Should SPL Meter face toward TV or aimed at each individual speaker?

Discussion in 'Archived Threads 2001-2004' started by Jake T, Oct 24, 2001.

  1. Jake T

    Jake T Stunt Coordinator

    Joined:
    Jul 4, 2001
    Messages:
    225
    Likes Received:
    0
    Trophy Points:
    0
    I've been searching the web on this subject, and came up with different methods.
    What do you guys think?
    [​IMG]
    ------------------
    Jake T
    --"The Things You Do In Life Echo In Eternity"
     
  2. Kevin. W

    Kevin. W Screenwriter

    Joined:
    Oct 27, 1999
    Messages:
    1,534
    Likes Received:
    0
    Trophy Points:
    0
    If you have a tripod mount it on this in the sweet spot of your HT seating area and have it pointing directly at the tv. If you don't have a tripod then sit in the same spot and have it pointed towards the tv.
    Kevin
     
  3. Charles J P

    Charles J P Cinematographer

    Joined:
    Aug 19, 2000
    Messages:
    2,049
    Likes Received:
    2
    Trophy Points:
    0
    Location:
    Omaha, NE
    Real Name:
    CJ Paul
  4. Thomas_Berg

    Thomas_Berg Screenwriter

    Joined:
    Feb 28, 2001
    Messages:
    1,422
    Likes Received:
    0
    Trophy Points:
    0
    Location:
    Dallas
    Real Name:
    Thomas
    do NOT point it towards each speaker. that defeats the whole purpose...
    ------------------
    -Thomas
    My HT
     
  5. Randy G

    Randy G Second Unit

    Joined:
    May 18, 2000
    Messages:
    460
    Likes Received:
    0
    Trophy Points:
    0
    I would think you'd get the most uniform response if you mounted it on a tripod at your seating position, and then pointed the mike straight up at the ceiling. Then, you could calibrate all the channels without changing the direction of the mike.
    ------------------
     
  6. PatrickM

    PatrickM Screenwriter

    Joined:
    Aug 10, 2000
    Messages:
    1,138
    Likes Received:
    0
    Trophy Points:
    0
    I typically mount my SPL meter on a tripod just behind my seating position so its right at head level and have it tilted forward with the mic pointing at the intersection of the front wall and the ceiling. The mic is then basically where my ears are and I make sure to stay back from the meter so that I'm not introducing reflections that add to the signal.
    Patrick
    ------------------
    Evidence of my obsession.
     
  7. Guy Kuo

    Guy Kuo Supporting Actor

    Joined:
    Mar 6, 1999
    Messages:
    581
    Likes Received:
    0
    Trophy Points:
    0
    Look at the response map for the meter. It's almost omnidirectional but falls off towards the back. That means aim isn't super critical. What is critical is positioning being constant and at the point between where your ears would be. Mount it there with the unit pointed about 20 or 30 degrees forward and you should get good coverage of all your speakers.
    ------------------
    Guy Kuo
    www.ovationsw.com
    Ovation Software, the Home of AVIA DVD
     
  8. Phil Iturralde

    Phil Iturralde Screenwriter

    Joined:
    Oct 7, 1998
    Messages:
    1,867
    Likes Received:
    0
    Trophy Points:
    0
  9. Randy G

    Randy G Second Unit

    Joined:
    May 18, 2000
    Messages:
    460
    Likes Received:
    0
    Trophy Points:
    0
    If the mike is omni-directional, why would you want to point it in a specific direction? I still suspect that pointing it straight up(perhaps a cumbersome procedure) will give the most uniform response at the mic.
    ------------------
     
  10. Luis Gabriel Gerena

    Luis Gabriel Gerena Second Unit

    Joined:
    Jul 18, 2000
    Messages:
    410
    Likes Received:
    0
    Trophy Points:
    0
    This has been a long debated issue here so you won't get a definite answer. As for the comments disregarding the importance of aiming it up or at 45º just try it and see for yourself that even a slight change of angle makes a difference. I tried it a 45º and aiming straight up with StarWars'THX optimode and got different results with each test. So all I did was try both settings with panning scenes in the movie and picked the one which to me delivered a seamless effect.
     
  11. Phil Iturralde

    Phil Iturralde Screenwriter

    Joined:
    Oct 7, 1998
    Messages:
    1,867
    Likes Received:
    0
    Trophy Points:
    0
    Randy G: Food for thought . . . if Dolby Labs recommends in their "5.1-Channel Production Guidelines" to . . .
    quote: ". . . hold the SPL meter at chest level, with the microphone facing up at an angle of approximately 45 degrees to the center speaker."[/quote], general guidlines / instructions for the Sound Engineer to Calibrate the SPL of their 5.1 Studio Monitor Speakers around them, used for Master Mixing / Recording and Playback Monitoring (5.1 DVD & Music Mastering usually includes the customer), . . . then, . . . why would you Calibrate your Home HT Speakers SPL's completely different from the Master Recording??
    quote: Luis - " . . .picked the one which to me delivered a seamless effect."[/quote]
    Which option did you choose?
    Just wondering,
    Phil
    ------------------
    http://www.geocities.com/p_iturra
    [Edited last by Phil Iturralde on October 25, 2001 at 10:03 AM]
     
  12. Jeremy Anderson

    Jeremy Anderson Screenwriter

    Joined:
    Nov 23, 1999
    Messages:
    1,049
    Likes Received:
    0
    Trophy Points:
    0
    I've done far too much fiddling with my SPL meter, and I finally discovered that I got the best results from the following:
    Some say to point it straight up, but if you look at the angular rolloff of the mic used on the RatShack analog SPL meter, pointing it straight up will usually accentuate your surrounds 1-2db (since the angle from your surrounds to the center axis of the mic will be less than the angle from your mains/center to the center axis of the mic).
    So in theory (and someone tell me if I'm wrong on this), the ideal angle for the SPL meter to match levels for all speakers is that which brings all speakers into roughly the same off-axis angle. In my room, I was able to find this by using a laser pointer taped to a protractor (Hey, I told you I've done far too much tweaking!). I found that if I put my SPL meter on a tripod at the listening position and angle it about 8-10degs from vertical toward the front of the room, all my speakers are at roughly the same off-axis angle (which theoretically should yield the same response from the SPL's mic). In my room, it only made a 1db difference in the surrounds, but after doing this my calibration sounds pretty damn perfect.
    One day I'll take a picture of my "home theater tool" -- an analog SPL meter with attached laser pointer for speaker aiming and small line-of-sight protractor carved into the side for estimating angles. God, I'm a geek... [​IMG]
     
  13. Jeff D

    Jeff D Supporting Actor

    Joined:
    Apr 6, 1999
    Messages:
    604
    Likes Received:
    0
    Trophy Points:
    0
    I just had this debate with myself on how to do this. I usually calibrate from the sweet spot, but this latest time I experimented with aming at each speaker. I think I'll switch back to the uni-position calibration tonight after checking this thread. =)
    Phil, (just down the road from me in Mt View) I was curious about using the balance to adjust the levels. My receiver's right surround is about +1.5db louder than the left. I don't know if it's correct to use the balance to adjust for level. I guess I'm confused how the balance works. Does it really just effect the level going to each channel?
     
  14. Bob D

    Bob D Extra

    Joined:
    Jan 26, 2001
    Messages:
    22
    Likes Received:
    0
    Trophy Points:
    0
    Everything that I have read states to hold the SPL meter at ear level from the listening position and point it towards the front wall and ceiling intersection, as has been stated by others in this thread. This is what I have done and the results were very good.
     
  15. Phil Iturralde

    Phil Iturralde Screenwriter

    Joined:
    Oct 7, 1998
    Messages:
    1,867
    Likes Received:
    0
    Trophy Points:
    0
     
  16. Randy G

    Randy G Second Unit

    Joined:
    May 18, 2000
    Messages:
    460
    Likes Received:
    0
    Trophy Points:
    0
    Jeremy the Geek,
    And that is precisely why I tend to trust people like YOU moreso than those who don't take the time and effort to experiment and tweak!
    Geekness has its rewards.
    I would also say that its POSSIBLE that the reason that Dolby, Radio Shack, etc. suggest that particular method is because its the most practical and easiest way to do it using just your hand to hold the meter. Doesn't necessarily mean it's the most accurate. Radio Shack doesn't want you to be feel obligated to purchase a tripod, and you'll see that the threads of the meter mount are on the underside of the controls...meaning that it's somewhat difficult to mount it on a tripod and have it pointing straight up at the same time. Actually, since the foot of the meter is flat, any old(appropriate height, of course) pedestal would probably do.
    ------------------
     
  17. Jake T

    Jake T Stunt Coordinator

    Joined:
    Jul 4, 2001
    Messages:
    225
    Likes Received:
    0
    Trophy Points:
    0
    Thanks for the info. I'll go with the meter on my tripod at the hotseat and aimed up at 45dg.
    ------------------
    Jake T
    --"The Things You Do In Life Echo In Eternity"
     
  18. Kieran Coghlan

    Kieran Coghlan Second Unit

    Joined:
    Oct 26, 1998
    Messages:
    262
    Likes Received:
    0
    Trophy Points:
    0
    Jake T. That will probalby work well enough. I find that pointing it more like 60 deg up, (30 deg down from vertical) is best in my experience.
    Others: DO NOT point the meter straight forward and horizontal. This will cause your center and front speakers to be set too low, and your rear speakers to be set to loud. Conversely, I find that pointing the meter straight up (as was suggested in the editor's response to a letter in the latest HT mag) causes the surrounds to be too quiet, and the fronts/center to be too loud.
    Remember, that our hearing is more sensitive to the front than it is to the rear, so you want to simulate this sensitivity with the spl meter. By tilting it slightly forward, you slightly bias the front (just as your ears naturally do). But if you point it straight forward, you give too much bias to the front.
    ------------------
    -Kieran
    My HT Page
     
  19. Jeff D

    Jeff D Supporting Actor

    Joined:
    Apr 6, 1999
    Messages:
    604
    Likes Received:
    0
    Trophy Points:
    0
     
  20. Luis Gabriel Gerena

    Luis Gabriel Gerena Second Unit

    Joined:
    Jul 18, 2000
    Messages:
    410
    Likes Received:
    0
    Trophy Points:
    0
    quote:
    --------------------------------------------------------------------------------
    Luis - " . . .picked the one which to me delivered a seamless effect."
    --------------------------------------------------------------------------------
    "Which option did you choose?"
    Honestly I think it was straight up but I am going to verify that tonight and post again later cause I aint 100% sure.
    Regards
     

Share This Page