BWC (Big Woofer Club): Why Big Woofers Matter

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

  1. nishan99

    nishan99 Friend

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    Eric Alexander the founder of Tekton Design always says that there are no speakers too big for a room. He believes that big speakers are more revealing for bad room treatments or bad setup. I never took his words seriously because he does sell big speakers :D.

    I still think horns are the exception tho.
     
  2. dark_energy

    dark_energy Friend

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    If ones gets this they can consider themselves relatively smart regarding what the chain needs to do, actually a challenging task if you think about it, electrical and mechanical part.




    Although I have quite a bit to learn about the details of it, we don't need to paint everything black and blue for the newbs...
     
    Last edited: Aug 7, 2020
  3. k4rstar

    k4rstar Britney fan club president

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    thank f**k that's over. back to some real speaker advice and recommendations

    this is why I like the original Klipsch Heresy. it has no bass, but it doesn't try to unlike the current production Heresy IV which is trying to be something its not. but the OG Heresy sounds like a coherent, point-source full-range driver even fairly up close or at odd angles, with extension down to maybe 60hz. a pair of these + small sub (nothing fancy) are great for an apartment living room. they can be found in good condition for $600 USD.

    my pair I foolishly sold. one cheap miller&kreisler sub + close to wall placement was enough to fill out the low mids and midbass nicely. high efficiency makes use of spud-power tube amps and Elekits and the like possible
    [​IMG]
     
  4. purr1n

    purr1n Desire for betterer is endless.

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    In general, he is correct. The reason is that the magnetic force is not linear throughout a cone's travel. The best speakers are the ones where we never see the cone move. We don't see tweeters move, or at least not often, because if they do, they will have already caught fire. Big woofers because of their large surface area, need to move less, much less than smaller woofers.

    Here is an example of how extremely NOT linear the BL force is throughout the travel of a high quality Morel SCW 636 6" woofer. It's not even symmetrical and after only a few mm of excursion, the magnetic force is already different!
    [​IMG]

    Same woofer, but stiffness of the suspension. Some symmetry, but as we move away just a few mm, the stiffness changes.
    [​IMG]

    This is where science actually intersects subjective observation. Keep in mind that a 6" woofer needs to move quite a bit to make bass. The more the 6" driver moves, the worse it gets, and this impacts not only the bass, but the mids that the 6" is going to have to reproduce.
     
    Last edited: Aug 7, 2020
  5. dark_energy

    dark_energy Friend

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    This is absolutely wrong. That's what probably triggered some people here.

    Big woofers can play up to 1kHz often but more common is like 12 - 15 inches playing up to 300 Hz to 600Hz via XO.

    The answer, in their range there is only to win with big woofers as has been explained by hardcore enthusiasts and people who build speakers.

    For their frequency, they have quite low moving mass. Ofc rigidity is a problem, guess what, paper woofers are still one of the best when it comes this regarding the weight to rigidity.


    (P.S I am just an enthusiast who has listened to what experienced people do and say. That's why I have a lot of RL experience now too. I am building my audio journey here, in the right direction)

    P.S.S If you think you discover your bitcoin nirvana here prepare to be disappointed. No cheap options, hehe.
     
    Last edited: Aug 7, 2020
  6. purr1n

    purr1n Desire for betterer is endless.

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    "You'd need a big f'ing motor structure and a zero-flex diaphragm."

    Engineers think of stuff of that, so naturally those things come with the bigger woofers. Added mass to make the diaphragm stiffer is easily overcome by magnetic force. It's physics. F = ma. Or acceleration = Force/mass. Here is the BL curve for a 10" sub from super respected manufacturer Seas.

    The magnetic force with this 10" woofer is twice as strong as the 6" woofer above. Not only that, it's symmetrical and stays linear at high excursion (note the x-axis is expanded here to 15mm out).

    [​IMG]

    With smaller woofers which will need higher excursion for a given SPL, we move out of the motor's linear region sooner than with big woofers. Outside of the linear region means we lose magnetic force. Will start losing steam as the woofer moves farther from the center of the voice coil.

    For steady state bass signals at lower levels, it won't be an issue. Drum hits or bass string plucks are going to momentarily push that cone pretty darn far. Granted there is compression in the recordings that we hear; but those of you musicians (I know there are quite a few drummers and bassists) will know how easily it is to see those cones move on x4 10" cabinet. FWIW, the x2 18" on my JBLs are harder to make move. I'd have to really crank it up and slap the strings.
     
    Last edited: Aug 7, 2020
  7. spwath

    spwath Hijinks master cum laudle

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    I worked at YG acoustics, they had a 21" subwoofer with a machined aluminum cone. Not exactly a super light cone, but super rigid, with a powerful magnet. According to what I have heard about it, super low distortion. Powered by built in 2k watt amp.
     
  8. purr1n

    purr1n Desire for betterer is endless.

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    How far do the cones actually move?

    To put things into context via calculations for drivers in a sealed box*:
    • A 6" driver reproducing a 40Hz signal at 90db will move 6.0mm (center to peak).
    • An 18" driver doing the same will move 0.67mm (center to peak).
    *BTW, the excursion for a ported box will be even more (too lazy to do a full sim right now).
    **Those SPL are for 1m is which almost nearfield. 2-3m listening distances will require higher SPL and more excursion


    Now take a look at the BL curves above and tell me which one is gonna sound soft, compressed, and mushy with the onset a bass drum hit at decent volume levels, not 70db background music while doing work. We can argue about the definition of slam, articulation, "fast", blah, blah, blah, but whatever it is, this is real science stuff which correlates to what the guys who have built their big woofers setups are hearing.

    The argument that 6" woofers can do the job is absolutely correct if one listens to music 15-25db below concert hall levels. However, I think most of us who have speakers probably crank up our music to have 95-100db peaks on the tympani hits with stuff like Copeland's Fanfare For the Common Man.

    As for the argument that 6" woofers can also go deep to 30Hz. Sure they can.

    A 6" driver reproducing a 30Hz signal at 90db will move 10.78mm (center to peak).​

    Did I hear a pop? I kill 6" speakers in my sleep. Then again, I have decent sized rooms and I crank it up.
     
    Last edited: Aug 8, 2020
  9. purr1n

    purr1n Desire for betterer is endless.

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    Let us speak of this no more. Day one was trying with my patience, but worth the effort in terms of conveying good information. Day two (today) has been a chore which has wasted a considerable amount of my time in bringing you fresh content. I'd almost think someone is trying to sabotage SBAF at this point.
     
  10. murphythecat

    murphythecat GRU-powered uniformed trumpkin

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    not sure how much of that is true. i mean, he's paid by elac to design small speakers. not sure it would look good for elac if Jones were to say how much better his TAD designs were
     
  11. purr1n

    purr1n Desire for betterer is endless.

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    Hahahaha. I photochopped it to parrot RobS.
     
  12. Armaegis

    Armaegis Friend

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    Pfft, here's a 32"... https://www.mach5audio.com/product/w0w-32-subwoofer/
    (prices in Canadian $, so not quite as bad as first glance, but still a lot)
     
  13. Hrodulf

    Hrodulf Prohibited from acting as an MOT until year 2050

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    Suspension compliance is also different as you stretch it out. Think - how hard it is to stretch an extra inch from a rubber band once it's already stretched, compared to when it's not. I've also heard that a similar effect is at play with small sealed enclosures - when you have a two liter box, compressing it to one liter will be way harder than expanding it to three liters. A speaker designer I know would combat this by adding a very low (~15Hz) tuned port to all of his boxes so they don't experience this effect.

    P.S. I don't know what that tells about me, but I immediately recognized the 10" by its BL(x) curve. It's a great driver. Probably not exactly BWC, but it was good enough for Linkwitz's LX521.
     
  14. purr1n

    purr1n Desire for betterer is endless.

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    Yup. The Klippel does all sorts of cool stuff. Mechanical compliance, suspension stiffness, Qts even (not pictured). This guy called npdang had a Klippel and did all sorts on measurements on a car audio site over ten years ago. This stuff is very interesting from an academic point of view. Extremely useful if you are a designer speaker drivers. And somewhat useful for speaker designers for selecting drivers (easier just to use ears)

    [​IMG]
     
    Last edited: Aug 8, 2020
  15. Psalmanazar

    Psalmanazar Most improved member; A+

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    Interesting about the ports.

    ATC claims that the ports on their three ways are more vents to lower distortion than extend the bass. Their two ways are all sealed. Granted their bass is usually lacking in weight and requires mental adjustment but they clearly are going for maximum perceived detail Uber alles. When you hear the three way with the SL drivers, or even the two ways with bass rolloff, they don’t crap out or sound wrong with certain poor recordings. Rather they play it back entirely as is like a PA from hell that shows what is wrong but plays it to the measured bass extension in your room. There is no one note port chewiness or slow woofer softness To let it all blend. It’s weird, like whoever designed them recognized what Japan fi and what Brit fi we’re both good for. Granted, this often prevents you from enjoying the music or being able to mix tracks without radically changing the sound, which the band might not like.
     
  16. 9suns

    9suns [insert unearned title here]

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    Yes, the bigger ATC use aperiodic vents instead of completely sealed cabinets:
    http://www.audiostereo.ro/ATC reviews/atc_el150psl_rev-stereoplay.pdf

    atc impedance.png

    Check the impedance peak, single like a sealed box and not double peak like a reflex box, and also maxs out at around 16-18 ohms instead of the typical 50-60 ohms, so apart from lowering distortion, the amp controls the bass much better than with a sealed box. Roll off still is 12db like a sealed box. Only downside is that woofer fs goes up a few hz compared to the sealed box. That and the SL drivers with those huge magnets is glorious bass ;)
     
    Last edited: Aug 8, 2020
  17. Thad E Ginathom

    Thad E Ginathom Friend

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    The thread is called General Speaker Advice.

    I just wanted to say that, if I didn't think so before, which I probably did, if I had to choose one person to give me general speaker advice, it would definitely be @Psalmanazar. Cheers!
     
  18. bixby

    bixby Friend

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    Speaking of "fast" big woofers, does JBL have any passives currently that could get down into the mid 40hz range for under $1k or so a pair? Or any older disc. stuff that sold well and is avail on the resale market?
     
  19. k4rstar

    k4rstar Britney fan club president

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    in my experience JBL stuff is all about the full midbass and then a clean rolloff, real extension into the mid 40s is rare for their affordable consumer models.

    my favorite compact JBLs are the L65, also known as the Jubal, from 1975-78. can't really be found for under $1k a pair anymore, more like $1200-1400. you want the earlier production with alnico drive units. 126A woofer, LE5 mid, glorious 077 slot tweeter. crossover points at 1kHz and 6.5kHz, so you get an unmolested midrange/presence region and a very full lower mid/midbass from the 126A.

    they work with all genres but like most JBLs of this vintage excel with rock/jazz. if a speaker bandit stole my La Scalas and replaced them with a pair of these I would not weep. I love these. very classy looks too, the cabinets are oiled walnut and they have smoked glass tops

    my friends pair, driven by Eico EL-84 monoblocks, maybe 10-12 watts a side. very efficient for their size.

    [​IMG]

    a review from the now defunct classicaudio.ru, accessed via way-back machine + google translate

     
  20. bixby

    bixby Friend

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    Thanks for the info. I am not sure what direction to go, and have never owned a pair of JBLs, aside from the craptastic Control One mini spkr. I do now tend to favor more efficient and dynamic speakers.

    I did have a pair of Klipsch Forte II in the house recently. I was impressed with the low end but alas I could not get used to the lower treble bite. I seem to be sensitive in the 3.5-6k range. Still pretty impressive and dynamic.

    I'll keep my eyes open for any brand candidates. I could even go down the diy rabbit hole as my friend is an excellent cabinet maker and is willing to help.
     

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