Low end Sub response: How low is low enough?

Discussion in 'Archived Threads 2001-2004' started by Brian Ruth, Nov 1, 2002.

  1. Brian Ruth

    Brian Ruth Supporting Actor

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    I just wanted to hear your opinions on how low a sub needs to go to reproduce quality sound. I've been pretty happy with my PB12 sub so far, but the spec of 25Hz seems a LITTLE high as far as response levels go.

    What do you guys think?
     
  2. John Garcia

    John Garcia Executive Producer

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    25Hz is acceptable, but lower will still be better. 25Hz is actually not that low for a good 12" sub, as there are plenty of 10" subs that can do this. I've never really been impressed with JBL subs. They are fairly tight, but nothing special, probably because they seem to tune for ouptur rather than low extension.
     
  3. Antonio_B

    Antonio_B Stunt Coordinator

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    hi Brian,25HZ is pretty good though, but you can still get better response of course.For example my 12" PS-1200 sub from Paradigm is a very good subwoofer and goes down to 22HZ(which is pretty deep IMHO).BTW,humans can only hear down to 19HZ,lower than that,you feel it in your chest.
    Ok,later now!
     
  4. Brian Ruth

    Brian Ruth Supporting Actor

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    Antonio... how much did your PS1200 cost?
     
  5. Dustin B

    Dustin B Producer

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    There is no real set frequency that peoples' hearing drops off at. It will vary from person to person and be dependant on the SPL the frequency is played at. You may not be able to hear a 18hz tone at 80dB but you may be able to at 100dB. And one person may be able to hear 22hz at 100dB but not 18hz while the next person can hear both.
    Also going low and quality sound aren't one in the same thing. There are many great sounding subs that don't do well below 30hz and there are subs that will extend into the last octave that sound aweful. There is a little music and a growing number of movies that make use of the last octave though. So although you can do without, a sub that can do the last octave properly definately adds to the experience with these select titles.
    The PS series from Paradigm is a 4th order bandpass design. I'm not a fan of bandpass designs.
    You can learn about various allignment types here. Does a pretty good job of explaining them.
    http://www.danmarx.org/audioinnovation/theories.html
    Paradigm is also significantly cheaper in Canada than the US. For what you would pay for it in the US you should be looking at the Hsu VTF2 or one of the cheaper SVS models. Unless of course you have the ability to build your own enclosure.
     
  6. Antonio_B

    Antonio_B Stunt Coordinator

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    Brian,i bought my PS-1200 for 600$ CAN.
     
  7. RichardH

    RichardH Supporting Actor

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    I think if you can stay flat to the single digit Hz that's pretty adequate. [​IMG] [​IMG]
     
  8. Michael R Price

    Michael R Price Screenwriter

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    The problem with trying to extend a sub into the nether regions of bass is that you compromise efficiency (or size). Compromising efficiency means you need boatloads of power to achieve a certain extension... there's a reason the Sunfire subs have 3000 watt amps or something like that. The flip side would be to have a gigantic horn or infinite baffle the size of a small room (then you could have low extension and high efficiency).

    Big amplifiers and materials for large enclosures cost money, so most commercial subs don't extend so low (most don't get to 25Hz). Vented subwoofers tuned somewhat higher have higher output capability in the more usual frequencies >30Hz, so factor this into your decisions and don't automatically assume the deeper-rated sub is better (example: SVS 25-31).

    As a side note, I wouldn't trust quoted subwoofer specifications since you're not told how they were measured. (And if the sub can go to 20Hz, if it will only do it cleanly at 70db it isn't of much help). Even the high-end model specifications are usually exaggerated quite a bit, and no two manufacturers use the same ratings system.
     
  9. Steve_Ma

    Steve_Ma Second Unit

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    Great response Michael! A big bottom is not necesarilly a quality bottom. :b
     
  10. Jason_Els

    Jason_Els Screenwriter

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    You certainly don't want to go below 9hz. Sustained 8hz is called, "the brown note" because it resonates particularly well with the human bowels causing one to lose a very important form of control.[​IMG]
     
  11. Michael R Price

    Michael R Price Screenwriter

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    I've heard lots of things about a supposed "brown note." I'm kinda skeptical though. There's only one way to find out if it's true. Tom Danley and some others might know from personal experience. [​IMG]
     
  12. Antonio_B

    Antonio_B Stunt Coordinator

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    hi guys,could someone tell more about the "Brown Note"?
    Has anyone heard it before,if not where could we have a chance to hear it?
    See ya.
     
  13. Mike Poindexter

    Mike Poindexter Stunt Coordinator

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    The "brown note" is total BS. If anybody wants to try it out, get a computer to feed a low frequency into a butt kicker. It won't make you crap your pants. If it did - I would sell a vibrating toilet seat and make a fortune at the expense of exlax's bottom line.

    Flat to single digits is not only tough, it is "nearly" impossible without a specifically designed sub that will set you back big bucks. I don't know many subs that can put out 110 db of 9Hz.

    Flat to 20 is the goal. Any more is icing on the cake. I go flat to 15Hz on every channel (yes, including center and surrounds) and have never once felt like I needed more bass. I don't even run a sub.
     
  14. Michael R Price

    Michael R Price Screenwriter

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    Mike, what kind of speakers do you have that can go to 15 Hz?!?

    Any word on how low the LAB horn goes if you use the corner of a room to extend the flare? Theoretically you could get the horn to go pretty low (a Klipschorn extends to around 35Hz and really isn't that big).

    The lowest response practically achievable is generally in a large infinite baffle with EQ due to the slow rolloff. Tom Nousaine built one that, when equalized, could do 120db at 10Hz or something crazy like that.
     
  15. Mike Poindexter

    Mike Poindexter Stunt Coordinator

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    Michael,
    The speakers are Infinity IRS V for the front, IRS Betas for the back and IRS Gammas for the centers.
    I don't think that the horns will go lower when in a corner because the walls will reinforce all frequencies of bass, making the rolloff the same and only changing the total spl output.
    There is another way to extend the lower frequency output and that is to use a feedback look with an accelerometer and a servo controller. That is what the IRS does and now is in the Genesis 1.1 and perhaps the slightly smaller genesis speakers as well. It takes a reading from the woofer with an accelerometer attached to the driver and compares it with the signal it is supposed to drive. The difference is added back into the input to the driver to make up for where it is lacking. It is also programmed with what type of additional excursion that it needs.
    When I was hooking up my system, I was warned that if I hooked up a phonograph, I would have to set the low end cutoff to 15 Hz, because it would try to play the .56Hz pattern from the record if there was any warp causing the needle to move up and down at 33.3 rpm, which equals .56Hz and the calculated extension would easily bottom out my speakers at anything above a whisper.
    I posted a link to these speakers in another thread, but here they are:
    http://www.avsforum.com/photopost/sh...at=500&thumb=1
     
  16. Steve_Ma

    Steve_Ma Second Unit

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    I don't know that I buy into the whole "brown note" theory either. However, when testing the FR of my sub: At around 16hz and below, I started to feel nauseous. My 2-year-old daughter ran out of the room. Wine glasses were clinking on the adjacent room, but no "audible" sound. Spooky stuff.

    I also don't think that high SPL's at certain frequencies necesarilly equals "quality." IMHO, A "quality" sub will also perform well on complicated (bass heavy) musical recordings. Boominess might be ok for effects, and movie explosions, but it can really ruin a good song.
     
  17. Mike Ford

    Mike Ford Extra

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    I've heard pursusive arguments that below 20 hz information can really enhance spatial perception, but what has really low bass recorded in it? A subwoofer flat to 5 hz won't do anything if the source is rolled off at 35 hz.

    My personal goal is substantial output at 12 hz, and pretty much flat to 16 hz. Thats because I have at least some recordings that have no low frequency roll off. Not so much high levels of low bass, but something way down.

    Wasn't there some software that would measure all the signals of a CD or DVD and show the peak levels of all the frequency bands?
     
  18. Guy Usher

    Guy Usher Supporting Actor

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    My father was in the military and during WW2 he worked on a new project where they used "Infrasonic" (i think thats the term) sound waves down into the single digits for cleaning purposes. One problem they had was that every time they tried out this machine everyone would crap in their pants. He has some funny storys to tell about that project. He knows nothing about and doesn't care about sound systems etc.
    As to wether or not this will happen, I have never experianced it, however I have heard low bass that made me "projectile vomit". A kid with 15 12 inch woofers in his little Blazer did that to me on more than 1 occasion.
    My personal subs consist of 4 12 in Dyna Audio drivers, 2 compound loaded in each box, these drivers were over $400 each and the system was built by a recognized Speaker Builder, all the math is right. they will get down to the high teens but at a very low level, they start rolling off at around 24 hz but from there up to 100hz they are flat as a biscuit +/- 2db
     
  19. Michael R Price

    Michael R Price Screenwriter

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    In the future I see movies using more and more infrasonic effects that could really enhance the experience of watching one, provided you have a system that can handle it.

    Theoretically with the current Dolby spec movies could demand something like 121db at listening position at any frequency under 80Hz. I believe some movies already use nearly all of this capablity down to the 20-25Hz range. The future of bass will be interesting.
     

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