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Digital delays

Discussion in 'd.i.y.' started by a.palfreyman, Sep 10, 2019.

  1. a.palfreyman

    a.palfreyman pfm Member

    Would like to know if there is a good quality digital delay available (product or kit / DIY) as I had thought about using something like this to help with speaker positioning. 3 microseconds is equivalent to 1mm of movement backwards or forwards of a speaker, so wondered if this is possible. Could of course delay both by a small amount and shift one relative to the other. Any ideas?
    AP
     
  2. davidsrsb

    davidsrsb pfm Member

    Easier to do with a PC or a MiniDSP
     
  3. Pete MB&D

    Pete MB&D Pete Maddex, the one and only!

    Won't the room interactions be the same as the position of the speakers haven't changed?

    Pete
     
  4. davidsrsb

    davidsrsb pfm Member

    I was guessing that the OP wanted to compensate for a listening position off the equal distance line.
     
  5. cooky1257

    cooky1257 pfm Member

    Do they also come with a listening seat head clamp?
     
  6. a.palfreyman

    a.palfreyman pfm Member

    Pete,
    Not sure how much an odd 1mm would have on room interactions but a valid point nonetheless. This was more about the relative timing of both channels and production of a good stereo image.
    davidsrsb,
    No, sitting on centre-line as near as I can tell.
    Cooky,
    Not joking, but funny you should say that as I'd considered a headrest of some sort as small sideways or back-forward movements do cause changes, probably due to nulls / peaks.
    However, I asked because amongst other pieces of music I have, there is a particular organ piece https://www.discogs.com/Johann-Seba...52-Fantasia-BWV-572-Pastorale-B/master/851482, track 5 (3rd movement of Fantasia In G Major, BWV 572) where there is a descending bass line and complex manual section which sounded "odd", i.e. ill-defined and messed-up. However, 1mm of movement backwards of one speaker cleaned this up considerably. I used a batten clamped to the speaker stand with a further movable piece which could be clamped on top so it was in contact with the bottom of the baffle. Moved the speaker back and then pulled it forwards again with a 1mm spacer at each side, thus moving it relatively accurately; 1mm is equivalent to 3µs. I would also like to experiment with other recordings so I can see if there is a decent compromise.
     
  7. Jim Audiomisc

    Jim Audiomisc pfm Member

    Adding a slight time delay to the input fed into the speaker isn't an exact equivalent of moving the speaker unless you're somewhere like an anechoic chamber. This is because it alters the relative timings of the direct *and* indirect paths from speaker to ear. One effect is, indeed, to alter the overall frequency response at the listening position.
     
  8. cooky1257

    cooky1257 pfm Member

    If you delay the signal to the speakers the room can only act on the output from the speaker so I fail to see how it changes relative direct/ reflected timings as these are room dependent.
     
  9. Jim Audiomisc

    Jim Audiomisc pfm Member

    Sorry, my line line in #7 wasn't clear! I meant that one effect of *moving the speaker* is to alter the response changes produced by the room. Whereas delaying the signal fed to the speaker doesn't.
     

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