But it has no relation to the idea of near field bass in a room
headphones cannot be compared in terms of near field bass
Good thing Mark100 responded, otherwise I'd have to educate you! They play down to 20hz, the motors are 0.6ohm and are electrical actuators, not traditional speaker motors.
Let's just say that if you think these are "normal" 18" cabinets, Dave has a stool he wants you to sit on!
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for those who went from 15" woofers to 18" woofers, still a clear advantage? going from 12" to 15" is such a obvious upgrade, I kinda hope going from 15s to 18s will still be a sizable upgrade... (range I ask is 30hz-300hz)
I went off what I saw on the website as I looked just before work. I stand corrected.
What is the disadvantage you believe you have with 15" drivers? I have a combination of custom made 10" and 12" subwoofers, with some DSP multiple subwoofer trickery...and I'm pretty sure I'm not missing out on anything except room modes!
It's fun to experiment, but I doubt there is anything to be gained. The larger drivers may distort more, even though it probably isn't audible. Setting up multiple sub system with DSP is the proven way to get the best possible bass response in a small room.
Why would they? Less cone movement for the same SPL would mean less distortion typically for the same motor design.
PS: where are the measurements? Pref CEA2034 so we can have some sort of reference with other drivers. What's the upper BW of them?
Just being large is like saying my car has 3000BHP. Impressive, but where are the times from the 'Ring that show it can actually use it real world? Even a 1/4 mile time would show it's able to put it down, which at least gives it some idea of it's worth. I had 4 LABsubs in my room at one stage (20ya), and whilst huge and have a 'wow' factor are far from the best performing subs I've had.
The wavelengths involved are just a bit longer than the chamber between the headphone and the ear, you can't really develop bass resonances in there.
In the headphone case, there is a room but it's very small. Any resonances or standing waves that might form would be well above the bass range.
With open back headphones, we also get some sound into the listening room, although very very little....
My point is that nearfield subs will be nearfield, as long as they are close enough. Like headphones.
My point is that nearfield subs will be nearfield, as long as they are close enough. Like headphones.
The reflections will not be at a "much lower level" (at least in a relatively live room of domestic proportions), they will be close to the same volume as the direct signal. Precedence won't help with wavelengths that long. What you hear will be the reverberant field with all of the reflections and resonances.
Room treatments that could absorb low frequencies enough to reduce the levels of reflected bass could change that, but those treatments would probably make the whole question moot by improving the bass no matter where the sub was placed. The Double Bass Array that Stig-Eric mentioned is another approach, but again not cheap, or easy to achieve in an average home.
Because the larger cone is likely to flex more at low frequencies, and that flexing causes distortion. The bigger the cone, the harder it is to make it stiff enough to not flex without adding excessive amounts of mass to it. Square-Cube Law applies.
It's been said that the best 18" subwoofer is a 15" subwoofer.
Are you confessing to making bad subwoofer decisions in your past?
The problems created by putting subwoofers in a room will never be fixed by a bigger subwoofer. All I can do is suggest getting in with the new school and working on DSP subwoofer control. Keep what you have and add DSP.
Dave's circle of super subs would be the ride of your life! I hoped that was obvious? You will have to go to a concert in a stadium, where these subs are being used, to see if they "sound good".
I got my first DSP in 02 and have been designing/using active speakers since then for hifi, HT, PA and some fixed install jobs.
Riiiight. So a larger driver is worse because of poor design choices. The motor is typically a far higher cause of distortion than cone flex. Of course, if you have actual measure data of high performance driver, not some cheap crap, that shows this (cone flex causing more distortion than the motor) to be the case, then please post it.
Quote me a reputable designer that states this, with full context for the comment.
As a human, most of my decisions are flawed in some way and the benefit of learning more. However, name me a sub that could be had at the time with more output and lower distortion.
Your comment is an attempt at a cheap shot rather than backing up your assertions with data.
That generalization makes no sense to me....it's all about cone materials employed.
This 21" IPAL looks pretty strong to me 😀
And you know Dave Rat's M-Force 30"s gotta be some pretty stiff suckers too.
To simply say a 15" is going to be stiffer than an 18" is way off the mark imo.
Funny....I don't even think a 15" qualifies a a sub driver, unless maybe it's horn loaded or something...
While I subscribe to the general conclusion I could not help but notice a few errors. At 20 Hz the sound field in a 5x10x3(?)m room is half way a pressure chamber, half way a modal field. Of course the point source approach in such a sound field isn’t correct so any decrease in SPL with increasing distance from individual sources isn’t that likely. Even more, room modes tend to build up SPL in the velocity nodes. And the calculation of SPL from a certain Vd at 1m distance normally is only valid for half space or full space placement. If using corner woofers, the SPL per 2,83V rises significantly due to the increased radiation impedance on the cone.
All I hear are contradictions! I asked what your 15" drivers are missing, but you didn't say.
And now you are coming after me because I said 18" drivers can have disadvantages compared to 15" drivers!
By questioning me, the burden of proof is now on you. So go ahead, prove to me that 18" drivers are always superior to 15" drivers. But keep in mind that if you do attempt to prove it, you also cast doubt on the intent behind your original question.
What's up with you guys? Is an 8" subwoofer not a subwoofer because today you decided that a "real" subwoofer is 21"? Is there an application process and a governing body that controls what drivers can and cannot be called a "subwoofer"?
I believe you know that what you're saying is BS.
No, no BS at all.
Thing is, displacement has to increase 4x per octave decrease, for direct radiators.
That simple fact dominates, when trying to produce low freq SPL.
No escaping it...other than increasing efficiency though horn loading or such.
Yep, single 21" woofer has cone area of about eight 8" drivers, or about two 15" drivers. One could use 8" subs, just use many enough to get some SPL out of the system. Use four 8" to match single 15" in capability.
Single 15" gets octave lower than single 8", or 6db louder with same extension with same input power. To get one octave lower quadruple cone area so instead of one 15" use two 21". Its just what the maximum SPL is out from the system with some particular extension. Simplified of course. If cone flexing is concerning you could use loads of 8" drivers. I'm not sure its much of a concern in home hifi use, systems are hardly pushed to max unless too small driver.
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Never seen pro woofers "flex", so googled around and youtube finds
with click bait title. Reading from the comments its a custom woofer with too thin cone, so, why its labeled pro woofer if its not for pro use..
Single 15" gets octave lower than single 8", or 6db louder with same extension with same input power. To get one octave lower quadruple cone area so instead of one 15" use two 21". Its just what the maximum SPL is out from the system with some particular extension. Simplified of course. If cone flexing is concerning you could use loads of 8" drivers. I'm not sure its much of a concern in home hifi use, systems are hardly pushed to max unless too small driver.
edit.
Never seen pro woofers "flex", so googled around and youtube finds
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