Do two 6" woofers = one 12" woofer ?
- Thread starter hpm40
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Lavane
Lunatic Member
I've had good luck with a few 2way speakers on there sides with the tweeters to the outside also for imaging and sound stage.
This is correct. In real life the effective diameter of a 12" or 6" (or any other size) driver is not 12" or 6" because cone surround decreases that and every surround has not the same width, but if the effective diameters really are 12" and 6", then a 12" driver has exactly 4 times the effective area than a 6" driver or 2 times the effective area of a 8,5" driver (if there is such a size).
If the linear excursion is the same in all those drivers, then the maximum displacement volume of one 12" driver will be the same as four 6" drivers or two 8,5" drivers and thus the maximum sound pressure level will be the same. This is independent of the room size. Bass tuning is disregarded here.
The inner half of the surround belongs to the effective area and the outer half of the surround does not. If we assume that the outer half reduces the effective diameter in both cases by one inch (half an inch on both sides) then the true effective diameters would be 11" and 5". Then one 12" driver would correspond five 6" drivers (4,84 to be exact).
In loudspeakers size matters.
So you're saying that multiple smaller drivers can correspond one bigger driver in some rooms but not in all rooms. Why is that?
If we’re discussing drivers and SPLs the distance from a driver (larger room) being inverse to SPL you will need larger driver(s), more drivers, or more excursion to project further into a room. The smaller driver can produce the frequency, but without additional excursion or more drivers to make up for the smaller area they will not be able to reach the SPL for that space. Much like how a headphone driver, very small, can produce ample bass right next to your ears but not in open space.
Sgt Shultz
Addicted Member
Vertical vs Horizontal Center Channel Speaker Designs – An Alternate Perspective
This article contains an in depth discussion of the trade-offs of different center channel designs (MTM vs WTMW, etc) and their real world applications and limitations.
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charles 1973
Super Member
Well said. This explains why the tiny 4" midbass drivers my Minimus 7's when used with the EQ on the matching System 7 receiver and placed close to my bed gets low enough to reproduce the bass guitar and full drumsets with the proper weight.
When operated flat and placed away from boundary walls, The Minimus 7's sound like the decent compact speakers they are. Placing them in corners and using the matching receiver with the EQ on makes them sound like speakers many times their size. But Don't play nearly as loud in a larger room.
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Yes, it is the reason for the mid and tweeter to be vertical. That DOES improve off-axis horizontal response, greatly.
The reason two woofers are used, is that it creates what's called a D'Appolito array- which SOMEWHAT mitigates the asymmetry of the dispersion, if the woofer was just on one side. With the right spacing, the comb filtering can be mitigated enough, so that a reasonably wide sound field can be had, with reasonable uniformity. The crossover frequencies on these, are also as low, between woofer and mid, as is possible without damaging the midrange, usually, to try and reduce the effect of the comb filtering, as well.
In any case- any horizontal woofer array- or any really wide driver trying to produce midrange frequencies- is an inherent soundstaging and dispersion compromise, way more than any vertical array. Vertical dispersion is much less needed (a narrower vertical dispersion can actually be HELPFUL- as it reduces floor and ceiling reflections), but uniform and wide horizontal dispersion is paramount, for a speaker to actually be able to create the illusion of soundstage, in a room...
Regards,
Gordon.
In such a speaker- the outer woofers are ONLY producing bass. As I said- the lowest crossover frequency possible. Only the two inner midbass drivers are producing midrange.
This works better than two woofers, because the drivers can be smaller- putting the midrange drivers closer together.
It's all about wavelength vs. driver spacing and size. That's one of those physical realities that won't, and can't, be denied, no matter how much anyone would wish it to be so...
Sgt Shultz
Addicted Member
The Infinity Emit tweeter comes to mind, very wide dispersion with limited vertical, very important these be at ear level.
Exactly. And- speaking of lots of small drivers instead of a few big ones- that's the same principle that line arrays work on- very wide horizontal dispersion, VERY NARROW vertical dispersion. Makes intelligibility a LOT easier to achieve, without all those floor and ceiling bounces- especially in the horrid acoustic environments of many public spaces.
The line arrays I use frequently (EAW Radius 208L), we wind up having to actually TOE THEM IN a bit, they have so much horizontal dispersion. Sounds awesome once it is done, though. A few degrees is all it takes. We actually have special sling/harnesses we attach to the arrays, to hold them at the proper toe-in. What a difference THAT made. Much better sound overall, even beyond the imaging and soundstaging improvement (and yes, we DO tune our stage array setups for best soundstaging. We are indeed that nuts.
)Regards,
Gordon.
A 3 cylinder Fiesta has lower mass than a Mustang GT. Which is quicker? A simplistic analogy but somewhat useful.
IME large sensitive woofers with strong motors can react to the signal well enough to give excellent midrange response and very punchy bass in the proper enclosure. I'm talking about the Altec 515, 414, 416 and 406-8C.
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Sgt Shultz
Addicted Member
Exactly. And- speaking of lots of small drivers instead of a few big ones- that's the same principle that line arrays work on- very wide horizontal dispersion, VERY NARROW vertical dispersion. Makes intelligibility a LOT easier to achieve, without all those floor and ceiling bounces- especially in the horrid acoustic environments of many public spaces.
The line arrays I use frequently (EAW Radius 208L), we wind up having to actually TOE THEM IN a bit, they have so much horizontal dispersion. Sounds awesome once it is done, though. A few degrees is all it takes. We actually have special sling/harnesses we attach to the arrays, to hold them at the proper toe-in. What a difference THAT made. Much better sound overall, even beyond the imaging and soundstaging improvement (and yes, we DO tune our stage array setups for best soundstaging. We are indeed that nuts.
Regards,
Gordon.
The Modulus are designed to face straight forward for the flattest response, this helps make a larger sweet spot. Any of the Infinitys with Emits are highly regarded.
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Yes, but in general a car like a 3 cylinder Fiests (or for that matter a V12 Ferrari) with tiny pistons (a woofer is like a piston) would be able to rev higher and more quickly than the large V8 in your Mustang example.
The V8 (or large woofer) might be more powerful but the smaller engine (or woofer) would be more responsive.
No, not necessarily. While two 8.5" may have the same cone area and even displacement, there will be points where the two sound waves come together and reinforce each other adding an additional 3 dB. There will also be areas where they cancel each other. The idea is to select the arrangement that lets these happen at the desired frequency.
There are also big woofers with low mass and small woofers with high mass. And even if smaller woofers usually have lower moving mass, their magnets usually are weaker. Magnetic flux density multiplied by voice coil length forms a force factor which drives the woofer. In addition to force factor and moving mass, also compliance, voice coil dc resistance and mechanical resistance comprise a so called Q factor which determines the woofer behaviour.
But you're right: if we reduce the woofer moving mass and all the other factors stay the same, the Q factor will be lower and the woofer will have better transient response, faster decay and higher sensitivity but it will also have higher resonant frequency and difficulties to produce very low frequencies.
If we increase the woofer moving mass and all the other factors stay the same, the Q factor will be higher and the woofer will have lower resonant frequency and a more extended bass response but it will also have worse transient response, slower decay with possible hangover and ringing and lower sensitivity.
So you get some and lose some. There are no free lunches here.
All those five factors and only those five factors (force factor, moving mass, compliance, voice coil resistance and mechanical resistance) comprise the Q factor of the woofer.
Uploaded today. L300s and two 15-inch subs. Separate Anthem amp driving subs. Close mic'ing recording.
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Off Steely Dan - "Aja." MFSL 1-033. Second variant. 1980.
Runout: MFSL-1-033-B3 A SR/2 ORTOFON 30MAY80 1 31 ☼☼.
Off Steely Dan - "Aja." MFSL 1-033. Second variant. 1980.
Runout: MFSL-1-033-B3 A SR/2 ORTOFON 30MAY80 1 31 ☼☼.