Question - how to hook up telephone through stereo?

Discussion in 'Pro Audio' started by daveallston, Sep 19, 2006.

  1. daveallston

    daveallston Guest

    I have a question that I'm desperately searching an answer for. I am
    wondering if it is possible (I'm pretty sure it is) to hook up the
    telephone through my stereo (or even the computer). I have a group
    meeting to host at my place, and would like to have a friend who will
    be calling in via phone participate. But I want to avoid having to use
    speakerphone, since speakerphone is always crappy sounding/distorted,

    I know in the past i messed around a bit with wires and what not, and
    was able to run my phone through my little tabletop tape/cd stereo. The
    sound was awesome.

    I'd like to do this again, and would like some on advice on what i
    might need to buy to make it happen. Or if its possible to hook the
    phone up through the computer, so the audio runs through my computer
    speakers (and I guess then I could hook up some mics to send the audio
    out).... would that work?

    Any advice on the best/easiest way I can do this to achieve the best
    possible sound is much appreciated. Thanks!!
    Dave Allston
    daveallston, Sep 19, 2006
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  2. daveallston

    Mike Rivers Guest

    Speakerphones sound crappy because many of them ARE crappy. You can buy
    a good one, but not for $19.95 with a built-in answering machine and
    beer tap. But there's a limit to how good a telephone converstation
    will sound because telephones are crappy, and the bandwidth is severely
    limited. Will this be listen-only, or will you want the group to talk
    to the caller? When you have a live microphone and a live loudspeaker
    in the same room, you need to do something to prevent feedback, and of
    course the person on the other end of the call will hear all your
    lovely room acoustics.

    There's a device called a "hybrid" which is used to interface a
    telephone line to a studio console. It's what radio statiions use when
    they have on-air call-in shows. JK Audio is one of the major suppliers.
    Sell it. Anything that can make a crappy telephone sound awesome has
    gotta be worth a lot.
    Buy a $1500 speakerphone. I sometimes work in an office that has a
    couple of Polycom speakerphones (I think they call them "conference
    station" to justify the price) and they work very well. That's best and
    easiest. Now your only problem is where to get the $1500.

    Oh, and you aren't going to build something at home using a few wires
    that will approach the quality of this unit. You can amplify the caller
    (listen only) fairly easily and it'll sound better than his voice
    coming through a $20 plastic box. But to make something that works like
    a telephone is more complicated.
    Mike Rivers, Sep 19, 2006
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  3. Radio and TV programs do this all the time. The device used is called a
    Telephone Hybrid Coupler. It provides for a line level input from a mic
    mixer, a line level output that can be added to a program mix and/or sent
    to a speaker, and a hookup across a phone line. A phone is use to
    establist the connection and then a button is pushed causing the coupler to
    "seize" the phone call.

    Telos Systems makes some of the best couplers. Visit
    to learn more.
    Roy W. Rising, Sep 19, 2006
  4. daveallston

    Julian Guest

    BTW, I have a big preference for the JK Audio ones Mike linked to over
    the Telos ones. JK's sound better and have less null problems IMO.

    Here's one even cheaper than the cheapest JK by a company I can
    recommend. I haven't used this particular device but I've bought
    maybe a dozen of this company's other devices and been on the phone
    with the owner/designer several times:

    Of course, the results will be less than perfect but for $119 instead
    of $700 and up, what do you expect?

    If that's still too much money you can always use a coupler (NOT
    hybrid), but there is no feedback prevention in a coupler. Still
    could work if money is your main limitation:

    For $88:

    Julian, Sep 19, 2006
  5. daveallston

    Mark Guest

    to the op...

    is your friend on the phone going to only be talking, or only listening
    or will (s)he do both???

    the problem with both is that simple bi-directional connections to the
    phone create a feedback path, thats what the hybrid takes care of....

    if you need a bi-directional set-up your best bet is to get a decent
    speaker phone...they have a hybrid and automatic talk/listen switching
    going's not a simple connection and an amplifer...

    Polycomms are very good, but not cheap...

    Mark, Sep 19, 2006
  6. daveallston

    Julian Guest

    Last month I was working on wiring a 16 mic Polycomm system for a
    video conference center at the University. It has an automatic
    camera control which follows whoever has their mic turned on and 3 of
    the largest damn plasma screens I've ever seen. It's awesome to see
    it working.

    Julian, Sep 20, 2006
  7. daveallston wrote ...
    Sure there are several ways of doing it. Which one is likely
    best for your situation depends on several things you did not
    disclose (budget? one-time vs. ongoing, one-way or two-way,
    etc. etc .etc.)
    What does "participate" mean? Will they be delivering a
    speech to the people assembled at your place, or do you
    expect a two-way conversation?

    If it is one way only (from the phone line to your stereo)
    then you could likely use one of the inexpensive gadgets
    from Radio Shack which are sold to people who want to
    record their phone conversations.

    OTOH, if "partcipate" means 2-way, then you have no real
    choice but to use at least a speakerphone, if not a real phone
    patch or "hybrid".

    Not at all clear whether the "crappy sounding/distorted"
    signal is caused by the speakerphone, or by the telephone
    at the other end and/or the telephone system itself. Remember
    that the telephone system is *by-definition* quite low
    There is significantly more to a speakerphone (or a phone
    patch/hybrid) than a speaker and microphone(s). There is
    actually a rather sophisticated circuit which prevents feedback
    at your end from the sound of your microphones coming back
    out the speakers at your end.
    What is your budget?
    How often are you going to do this?
    Do you need one-way ("simplex") or
    two-way ("duplex")?
    Richard Crowley, Sep 20, 2006
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