Fs advertised versus capability

Discussion in 'General Audio Discussion' started by opusarlo, Nov 2, 2017.

  1. opusarlo

    opusarlo Active Member

    Messages:
    188
    Location:
    Grand Rapids, Michigan
    I really wanted to avoid asking this embarrassing question, but I cannot get around it. In designing a infra-sub (if you will), I am realizing that most manufacturers will not list Fs below 20Hz, and many of those list 30Hz. My "Infra-Sub" will play only 30 Hz on down, and I will use a Linkwitz transform + a DSP to increase the sensitivity of those tones to at least 0. Here is the question: Am I creating or emphasizing tones at that point? I listen to high-res pipe organ music, and my goal is to reproduce the infrasonic tones you feel when listening to one of those roaring behemoths. I don't want to "create" at all. It is bad enough that I have to bring gain to tones that might be there.
     
  2. botrytis

    botrytis Trying not to be a Small Speaker Hoarder Subscriber

    If you want pipe organ music - get a big sub preferably 2 - 16 Hz is the lowest bass pipe note
     
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  3. ev13wt

    ev13wt Super Member

    Depending on the level you want to EQ - look at a fan subwoofer. Its really the only way - if you don't want to use 4000w and 4 15" woofers+ to get 17Hz up to the rest.

    Fun fact: 17Hz is the eyes resonant frequency, some gohst sightings have been attributed to that fact. Please very this when you have your sub :)
     
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  4. opusarlo

    opusarlo Active Member

    Messages:
    188
    Location:
    Grand Rapids, Michigan
    The fan woofers are insanely expensive, and require heaps of renovation. They are critical if I need to get down to .0001, but 16 hz is as low as my instrument goes. This outta get the job done just swell:

    http://stereointegrity.com/product/hst18-18-subwoofer/

    I am just concerned that once I build a box, those T/S numbers will be entirely different.
     
  5. eiraved

    eiraved AK Subscriber Subscriber

    Messages:
    1,385
    Location:
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    Previously discussed in "Big Boom" thread. Cough up 13K please!
     
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  6. opusarlo

    opusarlo Active Member

    Messages:
    188
    Location:
    Grand Rapids, Michigan
    by ")", I meant no roll-off...I was in no way saying I was going to hit .0001 Hz with radiating bass in a wooden box. lol, I read that over and figured I better clarify that.
     
  7. botrytis

    botrytis Trying not to be a Small Speaker Hoarder Subscriber

    Well, the new B&W 800 D3 are spec'ed as 15Hz - 28KHz =/- 3 dB . Also know someone with a pair and they tested to 16 Hz in their room.
     
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  8. whoaru99

    whoaru99 Epic Member

    Messages:
    39,362
    Location:
    LoTL
    If what you want is in the original material then it's a matter of reproducing it regardless, IMO, if that requires EQ to make any given speaker reproduce it.

    Creating would be what something like a DBX 120 Subharmonic Synthesizer does. It takes certain frequencies and creates new material from that then adds the synthesized material to the original.
     
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  9. nyhifihead

    nyhifihead Well-Known Member

    Messages:
    665
    Location:
    long island NY
    Fs is not the end all for low end capability, but it is a good indicator for sure. Xmax and woofer size will show you how much air you can move, which will translate to low end capability as well.

    FYI There's a few limitations with getting this kind of response

    1) physical size - to truely create these frequencies you are going to need a large amount of real estate, most enclosures start at 4-5 CU ft for a 12/15" and 6cu ft+ for 18s. Its going to be a large wood box, and these values are approximates for sealed, ported enclosures will be even bigger. If you have a bigger room you may need 2 subs to get the low end you desire, 4 would be ideal, even I'm not that crazy though.

    2) DSP- when modeling for frequenices this low you are going to have issues keeping it linear, DSP is a must. I like REW and miniDSP, I also use a calibrated umik-1

    3) power, even with "efficient" subs (90db+) these low freqs pull INSANE current. not to mention a good amount of amps high pass at 20hz!! say goodbye to a lot of information. Even some mfg that claim they can play below 20hz are still attenuated a few db in an effort to make the units more robust. You are going to want to invest into a large pro power amp that likely will have a fan. Many like the crown XLS series or behringer iNUKE, I use 2 QSC mx1500's bridged 1500w @ 4 ohm, 1 per 18"

    btw- the iNUKE does have the 20hz HPF, you can disable this with a software mod.

    I recommend checking out stereo integrity subwoofers, they all have ultra low FS (<20hz). Their subs are relatively easy to model as well, they respond well to sealed boxes with qtc of .707.

    you can grab bassbox pro 6 It's a great modeling program, you can also ask nick at SI his recommendation based on your intent.

    http://stereointegrity.com/

    I use 2 of the discontinued DS4, its a 18" with 4 ohm DVC 1200wrms rated 4" voice coil. Xmax is 27mm, they are in 6ft cu enclosures with an in room f3 of 17hz. With REW/DSP they are near linear 15-80hz. They produce everything down to 10hz effortlessly, and their implementation overall has contributed more sonically than anything else in my system.

    drivers + MDF + DSP will cost a lot.. but the bang per dollar compared to preassembled subwoofers is astounding. I spent near $2500 for everything and I couldn't be happier, I know $2500 thrown at JL or REL will get me nothing comparable
     
    Last edited: Nov 2, 2017
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  10. whoaru99

    whoaru99 Epic Member

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    It's good that excursion was mentioned too. Making a speaker/driver do 10Hz in a low power frequency sweep/response test is one thing. Making it do 10Hz with, for example, 100dB output is something else.
     
  11. manu et deo

    manu et deo Why can't I decide? Subscriber

    Messages:
    450
    Location:
    SW Riverside County, CA
    16hz at what db is the question for you. I have 2 12in infinties in 4cu ft tuned to 22hz and they will play a 10hz signal loud enough to make my head a little woozy and me a little queasy with just one channel of a XLS 2000. But I'm susceptible to infrasonics. YMMV
     
  12. opusarlo

    opusarlo Active Member

    Messages:
    188
    Location:
    Grand Rapids, Michigan
    This was a fantastic source of knowledge. Thank you. Interestingly enough, I am using Stereo Integrity subs. Both 18", but the infrasonic will be the mark II. The mid woofer (30 to 120ish...maybe 150) will be there economical 18. From there the Cornwalls will take over. I will download that design software in the morning. Thank you. Price wise, I could do Jensen XL 1200 ( eight 15" woofers) for 3k or do my own for just over half....guess which one will hit 10Hz?
     
  13. opusarlo

    opusarlo Active Member

    Messages:
    188
    Location:
    Grand Rapids, Michigan
    I am shooting for 115 dB, hence the reason for separate subs
     
  14. opusarlo

    opusarlo Active Member

    Messages:
    188
    Location:
    Grand Rapids, Michigan
    That is encouraging! Not that younget nauseous, but that you can achieve that level. It lets me know it can be done! W00T!
     
  15. opusarlo

    opusarlo Active Member

    Messages:
    188
    Location:
    Grand Rapids, Michigan
    Lol..no thank you
     
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  16. nyhifihead

    nyhifihead Well-Known Member

    Messages:
    665
    Location:
    long island NY
    I'm guessing you have the HT18 or HT18 v2? killer subs for the money.

    I also apologize. the in room f3 of my subs are actually around 25hz, I checked out my final design and went with 6.0 cu ft opposed to a larger design that would. Also the significant internal bracing I did brought my qtc almost perfectly to the .707 for sealed enclosure, increased f3. Although I dont listen to organ music, I do listen to "slowed" up songs with 808s that approach 15hz, it is extreme bass music and is awesome, it seriously makes these 18"s move and the back massage is a nice side effect. I used doubled up .75" MDF for all panels with an insane amount of bracing, those boxes are practically inert.

    you can easily model a different enclosure to get your desired bass response, I ultimately needed the subs to be flat to 60-70hz where my main speakers can pickup. If you are going for a true infrasonic you can make a massive enclosure and get an f3 of 10hz with these SI drivers, with multiple drivers tuned to that spec you are looking at true life emulation of earthquakes.

    I recommend emailing SI, nick is awesome with designing boxes, I got exactly what I wanted out of my system taking his advice. I supplied him with screenshots of my build and gave great feedback for my needs. I am a music guy but I love the deep bass, so my subs are tuned to hit down to the low 20s.

    [​IMG]
     
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  17. nyhifihead

    nyhifihead Well-Known Member

    Messages:
    665
    Location:
    long island NY
    Interested in what you have decided on regarding drivers and enclosure
     
  18. opusarlo

    opusarlo Active Member

    Messages:
    188
    Location:
    Grand Rapids, Michigan
    I am pretty sure I will be going with the HS 24" Mark II sub and a Speaker Power SPI-4000_HT in a 15 f^3 sealed enclosure firing down 17.5" to concrete. WIth that being said, I am over my budget. Also, Christmas is coming. I may have to wait until January to buy the gear, but I will be building and bracing the box in the meantime. Here is a pic of the plans I came up with.
    system layout.PNG
     
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  19. nyhifihead

    nyhifihead Well-Known Member

    Messages:
    665
    Location:
    long island NY
    Nice I'm happy your as crazy as I am, for your application I wouldn't have used anything other than 24" the HS 24" are remarkable drivers some dude over on avsforum did a cost no object build for infra bass and that was his driver choice as well.. he used 8 of them in addition to a bunch of SI 18s in a concrete shed he made! absolutely insane

    [​IMG]


    http://data-bass.ipbhost.com/topic/449-hst18-hs24/?page=12&tab=comments#comment-14887
     
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  20. eiraved

    eiraved AK Subscriber Subscriber

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