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Thread: Hafler effect?

  1. #1
    Join Date: May 2011

    Location: Torquay

    Posts: 2,544
    I'm Craig.

    Default Hafler effect?

    Reading the Holographic thread here, it reminded me of an experiment a lot of people tried some years ago.

    It involved using a third speaker, wired using positive from say the right speaker, and negative from the left.

    It was certainly an interesting result giving a strange but enjoyable effect, supposedly bringing back lost information on the record, that you would not get just using two channel stereo.

    Anyone else tried this?
    Naim Mu-So
    And other stuff.

  2. #2
    Join Date: May 2008

    Location: Lancaster(-ish), UK

    Posts: 16,963
    I'm ChrisB.

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    I think it was ideally meant to be two extra speakers and with some slight delay in the rear ones. I tried it out of interest a long time ago.
    A crude way to introduce a delay is to feed the rears through a tape loop.
    It's quite fun for a while.

  3. #3
    Join Date: Mar 2008

    Location: Leeds

    Posts: 12,881
    I'm inthescottishmafia.

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    I think stereo was originally intended to have a centre speaker if memory serves.

  4. #4
    Join Date: Apr 2012

    Location: Southall, West London

    Posts: 41,899
    I'm Geoff.

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    There were various interpretations of the Hafler circuit which was supposedly intended to use the out of phase information from the stereo signal. I may even still have a Dynaco (Hafler) 'quadrophonic' connection box somewhere.

    The general idea was to take a wire from the positive speaker terminals of left and right amplifier outputs and feed them through a second pair of speakers, commoning the negative sides of the speaker terminals.

    A variation was to take a feed from the commoned negatives on the speakers and place an 'L' pad (8 ohm?) in series back to one of the amplifier negative terminals, using the 'L' pad to adjust levels.

    The above could also be done with one speaker by commoning the postives and connecting to the positive speaker terminal then to the amplifier negative via an 'L' pad.

    I'm fairly sure you need a pretty tolerant amp to get away with all this.

    I tried various interpretations of the above and found the most effective was to just use a pair of tweeters with a series capacitor and connected between the two positive terminals and situated towards the rear of the room, but pointing up at the ceiling at an angle which would bounce the sound back down towards the listening position.
    Last edited by walpurgis; 04-03-2013 at 22:49.
    "when common sense, logic and plausibility are excluded. All that remain are foolishness and lies"

  5. #5
    Join Date: Apr 2012

    Location: Co. Durham

    Posts: 1,968
    I'm Stephen.

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    Paul Klipsch pioneered the 3 speaker system for use with his corner folded-horn speakers. The third speaker handled only the common in-phase signal. The R + L earths connect to it and the other connection goes to earth on the amp. The full Hafler set-up used this system plus the two rears

  6. #6
    Join Date: Mar 2009

    Location: north yorkshire

    Posts: 708
    I'm john.

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    I have a custom made 5.1 preamp with hafler built in sounds ok



    jon

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