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Subwoofer Question ?

Discussion in 'Subwoofers' started by Gordon @ Convergent AV, Mar 28, 2004.

  1. Gordon @ Convergent AV

    Gordon @ Convergent AV
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    Can someone explain to me how a subwoofer knows the notes it is to reproduce are from music and not film or vice versa?

    Gordon
     
  2. Ian J

    Ian J
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    Nic Rhodes is the forum's sub expert and I am sure that he would be delighted to explain the shortfalls of some subwoofers to you
     
  3. Nimby

    Nimby
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    Film needs square waves (buildings falling) SVS Boxes?

    While music needs nice round waves. SVS Cylinders?

    Though there are some things in between square and round.

    Metallica!! Two SVS? One box one cylinder?

    Hope this helps? ;)

    Nimby
     
  4. Gordon @ Convergent AV

    Gordon @ Convergent AV
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    I do not need someone to tell me the shortfalls of subwoofers thanks Ian.
    Speakers distort or they don't. They either have good ability to be dialled in with their partnering satellites or they don't. They have enough sound output or they don't.
    Something that is good for music will be good for film. Only difference I can actually fathom is that most folk want to play films far louder than they would their music.

    Gordon
     
  5. Nimby

    Nimby
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    Well, if you want a serious discussion on this issue:

    How about:

    Music has much more high frequency content compared with film.
    (Cerwin Vega argues that nobody screams for more treble)
    (The high frequency content is hard on the ears at high levels!)

    Most film has only brief high level/ low frequency content.
    (Not so tiring as music booming away all day).

    Music has almost continuous low frequency content.
    (Tiring to listen to for extended periods at high level)
    (Even live!)

    Most people are willing to put up with compromised bass on film because they don't know what a huge explosion or gunfire actually sound like.
    (Distortion has lower priority than volume)

    Most people have some idea what music should sound like or can easily guess from past experience.
    (Lower distortion & extended frequency are therefore more desirable than sheer volume)

    Nimby
     
  6. Gordon @ Convergent AV

    Gordon @ Convergent AV
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    TO ANYONE READING THIS THREAD:

    It has been taken out of context from another thread in which a poster was asking what subs he should consider.

    I stand by the fact that good subs are good for everything be it film or music.

    Gordon
     
  7. eviljohn2

    eviljohn2
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    The subwoofer itself won't have any idea what it's being fed beyond whatever signal is sent to it. In the same way as speakers don't "know" whether it's music or a film.

    What would make a difference is what DSP you run it through or whether you set it to "slam" or "depth". To my knowledge these are always manually selectable rather than automatically switched though.l
     
  8. Daneel

    Daneel
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    Gordon, I agree with your last post. However cheaper subs tend to do either low distortion (for music) or high volume (for films). I'd say that is the difference. How does the sub know? It doesn't but it is designed for one or the other in the lower price bracket, IMO. Once you get a serious sub I feel that they do both well.

    You could also split it by extension. Very few music tracks need strong output under 30Hz (yes I know there are exceptions) but for films 25Hz isn't uncommon. There seems to be a tendency towards bigger drivers to meet such depths which to me will increase distortion and speed simply because a bigger driver is harder to move. Therefore bigger drivers = lower bass but the speed and accuracy required for music is not as good. This is just my own theory and one of the reasons I feel that designs like the SVS PB2 using 2 12" drivers is a likely to be a good solution for both.
     
  9. Miniholic

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    When I bought my sub, the spotty yts looking kid in the shop was going on about how some subs are only any good for music, and others only for films. I asked him about films with music in them and it really shut him up, maybe you need two subs for those:D.

    I would think that music needs a more capable sub due to timing, whereas any sub can mae a loud noise that would add to a movie soundtrack, although perhaps not reproduce the finer details. At the end of the day, a good quality sub should be able to work well in all areas, afterall we do pay enough for them.

    Ian
     
  10. StevieDvd

    StevieDvd
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    Darn,

    And I thought the speech was from the centre, loud noises from sub, music from left/right and scary noises from satellites. Or have I just got my setup wrong?
     
  11. Smurfin

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    Speed and accuracy is just as important in movies imho, and as someone rightly says....there's music in movies too ;)

    I'm sure I read something which blew the theory of bigger drivers being crap for music out of the water. And if what you're saying is true, then subs like the DD-18, HGS-18, Servo-15, HGS-15 etc etc would not be any good for music?
     
  12. Daneel

    Daneel
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    Not that they wouldn't be any good, but that it would be harder to do. Maybe that's part of the reason they cost 3 times the price of a PB2+?

    You may well have read something that contradicts my little theory, but who wrote/funded it and did it make sense? My theory makes sense I think. Bigger driver = harder to move. No?
     
  13. rob_w

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    Hi Daneel,

    The thing you've missed in your theory is that a 15/18 driver moves way less than a 10/12 to produce the same volume.

    Also if you check the parameters of 15/18" driver against 10/12" ones you'll find that 'generally' the bigger drivers will produce more dB than the smaller ones for a given watt.(easier to move?)
    More generalising would say that the larger speakers would give less distortion at a given spl than a smaller driver aswell.


    On the movies/music Q.....

    Movies need large spl's in the lowest registers, music doesn't..

    If you look at sub designs then the most musical ones are -usually/subjectively- ib's, horns, or sealed boxes ( and di-poles if you've got lots of drivers going..)

    Many people equate 'tightness' with group delay (large in vented boxes, smaller in sealed)

    I feel most people on movies would rather have the spl there with a higher group delay, than have lower volumes and 'tighter bass' - this is why svs stuff is doing well - well designed ported subs that give a good, deep response at the right spl.

    I believe a pair of sealed 12's would sound better than an vented sub for music, but lack the output for movies..

    As a footnote, you'll notice a few people here choosing svs over the servo 15's - this makes sense as I believe the servo15 limited the output at 98dB @ 20Hz, meaning the 'less accurate' svs's actually attained nearer reference levels, but with increased group delay, poss. distortion. - unhearable with a film soundtrack, but probably hearable on music....

    For the info on the servo15's 98Db@20Hz see the footnote here:

    http://www.stereophile.com/loudspeakerreviews/955/index1.html

    Makes you wonder about the 'deep and flat - real bass blah blah blah' claims that have been made on this forum for ages does'nt it?;) Hmmm

    Cheers

    Rob
     
  14. Jeff

    Jeff
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    It depends on the frequency.
     
  15. Daneel

    Daneel
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    Hrm. Perhaps I will work on my theory some more. Then again I could just ask Ron at SVS why they use 12" drivers rather than 15" or 18".
     
  16. Nimby

    Nimby
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    15" & 18" drivers require larger diameter pipes. They already have WAF issues at 16".

    Don't smaller drivers (which require very long piston movements to produce bass at decent level) suffer from intermodulation distortion? Don't sealed boxes suffer from assymetric distortion as a result of one side of the cone seing a high compression chamber and the other side almost no compression at all?

    You can say what you like about SVS's use of reflex porting and distortion. Though I would urge you to do a search on distortion V SPL tests in US tests.

    My 16-46 is producing the tightest, fastest, most brutal, most subtle & incredibly musical bass I have ever heard. Did I forget to mention: "LOUDEST"? :D That shouts excellent transient response and very low distortion to me.
    Remember: The reflex cone can be lighter than a loaded dustbin lid in a sealed box.

    It's not the type of enclosure that matters. But the designer's skill in overcoming supposed theoretical weaknesses. By selecting suitable components and enclosure designs. All the rest is just theory.

    Nimby
     
  17. Craig Sowerby

    Craig Sowerby
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    Hi,

    Interesting stuff!

    Your room dimensions, seating position and subwoofer location will have more of an effect on what your hearing in terms of bass than what your subwoofer actually performs like.

    Most of you guys have pretty good subs, but i have read peoples posts who have the same units but are having totally different experiences.

    Way off the subject here anyway!!:)
     
  18. Gordon @ Convergent AV

    Gordon @ Convergent AV
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    Indeed Craig but assuming you get the thing in the right position (which I bet most folk don't) a good subwoofer is good for everything.

    Going to come see you guys on my next trip to the North (sounds weird calling somewhere south of me North.....)

    Gordon
     
  19. Craig Sowerby

    Craig Sowerby
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    Hi

    Thats right.

    May see you soon, its warm down here in the south!!
     
  20. Stellavision

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    Warm and sunny in Portsmouth today whats it like t'up north?

    :D

    (Sorry OT I know, just thought I'd rub it in in case it's snowing in Yorkshire or something!)
     
  21. bob1

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    Warm and sunny in Sheffield today:cool:
     

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