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Setting up speaker delays

Discussion in 'Home Cinema Speakers' started by dunkyboy, Oct 16, 2002.

  1. dunkyboy

    dunkyboy
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    Not sure if this is the right forum for this, but I want to know if anyone has any tips or suggestions for setting the speaker delay settings on an AV amp? Mine is a lowly Yamaha DSP-E800 so it's just a simple ms delay for each speaker (i.e. no fancy graphical interface for telling it speaker positions and things). Do you have to just do this by ear with a favourite movie, or is there a reference I might use? I ask because it's hard to know how it's supposed to sound, particularly as different soundtrack engineers obviously have different ideas about what surround channels should do...

    FYI, my room is about 12' x 14'/16' (bay window gives greater length) and I'm using a pair of Mission 77DS bipolars as surrounds, mounted on the walls about 2' above ear level, maybe 3' behind listening axis. My front three are ATC Active 10's nearly 3' apart, and about 8' from the listening position.

    Cheers,

    Dunc
     
  2. Jase

    Jase
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  3. dunkyboy

    dunkyboy
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    Thanks Jase. :)

    Actually, now that I have a play, I can't seem to find the settings for rear channel delay on my E800 - only centre delay... Is it possible this proc doesn't do it? Or am I just being thick? :p

    Dunc
     
  4. Jase

    Jase
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    I think it´s got them but you can only adjust the pair of surrounds together not individually. It´s a couple of years since I had my Yamaha so I can´t remember which buttons you have to press to adjust them.:blush: It´s not done via the main setup if I remember rightly. I think you press the Level Button on the front panel (if you have that on your model).
     
  5. NicolasB

    NicolasB
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    I reckon it's best to go back to first principles.

    The idea is that the sound from all of the speakers should reach your ears simultaneously. Let's begin by assuming direct-radiating (monopole) speakers.

    The speed of sound in air is (rather approximately) 330 meters per second, which means 1 millisecond of travel time roughly corresponds to 33 centimeters of sound propagation, or the sound takes 3 milliseconds to travel 1 metre. So, measure the distance from each speaker to your ears at your primary listening position (use a tape-measure). Set the farthest away speaker to have a delay of zero; then for each of the other speakers work out how much closer it is to you than the farthest away speaker, and give it a delay of 3 milliseconds per meter closer it is. (Or 1 millisecond per 33cm).

    Example: suppose the farthest away speaker is 5 metres away and the closest one 1.66m away. Set the 5m speaker to have a delay of 0 and the closest one to have a delay of (5 - 1.66) * 3 = 10 milliseconds.

    Things are going to get a little more complicated if you use non-monopole surround speakers, because the whole idea of non-direct-radiating speakers is that the sound shouldn't reach you directly, but only indirectly after having reflected off at least one wall. So you will have to check the geometry of the speaker and ask yourself: as arranged, can the sound get directly from the speaker to my ear? If so, treat it as a monopole. If not then work out at roughly what angle the sound will be travelling at to bounce off a single wall and hit your ears, then measure all the way along its path - speaker to wall to ear, and use that distance.

    You may need to do some additional tweaking because some reflected sound from multipole surrounds will experience more than one wall reflection before it hits you, and you may need to delay the other speakers so the sound from them doesn't hit you until you're more into the middle of the reflections.
     
  6. camlogan

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    hi there, My Yamaha 630 only allows me to set delays on my center and my rear center. So while I could set the delay on my rear center to say 5 I can't set the delay on my left and rights.

    What should I do in a situation like this?

    thanks for your help

    CaM
     
  7. NicolasB

    NicolasB
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    Assuming your left and right front speakers and your centre front speaker are all in a straight line the centre one will be closer to you than the sides. So the centre will need to be delayed relative to the sides. (For example, if the left and right fronts are 10 feet apart and you're sitting 12 feet away from the centre speaker then the side speakers will be 13 feet away and you need a 1ms delay on the centre). You'll need to make sure that the rear centre is closer to you than the front left and rights, and then set an appropriate delay on that too.

    As for your rear left and rights, I think the best you can do is try to arrange them so they're the same distance away from you as your front left and rights. If you can't control the delay of any of those four speakers relative to any of the other three then that's your only option.
     
  8. camlogan

    camlogan
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    hi there, thanks for your reply. After more times reading the manual and the dolby link it looks like I will be setting my front center to a delay of 1 and my rear center to a delay of 0 (my fronts are 5 metres away and my rears are 1 metre behind me).

    My yamaha amp lets me also set delays on surround modes but I'll probably just leave it as is - after refering to the dolby guide it probably wouldn't make much difference.

    thanks for your help

    CaM
     
  9. NicolasB

    NicolasB
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    If I were you I'd move my sitting position two metres forward....
     

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