Most efficient subwoofer available?

[mrbojang 8]

I was just reading the thread discussing running DVC subs off one coil compared to both and there was also talk of sub woofer efficiency...That got me thinking, what is the most efficient driver available for mobile audio applications? Also why is efficiency generally so bad? Given technological progress with computers, phones, etc you would think there would be great leaps in sound and driver efficiency also? Have drivers made progress over the past 20 years?

[Nirvalica 0]

I was just reading the thread discussing running DVC subs off one coil compared to both and there was also talk of sub woofer efficiency...That got me thinking, what is the most efficient driver available for mobile audio applications? Also why is efficiency generally so bad? Given technological progress with computers, phones, etc you would think there would be great leaps in sound and driver efficiency also? Have drivers made progress over the past 20 years?

I think efficiency hasn't changed because the speaker technology hasn't changed (still piston and magnet). I would bet the old Cerwin Vega 18" stroker were pretty high as far as efficiency. Says herethat it has 96 dB sensitivity (1w/1m). Also woofersetclists the 12" stroker's efficiency as 92 dB, so it would make sense that the 18's would be something like 96.

[mrbojang 8]

I was just reading the thread discussing running DVC subs off one coil compared to both and there was also talk of sub woofer efficiency...That got me thinking, what is the most efficient driver available for mobile audio applications? Also why is efficiency generally so bad? Given technological progress with computers, phones, etc you would think there would be great leaps in sound and driver efficiency also? Have drivers made progress over the past 20 years?

I think efficiency hasn't changed because the speaker technology hasn't changed (still piston and magnet). I would bet the old Cerwin Vega 18" stroker were pretty high as far as efficiency. Says herethat it has 96 dB sensitivity (1w/1m). Also woofersetclists the 12" stroker's efficiency as 92 dB, so it would make sense that the 18's would be something like 96.

Ah. I was reading about Phoenix Gold Cyclones just now..Can't seem to find an efficiency rating, although someone mentioned they probably are the most efficient.

[Nirvalica 0]

I was just reading the thread discussing running DVC subs off one coil compared to both and there was also talk of sub woofer efficiency...That got me thinking, what is the most efficient driver available for mobile audio applications? Also why is efficiency generally so bad? Given technological progress with computers, phones, etc you would think there would be great leaps in sound and driver efficiency also? Have drivers made progress over the past 20 years?

I think efficiency hasn't changed because the speaker technology hasn't changed (still piston and magnet). I would bet the old Cerwin Vega 18" stroker were pretty high as far as efficiency. Says herethat it has 96 dB sensitivity (1w/1m). Also woofersetclists the 12" stroker's efficiency as 92 dB, so it would make sense that the 18's would be something like 96.

Ah. I was reading about Phoenix Gold Cyclones just now..Can't seem to find an efficiency rating, although someone mentioned they probably are the most efficient.

Phoenix Gold Cyclone [audiojunkies] There they say it is 90 dB. Maybe it's more efficient at much lower frequencies then most subs though, I dunno.

[Impious 1,476]

I was just reading the thread discussing running DVC subs off one coil compared to both and there was also talk of sub woofer efficiency...That got me thinking, what is the most efficient driver available for mobile audio applications? Also why is efficiency generally so bad? Given technological progress with computers, phones, etc you would think there would be great leaps in sound and driver efficiency also? Have drivers made progress over the past 20 years?

Technology has improved greatly over the past 20 years......however the laws of physics remain the same, which is what we are battling in the realm of sensitivity.

An article on sensitivity can be found here (and was also linked in my post in the DVC thread) that will provide the answer to your question:

Subwoofer Sensitivity - SSA Car Audio Forum

[smgreen20 3]

The PG Cyclone is more efficient with the power it uses.

Subs 20 years ago had a higher sens compared to todays subs for the sole reason that people want more power, therefor the suspensions need to be beefier, which results in needing more power for the same output, and they need to be able to cool the motor better due to the increase in power.

Lanzar had some of the best subs back in the early/mid '90s both in sound ad output. The LANZAR Pro15 has a sens of 98 dB 1w/1m. I had 2 Pro12's w/a sens rating of 96 dB.

[Solid_State13 1]

Massive audio has some really efficient ones, the DMX 15 is rated at 100.1 dB

Massive Audio :: Subwoofers :: DMX 15- Car Audio Subwoofer

[Impious 1,476]

The PG Cyclone is more efficient with the power it uses.

Subs 20 years ago had a higher sens compared to todays subs for the sole reason that people want more power, therefor the suspensions need to be beefier, which results in needing more power for the same output, and they need to be able to cool the motor better due to the increase in power.

Lanzar had some of the best subs back in the early/mid '90s both in sound ad output. The LANZAR Pro15 has a sens of 98 dB 1w/1m. I had 2 Pro12's w/a sens rating of 96 dB.

The decrease in sensitivity has had more to do with enclosure size. Lower sensitivity allows for better low frequency extension in smaller enclosures.....the smaller enclosures being beneficial to car audio with our limited real estate, especially as cars (and hence available space) got smaller

Power wasn't the "sole reason".

[Impious 1,476]

Massive audio has some really efficient ones, the DMX 15 is rated at 100.1 dB

Massive Audio :: Subwoofers :: DMX 15- Car Audio Subwoofer

Sigh........

This is a case of not being able to take the specifications at face value....Massive is simply playing a numbers game. As I outlined in the Sensitivity article that I linked to earlier (which apparently went unread ), sensitivity "ratings" are not created equal. But if we have the T/S parameters, we can level the playing field with one simple formula

I couldn't get the manual on Massive's website to work (the T/S parameters are all blank and Adobe Reader gives me a font error), but from what I could find the relevant T/S for the DMX 12, which is rated 96.4db sensitivity on Massive's website, are; Fs - 31.1hz, Vas - 61.46L, Qes - .33

If we plug those numbers into the formula from the aforementioned unread article, we would find;

SPL = 112+10*LOG(9.64*10^(-10)*31.1^3*61.46/0.33) = 89.3db

The ACTUAL 1w/1m sensitivity isn't quite as high as advertised there with the "manufacturer rated" sensitivity, eh? I have no doubt you would find an equivalent difference between the actual 1w/1m sensitivity and the "manufacturer rated" sensitivity of the DMX 15 aswell. If anyone can find the T/S parameters, we could "set the record straight" so to speak.

[mr.sagat 10]

Impious,

Does the massive being quad voice coil manipulate the ratings any? What I mean, is massive getting that inflated sensitivity rating from powering all four voice coils with 1 watt each? Or is the sub wired in parallel and only give one watt to distribute to all four coils?

[Impious 1,476]

I really don't know how they arrived at that figure. There are multiple ways to manipulate sensitivity. The website lists a sensitivity of 96.4db, but the T/S I found were from a CA&E article that listed rated sensitivity at 98.2db, which would be a 9db difference. It could be a difference in power (5x more power for a 7db increase, 8x the power for a 9db increase). It could be a difference in "measurement style", meaning it might be an "in car" measurement. Or, decreasing the distance of the measurement by half (.5m instead of 1m) would result in a 6db increase in output, so they may have varied the measurement distance by some amount.

If they wired the driver to 4ohm and drove it with 2.83V, that would be a 3db increase. Halving the distance a 6db increase. Combine the two and you have a 9db increase. Or just wiring the driver to 1ohm and giving it 2.83V would also be a 9db increase.

[Impious 1,476]

Subs 20 years ago had a higher sens compared to todays subs for the sole reason that people want more power, therefor the suspensions need to be beefier, which results in needing more power for the same output,

Forgot to even mention yesterday that Cms (suspension compliance) doesn't directly affect sensitivity

Let's take an example of the BTL, a high power handling SPL-oriented subwoofer. It has the following relevant parameters (dual 1ohm version): Fs - 39.3hz, Qes - .21,

Vas - 25.7L. If we plug this into the formula for calculating sensitivity, we find;

SPL = 112+10*LOG(9.64*10^(-10)*39.3^3*25.7/0.21) = 90.5db

Now let's take the same driver and double the stiffness of the suspension, meaning suspension compliance (Cms) would be halved. This changes the relevant parameters (per WinISD) to: Fs - 55.9hz, Qes - .303, Vas - 12.8L. If we plug these parameters into the same sensitivity formula, we find;

SPL = 112+10*LOG(9.64*10^(-10)*55.9^3*12.8/0.303) = 90.5db

So we cut the compliance of the suspension in half (doubled stiffness), but the sensitivity of the driver remained unchanged.

You can alternatively calculate driver efficiency with the following formula;

Efficiency = (BL^2 * Sd^2) / (Re * Mms^2) * 5.445*10^-4

Which you can see, neglects to reference the suspension compliance or stiffness.

[Duran 387]

Because doubling the suspension is changing it mechanically, not electrically like sensitivity is calculated? If you divided Cms by half, would that change efficiency?

[95Honda 486]

If I had to do a single sub, high efficiency set-up right now, I would use the TC sounds version of the Aura NRT18 prosound driver. I has a low Fs, a ton of stroke and real world 1w/1M 94db+ sensitivity... And dual 2 ohm coils.... Only problem is, it costs over $1000...

But I would say that is probably the highest efficiency sub you could really get right now that would be right at home in a car.... Besides maybe a McCualey 6174..... Which I have used in the past, bad motherfucker also...

The only problem when you start looking at subs that push the 100db 1w/1M threshold is that they aren't really subs anymore. Fs goes way up, stroke goes down...... They have to give something to get something....

http://www.parts-express.com/pe/showdetl.cfm?Partnumber=293-674

Put it in a 10+ ft3 box tuned at, I dunno 50 or 60 Hz with a vent you could walk through and 100 watts would be retarded loud....

I built a pair of subs using 4 of these 18s and used 1000 watts per woofer... It was crazy...

I know TC doesn't list the Spl as 1w/1M but the original NRT18 was rated that way (I need to see how thay rate it) and was even higher..... I don't think they dropped the efficiency too much.... If they have, then this whole plan doesn't work, lol...

Edited June 9, 2010 by 95Honda

[todd.brust 29]

I was just looking at those TC subs and was going to mention them, looks like I was beat!

[Randal Johnson 544]

Damn guys !!! What an impressive read !!! Very impressed, great work.

[95Honda 486]

The 2nd gen of the original bad boy..... Like I said, I used 4 of these... They were devasting in the huge auditorium I had them in...

Aurasound NRT18-8 NRT18-8 Pro Sound 18" Woofer NLA from Madisound

Also, another long time bad-ass super efficient 18 that is truly a subwoofer.... I have used 2 of these before, they are awesome, but again, real expensive....

http://www.mccauleysound.com/accessory_overview.cfm?ID=126

This stuff always gets me thinking... I just want to build a wall with 2 or 3 nice efficent 18s and power it with around 100 watts..... And just destroy people....

[95Honda 486]

My 4 Auras....

[Aaron Clinton 2,372]

Is it the angle of the picture, or is the port area on the small side?

[95Honda 486]

Is it the angle of the picture, or is the port area on the small side?

Negative.

[Aaron Clinton 2,372]

Yeah, that is what I figured, carpet and angle of the picture tricked my eyes.

[Impious 1,476]

Because doubling the suspension is changing it mechanically, not electrically like sensitivity is calculated? If you divided Cms by half, would that change efficiency?

Nope, efficiency would remain the same aswell. Sensitivity is based on the relationships between motor force, cone area and moving mass.

[Duran 387]

Where does the suspension compliance factor in, or become a significant factor? Ever? Geez I need to take some physics courses, this is good stuff.

[Impious 1,476]

Ultimately you can't just arbitrarily adjust Cms without consequence even if it doesn't directly impact sensitivity. If you look at the BTL example I posted earlier, the Fs jumped by nearly a half octave when we halved Cms. So the engineer is going to have to balance Cms (and sensitivity) with the other performance goals for the driver.

[CrownVic 15]

Ultimately you can't just arbitrarily adjust Cms without consequence even if it doesn't directly impact sensitivity. If you look at the BTL example I posted earlier, the Fs jumped by nearly a half octave when we halved Cms. So the engineer is going to have to balance Cms (and sensitivity) with the other performance goals for the driver.

This would be why no one t/s parameter can be relied on to determine woofer quality? Also why there's no "perfect" woofer?