Sound pressure meter readings

Discussion in 'Home Cinema Speakers' started by pavlos, Jun 21, 2001.

  1. pavlos

    pavlos
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    Can you please guide me through the steps of setting up my Home Theater Center using the sound pressure meter by Radio Shack ,using the test tones of my Denon 3801.


    Thanks in Advance

    Pavlos
     
  2. slingshot

    slingshot
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    I'll give it a try :-

    Set weghting C (I think) on the meter and response to slow. Set the range to 80db

    Hold the meter at the normal listening position (normal head height) avoid getting your body in the way of speakers and meter.

    Start the test tome and on the left front adjust the amp volume until the meter reads 75db.
    Then go through each of the channels and adjust the level of each speaker until they are all at 75db on the meter, check it all again but stand in a different place, just to make sure that you weren't affecting any of the readings.

    If your adjusting the sub then this needs to measure 85db (unless using the VE test disc which already compensates for this).

    Hope this makes sense give me a shout if you have any questions.

    Slingshot
     
  3. Stuart Wright

    Stuart Wright
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    Slingshot - very clear answer which I think we must use in the FAQ :)
    One question though. Do you point the meter up towards the ceiling or at the relevant speaker?
     
  4. slingshot

    slingshot
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    It doesn't seem to make too much difference with the tandy meter where you point it, it's mic is fairly omni-directional, however I normally point it straight up.
     
  5. Matt

    Matt
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    You should have the meter facing forwards and angled towards the ceiling and def not at the speakers. You want the sound level from each speaker to appear identical in a single reference spot. Pointing the meter at each speaker in turn will not achieve this.
     
  6. pavlos

    pavlos
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    Hi Matt thanks for your reply, I tend to agree with you that is I should point the reader towards the ceiling but I am rather confused cos in the manual I got with the sound pressure meter it states that I should aim it towards each speaker.


    pavlos
     
  7. Matt

    Matt
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    The manual i imagine is written for general purposes and specifically for a multichannel surround system. If you wanted to know the sound level of a specifc object then you would point thte meter at that object. But if you were wanting to compare two sources, as is the case in home cinema, the only difference you want in your test is the source of the sound, not the posistion of the meter. The meter acts as the control. Although as said before there is not a great deal of difference between pointing it up and pointing at the source, but if you ghave spent money on the gear you might as well use it "correctly"
     
  8. PJONG

    PJONG
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    Where can I buy one of these meters? How much are they and can anyone recommend a model?

    Many thanks

    Phil
     
  9. pavlos

    pavlos
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    One more question guys, why it should be 75db and not 80 or 85db for examble and why the sub should be 85db...


    Thanks

    pavlos
     
  10. lmccauley

    lmccauley
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  11. slingshot

    slingshot
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    To get a meter in the UK try http://www.rs-rusk.com/

    Drop them an Email cause the sites under construction, I can't remember how much they were.
     
  12. Electric Mayhem

    Electric Mayhem
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    I picked up my digital sound meter from Tandy´s in the UK for 15 quid (it was on offer)

    It was a while ago though.

    Cheers
     
  13. mgmcinema

    mgmcinema
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    Is it really worth spending money on a spm?.
    Does it make a lot of difference when you watch a film?.
     
  14. lmccauley

    lmccauley
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    To be perfectly honest, I found that when I calibrated with the SPL meter I ended up with exactly the same settings I'd previously set "by ear".

    Cheers,
    Liam
     
  15. PJONG

    PJONG
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    Thanks for the info chaps,

    I suppose in an ideal world I would have an obliging mate who would lend me a meter, and the outcome, more than likely would be pretty much what I already have set-up. Alas none of my mates has one so I will have to buy one myself, still £15 - £25 is not going to break the bank and in the future I might just be that mate to lend it out.

    Phil
     
  16. slingshot

    slingshot
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    Too be honest my settings were almost exactly as I'd set by ear (except the sub was a tad too high, and it still is).

    It's still nice to know it's right though, and does make it easier if you move seating posititions etc.

    We also use it for checking bike exhaust's aren't too loud for track days, so you could find yourself renting it out.

    Slingshot
     
  17. mikeaitch

    mikeaitch
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    Guys-
    I've got a question....

    I have the Tandy SPM, and used it with the test tones on my 3801.

    The problem is, when I tried using the THX Optimode section on my region 1 DVD of Terminator2, the levels are way out, and need quite a lot of change on some of the channels.

    So which should I use???? :confused:
     
  18. slingshot

    slingshot
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    I'd always recommend using the tones on a DVD rather that the amp tones, since if your using them on a DVD your taking into account any variations of gains from the player and the amp, rather than just variations in the amp itself.

    I used Video Essentials to set test mine, and they were different from the player tones.
     
  19. mikeaitch

    mikeaitch
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    Thanks Slingshot, I've tried both ways and you're definitely right to my ears. Would I be better buying one of the set up discs, or is the THX Optimode on my T2 R1 as good?
     
  20. bob007

    bob007
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    Anyone who wants to purchase a sound level meter can goto :
    HAGARS TEL NO 01795-663336

    ANALOG S.L.M CAT NO 33-2050 £24.99
    DIGITAL S.L.M CAT NO 332055 £39.99
    MODEL RADIOSHACK

    try this link tnt-audio.com

    hope this helps :cool:

    [ 25-07-2001: Message edited by: bob007 ]
     

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