BWC (Big Woofer Club): Why Big Woofers Matter

Discussion in 'Speakers' started by nishan99, Aug 5, 2020.

  1. nishan99

    nishan99 Almost "Made"

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    FORWARD FROM THE EDITOR
    (original post below)

    For as along as I can remember (decades), there has been a huge misconception, especially in ORFAS audiophile circles, that large woofers sound "slow". This 150+ post thread started innocently enough: why is big woofer considered better than two smaller woofers with the same surface area? Unfortunately readers will have to wade through the entirety of the thread to get all the answers.

    The following bullshit myths are addressed in this thread:

    • Larger woofers have more mass thereby are slow and cannot accelerate as smaller ones thereby make lower quality bass
    • Larger woofers because of their slower impulse response cannot produce fast accurate bass like smaller ones
    • Larger woofers are only good or needed for bass extension - a smaller one is just as good if you do not need deep bass
    • Larger woofers are only needed if you need high SPL
    • Larger woofers will overly pressurize a smaller room producing stranger results than a smaller one
    • Smaller woofers make better quality and more accurate bass because well respected speaker designers like Andrew Jones only make small woofer speakers.
    • Respected speaker companies not do use large woofers because smaller woofers better quality and more accurate bass
    • Bass needs to be fast (as opposed to "fast" which may have varying meaning)
    • A larger woofer needs a bigger motor, stiffer cone, and stiffer suspension. These make the costs prohibitive to achieve the same level of performance as a smaller woofer.
    These myths are perpetuated because of the ORFAS / Audiophile Company Industrial Complex's self-interest. They are also because that big wide speakers are ugly, unwieldy, and do not sell. (All true points). This does not mean that we cannot do better for ourselves if we want to think different.

    ---


    ORIGINAL POST HERE:

    I read long time ago that a big woofer is better than smaller woofers with equal combined size. Which explains the obsession with big woofers here and some other forums.

    But I never understand exactly why. Point source bass is not a thing right?. And I guess a bigger woofer will flex and distort more, requiring a stiffer but heavier material.

    But I also thought about the sound intensity being greater because it's coming from a narrower space instead of delivering the sound across vertically like with smaller woofers. The surface area of those smaller woofers and the baffle area between them is greater than a single big woofer surface area. Hence the sound intensity.

    Everyone feel free to correct me or share your thoughts if you will.
     
    Last edited by a moderator: Aug 8, 2020
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  2. purr1n

    purr1n Finding his inner redneck

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    A single bigger woofer will have lower resonant frequency (deeper bass) and efficiency (SPL / watt) than two smaller woofers with same surface area. Going from a typical 10" woofer to a 15" woofer results in x2.3 more surface area. That is two 10" woofers is still "smaller" than a single 15".
     
    Last edited: Aug 5, 2020
  3. purr1n

    purr1n Finding his inner redneck

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    They will have more linear distortion (screwy FR and then massive dip) as we go up the audio band. Larger woofers can't play at higher frequencies and will require the use of a dedicated midrange. The suckiest thing about big woofers is that you ain't gonna be handling it off to a tweeter at 2-3kHz. This is probably a good thing.

    In terms of non-linear distortion and efficiency, larger woofers will have a huge advantage. While mass goes up and suspension gets stiffer, the surface area increases by a power of two. A = pi*r^2 and all that jazz we learned in geometry.

    Large surface area is huge because there is less cone displacement required. Motors (magnetic force and suspension) are not linear and things rapidly turn into shit once the voice coil moves away from center. This is why those super long subwoofers are a joke. Real subwoofers which are used in cinema such as the JBL 2241H only have about 7--8mm of linear excursion range. Many audiophile or dedicated home theater subs with their mega rubber surrounds advertise 40mm of xmax.

    Greater mass of cone is easily offset with bigger magnets and stiffer surround and spider.

    There is a limit, the gains seem to stop after 15 to 18".

    Sound could be more intense because a larger woofer doesn't need to move much. It stays in the center of the gap where the magnetic force hasn't tapered off and the suspension (surround and spider) isn't trying to push it back center.
     
    Last edited: Aug 5, 2020
  4. RobS

    RobS RobS? More like RobDiarrhea.

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    The bigger you go with the woofer, the more moving mass you have to deal with. This will make things much more difficult to control and your bass performance will suffer. You would need to have an extremely large sized speaker motor and have a diaphragm that doesn't flex which would give perfect pistonic motion. Then there are other issues of inertia, damping, power, etc. There exists no cone that will give you zero mass and infinite break-up mode frequency, because it is physically impossible.

    A properly designed woofer will eliminate mcuh of these issues and you can have extremely tight bass with negligible low distortion. Like linear extension down to 30hz.

    Size has nothing to do with how well a speaker is designed and engineered. Unless you really need a big woofer to compensate for having a small penis. My 6.7" woofers are still bigger than my penis but the bass speed, tightness and control is unbelievable.
     
  5. ChaChaRealSmooth

    ChaChaRealSmooth SBAF Gearmaster

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    There is no replacement for displacement (up to a point). I think @purr1n already addressed this pretty well. Big woofers in properly designed speakers are awesomesauce and I really wish I had the space for them.
     
  6. purr1n

    purr1n Finding his inner redneck

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    It's huge huge misconception that greater mass means difficult to control or compromised bass performance. Control or damping is through electrical (magnet and VC) and suspension (surround and spider). This isn't a car that needs to turn. The cone only needs to accelerate / decelerate. The problem of the heavier cone is easily resolved with a bigger motor.

    Size is everything. Woofers where we never see the cones move are the best kind. The fastest woofers are the ones which are super efficient without the insane excursion. The JBL 2241 especially in an Edgarhorn sub enclosure like this is super "fast". Moth Audio did their version of this in an Art Deco style.

    It's not about size, it's about bass quality.

    edgarhorn.png
    [​IMG]
    [​IMG]
     
  7. RobS

    RobS RobS? More like RobDiarrhea.

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    Properly designed means they are also super expensive. They are more difficult to get right. You need crazy diaphragm stiffness, huge motor, high flux denisty, and rigid basket. Oh and you need a cabinet to support all this.

    A bigger speaker gets you linear down to 20hz. That's the only advantage.
     
  8. purr1n

    purr1n Finding his inner redneck

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    Oh no, it also gets you a lot better bass quality, lower distortion. It's said that one gets big woofers not necessarily for the extension, but for the effortless midbass. In addition, bigger woofers will be more efficient. Try finding a 96db efficient woofer in 8" size. Efficiency is free power.

    I'll take an Eminence Beta 15 for $79 a piece than most any audiophile TOTL drivers less than 10" for frequencies below 350Hz.
     
  9. Vtory

    Vtory Illogical Spock

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    I was once in Robs's camp, fooled by claims of modern speakers manufacturers (and stereophile). Explanation-wise Marv and Chacha might very likely spot on, although I believe it's hard to experiment/prove as we all are space-limited.

    Empirically speaking, using 15" woofers now (neither super expensive nor super exotic), I don't think any <10" I've ever owned or auditioned stack against my current experience around 50-200hz. I'm not saying 20-40hz.

    "Real" biggest disadvantages of big woofers I've identified include (1) pretty low WAF, (2) limited in-production options (as per current hifi trend), and (3) if implemented in box enclosure, total volume should be almost like refrigerators.
     
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  10. AdvanTech

    AdvanTech Friend

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    Why do I get the feeling you’ve never heard big woofers?
     
  11. purr1n

    purr1n Finding his inner redneck

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    We've had this exact same conversation before, just with different people.
     
  12. purr1n

    purr1n Finding his inner redneck

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    (1) and (3) are definitely problems. (2) actually less so. Tons of options. Pro world. These $50k Voxactiv 9.87 use a "cheapass" custom-spec pair of Eminence 15s in an H-frame.

    [​IMG]

    The finished speakers are indeed expensive. The drivers not so much. The cones and materials have been perfected over decades by JBL and everyone else just copied JBL. This isn't high tech anymore. There are no secret formulas or construction methods for the cones or fancy folded surrounds or spider. The largest expense is probably the magnet.

    This is Voxactiv, where their individual drivers can sell for $2.5k. And they are using Eminence to fill out the lows for which they are probably paying no more than $75 per woofer.
     
    Last edited: Aug 5, 2020
  13. sphinxvc

    sphinxvc Gear Master (retired)

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    Those are active and ripole IIRC. I know ripoles were patented at some point, not sure if it's free for use now. Eminence is OEM for a lot of designers.
     
  14. k4rstar

    k4rstar Done his time

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    it's not just about bass quality either - size influences scale and ability to reproduce dynamic peaks approaching the real SPL of instruments. a small two-way box is not going to do it, even using the latest bleeding edge european drivers and fancy crossovers. improved low frequency resolution also adds weight and gravitas to the entire spectrum of sound.

    I partially blame the BBC mini-monitor movement and acoustic suspension fad in the late 70s for beginning to trick consumers into thinking that some sort of herculean design efforts could overcome physics

    in the 1950s when hi-fi was mainstream manufacturers and speaker designers had the will and incentive to make larger cabinets more appealing in the home, and allowing the use of larger drivers in space-efficient packages. a lot of advertisements made reference to space efficiency, and often showcased the speaker in a living room environment with the wife or the kids around.

    Screen Shot 2019-11-26 at 8.47.07 PM.png Screen Shot 2019-11-26 at 8.50.11 PM.png Screen Shot 2020-01-14 at 7.39.09 AM.jpg ev.jpg

    here is the best speaker system I've heard in reproducing the scale of a drum kit or other contrabass instruments. I assure you that no 'properly designed' speaker with an 8" woofer will resemble anything close.

    [​IMG]
     
  15. zonto

    zonto Friend

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    This tracks my experience as well trying to find something for the living room and basically being limited to gloss black and similar finishes. Anything like Klipsch Heritage or vintage JBL or other compression driver boxes aren’t going to fly. The biggest I’ve found in “audiophile” speakers at a local dealer are Revel Performas with dual 8” drivers (boring sound, with or without the Be tweeter). There’s also Legacy Audio towers with 10-12” drivers (but hard to find to demo).

    edit: And Dynaudio Contour 60 with dual 9” woofers, but no dealers stock because it is too tall...
     
    Last edited: Aug 6, 2020
  16. Hrodulf

    Hrodulf Prohibited from acting as an MOT until year 2050

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    Not necessarily. Those pesky Europeans with their hi-tech drivers have been making good BWC stuff for some time. FaitalPro, 18sound, BMS, Celestion make brilliant pro audio drivers which often blow the pants off of many boutique manufacturers.

    The lower/louder you go the more air you need to move, hence the expression about displacement. It's a bit of a paradox, but speakers drivers generally like standing still and the more you move them the worse they will perform. Thus big drivers due to their larger moving area don't need to move as much as a smaller driver to deliver the same SPL at the same frequency.

    This matter becomes more complicated when you ask whether multiple smaller drivers with the same Fs as the bigger one to match its cone area and sensitivity. Science says that it shouldn't matter. Making a good test would be difficult as you'd need the same driver in different formats.

    My experience is that for low end you need to go big, unless you absolutely can't. I'm a sucker for dome mids with 4g mms, but at the same time I've hard mids played by a coax array made from four 18" drivers and despite having 25x higher mms, there wasn't much missing. And dynamics were to die for.
     
  17. RobS

    RobS RobS? More like RobDiarrhea.

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    Lower moving mass enables better acceleration and deceleration. A smaller diaphragm means it can be more rigid. Think of bending a coat hanger. Easy to bend when you have the whole thing, but try bending it if it's only a 1 inch piece. Ain't gonna happen unless you're Superman.

    My argument ain't that a big woofer can't work, it's just much more difficult. In practice, you won't be able to achieve all the same conditions as a small woofer.

    A bigger woofer is inherently going to be more efficient because it's coupling more air. You can do the same with multiple low mass woofers to achieve similar results.

    Free power? Sure. Lower excursion distortion? Sure. Does it mean the woofer is fast? No.

    As an aside, I've seen 8" woofers from JBL measured with a F3 of 27hz which could go down to 24hz in a bass reflex.
     
    Last edited: Aug 6, 2020
  18. Hrodulf

    Hrodulf Prohibited from acting as an MOT until year 2050

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    VC inductance will impact that more than adding mass.

    This will dictate breakup modes. LF stuff is usually in the pistonic range where the woofer moves as a whole.

    Please forget about drivers being "fast". If a driver achieves a good frequency response in the needed range, then it will be fast enough. A "fast sounding" bass usually means that there's little room impact and decay is clean. Drivers are never slew rate limited unless you pile tons of inductance on them.

    upload_2020-8-6_16-31-40.png
     
  19. purr1n

    purr1n Finding his inner redneck

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    Not all all. The only condition a small woofer is better at is playing at high frequency where there is faster change in direction. Heavy still can accelerate quickly. Tesla Model X and Dodge Challenger? Those are two heaviest cars around. When it comes to speakers, the motors are cheap. It's easy to accelerate fast in a straight line which is what speaker drivers do. It's all about mass / motor.

    This is where you are dead wrong. More smaller woofers can be more sensitive (SPL / Vrms) when we wire them in parallel. However they will never be more efficient (SPL / Vrms). If you don't believe me, scour the datasheets. All things being equal (Fs, Qts, mml/BL, etc.). The surface area advantage to suspension material area becomes larger.

    "Fast" drivers IMO tend to be efficient. Efficient designs mean lighter less stiff surrounds and spiders. This usually, but not always means higher Qms. Lack of mechanical damping is made up for with electrical damping Qes. Lighter surrounds means less xmax, which means limits on excursion. Which lends itself to larger woofers given an Fs.

    After working with bigger woofers, I can't say that I'd consider any 6" or 8" "fast" that can also reach a given Fs.

    Which one? I am curious because JBL hasn't made an 8" or 10" in years. If that 8" reached 24Hz", I probably wouldn't use it. There would have to be to much of a tradeoff of efficiency for extension.

    --

    You do realize that I've built every speaker (with the exception of the JBL 4498 which I bought for less the cost of the woofers along) that I've owned in the past 20 years and have actual hands on practice with dozens of different kinds of speaker drivers? I'd be happy yo show you the back of my garage of old small woofer designs, skinny, towers, that I haven't quite been able to throw away.

    Look, it's obvious you are going to disagree with me no matter what based on your inexperience. I would advise you to build your own speakers using large woofers like how many have discovered here. Many would be happy to advise. There is nothing like hands-on experience. There also also a ton of drivers which are fairly cheap.
     
    Last edited: Aug 6, 2020
  20. purr1n

    purr1n Finding his inner redneck

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    Low inductance is a factor that I look for. The lower the better within a set a models all other parameters being similar.

    It's based on inexperience and misconception. People think of low mms to BL stuff like ribbons which are fast, so associate fast with smaller lighter drivers. The problem is that bass is not fast. Bass is extremely slow.

    "Fast" bass usually equates with higher efficiency, lower Qts (mostly from Qes because a heavy suspension will kill efficiency), and lower distortion as far as specs that correlate.
     
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