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Coaxial Audio Filter

Discussion in 'Electronic Basics' started by [email protected], Sep 6, 2005.

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  1. Guest

    Hi,

    I have a quastion to ask. It requires a bit of explanation so listen
    up!

    I have a very, very old television at home (I estimate it was purchased
    around 1985). Due to its age, it lacks any facility for changing the
    tone of the audio (i.e bass, middle treble). The tone of the audio has
    a lot of bass in it. Basically (no pun intended), I want to get a
    higher frequency tone (i.e more treble) and reduce the bass. I suspect
    I might need some kind of filter. Preferably , I would not like to have
    to open the television. I imagine some kind of filter unit could be
    placed between the cable (coaxial) and the RF on the televison. The
    television has no SCART.

    Please Help!!!!
     
  2. DBLEXPOSURE

    DBLEXPOSURE Guest

    Can't be done via the coax. you would need to put a low end blocking filter
    or a high pass filter on the speaker or speakers themselves.

    I suppose you could find a tuner box or a VCR that allows you to adjust the
    tone and then outputs your TV on chnl 3 or 4...
     
  3. Bob Masta

    Bob Masta Guest

    Filtering at the low impedances of the speakers will be a problem...
    he'd need to be hand-winding big inductors, etc. If he's
    opening the case anyway, he should put his filter just
    ahead of the volume control, which should be easy to find.
    Or he might even find the shunt cap around there that
    is causing the present low-pass response.

    Otherwise, he would essentially have to cut the bass while passing
    the treble, then boost the overall volume to compensate.
    That would give increased hiss... and my guess is that
    the reason the TV was built this way in the first place
    was to make the hiss less noticeable.

    May not be worth a lot of trouble....

    Best regards,


    Bob Masta
    dqatechATdaqartaDOTcom

    D A Q A R T A
    Data AcQuisition And Real-Time Analysis
    www.daqarta.com
    Home of DaqGen, the FREEWARE signal generator
     
  4. Jasen Betts

    Jasen Betts Guest

    Get a TV serviceperson to fit headphone or audio-out sockets
    and attach a mixer and amplifier there.


    doing it the way you want requires demodulation and re-modulating the FM
    audio signals that are coming up the antenna lead for whichever channel you
    have selected... the only practical way I can see to do that would be to
    inperpose a tuner (eg a VCR - possibly one with a broken playback mechanism)
    and then feeding the audio out signal from that into a mixer and then
    feeding it into a modulator (another broken VCR) and even then you have to
    select channels with the tuner (first broken VCR) rather than use the tuner
    that's built into the TV and you'll lose picture quality in the
    demodulation/remodulation process...


    Bye.
    Jasen
     
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