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I made an error in the formula from Eighth Nerve...

12.107.18.54

In Reply to: RE: Thanks for the clarification... posted by David Aiken on August 13, 2007 at 18:23:36

that should have read 70% - 80%. Ex.: If the listening position is 10' from the tweeter then the speakers should be 7' - 8' apart.

I'll try the 72 degree configuration as well. Thanks for your help.

Follow Ups:

Oops... - David Aiken 23:26:28 08/13/07 (9)
That makes more sense. Still, that comes out at around the 40-45 degree mark, still a bit narrower than 60 degrees and probably narrower than a lot of people would like. I'd also say it's still a short wall placementrather than a long wall placement.

Does he give any reasons for that recommendation?

David Aiken
- RE: Oops... - clio09 07:43:05 08/14/07 (8)
  Only that Nathan feels it sounds better. I have provided a link below to an article in 6Moons that discussed the earlier model Eighth Nerve products, as well as more of Nathan's speaker placement philosophy.
  
  Also, here are a couple of comments from Robert Greene on my speakers:
  
  "Because of their deliberate beaminess, the SP1/2s have to be pointed at the listener if their full potential neutrality is to be appreciated."
  
  So it appears significant toe-in (Or is it toe-out? I get confused as to which is which sometimes) is recommended.
  
  Also, another comment that if you could clarify I would appreciate:
  
  "Incidentally, I should add that the SP1/2s should be placed widely apart, in something along the lines of the theoretical Blumlein position (90 degrees apart, from the listener's viewpoint)."
  
  Lastly, I tried using your formula but not sure I used it correctly. Given the following measurements what would the 72 degree angle equate to in distance between the speaker tweeters?
  
  Distance between tweeters = 84"
  Distance from listening position to plane of speakers = 78"
  - Eighth Nerve (Open in New Window)
  - RE: Oops... - David Aiken 21:05:08 08/14/07 (7)
    The reason for using the tangent of 36 degrees is because we're dealing with 2 sides of the right angled triangle that connects 1 speaker, the listener, and the mid-point of a line drawn between the speakers. The side of that triangle connecting the mid-point of the line between the speakers to the listener bisects the 72 degree angle so you've got 36 degrees on either side of that line.
    
    The tan of 36 degrees is 0.726. The distance from the speaker plane to the listener is 78" so the distance from the speaker to the midpoint will be 56" (78" x 0.726) and that makes the total distance between the speakers 112".
    
    -----------------------------------------------
    
    I haven't got any experience with Spendors but I do have my Dynaudio Contour 1.3 SEs pointed directly at me. If the on axis response is flat there shouldn't be a problem and it may actually help. Pointing the speakers directly at the listener means that the early reflections are going to come from a fair degree off axis. Since the top end usually rolls off some as you move off axis, that takes some of the energy out of the early reflection. The early reflection would still be off axis if the speakers were pointed straight ahead (no toe in) but they become more off axis as you increase the toe in by angling the speakers more towards the listener. Different speaker designers have different views on what the most desirable listening axis is, and your views don't necessarily have to coincide with those of the designer. In my view toe in is something that you adjust to suit your ears and the room.
    
    David Aiken
    - That is the number I came up with as well... - clio09 10:56:57 08/15/07 (6)
      which means the speakers will need to be a little more than 9' apart, leaving them about 4' from the side walls. Not bad I suppose and hopefully with the toe in will minimize side wall reflections. I would also have to test the center image to see how it sounds. I've never had these speakers that far out before.
      
      A couple more things. The 78" I referenced was measured from my listening position to the front of the plane at the mid-point between the speakers, not the distance from the listening position to the tweeter. Is this the correct measurement? Now the last question. According to Robert Greene the Spendors should be placed 90 degrees apart, from the listener's viewpoint. Does this equate to Tan45 degrees?
      
      Looks like I have some fun stuff ahead of me with my new room. Thanks for your help.
      - RE: That is the number I came up with as well... - David Aiken 23:45:18 08/15/07 (5)
        
        In Reply to: RE: That is the number I came up with as well... posted by clio09 on August 15, 2007 at 10:56:57
        
        Unfortunately the Audio Physic setup documents on Immedia's site aren't all that precise on some things. They say that most people prefer a 72 degree angle, talk about placement at the focal point of an ellipse which all 4 walls contact tangentially, and use a grid which shows placement at quarter and three quarter width points. There's no guarantee that the focal points will give a 72 degree placement with the listening position�that angle will be determined by room dimensions if you use the focal points. As I said previously, I use the quarter and three quarter points and that gives roughly a 66 degree angle in my room�the angle here is also going to be determined by your room dimensions. I have tried the focal point placement and found it too far apart in my room. I haven't worked out what the angle was there but it would have been less than 90 degrees. 90 degrees is going to be a very wide placement and I would think you would run into problems.
        
        You asked:
        
        "The 78" I referenced was measured from my listening position to the front of the plane at the mid-point between the speakers, not the distance from the listening position to the tweeter. Is this the correct measurement?"
        
        Yes, from the speaker plane to the listening position
        
        "Now the last question. According to Robert Greene the Spendors should be placed 90 degrees apart, from the listener's viewpoint. Does this equate to Tan45 degrees?"
        
        Yes, but the Tan of 45 degrees is 1 so the calculation gets very easy. What you want is a speaker to speaker distance that is exactly twice the speaker plane to listening position distance in order to get the 90 degree angle.
        
        David Aiken
        
        I calculated Tan45 and came to the same conclusion... - clio09 07:01:04 08/16/07 (4)
        
        In Reply to: RE: That is the number I came up with as well... posted by David Aiken on August 15, 2007 at 23:45:18
        
        which is that the speakers would be placed too far apart (13'). I think the 17.5' x 11.5' room (the walls do meet tangentially) would make for a nice elliptical set-up. I have read the Immedia instructions before and will try to set the speakers up according to that method. I think what I'll do is start with the speakers 7' apart and then move them out further from there until the center image collapses. Then see after setting them up for depth (5' - 6' into the room) and toe in if I like what I hear. If I get to the 72 degree angle great, if not I'm sure whatever I come up with will be better than what I have now.
        
        RE: I calculated Tan45 and came to the same conclusion... - David Aiken 19:05:25 08/16/07 (3)
        
        In Reply to: RE: I calculated Tan45 and came to the same conclusion... posted by clio09 on August 16, 2007 at 07:01:04
        
        "I think what I'll do is start with the speakers 7' apart and then move them out further from there until the center image collapses."
        
        When I put my speakers further apart, at the focal points of the ellipse, what I found was that the centre image didn't collapse as I expected, but that I started to get a gap in the soundstage between each speaker and the centre, so I ended up with some sound coming from the centre and other sounds coming from an area centred on each speaker. Very strange, and not at all what I expected.
        David Aiken
        
        I'll keep that in mind as I experiment with the distance. (nt) - clio09 19:33:14 08/16/07 (2)
        
        In Reply to: RE: I calculated Tan45 and came to the same conclusion... posted by David Aiken on August 16, 2007 at 19:05:25
        
        nt
        
        New news from the mobile speaker room - David Aiken 13:45:35 08/18/07 (1)
        
        In Reply to: RE: I'll keep that in mind as I experiment with the distance. (nt) posted by clio09 on August 16, 2007 at 19:33:14
        
        In a fit of craziness, last night I dug out the tape measure and metre steel rule and moved my speakers back to the focal points of the ellipse. It's probably close to 3 years since I last had them there.
        
        I didn't notice any problems that might not be recording related, and I quite liked the result. The room has changed a fair bit in that time due to the addition of 2 pairs of DIY acoustic panels at early reflection points and that has probably helped.
        
        The soundstage has changed. With speakers at the quarter/three quarter points I routinely get a soundstage that extends to the outer side of each speaker. At the focal points, that only happened on a few tracks last night. Instead the soundstage didn't quite seem to extend as far as the speakers a lot of the time, but it was still probably the same width as before since the speakers are now further apart, and it's still a very wide sound stage. The depth of the soundstage seems a little deeper and images maybe a little less holographic and a little more rounded but quite precise. The height of some sources, especially voices, seemed higher on a lot of material and that's a plus for me. I didn't notice a down side but I only played about 3 discs before going to bed around midnight.
        
        Given that the only real difference between my first attempt at this placement and now is the room treatment at early reflection points and that placement at the focii puts the speakers closer to the side walls, I think side reflections may have been the cause of the soundstage issues the first time around. Interestingly, on one disc the soundstage did seem to group into 2 areas around each speaker and the centre image but this did not occur on the other discs and I didn't get the feel of a break in the soundstage between each speaker and the central image area. That disc was obviously mixed that way so perhaps what was happening last time was that due to the exaggeration of that mixing choice by early reflection issues.
        
        David Aiken
        
        Well now you've gone and thrown a wrench in it... - clio09 07:21:50 08/19/07 (0)
        
        In Reply to: RE: New news from the mobile speaker room posted by David Aiken on August 18, 2007 at 13:45:35
        
        I had pretty well settled on a set-up that used the quarter/3 quarters points and have the speaker no more than 8' apart. Even though this would not give me the 72 degrees or even the 90 degrees that Greene recommended, it was going to minimize side wall reflections. I can move the speakers further apart as I do have some 4' x 2' x 2" fiberglass panels to use for the side wall reflections, so maybe I should experiment both ways and see what happens. I'm somewhat of a set it and forget it kind of guy so tis would be a little out of character for me.
        
        At 8' apart the speaker/listening position distances would be close to an equilateral triangle, which I'm not striving for, but it just turns out that way. One thing about the wider placement of the speakers at the focal points and beyond is that the distance between the tweeters will exceed the distance from tweeter to listening position. I've never had placement like this before. I'm wondering how this will affect the sound. I guess there is only one way to find out.

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