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For BASS lovers who like to tweak try this..

Discussion in 'Subwoofers' started by Apone, Nov 16, 2004.

  1. Apone

    Apone
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    BTW this will mainly benefit those with a separate processor and amp and an active sub although AV amp users may also be able to try.

    Turn your processor on only and leave all power amps off and turn volume to reference level and play a bass heavy dvd at reference level.

    You will find it suprising how much of the soundtrack is located with that speaker and while the movie is playing it is a good way to do a rattle test in the room to see which window or door is adding its 'own' sound effect so that you can also fix anthing that rattles in the room.

    A few bass heavy scenes to try..

    STAR WARS ATTACK OF THE CLONES (start of the movie)
    MAN ON FIRE (kidnapping scene)
    SAVING PRIVATE RYAN (beach landing scene near the start)
    LILO AND STICH (space ship chase)

    Come and have a go if you think your hard enough :p

    Regards

    Mahmood
     
  2. Stellavision

    Stellavision
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    :rolleyes:
     
  3. avanzato

    avanzato
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    Yep I've done that several times. It's surprising the number of things in a room that do rattle.
     
  4. chrisgeary

    chrisgeary
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    Be careful when advising people to use reference level as a means of testing their system/room.. you might just be advising them to slowly destroy their equipment! Most systems will not play cleanly at 0db, except maybe in the smallest of rooms.

    You would be better off acquiring Avia or Digital Video Essentials, or some disc with frequency sweeps on, and play it at between -30db and -15db. Should be plenty loud enough to find room rattles.
     
  5. ajkean

    ajkean
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    If I played my sytem at 0db, it would be very, very loud. If I'm watching an action movie and want it up quite high, I'm usually looking at about -18db. Any higher than that and it starts to get uncomfortable and unrealistic.
     
  6. bob1

    bob1
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    :lease:
     
  7. Ian J

    Ian J
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    Different people are happy at different volume levels but the quality of the subwoofer makes a big difference. Reference level is loud but it will sound considerably worse if all you are listening too is distortion
     
  8. Stellavision

    Stellavision
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    You'd probably get on well with my wife!
     
  9. ajkean

    ajkean
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    No honestly, when I say it would be loud at 0db, I mean: LOUD!
    No distortion, just very loud. Maybe I just need a bigger room!? :laugh:
     
  10. Stellavision

    Stellavision
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    Admittedly, 0db is very loud and I personally do not enjoy prolonged periods of listening at that level. I find -7 my favourite setting setting.
    0db should sound exactly the same in a bigger room as in a much smaller room if the system is correctly setup.
     
  11. mariob33

    mariob33
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    Wow im usually in the 20's r the wife would boot me outta me lovely abode :mad:
     
  12. Nimby

    Nimby
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    I don't think so. There is more boundary gain in a small room and pressurisation is also much improved. Since the speakers/sub are being fed with the same signal strength. Then a small room will be louder than a large one. Around 114dB in the bass is reference level I believe.

    At normal frequencies you would be allowed under 30 seconds without the use of approved ear defenders in an idustrial situation. So take off your 'pinnies' and no vacuuming or dusting while you're listening at 0dB! :blush:

    Nimby
     
  13. Stellavision

    Stellavision
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    If I set my speakers to 75db from the listening position in a 14' & 12' room, or 75db from the listening position in a 28' X 24' room, why would the sound be any louder or quiter in a different size room? I can understand a smaller room getting more pressurized, but if the speakers are calibrated to 75db in all sized listening enviroments that means your ears should be getting the same sound pressure levels at reference level or otherwise.
    You need more power to fill a larger room, so sub/amp gains, etc. will be higher and I expect if you are sat closer than the calibrated listening position that the sound could get very uncomfortable!
    Thats my personally theory, and if there are any contracting theories I would love to hear them.
     
  14. recruit

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    Barrie that is how i perceive it, aslong as you have all the speakers calibrated the same then it should not be any different.. :)

    John
     
  15. Nimby

    Nimby
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    The sub and speakers are indeed balanced at the crossover point.

    But thanks to the smaller room a subwoofer will usually provide increased output with sinking frequency over a larger room. And will reach a slightly lower frequency in a smaller room.

    Loud passages and transients will also be of a lower peak dB in a larger room unless more powerful amplifiers and speakers capable of higher levels are used. Otherwise the effect is much like compression on sound output.

    Nimby
     
  16. Stellavision

    Stellavision
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    I don't see how the crossover point is relevent to volume levels.

    Maximum output and extension of the sub should also be irrelevant.

    Why?
    Volume is scientifically called sound pressure level.
    Why would the sound pressure be different from a listening position 20 feet away from the front, than sound pressure from a listening position 10 feet away?
    More powerful amplification may be needed to achieve the same spl in a larger room or weaker equipment may have to work a lot harder. Subsequently thresholds of equipment are more likely to be obtained while trying to acheive reference levels. For instance if a subwoofer has a maximum output of 108db, this figure is often tested from as close as 1 metre away by manufacturers. But, from your listening position 20 feet away your sub may only peak at a much lower level, 105 db or less maybe.
    However, these maximum output figures are irrelevent, so long as the equpment is up to the job of acheiving the desired reference level from where I will park my bottom.
     
  17. Nimby

    Nimby
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    Sound pressure level follows the inverse square law. The further you are from the speakers/sub the harder they have to work (very) to achieve the same levels. (dB) More powerful amplifiers need to double their power (and double them again) with increasing distance. Because speakers are so innefficient Watts are soaked up like a sponge.

    The subwoofer roll-off point set by the receiver is very near the top of the subwoofer's frequency band. Room boundary gain in the bass will favour a small room over a large room. The so-called "house curve" is almost built in to a small room. As I said before the lowest frequency reached will also occur in a smaller room. The opposite of what one might expect from the boundary seperation wavelength alone. Pressurisation is more important at very low frequencies. Leaky rooms with open doorways should tend to nullify small room bass gains and require a more powerful subwoofer.

    The downside is the usually awful frequncy response curve in small rooms. Because of the small distance between boundary surfaces. Which accentuates peaks and troughs in the mid-bass region. Rather than the sub-bass where large rooms might affect the response curve. But at too low a frequency to be clearly audible. The smaller room will probaby require a BFD to iron things out.

    Nimby
     
  18. Pollywoggle

    Pollywoggle
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    I love it when you two talk technical :confused:
     
  19. Stellavision

    Stellavision
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    I've looked at this, but I've had a few too many Stella's :beer: !
    I'll have another look tomorrow! :zonked:
     
  20. Stellavision

    Stellavision
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    Nimby, I hear what you are saying, but I'm not 100% that your theory contradicts my own thoughts.
    I'm going to leave it at that because this whole thing is giving me a headache (or making the hangover I have now even worse! :( )
     
  21. Nimby

    Nimby
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    It's not rocket science. :cool:

    But then I'm not a rocket scientist. :blush:

    So it doesn't matter if I'm wrong.

    As long somebody corrects me if I am wrong.

    Get well soon? :devil:

    Nimby (reaching for his Friday evening glass of beer)
     

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