 ohms as a reference in studio work...
  9. Robert Baer

    Robert Baer Guest

    I think that the full RS-232 spec covers both hardware and protocol.
  10. Eeyore

    Eeyore Guest

    Not in anything built in the last several decades.

  11. Eeyore

    Eeyore Guest

    It standardises the connector(s), their pin connections and voltage levels AIUI but
    is widely ignored anyway in recent kit.

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