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  1. #1
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    Jan 2006

    sound expander????

    what is a "sound expander" i saw one at a thrift/junkyard. in good condition. it looks like an equalizer only heavier; has one "tape in" and one"audio out" and an "a.c. in". and also its made by pioneer.

  2. #2
    M.P.S.E /AES/SMPTE member Sir Terrence the Terrible's Avatar
    Join Date
    Jul 2002
    Quote Originally Posted by frenzy55
    what is a "sound expander" i saw one at a thrift/junkyard. in good condition. it looks like an equalizer only heavier; has one "tape in" and one"audio out" and an "a.c. in". and also its made by pioneer.
    When we listen to stereo signals, our right ear hears the right channel and the left channel delayed flipped in phase and lower in level. The same goes for the reverse, we hear the left channel with our left ear and the right channel signal delayed flipped in phase with lower volume. This is called Interaural crosstalk, and its effect narrows the soundstage that we percieve from stereo sources.

    A sound expander creates a embedded reverse phase signal designed to cancel the opposite channels output out of the stereo signal. In other words it creates a in phase signal to the opposite ears to cancel out the delayed flipped out of phase signal. So your left ear hears the left speaker and a out of phase signal generated by the sound expander which cancels out the output heard in the right ear. This will give the stereo signal a very expanded quality hence, sound expander.

    Most incarnations of this kind of processing are not very good as they create a "phasey" quality that is added to the signal. Polks SDA system, sound concepts processor, and Carver's sonic holography are the only quality implimentation of this kind of processing.

    If it is dirt cheap, buy it and give it a try. If you do not like the way it sounds, then little is lost and you can sell it at your next rummage sale.
    Sir Terrence

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  3. #3
    Suspended markw's Avatar
    Join Date
    Dec 2001
    Noo Joisey. Youse got a problem wit dat?

    Didn't DBX make these?

    I always saw these as the exact opossite of comperssors, to increase the dynamic range of compressed media. I don't thing accuracy was the goal so much as was a more "dynamic" listening experience.

  4. #4
    Phila combat zone JoeE SP9's Avatar
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    Jun 2003
    Philadelphia, PA
    Could it be a Dynamic Range Expander that you are thinking of. I think SrTtT is correct about the pioneer device. DBX sold Dynamic Range Expander's. they had several models. They were supposed to expand the dynamic range of recordings. You could dial in the amount of expansion you wanted.
    At one time there were specially cut DBX LP's. I believe they were mastered and cut with a straight 2to1 compression. The goal was greater dynamic range on LP's. While the DBX encoded LP's were very quiet and very loud you needed the DBX processor to listen to the LP's.
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