12" vs 15"

[VWBobby 10+ year member]

You are taking what I am saying out of context or splitting hairs with my statements.

I was talking about pushing your equipment to 75% or higher, not your "stereo". If you have a sub that can handle 1000W RMS, you are powering it with a 1200 or 1500RMS amp to have a little headroom, 750W RMS or higher would be 75% (of 1000W RMS). It has nothing to do with the amplifier. We are talking about subwoofers.

In my statement about Paper and Wool cones, I mention nothing about a Pulp reinforced cone. A pulp fiber cone is nowhere near as light as a paper or wool cones. Its almost similar to cardboard or MDF in materials....

Nice try, but anyone who can read between the lines isn't falling for it. //content.invisioncic.com/y282845/emoticons/wink.gif.608e3ea05f1a9f98611af0861652f8fb.gif As stated above, there are very few SQ oriented 15"+ subs in the car audio world, for a good reason. Most SQ subs have very high sensitivity (90DB or higher) and would require a huge box to perform optimally.

Just because the sub is round does not mean that the coil will not rock when the cone or suspension distorts. There are a lot of subs with tight gaps that will bind when/if the coil rubs. Coil rub is not always caused by a burnt or damaged coil. It can also happen from abused speakers. By that same token, it would be almost impossible for Kicker to keep their square subs aligned. The spider supports the upper half of the coil, the surround supports the upper half of the cone and keeps the coil perpendicular in the gap. Some high excursion subs even have 2 sets of spider landings to keep the coil centered in the gap. This is all to help prevent distortion, possible coil bind, or variations in the BL curve (coil not staying centered).

 

[IonRL205 10+ year member]

Most properly done 15 inch subwoofers are not suited for car audio use simply due to box size requirements. Most sound best in sealed boxes much bigger than 2cu ft, and for ported they need even more space. There is also the woofer size issue. My car trunk, the subwoofer box can't be taller than exactly 13 inches. So this rules out the 15 inch subs in back firing position. Perhaps because of this a lot of SQ sub manufacturers do not make 15 inch sub version of their subs. Though, you can find a 15inch sub if you wish. For example, Dayton Reference HO15, which is basically as SQ as it gets and will work in a reasonably small box.

??? So companies make 15" subs but they shouldn't be used for car audio because you need a big box?

wat

That makes absolutely no sense whatsoever. Just cause your car has a small trunk doesn't mean people shouldn't use 15" woofers. I can fit a 15" sub in a 4ft³ box inside of my trunk...and there are plenty of 15" subs that sound great.

 

[zako 10+ year member]

??? So companies make 15" subs but they shouldn't be used for car audio because you need a big box?
wat

That makes absolutely no sense whatsoever. Just cause your car has a small trunk doesn't mean people shouldn't use 15" woofers. I can fit a 15" sub in a 4ft³ box inside of my trunk...and there are plenty of 15" subs that sound great.

Why no sense? What I am saying is that most people do not want to give up the space that's needed for a proper box for a 15inch subwoofer. Of course, they're made and sold, but the market is much smaller. For a lot of people, giving up so much trunk space for bass is simply not practical.

 

[audioholic 5,000+ posts]

You are taking what I am saying out of context or splitting hairs with my statements.
I was talking about pushing your equipment to 75% or higher, not your "stereo". If you have a sub that can handle 1000W RMS, you are powering it with a 1200 or 1500RMS amp to have a little headroom, 750W RMS or higher would be 75% (of 1000W RMS). It has nothing to do with the amplifier. We are talking about subwoofers.

In my statement about Paper and Wool cones, I mention nothing about a Pulp reinforced cone. A pulp fiber cone is nowhere near as light as a paper or wool cones. Its almost similar to cardboard or MDF in materials....

Nice try, but anyone who can read between the lines isn't falling for it. //content.invisioncic.com/y282845/emoticons/wink.gif.608e3ea05f1a9f98611af0861652f8fb.gif As stated above, there are very few SQ oriented 15"+ subs in the car audio world, for a good reason. Most SQ subs have very high sensitivity (90DB or higher) and would require a huge box to perform optimally.

Just because the sub is round does not mean that the coil will not rock when the cone or suspension distorts. There are a lot of subs with tight gaps that will bind when/if the coil rubs. Coil rub is not always caused by a burnt or damaged coil. It can also happen from abused speakers. By that same token, it would be almost impossible for Kicker to keep their square subs aligned. The spider supports the upper half of the coil, the surround supports the upper half of the cone and keeps the coil perpendicular in the gap. Some high excursion subs even have 2 sets of spider landings to keep the coil centered in the gap. This is all to help prevent distortion, possible coil bind, or variations in the BL curve (coil not staying centered).

Between you denoting a difference between your 'stereo' and your stereo 'equipment', but not saying what the difference is... and your arbitrary example of some 1000 watt sub with a 1500 watt amp hooked to it to somehow prove "75%" is a universal threshold... Ive lost sight of what this portion of your replies is getting at.

Every cone material type has its advantages and disadvantages. Metal cones advantage main advantage is rigidity. They aren't light (generally speaking), and they have poor damping compared to other materials like paper and carbon fiber. Paper cones advantages are good damping qualities (generally speaking) and light weight. Paper cones disadvantage is rigidity. This is all basic speaker cone 101 info. Im not saying that to be crass, but again Im starting to wonder where this portion of the discussion is leading.

Now box size is the reason there are fewer "SQ" 18's than there are 10's? I thought your stance was because of higher moving mass? There are fewer 15"+ sized SQ oriented drivers than smaller sizes because fewer SQ guys feel the need for 18's subs than do SPL guys. Marketing and profit are the reason you dont see many SQ oriented 18's.

Lets approach your moving mass theory from another direction. Say you were right and moving mass did play a significant role in SQ potential of a subwoofer. So common sense tells us a 10 has lower mass, therefore lower "moving mass", and thus must be more accurate. That is your stance, correct? The problem is more mass does not necessarily mean more inertia. Yes, the 18 will have more mass, but its greater displacement will also mean it wont need to move as far/fast (less excursion) to reach the same output level as the 10" would require. Less excursion means less BL loss (less BL distortion), AND it means that larger mass of the 18 isn't moving as fast as the 10".

Im far too lazy to calculate the difference in displacement potential between a 10" and 18", and then calculate the difference in excursion it would require to make up for the cone area difference, so I will agree that the difference in cone area versus excursion required may not cancel each other out (probably dont), but this points out yet another way that mass differences between cone sizes is not the significant factor that common sense may tell us it is.

I understand about coil rock. In fact, I still remember the radical design by Memphis, the LVS, that stacked 3 frames end to end to allow for widely spaced spiders to help decrease coil rock. Guess what, it didnt catch on. Because coil rock is not a significant portion of the distortion a speaker creates. As I think I said earlier in this thread, BL distortion (caused bu the loss of BL motor force as the coil leaves the gap) accounts for 70-80% of speaker-side distortion with traditional motor designs. But that is beside the point that, again, if cones truly warped like that camera-modified video suggested, the coil would simply short out. That is NOT normal speaker operation.

 

[VWBobby 10+ year member]

Sounds like we are on the same page now. Yes, you are correct in assuming that I feel a smaller sub is more accurate, therefore reproduces sound more accurately (less distortion). The exception to the rule however, is extremely low frequency productions (~20-35Hz). A larger sub definitely shines in this regard. It also doesn't have to be very accurate to reproduce a 20hz tone, compared the amount of movement at 60hz or higher. Imagine trying to precisely control 300 grams (for example) compared to 100 grams at 60hz and back to 40hz, etc. Most music is very dynamic and trying to control a heavy mass to react exactly the way you want, right when you want, is a very hard thing to do. This is where the LMS motors and other extremely linear motors shine. However, even the best motor can't control a cone that isn't stiff or light enough to control.

The part about the enclosure refers to how a sensitive speaker usually performs best in a larger enclosure. A sensitive speaker is usually a better sounding one.

A long time ago, I came up with a working model of a tymphany array type design....before I even knew there was a term for it (~1996). What I found was that it is much easier to control a cone when there is little room for it to go. In other words, the problem with conventional speaker designs are the lack of support for the coil and cone while still allowing the cone to move freely. This is why its better to have several smaller cones to reach the same effective displacement as 1 larger cone.....imho.

 

[VWBobby 10+ year member]

dblpost

 

[IonRL205 10+ year member]

Why no sense? What I am saying is that most people do not want to give up the space that's needed for a proper box for a 15inch subwoofer. Of course, they're made and sold, but the market is much smaller. For a lot of people, giving up so much trunk space for bass is simply not practical.

And that's why there are smaller woofers. But saying that 15" subs that are designed for car audio applications shouldn't be used for car audio cause some people don't wanna take up the trunk room is just plain retarded.

 

[audioholic 5,000+ posts]

Sounds like we are on the same page now. Yes, you are correct in assuming that I feel a smaller sub is more accurate, therefore reproduces sound more accurately (less distortion). The exception to the rule however, is extremely low frequency productions (~20-35Hz). A larger sub definitely shines in this regard. It also doesn't have to be very accurate to reproduce a 20hz tone, compared the amount of movement at 60hz or higher. Imagine trying to precisely control 300 grams (for example) compared to 100 grams at 60hz and back to 40hz, etc. Most music is very dynamic and trying to control a heavy mass to react exactly the way you want, right when you want, is a very hard thing to do. This is where the LMS motors and other extremely linear motors shine. However, even the best motor can't control a cone that isn't stiff or light enough to control.
The part about the enclosure refers to how a sensitive speaker usually performs best in a larger enclosure. A sensitive speaker is usually a better sounding one.

A long time ago, I came up with a working model of a tymphany array type design....before I even knew there was a term for it (~1996). What I found was that it is much easier to control a cone when there is little room for it to go. In other words, the problem with conventional speaker designs are the lack of support for the coil and cone while still allowing the cone to move freely. This is why its better to have several smaller cones to reach the same effective displacement as 1 larger cone.....imho.

You refer right back to smaller cones are more accurate, but completely ignored my point that the larger sub will be required to move less/slower in order to maintain the same output level as the smaller sub. I think this was a pretty significant point for you to overlook. More mass does not necessarily mean more inertia, in this context.

And again, 'trying to control 300 grams' when we are referring to stopping and starting it 20-80 times a second, boils down to motor force much more than a few grams difference in weight. You say yourself that 'linear motors shine' at control... why do they "shine"? Because they exhibit linear motor force throughout the cone excursion range. Motor force, not moving mass.

I referred to this much earlier in the thread. Your lack of response on it suggests you didn't look into it like I suggested, so here is the direct link for you to read... http://www.adireaudio.com/Files/WooferSpeed.pdf

Cheers.

 

[VWBobby 10+ year member]

That article was supposed to prove what? That added mass slows down the woofer below 700hz and "pretty much equal" (NOT!) above 700hz?

"Note the red and blue - raw and mass loaded, respectively. They are pretty much equal from 700 Hz and up

(I assume we all accept the Fourier transforms, and that the Fs/efficiency of the driver is affected by the

added mass, accounting for the differences down low."

I think its a stupid test, because most people only play their woofers to 500hz at most, and since this is a Subwoofer question, we generally don't play above 80hz at most. //content.invisioncic.com/y282845/emoticons/wink.gif.608e3ea05f1a9f98611af0861652f8fb.gif At 80hz, a 28 gram difference creates a huge transient response deadener, of sorts. Look at how the added mass affects the peaks and valleys in the blue lines on those graphs.

Smaller cones are more accurate because they are easier to control. You can create a lighter cone that is just as rigid as a larger cone, because you don't have the leverage on the cone from the former and surround. (less distance from former to surround) Since the cone is lighter, it has an inherently higher transient response. Transient response and sensitivity are some of the greatest factors in SQ, imho.

The output of a smaller cone is going to be less, yes. Increase the number of cones (woofers) and the problem is solved, without the sacrifice of sound quality/transient response. //content.invisioncic.com/y282845/emoticons/smile.gif.1ebc41e1811405b213edfc4622c41e27.gif

Cheers.

 

[Falcons 5,000+ posts]

this **** gets heated lol.

 

[T3mpest 10+ year member]

That article was supposed to prove what? That added mass slows down the woofer below 700hz and "pretty much equal" (NOT!) above 700hz?"Note the red and blue - raw and mass loaded, respectively. They are pretty much equal from 700 Hz and up

(I assume we all accept the Fourier transforms, and that the Fs/efficiency of the driver is affected by the

added mass, accounting for the differences down low."

I think its a stupid test, because most people only play their woofers to 500hz at most, and since this is a Subwoofer question, we generally don't play above 80hz at most. //content.invisioncic.com/y282845/emoticons/wink.gif.608e3ea05f1a9f98611af0861652f8fb.gif At 80hz, a 28 gram difference creates a huge transient response deadener, of sorts. Look at how the added mass affects the peaks and valleys in the blue lines on those graphs.

Smaller cones are more accurate because they are easier to control. You can create a lighter cone that is just as rigid as a larger cone, because you don't have the leverage on the cone from the former and surround. (less distance from former to surround) Since the cone is lighter, it has an inherently higher transient response. Transient response and sensitivity are some of the greatest f

The output of a smaller cone is going to be less, yes. Increase the number of cones (woofers) and the problem is solved, without the sacrifice of sound quality/transient response. //content.invisioncic.com/y282845/emoticons/smile.gif.1ebc41e1811405b213edfc4622c41e27.gif

Cheers.

Do you even know what that graph was showing? Sounds like you don't. It affects the "peaks and valleys" as you called it because the added mass LOWERS EFFECIENCY. The transient response of the driver was fine compared to the original. Transient response offset shows up in the time domain, that's the X asis in those graphs. Look at the one he zoomed in on, the green driver is actually offset vs the the mass loaded and raw driver. That's bad transient response. A change in the magnitude of the graph is simply an error in frequency response in terms of output. That's due to the heavier cone having lower effeciency...

Cars and speakers aren't the same. The exact same force that accelerates a driver forward will be the force accelerating it backwards. Electricity and shifting magnetic fields move FAR faster than the driver. A drivers ability to respond to it's input signal isn't limited by mass in terms of speed, it's limited by the shifting of the magnetic field. That's the coils inductance. More mass just means you need more BL to get the same output.

Lastly since audioholic asked about excursion. According to a quick run through winisd. A 10 and a 15 with equal output at 40hz... 10 needed 39mm of excursion to get equal output as a 15 moving 16mm.

 

[Buck 5,000+ posts]

15>12

Simple math

/thread

 

[VWBobby 10+ year member]

Do you even know what that graph was showing? Sounds like you don't. It affects the "peaks and valleys" as you called it because the added mass LOWERS EFFECIENCY. The transient response of the driver was fine compared to the original. Transient response offset shows up in the time domain, that's the X asis in those graphs. Look at the one he zoomed in on, the green driver is actually offset vs the the mass loaded and raw driver. That's bad transient response. A change in the magnitude of the graph is simply an error in frequency response in terms of output. That's due to the heavier cone having lower effeciency...
A drivers ability to respond to it's input signal isn't limited by mass in terms of speed, it's limited by the shifting of the magnetic field. That's the coils inductance. More mass just means you need more BL to get the same output.

The difference between efficiency and transient response go hand in hand (they both have similar effects). If you have an inefficient speaker, do you think it will have the same sensitivity or same transient response as the more sensitive one? The purpose of the speaker is to reproduce sound as accurate as possible. A lazy speaker isn't going to react or move as effectively as a lightweight (but rigid!) one with a stronger motor force.

I don't see how your argument is in any way against what I said originally.... :-/

 

[Kangaroux 5,000+ posts]

15>12
Simple math

/thread

18>15>12

 

[THATpurpleKUSH 5,000+ posts]

A sensitive speaker is usually a better sounding one.

Most smaller speakers have lower sensitivities than larger versions of the same model. This goes against your whole arguement.

Explain.