12" vs 15"

[ejschultz 10+ year member]

not always. thats my version of a fart cannon lol

lol. Now I can hear the sound in my head, to the degree I believe you intended.

 

[Falcons 5,000+ posts]

lol. Now I can hear the sound in my head, to the degree I believe you intended.

yupp but aparently i fail at life sometimes lol

 

[Liquid Bass 10+ year member]

This is actually a null argument....there are some factors that would support these theories

 

[T3mpest 10+ year member]

This is actually a null argument....there are some factors that would support these theories

Such as? I'll refute any of it if you'll play devils advocate. I'd like to hear what you think would support a bigger driver being sloppier.

 

[Chriszle 10+ year member]

Larger subwoofers have higher mms. Nuff said. However, enclosure design is the single largest factor that will determine how any sub performs.

 

[audioholic 5,000+ posts]

Larger subwoofers have higher mms. Nuff said. However, enclosure design is the single largest factor that will determine how any sub performs.

Moving mass is what most common sense reliant people refer to when suggesting larger woofers are sloppier or slower. If we apply that same logic to something we tend to understand better, we can see how false that logic really is. For example, are heavier cars always slower than lighter cars? Why not? Because moving mass is not the sole determining factor in performance of a car. Its not the sole determining factor in a speaker's performance, frequency response, or its transient abilities either.

Read up on Dan Wiggin's testing/write-up about modifying the moving mass of a speaker, and what affect it caused versus modifying speaker inductance. You'll be surprised.

Larger speakers, generally speaking, actually have the potential to output LESS distortion than their smaller counterparts, given a specific output level. In other words, larger subs can get louder than smaller ones, so the larger one wont need to work as hard as the smaller one to achieve a certain output level. As excursion increases, BL drops and distortion goes up (less cone control). So if your goal is minimizing distortion, the less excursion required, the better. Hence, a larger diameter sub that doesn't have to excurt as far may very well be the better choice. Of course, many factors affects this, such as fs, freq of the material, listening levels, etc etc. Again, Im speaking in very general terms here.

Its becoming popular to suggest SQ is 'all in the box', that is definitely not true. I like to look at it like this: the box has the potential to really screw up performance if its built wrong. If its built right, it simply allows the driver to perform as it should. Obviously a well designed/built box will perform better than a bad one, but dont take that logic so far as to decide the speaker plays very little role in final performance. Again generally speaking, the box tends to be a more dominant factor in frequency response, while the driver itself tends to be the more dominant factor in distortion audibility. There are exceptions of course, notably being the bandpass styles of enclosure, but my generalization holds true *usually*.

 

[ejschultz 10+ year member]

I like the analogy using cars. That's definitely breaking it down nicely for everyone to understand why moving mass doesn't necessarily affect the "cleanliness" of a speaker.

 

[VWBobby 10+ year member]

If moving mass doesn't affect a speaker, how come no matter what level of brakes you put on a 4000lb car, its still going to take at least 130 feet to stop it from 60mph? Now, you are going to say "that's what stronger motor force is for". Stronger motor force can help control the speaker better, true, at the sacrifice of sound quality (distortion introduced).

Sensitivity. Lets say you have a lightweight cone/suspension. The speaker should have a higher sensitivity. It will require a lighter motor to control this mass. The speaker should be able to reproduce more subtle tones, more accurately. For instance, high quality pro audio or home theater speakers will reproduce drum sounds, guitar or vocals with more accuracy than a typical car audio speaker.

This is because the speakers are generally made from lighter materials, paper or wool cones, and generally have much lighter suspensions.

This is where car audio speakers normally fail in SQ. Their mateirals and contruction generally lend themselves to be more sloppy, either not producing the sounds (at all), or not producing them accurately (distortion). At least that's my understanding.

Feel free to discuss. //content.invisioncic.com/y282845/emoticons/smile.gif.1ebc41e1811405b213edfc4622c41e27.gif

 

[THATpurpleKUSH 5,000+ posts]

how come no matter what level of brakes you put on a 4000lb car, its still going to take at least 130 feet to stop it from 60mph?

Bad analogy. If this was true then running ****** brakes from Pep Boys would yeild the same results as ceramic brakes on race cars, which is definitely not true.

 

[VWBobby 10+ year member]

No, its a great analogy. Newton's 2nd law: Force = Mass x Acceleration. The fastest braking cars are Formula 1 race cars and weigh 1,411 lb or more (minimum weight requirement). They can stop in approx 48 feet from 60mph. If the car was to weigh 4000lbs, the stopping distance would increase to around 130 feet..

Point being, you cannot just overcome all weight limitations by using a stronger motor(brakes). //content.invisioncic.com/y282845/emoticons/wink.gif.608e3ea05f1a9f98611af0861652f8fb.gif

 

[IonRL205 10+ year member]

You do know your brakes aren't the only thing that determines how fast you're gonna stop, your tires play a big role in it too.

 

[Chriszle 10+ year member]

Moving mass is what most common sense reliant people refer to when suggesting larger woofers are sloppier or slower. If we apply that same logic to something we tend to understand better, we can see how false that logic really is. For example, are heavier cars always slower than lighter cars? Why not? Because moving mass is not the sole determining factor in performance of a car. Its not the sole determining factor in a speaker's performance, frequency response, or its transient abilities either.
Read up on Dan Wiggin's testing/write-up about modifying the moving mass of a speaker, and what affect it caused versus modifying speaker inductance. You'll be surprised.

Larger speakers, generally speaking, actually have the potential to output LESS distortion than their smaller counterparts, given a specific output level. In other words, larger subs can get louder than smaller ones, so the larger one wont need to work as hard as the smaller one to achieve a certain output level. As excursion increases, BL drops and distortion goes up (less cone control). So if your goal is minimizing distortion, the less excursion required, the better. Hence, a larger diameter sub that doesn't have to excurt as far may very well be the better choice. Of course, many factors affects this, such as fs, freq of the material, listening levels, etc etc. Again, Im speaking in very general terms here.

Its becoming popular to suggest SQ is 'all in the box', that is definitely not true. I like to look at it like this: the box has the potential to really screw up performance if its built wrong. If its built right, it simply allows the driver to perform as it should. Obviously a well designed/built box will perform better than a bad one, but dont take that logic so far as to decide the speaker plays very little role in final performance. Again generally speaking, the box tends to be a more dominant factor in frequency response, while the driver itself tends to be the more dominant factor in distortion audibility. There are exceptions of course, notably being the bandpass styles of enclosure, but my generalization holds true *usually*.

Not a fan of your car example. If two cars are exactly the same in every aspect, except that you add 500 lbs of weight to one car, it will be slower to accelerate and decelerate always. Maybe I should not have simplified it so much, as no one T/S parameter will give insight as to how a sub will perform .

 

[wickedwitt 10+ year member]

I like the 18s cause they play the deep bass //content.invisioncic.com/y282845/emoticons/rolleyes.gif.c1fef805e9d1464d377451cd5bc18bfb.gif

Put them in a ported box and you get continuous bass:naughty:

 

[VWBobby 10+ year member]

Especially if you have a big air hole. //content.invisioncic.com/y282845/emoticons/wink.gif.608e3ea05f1a9f98611af0861652f8fb.gif

 

[audioholic 5,000+ posts]

If moving mass doesn't affect a speaker, how come no matter what level of brakes you put on a 4000lb car, its still going to take at least 130 feet to stop it from 60mph? Now, you are going to say "that's what stronger motor force is for". Stronger motor force can help control the speaker better, true, at the sacrifice of sound quality (distortion introduced).

This is a point at which the car analogy breaks down. The stopping force of a car is determined by many factors that have no relation to a speaker. Tires used, road conditions, rotor diameter, the number of pistons per caliper, etc. Dont take the car analogy to the N'th degree.

For example, the force/mechanism that propels the speaker cone into motion, is the same one used to stop it. Going back to cars, imagine their brakes being the engine, you simply reverse direction of the driveshaft and viola, you are stopping, and then moving the other direction. This is how a speaker starts and stops, using the same mechanism. Obviously, a car works much differently. This is why the analogy fails so rapidly if you try to apply it too closely to speaker physics.

A stronger motor does not sacrifice SQ and introduce distortion. In fact, the stronger the motor, the more control over cone motion is has (starting AND stopping), so the less (BL) distortion it would produce.

There are other factors that come into account besides simple motor force however. Most notably being the BL curve of the speaker. It could have a massively strong motor, but if BL drops off rapidly due to the design of the motor (narrow magnetic field, short coil, etc), then SQ will suffer. Conversely, a motor with less BL force, but a more consistent BL curve, could end up outputting less distortion then the motor with a higher BL spec, depending on excursion.

Split gap, xbl^2, and the various methods JL uses on the W7, are known as BL optimized motor types. This means their design allows them to have a consistent motor force (BL) throughout its specified excursion limits (xmax). Why do companies go through the trouble of keeping their BL force consistent? Because BL distortion accounts for 70-80% of the audible distortion created by a speaker (not to be confused with signal distortion however). That is more evidence of the significant role motor force plays in cone control (and how little mms plays a role)

Sensitivity. Lets say you have a lightweight cone/suspension. The speaker should have a higher sensitivity. It will require a lighter motor to control this mass. The speaker should be able to reproduce more subtle tones, more accurately. For instance, high quality pro audio or home theater speakers will reproduce drum sounds, guitar or vocals with more accuracy than a typical car audio speaker.This is because the speakers are generally made from lighter materials, paper or wool cones, and generally have much lighter suspensions.

Less mass, or more motor force, both gets you to the same place... better cone control. But my point is, motor force plays a much larger role than mms.

The home audio drivers you are talking about that use lighter materials etc (because they aren't in a harsh environment like a car) are midrange, tweets, and (most common) "fullrange" drivers. But again, my comments on mms relate to subwoofers only. The W7, with its 'heavy' car audio inspired cone and suspension, are being used quite successfully in a home audio environment. So have other car audio inspired subs, like the maelstrom, avalanche, etc. And guess what you usually see in a car audio sub converted over to a high-end home audio setup... BL optimization.

Also worth noting, home audio speakers tend to have looser suspension, and higher sensitivity, because enclosure size is a smaller issue in home audio than car audio. Hoffman's Iron Law tells us: sensitivity, low frequency extension, small enclosure.... pick two. Since most subwoofer builders dont want to sacrifice LFE, sensitivity is generally the trade off between home and car audio. In car audio, we tend to use low efficiency subs, and pump mega watts through them, because we want to cram then into tiny boxes in our trunk.

There is certainly something to be said for lower mms subs, the IDMax is a good example of a sub designed to (pretty much) minimize moving mass. It has a light cone, loose suspension, and its relatively efficient. There aspects of speaker performance we rarely discuss here, like timbre. This is where mms plays a larger role, the subjective end of SQ. But in terms of simple distortion output, no, mms plays a very small role, and BL plays a MUCH larger one.

Hope that helps make more sense of the topic.