My Contribution: A Comparison of SQ Subwoofers
So its time for me to give back to the community 😀 I'll try to make this short and sweet 😱
So as always, there is always a large debate on what makes a good sounding subwoofer. Many speculate that the best subwoofers have certain variables, such as high sensitivity, extremely low Qts, and high Bl.
The problem with this viewpoint is that very generally speaking, the best sounding boxes are sealed (and more recently, dipole has become popular). Horns, Transmission Lines, and Ported Boxes have their various SQ issues that are hard to design around. Unfortunately, both sealed and dipole subwoofer configurations don't mix well with extremely low Qts parameters. Regardless of biases, let's let the best SQ woofers speak for themselves.
Here is an investigative compairson of some of the most popular subwoofers from both car audio and home audio enthusiasts, and their respected T/s parameters. All of these subwoofers were chosen for their general well regard and high popularity; a quick search of any of these subwoofers will quickly yield very positive reviews.
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What do we find?
1. Extremely low QTS is not found in any of these highly-regarded subwoofers. In fact, they all average around a Qts of .45. From an engineering perspective this makes perfect sense, as critically dampened resonating systems have a Q of 0.5. As per wikipedia "Critical damping results in the fastest response (approach to the final value) possible without overshoot." Additionally, the farther we get from a Qts of 0.4, the larger our enclosure gets. A Qts from 0.4 to 0.5 makes perfect sense, and of course the average is 0.45.
2. High BL is found in none of the SQ subwoofers but the Infinity Kappa 120.9W. None of the SQ subwoofers have a BL higher than 20.
3. Sensitivity of the subwoofers were merely average, not extremely high.
4. Majority of the subwoofers use lossy cone materials.
5. FS is generally low, usually below 30Hz.
6. Inductance was always 2-3x lower in SQ subwoofers than Non-SQ subwoofers.
7. Mms was always relatively low in the SQ subwoofers.
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Conclusions: So what makes a SQ subwoofer different than a regular subwoofer?
The SQ subwoofers always had lower Inductance (Le) and moving mass. Generally speaking, the SQ subwoofers also had a lower Fs. Additionally, it's important to remember that SQ-oriented subwoofer or not, all of these subwoofers are popular subwoofers for a reason, and it is reasonable to conclude that from an engineering perspective, lossy cone materials such as paper and polyprop are generally easier to make sound good than ringing materials such as metals, kevlar composite, glass composite, and carbon fiber.The greatest common denominator among all well-regarded subwoofers was a Qts of ~.45. So in my opinion, the most important factor in finding a good sounding subwoofer is Qts (~.45), followed by an average of Fs, Le, and Mms.
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Odds and ends:
*I have a personal bias against companies that aren't completely transparent with their driver parameters. While all of these drivers are well regarded, i'll always buy any driver from a transparent company over a non-transparent company. To me, if you have a good product, you don't have anything to hide.
*Just going off of T/s parameters, the Morel Ultimate probably has the best performance, but at a whopping $411 a driver, it's out of the budget of all but the most well funded audio enthusiasts. At $65 a driver, the Infinity Reference 1262W has great similarity (lossy cone, lower inductance, low Fs, slightly heavier cone. It's also worth noting that you could use the cheaper drivers in a push-pull configuration to greatly reduce harmonic distortion, and damplifier pro to dampen stamped steel baskets greatly.
*Surprisingly, the moderately priced Infinity Kappa 120.9W had the highest motor strength (If that's still your bias). It does come with a bit higher Fs than others, and a rigid cone material though.
So its time for me to give back to the community 😀 I'll try to make this short and sweet 😱
So as always, there is always a large debate on what makes a good sounding subwoofer. Many speculate that the best subwoofers have certain variables, such as high sensitivity, extremely low Qts, and high Bl.
The problem with this viewpoint is that very generally speaking, the best sounding boxes are sealed (and more recently, dipole has become popular). Horns, Transmission Lines, and Ported Boxes have their various SQ issues that are hard to design around. Unfortunately, both sealed and dipole subwoofer configurations don't mix well with extremely low Qts parameters. Regardless of biases, let's let the best SQ woofers speak for themselves.
Here is an investigative compairson of some of the most popular subwoofers from both car audio and home audio enthusiasts, and their respected T/s parameters. All of these subwoofers were chosen for their general well regard and high popularity; a quick search of any of these subwoofers will quickly yield very positive reviews.
_________________________________________________________________
What do we find?
1. Extremely low QTS is not found in any of these highly-regarded subwoofers. In fact, they all average around a Qts of .45. From an engineering perspective this makes perfect sense, as critically dampened resonating systems have a Q of 0.5. As per wikipedia "Critical damping results in the fastest response (approach to the final value) possible without overshoot." Additionally, the farther we get from a Qts of 0.4, the larger our enclosure gets. A Qts from 0.4 to 0.5 makes perfect sense, and of course the average is 0.45.
2. High BL is found in none of the SQ subwoofers but the Infinity Kappa 120.9W. None of the SQ subwoofers have a BL higher than 20.
3. Sensitivity of the subwoofers were merely average, not extremely high.
4. Majority of the subwoofers use lossy cone materials.
5. FS is generally low, usually below 30Hz.
6. Inductance was always 2-3x lower in SQ subwoofers than Non-SQ subwoofers.
7. Mms was always relatively low in the SQ subwoofers.
_________________________________________________________________
Conclusions: So what makes a SQ subwoofer different than a regular subwoofer?
The SQ subwoofers always had lower Inductance (Le) and moving mass. Generally speaking, the SQ subwoofers also had a lower Fs. Additionally, it's important to remember that SQ-oriented subwoofer or not, all of these subwoofers are popular subwoofers for a reason, and it is reasonable to conclude that from an engineering perspective, lossy cone materials such as paper and polyprop are generally easier to make sound good than ringing materials such as metals, kevlar composite, glass composite, and carbon fiber.The greatest common denominator among all well-regarded subwoofers was a Qts of ~.45. So in my opinion, the most important factor in finding a good sounding subwoofer is Qts (~.45), followed by an average of Fs, Le, and Mms.
_________________________________________________________________
Odds and ends:
*I have a personal bias against companies that aren't completely transparent with their driver parameters. While all of these drivers are well regarded, i'll always buy any driver from a transparent company over a non-transparent company. To me, if you have a good product, you don't have anything to hide.
*Just going off of T/s parameters, the Morel Ultimate probably has the best performance, but at a whopping $411 a driver, it's out of the budget of all but the most well funded audio enthusiasts. At $65 a driver, the Infinity Reference 1262W has great similarity (lossy cone, lower inductance, low Fs, slightly heavier cone. It's also worth noting that you could use the cheaper drivers in a push-pull configuration to greatly reduce harmonic distortion, and damplifier pro to dampen stamped steel baskets greatly.
*Surprisingly, the moderately priced Infinity Kappa 120.9W had the highest motor strength (If that's still your bias). It does come with a bit higher Fs than others, and a rigid cone material though.
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Found an 8 with awesome specs for you 8" fans.
Dayton Audio RSS210HF-4 8"
Qts: 0.50 (perfectly dampened!)
Le: .68 mh (!)
Fs: 28Hz (Crazy for an 8!!!)
Mms: 66g (!)
Those are better specs than the $325 Morel UW958 😱 (Although the Morel is paper)
Of course it comes with the extra Dayton Reference Series goodies too though, such as three shoting rings
Dayton Audio RSS210HF-4 8"
Qts: 0.50 (perfectly dampened!)
Le: .68 mh (!)
Fs: 28Hz (Crazy for an 8!!!)
Mms: 66g (!)
Those are better specs than the $325 Morel UW958 😱 (Although the Morel is paper)
Of course it comes with the extra Dayton Reference Series goodies too though, such as three shoting rings
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Horns rarely can extend down to 20Hz and suffer from horn distortions. A good page over this is here.
Ported boxes suffer from port compression easily, and the only way to remedy this is making a long port with large surface area, which makes the port prone to resonances and loses efficiency. Ports also suffer from midrange leakage if used higher than 80-100Hz. It's very hard to design a good ported enclosure down to 20Hz.
Transmission lines can sound good, but again have resonance problems. Not saying good sounding TL's don't exist; they are just super hard to design. Tapering a TL helps with resonance problems, but lowers output. Not to mention a 20hz tuned TL is 14 feet long, still smaller than a 20hz horn though 😛
Sealed boxes aren't perfect, but are close. They can be made small so suffer less from panel resonance issues. They also allow to be made a bit too small on purpose, then stuffed with polyfill to allow some of the resonance's to be dissipated in the polyfill. The problem with sealed boxes (like all monopoles) is the interaction with room modes.
Dipoles are awesome because you can use them in push/pull (without looking funny atleast) to cancel out some of the distortions. Their biggest advantage comes from their minimal interaction with room modes, unlike monopoles. Unfortunately they pretty much require active EQ'ing with a miniDSP to get the response you want.
Hi,
My previous statement might have come across as rude, .. so first off, .. no offence meant.
David Lee (with whom I coincidentally have a passing acquaintance,) himself says in the article you quote:
"BUT low frequency response is NOT what people love about horns. It’s the impact and immediacy of their delivery. It’s the tight and punchy-ness and the tremendously dynamic transient response. Therefor, if you use the horns for THAT function and use direct radiators for the extended low frequency response, you can use smaller horns that are specifically designed and perfectly suited to delivering the impact that people love about them."
"The combination allows the horn to deliver the impact they are known for and leaves the low frequencies to the slower cones for which they are better suited. "
1. 20 Hz is less important than many would believe. 30 Hz is definitely mandatory for music and home theater. At low frequencies, room treatments etc become more important, rather than just the anechoic subwoofer performance .
2. Horns can extend down to 20 Hz, . and even if compromised a bit to make them domestically acceptable, they still do something that other subs haven't been able to do for me (and I've built several examples of almost all known subwoofer alignments, even the awful ripole 🙂 ) . I'm guessing I like their dynamics. In any case, down low, room effects typically swamp any claims to linearity.
FWIW, .... my best personal successes with subwoofers have been horn loaded , dipole (so we're partly in agreement) and karlson K-15 (above 50 Hz, so technically not a sub)
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SQ woofers
Do you mean "SQ" like in "SQ vs. SPL" woofers?!
Or do you mean subwoofers...
A lot of issues with your explaining that is difficult to follow. NPI
If in choosing a "the best" woofer your list is very short. Maybe more like "The-woofers-I-like-most! 😀
Certain aspects are very important like SPL or sensitivity, impedance, enclosure volume (net), Q and LF extension. Also there are good subs and good woofers, better than subs so, choose your poison. 🙂
Do you mean "SQ" like in "SQ vs. SPL" woofers?!
Or do you mean subwoofers...
A lot of issues with your explaining that is difficult to follow. NPI
If in choosing a "the best" woofer your list is very short. Maybe more like "The-woofers-I-like-most! 😀
Certain aspects are very important like SPL or sensitivity, impedance, enclosure volume (net), Q and LF extension. Also there are good subs and good woofers, better than subs so, choose your poison. 🙂
It's perfectly fine, i know first hand that language and cultural barriers are hard to get through. 🙂
Ah yes, horns properly implemented can be amazing no doubt. I was merely suggesting that a proper horn is an extremely hard thing to achieve.
And of course, best for one person is not necessarily the best for another. 😛 For home theater a dipole subwoofer probably wouldn't be most people's preference for example. I'm sure most people would love a giganticly high output Folded Horn, Tapped Horn, TL, or maybe even ported box for home theater. There's nothing like not knowing if an earthquake is happening or your subs are just awesome during a movie 🙄.
I think it's worth mentioning (even though you probably already know, some people might not) that subwoofers for horns do best with extremely low Qts (~0.3) from my understanding.
Sorry, i was using "woofer" as shorthand for "subwoofer". I'll try to go back and fix everything. Anyway, this post is all about subwoofers only, not woofers. With that said, I'm sure the same findings still apply for other drivers.
To put it in short, the drivers i chose aren't an all-inclusive list of every subwoofer. Nor is it saying that the subwoofers i chose are the best. I merely chose subwoofers that are extremely popular, and compared them to see if all the popular subwoofers had anything in common (if at all). Turns out most popular subwoofers do in fact have a lot in common which is:
Qts: ~0.45
Low Fs for driver size
Low Le
Low Mms
So in short, what I'm trying to say here is that it's very likely that those aspects in any subwoofer driver can be sought after to find a good sounding driver.
The exception of course would be a horn subwoofer driver, which requires a very strong BL and low Qts.
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You forgot to mention that you have to use a sledgehammer approach to get any LF in a dipole system: a 15" woofer per side is pretty much mandatory, and even then you'll struggle to hit below 40Hz.
However, a 6.5" mini-sub in a suitable tapped horn will pass 25Hz with considerable output.
IMO, dipoles waste an awful lot of potential output from the driver.
Chris
These use 8's and manage to get down to 40hz just fine.
Not to mention their not even dedicated subs.. but even if they were, two 8" drivers have roughly less surface area than a single 12". If we use push/pull drivers on each size, for a total of 4 subwoofers, we would get:
Four 8" = 201.06
Four 10" = 314.16
Four 12" = 452.39
Four 15" = 706.86
Four 18" = 1017.87
vs
One 8" = 50.27
One 10" = 78.54
One 12" = 113.1
One 15" = 176.71
One 18" = 254.47
Not to mention 4 Subwoofers at once mean that the gain is 9db vs 1 subwoofer, and the load is distributed over 4 drivers. Not really seeing how horns have an advantage at all here.
Lets make a worse case scenario and say we have 4 8" subwoofers with 84db sensitivity for a single driver. That would mean the sensitivity for 4x8" subwoofers would be 93db1w/1m. Say we can feed these 8" a max of 400w, which is reasonable.
1w- 93db
2w- 96db
4w- 99db
8w- 102db
16w- 105db
32w- 108db
64w- 111db
128w- 114db
256w- 117db
We nearly reach 120dB, using nothing but 8's, with less than 300 watts. That's loud enough for most.
Also, we didn't excite room modes, we used active cancellation of harmonic distortion (push-pull), and our drivers had an Mms of 66 grams, Qts of a perfect .5, and an Le of 0.68 mH. As far as SQ goes, there isn't much to improve here.
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I use the Alpine Type R 12D2s in my car. They have considerably less measurable distortion than my previous subwoofers, which were not bad in that regard either. Their measured parameters (which are a near identical match to the published ones, except for Le), suggest they'd be a good match for either sealed or vented alignments.
The problem of using woofer and subwoofer is that "usually" woofers "need" low Le for the mid-range and subs not. So, if we where going to compare what we can not compare, but following your logic, what 21" subwoofer below would you choose; sub #1 or sub #2?
One subwoofer does exactly the same thing than the other (Q, F3, SPL and Sensitivity) 
but one needs a much smaller enclosure volume or less a third than the other driver. I know that this is not important for you, but for most of us is. Actually one of them has better parameters for a better sub performance than the other. Which one would you rather choose and what is a "good sounding driver"... or which one in your perspective? 🙂Sub #1:
Qms 4,00
Qes 0,35
Qts 0,33
Fs 28,50 Hz
Re 3,50 Ohm
Mms 520 g
Cms 0,06 mm/N
Bl 30,40 T*m
Sd 1662 cm2
Vas 232,41 liter
u0 1,42 %
XMax 18,3 mm
Le 2,4 mH
Rms 20,24 Kg/s
Efficiency Bandwidth 80,82
Sub #2:
Qms 18,93
Qes 0,35
Qts 0,34
Fs 32,20 Hz
Re 6,22 Ohm
Mms 349,58 g
Cms 0,07 mm/N
Bl 35,70 T*m
Sd 1662,00 cm2
Vas 270,82 liter
u0 2,53 %
XMax 12,75 mm
Le 1,47 mH
Rms 3,74 Kg/s
Efficiency Bandwidth 93,29
The problem of using woofer and subwoofer is that "usually" woofers "need" low Le for the mid-range and subs not. So, if we where going to compare what we can not compare, but following your logic, what 21" subwoofer below would you choose; sub #1 or sub #2?
Sub #1:
Qms 4,00
Qes 0,35
Qts 0,33
Fs 28,50 Hz
Re 3,50 Ohm
Mms 520 g
Cms 0,06 mm/N
Bl 30,40 T*m
Sd 1662 cm2
Vas 232,41 liter
u0 1,42 %
XMax 18,3 mm
Le 2,4 mH
Rms 20,24 Kg/s
Efficiency Bandwidth 80,82
Sub #2:
Qms 18,93
Qes 0,35
Qts 0,34
Fs 32,20 Hz
Re 6,22 Ohm
Mms 349,58 g
Cms 0,07 mm/N
Bl 35,70 T*m
Sd 1662,00 cm2
Vas 270,82 liter
u0 2,53 %
XMax 12,75 mm
Le 1,47 mH
Rms 3,74 Kg/s
Efficiency Bandwidth 93,29
It depends on the application, as always. A qts of .35 and .33 indicates that these subwoofers will both do much better in ported and horn enclosures than sealed, dipole, transmission line, or infinite baffle.
If going for a ported or horn subwoofer, I'd personally choose Sub #2.
Here is my reasoning:
1. Both have a Qts within .01 of each other, so its important that we closely look at other parameters for evaluation, rather than just Qts.
2. Ported and Horn subwoofers don't necessary need lots of xmax, so while subwoofer #1's extra xmax is nice, its not really necessary.
3. Subwoofer #2 has lower Le, which means faster response than #1
4. Subwoofer #2 has lower Mms, which means faster response than #1
5. Both ported and horn enclosures are hard to get under 30hz, and most people like to tune ported boxes to 32 Hz, so the lower Fs of subwoofer #1 isn't really necessary.
6. Qms is higher in Subwoofer #2, which means its more forgiving of lower quality amplifiers (lower damping factor).
7. Bl is higher in subwoofer #2
So in conclusion, subwoofer #2 has much better specs overall than subwoofer #1. The only reason I'd recommend subwoofer #1 over #2 is if you physically don't have the space. We can't get around physical limitations unfortunately 😛
If you want a box Q = 0.5 and you start with a woofer with free air Q = 0.5 then the box needs to be infinitely large (or close enuff). Putting a driver in a finite size dealed box raises Q.
Unless these woofers have very low Vas the sealed boxes will be big. And of they fit into a "small" box efficiency will be low.
It isall a juggling act.
dave
let's hope it won't move too fast then
🙂or by faster response, maybe you mean more dynamic
funny, but I recently bought two woofers
one had small magnet cracks
and using my bass guitar it was audible
it did not have the same perfect snabby response as the other woofer
but it was not very easy to detect
probably only because I know my bass
many might not have noticed
it kind of tells me that a woofer with very high mass combined with highish Qts will struggle to produce correct dynamic
but maybe the problem is not very audible
I measured some old fifteens I bought in 1997, which offered:
Fs: 23 Hz
Qts: 0.67
MMS: 50
Personally, I don’t require subs to achieve a lot of emphasis around 80 Hz onwards as my low mid cabinets are capable of delivering those frequencies. Having 18 and 15 inch drivers offering a QTS anywhere from 0.5 – 0.7 is what I prefer over the more popular 0.3 – 0.2 QTS in abundance on the market.
Fs: 23 Hz
Qts: 0.67
MMS: 50
Personally, I don’t require subs to achieve a lot of emphasis around 80 Hz onwards as my low mid cabinets are capable of delivering those frequencies. Having 18 and 15 inch drivers offering a QTS anywhere from 0.5 – 0.7 is what I prefer over the more popular 0.3 – 0.2 QTS in abundance on the market.
Read the post: "not much SPL", and "the woofers are working hard".
What do you suppose the LF sensitivity of that system is? I'd be surprised if it managed 80db@1w@50Hz.
The same drivers in a suitably sized ported or sealed box would be more than ample for most people out there, yet on a dipole they struggle to put out the SPLs before bottoming out.
Chris
Note that BL rating alone tells you nothing without also considering the Re of the driver. The same also holds true for the inductance. In the case of subwoofers and powerful woofers a 1khz inductance rating is virtually worthless and tells almost nothing of value. Inductance is complex and at least an impedance measurement of the driver is required to make any real determinations with a raw response plot also being useful. The best way to judge either motor force or inductance is via a series of positional measurements of the coil at varying input power as via Klippel or similar.
Woofers are often driven harder than any other element in the speaker system and small signal parameters often have very little to do with the driver behavior in actual use with large signals.
Woofers are often driven harder than any other element in the speaker system and small signal parameters often have very little to do with the driver behavior in actual use with large signals.
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I've not found that to hold true. Subwoofer drivers with high normalized Le (Le/Re) more often than not have pretty big FR humps in the typical subwoofer passband. There does seem to be "something" about high-Le bass drivers that, when they're used for anything but the lowest couple octaves (say 40Hz as a useful upper bandwidth limit) results in lesser reproduction quality compared to drivers with lower inductance. (In the really deep stuff, I agree that it's more-or-less a non-factor.) Go to Josh's site, data-bass.com, and see for yourself in some measurements.
I really thought it was all about throw for a while. Then I tried to work with a TC Sounds 15" woofer (badged "Stryke HE15") that had huge throw (like 30mm) but no shorting rings in the motor and a very long overhung voicecoil.
I did have to chuckle at that Morel driver with basically no throw being considered anything but massively overpriced and extremely underwhelming little thing, though...
"Comparison of quality wrenches. I have compared the wrenches that are generelly regarded as best quality and found them to all have a size of around 0.5 inches."
I hope you see the general problem with this approach. What if you have a 1 inch screw? Is the 0.5 inch wrench still the best solution?
The T/S parameters are, except some very extreme outliers, no indicator of loudspeaker quality. You use them to tailor an enclosure to a speaker for a specific use scenario.
I hope you see the general problem with this approach. What if you have a 1 inch screw? Is the 0.5 inch wrench still the best solution?
The T/S parameters are, except some very extreme outliers, no indicator of loudspeaker quality. You use them to tailor an enclosure to a speaker for a specific use scenario.
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