# Myth: More cone area = deeper/"slower" bass



## emilimo701

This I hear frequently from dabblers and laymen.

May we start an official thread on quashing these two myths? Let me start:

"15's go deeper than 12's"

I think this myth is due to the fact that sometimes more cone area sometimes _does_ correlate to lower frequency extension. For example, the extra cone area may increase the mass, ultimately lowering its resonant frequency a little bit or alter the Q. But all things being equal, what more cone area does is increase the output ("loudness"/sound pressure). As you increase the cone area, the woofer _usually_ becomes more efficient. Sometimes, a side effect is a higher QTS or lower Fs (or both). But the bottom line is, don't use cone size to judge how low a woofer can reach. Check for known Theile–Small parameters for the best idea of the frequency response of a subwoofer.

"10 inch subs are faster than 12's or 15's" or "10 inch subs are better for SQ"

This sums it up better than I could:

http://www.stereointegrity.com/docs/WooferSpeed.pdf


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## dougelam

Why does everyone state that their 10 inch is faster than a 12-15??
The faster it travels back n forth is equivalent to the frequency it produces. The last time I was designing a system I wanted to have the driver that moved slower to produce lower frequencies, the purpose for having a subwoofer. The larger the cone area means more air moving doesn’t it?

I always felt the bigger the hammer


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## Ludemandan

Agreed. I've yet to read any science behind the idea of a "slow" speaker. If it's playing at 60 hz, it's oscillating 60 times per second, and presumably the first excursion comes within 1 120th of a second. Even if you were to miss one cycle, I don't think you could hear the difference. If it were truly moving slower throughout all cycles, it would simply reach less excursion and you'd experience that as lower volume.


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## Zolty

Isn't the "slowness" of a larger cone caused by it's mass? It might be "harder" for the amplifier to "calm it down" as cone vibrates after the signal from the source has stopped.
Not sure if what I wrote above is understandable, but to put it simple - doesn't larger cone require High-Dumping-Factor-amplifier to sound "quicker and punchier" due to cones' inertia?


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## jacampb2

Zolty said:


> Isn't the "slowness" of a larger cone caused by it's mass? It might be "harder" for the amplifier to "calm it down" as cone vibrates after the signal from the source has stopped.
> Not sure if what I wrote above is understandable, but to put it simple - doesn't larger cone require High-Dumping-Factor-amplifier to sound "quicker and punchier" due to cones' inertia?


Kind of-- the more mass the driver's cone has, the slower it is going to be to respond to a change in amplitude or frequency, it will also have more inertia once moving and will be harder to slow down as well, but, as mentioned above, it doesn't make the sound any slower or faster, the speed that the wave cycles is what defines it's frequency. 

You can't have one driver playing 45Hz faster than another driver playing 45Hz. It's like saying that when I am driving 70Mph in my car, it is faster than 70Mph in your car. 

I think the problem is that music is not just sine wave test tones, it is multiple frequencies riding on top of other frequencies on top of others. So, you have a multiple moves that the driver has to make in microseconds and the more mass it's cone has the less likely it is going to be to be able to respond to every instantaneous change, just like a Semi truck is much harder to stop and reverse than a Ferrari is. This is likely why bigger subs seem to sound less accurate and clear, and smaller subs tend to be more crisp and punchy. 

The drivers motor and the amplifier are often overlooked in these discussions. Within limits, the drivers motor should be able to make up for the added mass of the larger cone, but the manufacturers don't always build them like they should, and for the most part, the stronger the motor, the lower the efficiency, so the designers have a lot of trade offs and compromises that have to be made.

The amplifier also plays a role. It will take more power to get that additional mass and/or that more powerful motor moving. Dampening factor also plays a roll in how well the amplifier can control the reactive load. 

The root of it is that there is far more at work than just the mass of the cone. And, a "slow" sound is completely different sound from a "fast" sound.

Confused? I hope I didn't do any harm!

Later,
Jason


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## dark41

Zolty said:


> Isn't the "slowness" of a larger cone caused by it's mass? It might be "harder" for the amplifier to "calm it down" as cone vibrates after the signal from the source has stopped.
> Not sure if what I wrote above is understandable, but to put it simple - doesn't larger cone require High-Dumping-Factor-amplifier to sound "quicker and punchier" due to cones' inertia?


I'd think this is the proper answer. Larger areas and heavier objects take more to get them moving, and more to stop them once they've started. 

I hadn't heard the term "faster" used before. But the term "tighter" sound is what I've often heard others use, and my own ears tend to agree. Its all about "response" time, and response simply has to suffer somewhat with larger cones. The audible difference can be quite noticeable.

That's my preference, tight sound. But to qualify my preference I'm also a bit partial to my 2 x 10" MTX subs (bought in 2002?) - even though they're ancient by today's standards. They may not achieve the low frequencies of larger subs, but *they much more resemble the actual sound of a Ludwig bass drum than larger subs do with my classic rock*. Having played guitar around these drums for many years, I'm pretty picky about the sound being "right" rather than "more thunderous". If the latter is your preference, the larger subs would probably be more to your liking.


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## myyykeym46

It does seem that a heavier cone would require a higher damping factor amplifier to respond to transients in the same manner as a lighter cone would using a less capable amp. However this also implies that the electromagnetic circuit of the driver is proportionately more capable of transducing the lingering cone motion back into electricity for the amplifier to damp. If the manufacturer is using the exact same motor structure on a 10" and on a 12" or 15", this in an invalid assumption.

This could possibly account for some of the persistent feeling (which I've also experienced btw) that 10s give tighter bass than 15s. If the two drivers had motor structures, cabinets, and amplifiers that were proportional to the mass and surface area of their cones, you would indeed have larger drivers with superb transient performance. For example, in a concert setting you have the chest-pounding punch of the huge-magnet double-18 EAW SB850s driven by Macro Tech amps (which have lots of power and high damping factor to match).


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## jacampb2

Another piece of the puzzle could simply be tuning. It could simply be that if the end user is expecting to get the same frequency response from an 18 as from a 10, then that could be the muddy Vs punchy explanation. The place where the additional mass is going to really show is at higher frequencies. 

I really believe that if the driver is built correctly, the amplifier is of sufficient power and quality, the crossover points set correctly, and the enclosure is designed correctly that you theoretically should not be able to differentiate based on size alone, with the exception of the frequency response.

Later,
Jason


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## jmhinkle

jacampb2 said:


> I really believe that if the driver is built correctly, the amplifier is of sufficient power and quality, the crossover points set correctly, and the enclosure is designed correctly that you theoretically should not be able to differentiate based on size alone, with the exception of the frequency response.
> 
> Later,
> Jason


That's what the physics of it would show. Unfortunately, and to my ears, it's never the case. I don't like 10's because they are always too punchy. I like the sound and feel of a 12. I don't think it's a myth we are discussing here more than a personal taste or description of sound. No matter the set-up, my ears hear and my body feels "deeper" bass from a 12 than a 10. Not saying it is in reality just what I get out of it from listening.


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## tornaido_3927

Zolty said:


> Isn't the "slowness" of a larger cone caused by it's mass? It might be "harder" for the amplifier to "calm it down" as cone vibrates after the signal from the source has stopped.
> Not sure if what I wrote above is understandable, but to put it simple - doesn't larger cone require High-Dumping-Factor-amplifier to sound "quicker and punchier" due to cones' inertia?


No!

The *enclosure size* for the particular driver would have the most bearing on the overshoot/ringing of the driver.

And IIRC after the damping factor of an amp goes above about 50, it really doesn't make much difference how much damping you have, especially in relation to the size of a cone and it's mass.


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## Z80_Man

If both subwoofers had equivalent characteristics, the one having the larger cone surface would obviously generate more pressure !

But to achieve this, it should have a more powerful motor too, so the characteristics wouldn't be the same anymore.

Anyway, it won't change the played frequencies.

If we use larger membranes since the eletrodynamic speakers were invented, it's partly because they are unable to produce decent high frequencies because of their mass, so they obvioulsy become more specialized, and partly producing bass frequencies at the same accoustic power than the other frequencies requires much more power (the fact that the human ear is more sensitive in the high medium range also force to play basses louder).

So we must make more powerful motors, so they're even heavier... Pushing a small membrane with a big motor can still be a solution (some recent subwoofers are just pistons with a huge elongation), but if you want to produce a good deal of pressure at that frequency range with a standard and cheap motor (allowing a modest elongation), then having it moving a large membrane does the same thing : moving an important volume of air to achieve the wanted accoustic pressure.

Anyway, the motors have to be big. At low frequencies, the current changes directions so slowly it's almost DC, and the coils have to stand that. Some are even wired with large flat cable.

So finally, the large membrane choice is just a question of efficiency : you have a big fat heavy motor, and you won't certainly spill the power to move a ridiculously tiny membrane, while it's powerful enough to move a large one despite the air resistance to the movement.

It's just a question of getting the most SPL you can with the motor you have.

You can actually get very deep bass with a modest membrane... Unless it has a monstruous elongation, it will just play much less loud when applied the same electrical power.

A famous example was the Focal Utopia 27WX 11" subwoofer : it gave ultra deep bass, much deeper than the 13" (the one I own) and 15" ones... But it's efficiency was also much lower. It was still a perfect choice for an SQ setup.


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## Zolty

dark41 said:


> I hadn't heard the term "faster" used before. But the term "tighter" sound is what I've often heard others use, and my own ears tend to agree.


I'll remember that - "tighter" not "faster", learning all my life and will still die supid 
The other thing - cone material, it also does make a difference in punchiness - see paper vs. kevlar etc.

Regarding the frequency response - of course if signal is let's say 60Hz, then no matter what the cone size is, it should still be played as 60Hz, but.....
In real music we do not get such clean frequencies - there is always a bunch of them. Being absolute green in theory of speakers I just think the larger cone the lower frequency it can play (assuming proper installation etc) - so we can hear frequencies which are below "capabilities" of the smaller cones thus "deeper" bass. Should there be no difference we all could use tweeters as subs


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## Z80_Man

Focal actually made 5" real subwoofers, and they were rather efficient (of course, depending on the enclosure).

SPL was unsurprizingly not huge, of course. They were often used by pairs, or even more. Their main quality was the rather small load volume needed. Of course, their price was a problem too if you wanted to multiply them !


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## Sawzall

Cone material is just as important a factor as motor or size. A stiff cone more resembles the perfect piston. In the best of worlds, you would have a perfectly stiff cone that had zero mass - which of course is impossible.

A general rule: Any general rule that is one sentence long is wrong. There is almost always many more factors to consider - and in this case, there is a reason that a good spec sheet has more than just the T/S - those are just the beginning of what you need to know to design a good speaker system. But its a lot easier to sell "these are the biggest drivers that will fit in the box."


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## PaulD

I thought this thread was going to be about dispelling the myth yet most of the posts seem to AGREE with the premise (that larger speakers are "slower")


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## Zolty

Myth Not Busted !?!?


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## raamaudio

I have built mostly sealed 10 and sometime 12" systems and have to agree, at least nearly all the time, the tens are "quicker" sounding, really punchier is more accurate, but a very stiffly coned but low weight 12 can sound that way as well. 

But, my favorite sounding subs of all time were even larger and not overly high in output but played with enough authority for real music in an incredible, world championship winning, car with ID horns and Big mid bass drivers. IB is the best I have ever heard but have never owned the right vehicle to do it in, until now. 

The Studevette we are building over the next few years will have, hopefully, at IDW subs, at least 2 of them, IB install, they are quite hard to find. If not able to then probably ID15's as I run two in my home system in a huge (63.5x39x34") double chambered horn loaded enclosure and they sound great paired with the Egarhorns, modified 10 watt tube amp and Oppo BDP83SE Blu Ray player with quad 24bit DAC outputs on each stereo channel. I have 1kw running now, it works better with 2kw to the subs Those IDs are quite musical and do not weigh a ton which I need to avoid since the target weight of the car is less than 3k lbs, with a cage, race seats, fire system, etc....

Anyway, back to the topic, I love a lot of bass but not enough to blow out the windows and it must be very very accurate, a properly built system will do it with whatever size you pick, with the right gear and install, power, etc.......but easier with smaller subs, just add more until it is loud enough for you

Rick


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## chad

This can easily be solved with testing say, a 10" driver and a 18" driver with the center of the VC's on the same plane.

I can assure you that the impulse arrival time will be tits on, the same. Thus negating one driver being slower than the other.


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## ChrisB

What size sub will allow me to feel those low notes when reproducing Toccata & Fugue in D minor from Don Dorsey's Bachbusters? A sealed 10 with a predicted F3 response of 57 Hz or a ported 15" sub with a predicted F3 of 15 Hz?


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## el_chupo_

If a 40z tone is a 40hz tone on a 10, and the 15 is slower, then it would be a 37hz tone or something, right? Hmm, seems like some simple logic solves this one. Or you can do the experiment chad listed


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## raamaudio

If you just want to play single notes, not musical instrument driven, then yes, the output should be the same frequency, pretty simple to understand but the audible results can be significantly different due to the mass involved and what you have done to control it. 

Add in all the harmonics, etc, and now you have a very complex signal, the stiffer the cone, the less it weighs, the more accurately it will be able to reproduce the signal, pretty simple to understand. 

Since the smaller driver generally has less mass and is stiffer, it can be generally said that it will be more accurate, everything else being equal of course. We are not talking about playing a single note, we are talking about reproducing an accurate musical passage. 

Since the majority of recorded music is of poor quality the differences are not as dramatic as they are when a superior quality source material is played of course. Another issue is the listeners real world experience and particular set of ears, they do not all work exactly the same way nor does our brain process what we hear the same, we are far to different from each other to make that possible. 

Sometimes I wish I could go back to the Motorola 8 track and 6x9s I installed in my mothers 58 Pontiac when I was 16 as it was the only system around and I though it was the sheat........42 years ago things were much simpler than now

Rick


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## chad

Actually smaller MODERN drivers have a much heavier cone than their larger older counterparts because they are designed to handle being shoved into enclosures not much larger than their shipping carton.

As for tones/vs music..... not buying it, it's simple intermodulation, no mater how low that tone it, the inter-modulated higher freq is coming off of it jsut fine sans damping, which after writing the above, voids the fact for most modern small drivers.


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## CBRworm

What they should be saying instead of 'faster' is that a smaller (and lighter) driver has a potential to play a higher frequency all other things being equal. The 18 inch sub will do a wonderful 60hz, will it do a wonderful 600hz kick? (obviously no one would want their sub to play that high, but...maybe). And it is possible to have large diameter low xmax woofers that will do it well but not do so well in the 'sub' frequencies.


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## Miniboom

el_chupo_ said:


> If a 40z tone is a 40hz tone on a 10, and the 15 is slower, then it would be a 37hz tone or something, right? Hmm, seems like some simple logic solves this one. Or you can do the experiment chad listed


I think they're suggesting that the bigger woofer takes longer time to get moving, and longer time to stop. So the sound starts a fraction of a second later, and stops a little later than it should too. Hence the 40hz tone (between start and stop) is still 40hz, but the 40hz beat you hear is supposedly delayed an "x" amount of ms compared to a "smaller" subwoofer.

What some people forget, is that the movement in the speaker follows the signal in the voice coil. When the amp turns the signal, the polarity turns in the voice coil, and the speaker changes direction. If the mass is very high in relation to motor strenght, the speaker will move a shorter length between each turn, but will still change directions at the same time. This will be noticed by loss of efficiency. 

The consequences of adding inductance vs adding mass and its effect on woofer speed is measured and well documented by the techs at Adire Audio, *years ago*. If I only had downloaded that .pdf from them! 

Due to good documentation from Adire, I feel it's a "truth" that the voice coil is the only SPEAKER-specific element capable of making the sound delayed in relation to the applied signal. 

Group delay in the enclosure and other issues are in addition to this delay, off course.

A low inductance subwoofer in the right box won't sound "slow" when it's playing the frequencies it is supposed to.


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## Ludemandan

Exactly. A speaker has to get moving again every cycle. For a 40 hz tone the speaker has to "get moving" 40 times per second.


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## chad

Ludemandan said:


> Exactly. A speaker has to get moving again every cycle. For a 40 hz tone the speaker has to "get moving" 40 times per second.


Back to the Saturn rocket.

It has everything to do with motor. Again, that would be seen in impulse response, therefore lining up a 10" driver and a 21" driver, center of coils on same plane, and measuring impulse response will prove this.

And yes, it's not uncommon to cross an 18 pretty damn high, like in the JBL SR4738

http://www.jblproservice.com/pdf/SR-Series/SR4738A.pdf

600 cycles.


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## dark41

Now I'm more confused than I was when the thread started. 

If the myth is that smaller cones are faster, that's one thing. I haven't really seen where anyone has claimed that smaller cones move faster than larger cones at the same frequency. As far as I can tell, that myth has been proven to be false.

Then there's response time, which whether its a factor or not, still doesn't change the speed of the cones?

But if the myth is that smaller cones sound differently to larger cones (which I describe as "tighter" and I think some were calling "faster" or "punchier"), that myth has yet to be proven wrong.

I won't pretend to know all the numbers, but as far as the cone centers at the same frequency, I get that. 

What I don't get, is how people think that these numbers mean the sound will be identical. Any way you look at it (listen to it), a 15" sub is moving more air than a 10" sub and the sound will reflect that?

If you do whatever you have to with the setup of a 15" sub to match the setup of a 10" sub... is anyone going to go out on a limb and say they can match the setups so closely that no one can tell the difference? I mean its a simple test with a steady bass drum beat - if someone had the setups. I just find it hard to believe anyone would make such a claim based upon what my ears have heard over the years.


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## chad

One may say, that in most common situations that a larger cone surface area, in a proper enclosure, will produce more ELF response, possibly masking the higher "kick frequencies" in a car.[see subnote] This gives the impression that it's "slower." When, in reality, lowering the amount of LF information, because of transfer function, will bring a larger driver RIGHT back into check, and yield more"headroom" for the super low information.

[subnote, there are ways to increase the efficiency of smaller drivers in ELF land such as venting, passive radiators, horn loading with the proper flare dimensions, etc. This should be taken into account also when applying a cut on the ELF end]


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## chad

Another thing to consider, and example, my car LIGHTS UP at around 30 cycles. It resonates there (actually just a tad lower,typical hatchback.) It takes a while to get all the body panels moving in a cohesive manner. BECAUSE OF THIS, if I don't set my gating right in my impulse measurement software it tells me that my sub is 40 feet away.. In a civic hatchback. It's looking for the first strongest peak, which happens to be about 40 milliseconds, the time it takes all the body panels to get cooking. Changing the properties of said body panels changed the response time for resonance. Changing the gating of the software did also so I could get an accurate measurement  Playing the sub out full-range did the same thing.


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## Ludemandan

Maybe a smaller woofer cone just produces more high-frequency harmonics, therefore giving the impression of tighter bass, and you could produce the same effect with a large cone by reinforcing the proper high frequencies in your other speakers. Just a thought.


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## squeak9798

This thread is a train wreck


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## emilimo701

Zolty said:


> Isn't the "slowness" of a larger cone caused by it's mass? It might be "harder" for the amplifier to "calm it down" as cone vibrates after the signal from the source has stopped.
> Not sure if what I wrote above is understandable, but to put it simple - doesn't larger cone require High-Dumping-Factor-amplifier to sound "quicker and punchier" due to cones' inertia?


Yeah I guess what I was trying to say is that this concept is misunderstood. Mms does have something to do with transient response (decay) but the most important/dominant factor is inductance which you think wouldn't affect the lower frequencies but many commercial woofers, if you do the math, are affected by this. Unless you have your low pass at like 40Hz..

A more technical translation would be appreciated


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## emilimo701

tornaido_3927 said:


> No!
> 
> The *enclosure size* for the particular driver would have the most bearing on the overshoot/ringing of the driver.
> 
> And IIRC after the damping factor of an amp goes above about 50, it really doesn't make much difference how much damping you have, especially in relation to the size of a cone and it's mass.


Ahh. Good point on the damping factor & enclosure.

Question:

If you have two different woofers with very different specifications and physical/electrical properties, then put them in two different sealed enclosures so that both sub/boxes had the SAME Qtc (say, .5) and frequency response curves (would their resonant frequencies would have to be the same?), would both have the exact same transient response qualities?


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## chad

emilimo701 said:


> Question:
> 
> If you have two different woofers with very different specifications and physical/electrical properties, then put them in two different sealed enclosures so that both sub/boxes had the SAME Qtc (say, .5) and frequency response curves (would their resonant frequencies would have to be the same?), would both have the exact same transient response qualities?


EXCELLENT THOUGHT MAN!

the enclosure largely effects it's performance, but the electrical parameters (such as impedance response,) combined with the enclosure, will cause it to have a different frequency response. I have not matched it down that far by hand, but I'd be willing to bet, within the limits of the lesser driver, they would sound similar.


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## emilimo701

Miniboom said:


> I think they're suggesting that the bigger woofer *takes longer time to get moving*, and longer time to stop.


Except, it doesn't. http://www.stereointegrity.com/Files/WooferSpeed.pdf

And "the longer time to stop" is either very overrated and in most cases completely in audible.


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## emilimo701

Miniboom said:


> The consequences of adding inductance vs adding mass and its effect on woofer speed is measured and well documented by the techs at Adire Audio, *years ago*. If I only had downloaded that .pdf from them!


Check the link in original post. I believe that is exactly the paper you are referring to.


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## tornaido_3927

From the teachings of Lycan, as I understand it, the Qtc of the enclosure directly correlates to the transient response of a speaker. So yes, if they both have the same system Q, their transient response should be the same. However, that does not mean they will sound the same!!

Also, inductance does affect the rise time of a woofer which does affect the transient response, but it is the Qtc that will determine it the most. 

Edit: also, don't confuse transient response with frequency response. The transient responses may be the same but the FR may still differ.. As Chad said


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## chad

tornaido_3927 said:


> From the teachings of Lycan, as I understand it, the Qtc of the enclosure directly correlates to the transient response of a speaker. So yes, if they both have the same system Q, their transient response should be the same. However, that does not mean they will sound the same!!
> 
> Also, inductance does affect the rise time of a woofer which does affect the transient response, but it is the Qtc that will determine it the most.


think inside the box (*NOT* driver alone)


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## tornaido_3927

chad said:


> think inside the box (*NOT* driver alone)


But I thought the system Q is the Qtc, as in the Q of the enclosure + driver?

Or have I mixed something up..?


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## squeak9798

jacampb2 said:


> Kind of-- the more mass the driver's cone has, the slower it is going to be to respond to a change in amplitude or frequency, it will also have more inertia once moving and will be harder to slow down as well,


There's much more going on in a loudspeaker than that. 

For one, the inductance (or lowpass filter) is going to determine how "quickly" the driver responds. The lighter driver may have a lighter cone, but if it's inductance is higher it won't be able to respond as "quickly" to those changes as the heavier coned driver.

Second, the strength of the motor in relation to the mass is largely going to determine how much acceleration there is at the time of the change. The larger driver may have a heavier cone, but if the motor is stronger it's acceleration will be higher or equal. Or, if we increase mass on a larger cone but not the motor strength, while acceleration may be lower the net amplitude may still be higher or equal since the cone area is larger so there is more swept volume. 

Third, the total damping of the system (subwoofer motor, suspension and enclosure alignment) is going to determine how much time it takes for the subwoofer to stop. 

To say a heavier coned woofer is going to be "slower" in it's ability to respond to a change in amplitude or frequency is not accurate as it's not the mass (for the most part, or atleast mass alone) that determines this. It's the total subwoofer + enclosure. Mass is a part of it, but it's only _a_ part.

On top of that, it's entirely possible for a smaller woofer to have a higher Mms than a larger woofer as the Mms includes more than simply the weight of the cone. 



> So, you have a multiple moves that the driver has to make in microseconds and the more mass it's cone has the less likely it is going to be to be able to respond to every instantaneous change,


See above. The start and stop times are determined at best only indirectly by the Mms. Start time is inductance and lowpass crossover based, stop time is primarily Q based (which is more than just Mms), and acceleration force is primarily motor strength in relation to Mms based.



> This is likely why bigger subs seem to sound less accurate and clear, and smaller subs tend to be more crisp and punchy.


Erm....no. As chad pointed out, most of this is probably an illusion created by the increased low frequency output of the larger driver in relation to the smaller driver (assuming all else was equal, such as alignment). 



> and for the most part, the stronger the motor, the lower the efficiency,


The stronger the motor, the higher the efficiency. Which is why high efficiency drivers are low Q drivers. They have strong motors.


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## chad

tornaido_3927 said:


> But I thought the system Q is the Qtc, as in the Q of the enclosure + driver?
> 
> Or have I mixed something up..?


nope you are cool, sorry for the misunderstanding.


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## jacampb2

Ok, I am willing to admit I may be wrong, and for the record, I never said that I agreed there was slow or fast blah blah blah, I actually said that I thought this is why it "seemed" that one size driver might be punchier than another. It is a perception of something-- what the cause is seems yet to be determined. 

I mentioned later in the thread that maybe it was simply a frequency response difference that is causing some of us to "perceive" a difference in the sound of a 10 and a 15. It seems this thought was further corroborated later in the thread.

I was merely thinking out loud, and it was late here. I appologize. I do have a huge problem with a premise that starts with "all other things equal". It is pretty much a theoretical discussion at that point, because two different drivers are never going to be exactly the same, and if you add the difference in radiating area being discussed, well, you see where I am going, it isn't possible "for all other things to be equal". 

Do I think that you could get a large driver to sound exactly like a smaller driver, or vice versa? Absolutely. Do I think that that is normally the case? Absolutely not, and it comes down not just to the driver size but likely dozens of other factors. 

Later,
Jason


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## emilimo701

Ludemandan said:


> Maybe a smaller woofer cone just produces more high-frequency harmonics, therefore giving the impression of tighter bass, and you could produce the same effect with a large cone by reinforcing the proper high frequencies in your other speakers. Just a thought.


Yeah I think that the perception of "tighter" or "slower" bass is due NOT to transient response but to Q and frequency response of the woofer and its enclosure as a system. Yes, I realize that frequency response (bandwidth) and transient response are directly related to each other. But I do not think that that's what people are referring to when they talk about sound being "tighter" or "fuller" or "slaptastic" or however unscientifically arbitrary they want to qualify it.

There are two issues that engineers and hobbyists alike seem to agree on as the definition of "transient response": rise time and decay time.

RISE TIME: According to the paper I linked to in the original post, rise time is completely determined by the electrical properties (namely, inductance) of the woofer. A woofer will not be slower because of added cone mass, suspension stiffness, etc. It is determined by the coil inductance. However, there sometimes is correlation between bigger woofers and diminished transient response; many manufacturers use a separate motor for each cone diameter within a specific series/model. For example, in JL's W7 motors, each size has an increasingly larger coil (from 2.25 to 3.75 in). The larger the coil, the higher the inductance. If countermeasures aren't taken to lower the inductance, there is a very good chance that high (high is a relative term here since we're talking about bass) frequency extension will be poor enough to affect the transient response even in the band after a low pass filter has been applied.

However there are two things to realize:

1) Countermeasures are very frequently taken to lower the coil inductance of larger/longer coils.

2) According to this thread, effects of transient response will not even apply as long as this inequality is satisfied:
f = crossover freuency
f < Re / (pi * Le)

DECAY TIME: Decay time can be affected by compliance, diaphragm mass, coil resistance, and strength of magnet. My understanding of exactly how all of these affect decay time is not that great. But as I asked a couple posts above, my understanding is that decay time transient response depends ultimately on two things only: damping factor of amplifier, and the total Q (Qtc) of the subwoofer–box system. For example, a 10" subwoofer in a box with Qtc of .65 will have the same transient-response properties as a 15" subwoofer on the same amp in a box with Qtc of .65.
Check out this thread: http://www.diymobileaudio.com/forum...bers/30-transient-response-stored-energy.html

Am I on the right page?


----------



## emilimo701

jacampb2 said:


> Ok, I am willing to admit I may be wrong, and for the record, I never said that I agreed there was slow or fast blah blah blah, I actually said that I thought this is why it "seemed" that one size driver might be punchier than another. It is a perception of something-- what the cause is seems yet to be determined.
> 
> *I mentioned later in the thread that maybe it was simply a frequency response difference that is causing some of us to "perceive" a difference in the sound of a 10 and a 15. It seems this thought was further corroborated later in the thread.*
> 
> I was merely thinking out loud, and it was late here. I appologize. I do have a huge problem with a premise that starts with "all other things equal". It is pretty much a theoretical discussion at that point, because two different drivers are never going to be exactly the same, and if you add the difference in radiating area being discussed, well, you see where I am going, it isn't possible "for all other things to be equal".
> 
> Do I think that you could get a large driver to sound exactly like a smaller driver, or vice versa? Absolutely. Do I think that that is normally the case? Absolutely not, and it comes down not just to the driver size but likely dozens of other factors.
> 
> Later,
> Jason


I think this is the case and one of the greater impetuses (impeti?) for the half-myth we are speaking of.


----------



## emilimo701

squeak9798 said:


> The stronger the motor, the higher the efficiency. Which is why high efficiency drivers are low Q drivers. They have strong motors.


I have some questions: 

What techniques are used to raise the BL of a motor?

Do any of the techniques to raise BL also raise inductance?

What are other negative effects of increasing BL (if any) of a woofer?


----------



## emilimo701

squeak9798 said:


> Second, the strength of the motor in relation to the mass is largely going to determine how much acceleration there is at the time of the change. The larger driver may have a heavier cone, but if the motor is stronger it's acceleration will be higher or equal. Or, if we increase mass on a larger cone but not the motor strength, while acceleration may be lower the net amplitude may still be higher or equal since the cone area is larger so there is more swept volume.


So, are you saying that inductance _isn't_ the only determinant of rise time?


----------



## chad

emilimo701 said:


> So, are you saying that inductance _isn't_ the only determinant of rise time?


How high are you playing it? This is a simple calculation, first order LP filter.

In inductance land, electrically, plug and chug.


----------



## jacampb2

One point I am attempting to make is that if all things are equal, except for the driver diameter, then how can we surmise in the next breath that the manufacturer increased the VC diameter and therefore inductance, and that the manufacturer did indeed use a different stronger motor for the larger driver.

It may be uncommon now, but 10 years ago or so it was not uncommon at all to find 3 different sized driver offerings from a manufacturer with pretty much the exact same motor. You cannot tell me that there is not going to be difference in performance from those three drivers. The only way I can see that being a possibility is if the smallest is enormously overbuilt, the next larger just overbuilt, and the largest just right-- I have no proof, but I don't think it that is the case.

Anyhow, carry on. This is quite interesting and enlightening.

Later,
Jason


----------



## chad

I have several 4" VC's here with lower inductance than 1" VC's. As for the same motor for different diameters, yeah, I'm with you totally. Look at my NEVER ENDING rant about the Dayton 12" vs/ the 10"

The 10 does the same damn thing almost exactly in half the enclosure.

Think about it.

But some people just have to have those 12 inches as opposed to 10 inches. 

They think it impresses the girlz.


----------



## mikey7182

chad said:


> I have several 4" VC's here with lower inductance than 1" VC's. As for the same motor for different diameters, yeah, I'm with you totally. Look at my NEVER ENDING rant about the Dayton 12" vs/ the 10"
> 
> The 10 does the same damn thing almost exactly in half the enclosure.
> 
> Think about it.
> 
> But some people just have to have those 12 inches as opposed to 10 inches.
> 
> They think it impresses the girlz.


Now imagine what TWO of those 10s would do... or *gasp* one 15!!  I getz teh ladiez.


----------



## jacampb2

Lol, I made another assumption I shouldn't have. I wrongly assumed that the larger diameter VC would have to have a higher inductance, but that doesn't have to be the case, it's number of turns, height and width of the coil, as well as core material that specifies inductance. It is possible as you say to have a larger diameter and lower inductance, but that is not the norm, is it?

My related question though, is how does the core affect the inductance in the VC? It seems the inductance would be variable as the VC moved in and out of the gap. Above, it was asked how the magnet strength effects the inductance, and I have to believe it does, doesn't it? Inductance is the result of interacting magnetic fields, correct? Doesn't this mean that VC "air core" inductance is going to be different, possibly even drastically different, then it would be while installed in the and moving in the gap respectively?

It probably isn't necessary to get into it for this discussion, but I am curious, and I did come here to learn...

Thanks,
Jason


----------



## Sarthos

I can't remember exactly how, but if nobody else responds by the time I've got a chance to, I'll find my physics book. But different core materials do affect the inductance of the voice coil, that is true. How the magnet affects it I'm not entirely sure. I know a magnet can induce current in a wire, and current can induce magnetic fields. Not 100% sure of the equations at the moment.


----------



## Miniboom

Well, an iron cored inductor (like in some crossovers) are cheaper because they allow for shorter wire for same inductance as an air cored coil. Hence iron inside an inductor increases its inductance.

Aluminium, I'm not sure. It's not magnetic, so perhaps no effect. Voice coil formers are usually aluminium, kapton, pressed paper, fiber glass or plastic, right? Can't remember seeing magnetic material in there. It has to be light, and magnetic stuff generally aren't.

The inductance of a coil may vary upon usage, I don't know - I just know whether it does or doesn't vary, it's probably completely irrelevant anyway, since it must be one of those variable and non-predictable-for-common-usage-playing-regular-music kind of subjects. 

If one should discuss each and every aspect of variables in a situation where you have a given subwoofer in a given enclosure, I'd think one would need a lot of spare time.

...speaking of spare time. I have a trunk to go look at while freezing my nutsack right off!


----------



## Oliver

chad said:


> But some people just have to have those 12 inches as opposed to 10 inches.
> 
> They think it impresses the girlz.





mikey7182 said:


> Now imagine what TWO of those 10s would do... or *gasp* one 15!!  I getz teh ladiez.


German girls think 12 is quaint


----------



## squeak9798

emilimo701 said:


> So, are you saying that inductance _isn't_ the only determinant of rise time?


Nope, not what I said 

Inductance is going to affect the _rate of change_ of acceleration. This is going to determine the impulse response. This is going to determine how quickly the driver can respond. 

The _amount_ of acceleration is going to depend on the motor strength in relation to the mass. This is going to determine the amplitude. This is, basically, sensitivity (although actual sensitivity also takes cone diameter into account).


----------



## Oliver

*Leap tall ... jump speeding ... in a nano-second*




> In the case of GTi, the answers are as simple as the questions: *better, louder, and a whole lot more."
> *
> Differential Drive Design is an important advancement in subwoofer motor technology. The dual-coil design, which uses two 3-inch-diameter voice coils, results in significantly higher power handling through increased surface area, and maintains the low-moving mass, which is not possible with single large-diameter voice coils. Because the subs feature two coils in two separate gaps, they provide twice the heat-dissipating surface area of single-coil subs with similar coil and gap dimensions. This offers a distinct advantage over conventional dual-coil designs, in which one coil is wound on top of the other in the same gap, and each coil layer heats an adjacent layer until the outermost layer transfers heat to the woofer's top plate. Because of the dual inner-hung positioning of the voice coils, JBL's DDD maximizes the woofer's linear excursion, which is important for SPL operation and sealed-enclosure applications. The GTi coils are biased inward, toward the center of the motor structure, creating more coil "innerhang" and, thus, nearly twice the linear excursion of conventional motor designs (in which the coil is centered in the gap). With moderate input power, both the GTi's coils drive the woofer in the same direction and operate in reverse electrical and magnetic polarity, creating less distortion than conventional subs do. However, at higher excursions, one coil can leave the gap while the other coil drives the cone to the excursion maximum.
> 
> JBL has also utilized its Symmetrical Field Geometry‘ (SFG) technology in the DDD to create a magnetic field that is absolutely symmetrical. This second generation of JBL's SFG significantly reduces distortion at high excursion. In this application, the two voice coils work together to produce large linear excursion by operating within summing magnetic circuits of opposite polarity. Since each coil works within its own gap, the design ensures precise linear control.
> 
> Using its proprietary Finite Element Analysis‘ (FEA) software, JBL carefully designed the cone, suspension, and frame to optimize the new GTi subwoofers' DDD magnetic system. In the end, JBL opted for a spider made of NPC (a blend of Nomex‘, polyester, and cotton) because of its strength and durability. Also new to the GTi Series are interwoven speaker leads (on W12GTi and W15GTi), ensuring long life and noise-free operation at high excursion.



note: not designed on Krypton


----------



## darkist240sx

good read


----------



## darkist240sx

So i guees it is tru, smaller subs are capable of keeping up with fast beats better


----------



## tornaido_3927

darkist240sx said:


> So i guees it is tru, smaller subs are capable of keeping up with fast beats better


Please tell me you are joking 

And Squeak, I'm pretty sure that the inductance only actually affects the *rise time* near the frequencies that the inductance affects. Inductance does not affect all of the frequencies across a drivers' range. It is what causes high frequency rolloff and if you cross a sub lower than the where the inducance has a bearing, it will not affect the frequency, impulse or transient response.


----------



## Oliver

darkist240sx said:


> So i guees it is tru, smaller subs are capable of keeping up with fast beats better


I use a DVC 5" sub with time advancement for my mid and an 18" SVC with time delay for my extreme low frequencies , this alloows me to screw and chop my RAP music in thee car


*Drake - Over - Chopped & Screwed *- YouTube - Drake - Over - Chopped & Screwed


----------



## tornaido_3927

I'd suggest for some people in here to go through at least the second page of this topic http://www.diymobileaudio.com/forum/diyma-sq-forum-technical-advanced/87371-fast-bass-slow-bass-myth-vs-fact-2.html

Some great stuff about inductance, transient response and the "speed" of a woofer.


----------



## emilimo701

squeak9798 said:


> Nope, not what I said
> 
> Inductance is going to affect the _rate of change_ of acceleration. This is going to determine the impulse response. This is going to determine how quickly the driver can respond.
> 
> The _amount_ of acceleration is going to depend on the motor strength in relation to the mass. This is going to determine the amplitude. This is, basically, sensitivity (although actual sensitivity also takes cone diameter into account).


Okay I understand now. Thank you!


----------



## emilimo701

tornaido_3927 said:


> I'd suggest for some people in here to go through at least the second page of this topic http://www.diymobileaudio.com/forum/diyma-sq-forum-technical-advanced/87371-fast-bass-slow-bass-myth-vs-fact-2.html
> 
> Some great stuff about inductance, transient response and the "speed" of a woofer.


Definitely a good addendum to this thread (or the other way around). I think I saw that used the equation in post above. There's another one too but I can't find it anymore.


----------



## squeak9798

tornaido_3927 said:


> And Squeak, I'm pretty sure that the inductance only actually affects the *rise time* near the frequencies that the inductance affects. Inductance does not affect all of the frequencies across a drivers' range. It is what causes high frequency rolloff and if you cross a sub lower than the where the inducance has a bearing, it will not affect the frequency, impulse or transient response.


Correct, if the inductive corner frequency of the driver is sufficiently above the lowpass crossover then it's not going to limit the impulse response. Which is why in my original response I included (or lowpass crossover) as for some subwoofers that will be the limiting factor.

But the moral of the story relating to the driver itself is that in general terms, it's the inductance and not the mass that is going to limit the impulse response.


----------



## divvide

so to recap the thread

1. A 15 can stop and go as fast as a 10 as long as the motor is designed to handle the mass of the subwoofer

2. A 10 can slow down its transitions and play low tonal bass hz just as well as the 15 ( as long as box dimensions meet the requirements)

3. The only reason to get a 15 over a 10 is to get larger output figures across the band.

Am i getting all this right?


----------



## tornaido_3927

divvide said:


> so to recap the thread
> 
> 1. A 15 can stop and go as fast as a 10 as long as the motor is designed to handle the mass of the subwoofer
> 
> 2. A 10 can slow down its transitions and play low tonal bass hz just as well as the 15 ( as long as box dimensions meet the requirements)
> 
> 3. The only reason to get a 15 over a 10 is to get larger output figures across the band.
> 
> Am i getting all this right?


1. A 15" can "stop and go" as fast as a 10" if it is in the right box, i.e. one that is not too small.

2. A 10" or even a smaller driver can go low if it has a low Fs, so if it is *designed* to go low.

3. There are other reasons, such as using a 15" will mean requiring less excursion to get to the same dB level, usually resulting in lower distortion.


----------



## Oliver

Multiples of drivers allow for more and cleaner levels of sounds if not overdriven.


----------



## divvide

tornaido_3927 said:


> 1. A 15" can "stop and go" as fast as a 10" if it is in the right box, i.e. one that is not too small.
> 
> 2. A 10" or even a smaller driver can go low if it has a low Fs, so if it is *designed* to go low.
> 
> 3. There are other reasons, such as using a 15" will mean requiring less excursion to get to the same dB level, usually resulting in lower distortion.



Thanks for clearing that up.


----------



## subwoofery

chad said:


> One may say, that in most common situations that a larger cone surface area, in a proper enclosure, will produce more ELF response, possibly masking the higher "kick frequencies" in a car.[see subnote] This gives the impression that it's "slower." When, in reality, lowering the amount of LF information, because of transfer function, will bring a larger driver RIGHT back into check, and yield more"headroom" for the super low information.
> 
> [subnote, there are ways to increase the efficiency of smaller drivers in ELF land such as venting, passive radiators, horn loading with the proper flare dimensions, etc. This should be taken into account also when applying a cut on the ELF end]


When looking for a substage, I'd rather have too much low end. 
When you have too much low end (10 to 30Hz)
EQing the low end = less Xmax = less distorsion 
EQing the low end = less Xmax = easier on your charging system 
EQing the low end = less Xmax = lower group delay 

I will always choose the biggest subwoofer I can fit within my space requirements. I'd rather cut than boost. 

Kelvin


----------



## ncv6coupe

subwoofery said:


> When looking for a substage, I'd rather have too much low end.
> When you have too much low end (10 to 30Hz)
> EQing the low end = less Xmax = less distorsion
> EQing the low end = less Xmax = easier on your charging system
> *EQing the low end = less Xmax = lower group delay *
> I will always choose the biggest subwoofer I can fit within my space requirements. I'd rather cut than boost.
> 
> Kelvin


All great points in addition to what Chad said, the hard part is having proper equalization whether it be subsonic filter, port EQ, parametric or graphic(need much more bass bands) and getting the group delay to not be all wavy>>>Not that you should be able to hear it anyway.

One of my subwoofer tuning tricks I've used before since I love me a ported box is to boost the eq to compliment the port gain then cut the overall levels. Unorthodox yes but I'm about to build another box to do that and cut the eq out of the picture all together. If its not right then I have to build another box, which is why I choose to delay that little project for right now


----------



## smokeybehr

I haven't read anyone really discussing the physics that's going on here. 

The whole point of reproducing sound is for the transducer to move the air. The more air moved, the louder the perceived sound. Theoretically, an 18" driver can push as much air as a 10" driver, as long as the 10" driver has a long enough excursion voice coil and cone surrounds, and the voice coil wire can handle the power needed to move the cone. There will also be some heat generated, so there needs to be some cooling involved. 

My first box was built with 12" long excursion EV drivers in a box that had about 1CF of airspace for each driver. This was long before I understood all of the numbers that went into building and tuning a box. It was loud, and it hit hard, but it didn't sound as good as I thought it should, but I chalked it up to the electronics I was driving it with.


----------



## 8675309

At usaci finals this year I did not run subs I ran nothing more than my Focal 165KRX3 woofers. And every one that got in loved them. NO SUBS with a pair of 6.5s and it was nice!


----------



## Oliver

*Did you win ?*


----------



## 8675309

yes!


Oliver said:


> *Did you win ?*


----------



## Oliver

*Congratulations !!*


----------



## Z80_Man

I'm actually OK with just my pair of 7W2, but my final project still includes the 33WX.

It's not easy to go down without serious door surgery, and I can hardly afford it as I can't spend a long time with disassembled doors, nor I want to modify them too much (more exactly, I don't want to do that dirty, and it would involve even more time with the car unusable, what I can't afford at all).

Sooo... I'll go for a sub for which I can at least easily (and outside of the car) design the required rigid and non resonant enclosure.

It was planned from the beginning anyway, and the 7W2 were intended as midbass only, though they produce very efficient bass in general.

In any cases, the cone diameter isn't responsible from bass emitting on its own, though it's obvious for everyone you wouldn't build a tweeter featuring a 18" membrane, would you ? 

It's just that low frequencies are harder to hear, so they need much more power. That's basically the reason for large cones and/or long elongations, as the aim here is to move a lot of air, but the electromechanic characteristics of the subwoofer itself (and its enclosure as well) are responsible for deep bass.


----------



## Dangerranger

You really have to define "fast" to answer such a question. 

Inductance determines "fast" in the sense of how quickly a speaker reacts to the input signal, and mass has no effect nor does cone size. With that in mind, inductance also is the parameter that affects how high a speaker can play (eliminating things like beaming and cone resonances of the speakers in question which is a different dilemma)

Low mass does not inherently mean a "tight" or "fast" speaker. Does more mass mean more inertia? Of course. It's just physics. But that simply means it will require a motor with more force to control it. It's just as easy to design a motor and suspension that can control the mass of a 15" speaker in exactly the same fashion as a 10" speaker.

Note: How well the motor of your speaker controls the mass of it's cone is fully reflected in it's Qts. Probably the best explanation of speaker Q and system Q and much more than I'd be willing to type was a post andy had:

http://www.diymobileaudio.com/forum/449352-post21.html


To sum it up: Are 10's inherently "faster" than 15s? No. It has nothing to do with cone size. It has nothing to do with anything other than how strong the motor is compared to the cone mass.

Mass does not hinder the frequency range that a speaker can produce. Transient response is frequency response related via the Fourier Transform. And transient response is determined/limited by how fast you can change the current in the voice coil (change the SPL).

Mass does affect efficiency, meaning it will definitely affect the amount of current required to reach a given excursion level. That simply says that if the cone is heavy, you need more current to get a given acceleration (and hence, SPL) out of it. Mass simply scales the relationship of force to current, but does not alter how current changes over time (that is determined by inductance).


----------



## subwoofery

Dangerranger said:


> You really have to define "fast" to answer such a question.
> 
> Inductance determines "fast" in the sense of how quickly a speaker reacts to the input signal, and mass has no effect nor does cone size. With that in mind, inductance also is the parameter that affects how high a speaker can play (*eliminating things like beaming* and cone resonances of the speakers in question which is a different dilemma)
> 
> Low mass does not inherently mean a "tight" or "fast" speaker. Does more mass mean more inertia? Of course. It's just physics. But that simply means it will require a motor with more force to control it. It's just as easy to design a motor and suspension that can control the mass of a 15" speaker in exactly the same fashion as a 10" speaker.
> 
> Note: How well the motor of your speaker controls the mass of it's cone is fully reflected in it's Qts. Probably the best explanation of speaker Q and system Q and much more than I'd be willing to type was a post andy had:
> 
> http://www.diymobileaudio.com/forum/449352-post21.html
> 
> 
> To sum it up: Are 10's inherently "faster" than 15s? No. It has nothing to do with cone size. It has nothing to do with anything other than how strong the motor is compared to the cone mass.
> 
> Mass does not hinder the frequency range that a speaker can produce. Transient response is frequency response related via the Fourier Transform. And transient response is determined/limited by how fast you can change the current in the voice coil (change the SPL).
> 
> Mass does affect efficiency, meaning it will definitely affect the amount of current required to reach a given excursion level. That simply says that if the cone is heavy, you need more current to get a given acceleration (and hence, SPL) out of it. Mass simply scales the relationship of force to current, but does not alter how current changes over time (that is determined by inductance).


I'm pretty sure inductance won't have any effect on beaming. Beaming is only affected by cone diameter. 

Kelvin


----------



## Miniboom

subwoofery said:


> I'm pretty sure inductance won't have any effect on beaming. Beaming is only affected by cone diameter.
> 
> Kelvin


I don't think you fully understood what he wrote, or maybe he wrote it so it could be misunderstood. It is my impression that he stated that inductance limits bandwidth in higher frequencies (by reducing cone speed/acceleration).

Then I think he mentioned beaming and cone resonances as other factors that become important when deciding at which frequencies a certain driver is considered usable, without those factors having anything to do with the speakers performance in the "time domain".

He actually wrote a very understandable and correct post as far as my knowledge goes.

PS: I think beaming also is affected by cone shape and things like phase plugs etc.


----------



## Oliver

subwoofery said:


> I'm pretty sure inductance won't have any effect on beaming.* Beaming is only affected by cone diameter.
> *
> Kelvin





Miniboom said:


> I don't think you fully understood what he wrote, or maybe he wrote it so it could be misunderstood. It is my impression that he stated that inductance limits bandwidth in higher frequencies (by reducing cone speed/acceleration).
> 
> Then I think he mentioned beaming and cone resonances as other factors that become important when deciding at which frequencies a certain driver is considered usable, without those factors having anything to do with the speakers performance in the "time domain".
> 
> He actually wrote a very understandable and correct post as far as my knowledge goes.
> 
> PS: I think beaming also is affected by cone shape and things like phase plugs etc.



*Umm ... NO *on the beaming being affected by anything more than the diameter of the cone. 

http://www.webervst.com/blocker.html


----------



## Dangerranger

Miniboom is right, I didn't mean that inductance and beaming were in any way related. What I meant was that inductance is the only parameter that affects how high a speaker can play (not mass), not counting things like beaming and cone resonances. In other words, a woofer with inductance as low as a tweeter could play to 20khz and above, if it weren't for things like beaming and cone resonances limiting that.

I think another thing to note on the topic (not related to my response on inductance) is that as far as mechanical and electrical control of a driver is concerned, it's all in proportion. In other words, a 10" sub is limited to a given frame size so you can only fit so much spider into it and you can only fit so large of a motor. A 15" sub will have a larger frame size and more room to work with, so you can use a proportionally larger spider to get the required compliance as well as a wider magnet. Think it's not an issue? look at all the subs that use dual spiders and such. Also look at the limitations of large voice coil, inset magnet drivers like Dynaudio, Morel, the Hivi knockoffs and such. They have a LOT of suspension induced distortion because they have a tiny spider supporting them. If you look at all the neo magnet speakers/subwoofers, and the hybrid neo/ferrite motors, and even the ferrite ones, it's not a problem to get enough motor to control the cone of a speaker in the given space.


----------



## thehatedguy

Actually mass does effect transient response...this is what we are talking about when we talk about a speaker being "fast" or "slow." The problem with the inductance only definition came from Dan Wiggins using a pretty none standard definition of transient ability. Jeff (lycan) has shown the math on here why mass matters.


----------



## subwoofery

thehatedguy said:


> Actually mass does effect transient response...this is what we are talking about when we talk about a speaker being "fast" or "slow." The problem with the inductance only definition came from Dan Wiggins using a pretty none standard definition of transient ability. Jeff (lycan) has shown the math on here why mass matters.


That's why I'm using horns... 
Dynamics - there's something about that word that just makes me smile  

Kelvin 

PS: just waiting to try a tapped horn design


----------



## DonH

damn good read here fellas


----------



## Miniboom

The "slow mass"-crowd are welcome to post test results showing _equally inductance woofers with different masses _performing different as far as the speaker's speed is concerned.

So far, the only PROOF (graphs and measurements) I've seen are by Adire Audio, and indicate that mass has no effect on woofer speed....

Now, I'm not saying the tech guys at Adire are GODS, but they built woofers known for their capabilities, and not least: They have done the measurements and shared them with the world. 

I wonder if those arguing against this have seen the graphs, or even ever heard a fast 18-inch woofer?

Finding a good 18" is not like finding a Yeti in Miami.


----------



## cubdenno

Miniboom said:


> The "slow mass"-crowd are welcome to post test results showing _equally inductance woofers with different masses _performing different as far as the speaker's speed is concerned.
> 
> So far, the only PROOF (graphs and measurements) I've seen are by Adire Audio, and indicate that mass has no effect on woofer speed....
> 
> Now, I'm not saying the tech guys at Adire are GODS, but they built woofers known for their capabilities, and not least: They have done the measurements and shared them with the world.
> 
> I wonder if those arguing against this have seen the graphs, or even ever heard a fast 18-inch woofer?
> 
> Finding a good 18" is not like finding a Yeti in Miami.


I have heard "fast" 18" subs. And 15" and 21" and 12" and so on. Considering the enclosure is the main determinate of the woofer's "sound" followed by the midbass response.

This whole speed thing is just silly. Most people are running their subs 80 and down. Some a bit higher, some a bit lower. the result is still, you are pretty much using the subs for pressurization at those low frequencies. I think it was posted in this link earlier, but take out your midbass drivers (shut them off) and listen to your subs. tell me how fast they sound. Look at the pro audio world with the big woofers that they use. 

Better use of time spent arguing about something relevent. Like which super high end platinum coated cables make your stereo the bomb-diggity!!


----------



## stalintc

The only pertinent thing I have to offer at this point is this: the idea that the listener perceived attributes of dynamic "kick" and "tightness" are functions of cone size/mass/ any other spec (within reason here) between 2 similar bandwidth drivers is not accurate. It can be true, but more specifically these perceptions are frequency response dependent. I say it can be true, since the above mentioned specs can change a drivers response, but it is the response change, not the mass/size delta that dictate this. Floyd Toole and Sean Olive cover this, and how much these and other factors influence listener preferences, in "Sound Reproduction".


----------



## thehatedguy

Inductance is a crossover. All it will do is limit the upper FR of a speaker.

The proof that was offered was based on a non standard definition of transient response. So how does that "prove" anything outside of the definition they were using?




Miniboom said:


> The "slow mass"-crowd are welcome to post test results showing _equally inductance woofers with different masses _performing different as far as the speaker's speed is concerned.
> 
> So far, the only PROOF (graphs and measurements) I've seen are by Adire Audio, and indicate that mass has no effect on woofer speed....
> 
> Now, I'm not saying the tech guys at Adire are GODS, but they built woofers known for their capabilities, and not least: They have done the measurements and shared them with the world.
> 
> I wonder if those arguing against this have seen the graphs, or even ever heard a fast 18-inch woofer?
> 
> Finding a good 18" is not like finding a Yeti in Miami.


----------



## Dangerranger

thehatedguy said:


> Inductance is a crossover. All it will do is limit the upper FR of a speaker.
> 
> The proof that was offered was based on a non standard definition of transient response. So how does that "prove" anything outside of the definition they were using?


Exactly right. And I believe the responses you mentioned that came from a certain furry canine are in this thread 

http://www.diymobileaudio.com/forum/diyma-sq-forum-technical-advanced/9243-speaker-modification-effect-cone-mass-loading.html


----------



## subwoofery

thehatedguy said:


> Actually mass does effect transient response...this is what we are talking about when we talk about a speaker being "fast" or "slow." The problem with the inductance only definition came from Dan Wiggins using a pretty none standard definition of transient ability. Jeff (lycan) has shown the math on here why mass matters.


To complete the above, I've copied something I've found on a Focal catalogue: 
_"Reminder of fundamentals: the cone accele- ration is expressed by the a=BLi/m formula, where B is the magnetic flux in the air gap (in Tesla), L the voice coil length, i the current delivered by the amplifier and m the mass of the moving assembly (cone, voice coil, sur- round). We can always tell nice stories, but to speed up the cone and to get a maximum of dynamics, it’s better to start with a high BL." _

Their 16" Utopia Be has a BL of 34T.m. - efficiency of 97dB 1w/1m - and an FS of 24Hz. 

Kelvin


----------



## Quagmire

@jmhinkle: just want to make sure after all this discussion that you surmised that your stated opinion earlier was based purely on the systems you've heard and or payed attention to. That they "just so happen to have had" larger drivers in them to create the sound characteristics you were listening for, rather than the diameter of the subs being THE reason why they sounded that way. If you embibed that thru all the information displayed, you have the ability now to share that with a nearly infinite amount of those that would say the same thing you did because they've not experienced anything else yet.


----------



## Oh.humes

It's not easy to go down without serious door surgery, and I can hardly afford it as I can't spend a long time with disassembled doors, nor I want to modify them too much (more exactly.


----------



## Z80_Man

Oh.humes said:


> It's not easy to go down without serious door surgery, and I can hardly afford it as I can't spend a long time with disassembled doors, nor I want to modify them too much (more exactly.


I'm in the same case, at least until now.

That's why I said my 7" will stay used as midbasses (what they were intented for anyway), though they produce wonderful infra... 

It's just easier to tune a real enclosure with a real subwoofer and dedicated amp.

Now there's still an easy way to produce real bass in doors without turning them into enclosures the hard way : small aperiodic enclosures.

I was even wondering if I wouldn't do that for the 7W2... I think I'm even not forced to mess up with resin and glass fiber : just piling up MDF discs and tightning all them up with long bolts through the inner door should allow for a nice small enclosure (using glue and gaskets for better airtight), and I'll just have to cut the hole at the rear to insert the variovent. The entire enclosure also has to be stuffed with flocking material.

Audionutz once published a nice article about small aperiodic enclosures in the past, and the results obtained were very interesting : nice, tight and clean bass in a ridiculously small volume (the smaller the better, actually), and the low air pressure exiting from the variovent into the door volume caused no unwanted vibrations or noise.

The only drawback with this setup is the efficiency is cut in half (- 3dB), but at least you don't have to transform your entire doors.

Here's the link : AP Enclosures-The Aperiodic Cookbook | Tutorials | Team Audionutz

Enjoy !


----------



## 2fnloud

ChrisB said:


> What size sub will allow me to feel those low notes when reproducing Toccata & Fugue in D minor from Don Dorsey's Bachbusters? A sealed 10 with a predicted F3 response of 57 Hz or a ported 15" sub with a predicted F3 of 15 Hz?


Chris,

Just to know that you use T&D in Dm from Bachbusters is awesome, I thought I was the only person that would use classical to SPL.


----------



## Jaredturp

Through mathematics I drew a different conclusion than the article. The graphs are fairly convincing, however, when I tried to simplify the equation I found that it would be variant on mass. The writer simply canceled out the constants after combining the equations.
My logic went as follows. Can someone tell me where I went wrong?? And can we just ignore the elastic potential energy converted into the spider and back into kinetic?
Mt= Mass total, a= acceleration, F=Fnet (apparently disregarding the spider), and ▲= change in.

Mt(a)=F
F/Mt=a
Then I broke down the two elements that are time variant: force and acceleration. The force is (▲current)/time) and the acceleration is (▲v/t)

When I plugged those in I got: ((▲c)/t))/Mt)=(▲v)/t
Through arithmetic you get that the times cancel and you are left with:
▲c/Mt=▲v
What that tells me is that the current is directly proportional to the change in velocity, but we must recognize that Mt has a definite influence on the ▲v. But ▲v just talks about the final velocity. So that just proves that the more mass that is added, the less output you get. BUT when we look at the broken down version of the equation before we cancel times: ▲c/(Mt*t)=(▲v/t) => ▲c/Mt*t=a so what that tells me (correct me if I'm wrong) is that the more current you have during a shorter period of time, the more acceleration you will get. So doesn't that mean that a more powerful amplifier that can be very precise powering a very light speaker (so that the denominator is lower and the numerator is higher) is the way to get better transient response?

Sorry for the rant.


----------



## Jaredturp

I get confused when he just states that the constants do not matter. Doesn't the F/Mt=a itself basically say that more force=more acceleration, however, lowering the mass and leaving the force constant does the same thing?


----------



## ncv6coupe

Well see, your math looks good but then how audible is group delay? Older studies show up to one cycle but they never measured anything below about 250hz in the studies??

How fast are bass frequencies below 100hz?? But harmonic distortion is how audible again???

See where I'm going with this?? 

Exotic enclosures sure do stand out as g(reat) candidates here..... I'm just saying!


----------



## Jaredturp

Dangerranger said:


> Exactly right. And I believe the responses you mentioned that came from a certain furry canine are in this thread
> 
> http://www.diymobileaudio.com/forum/diyma-sq-forum-technical-advanced/9243-speaker-modification-effect-cone-mass-loading.html


This article brings up the spider element that I mentioned earlier. Wouldn't the spiders have a definite role in the speaker's ability to accelerate? I mean ideally they wouldn't, but we never work ideally. (K*DeltaX) and all that.


----------



## Oliver

Jaredturp said:


> This article brings up the spider element that I mentioned earlier. Wouldn't the spiders have a definite role in the speaker's ability to accelerate? I mean ideally they wouldn't, but we never work ideally. (K*DeltaX) and all that.





> *Andy Wehmaye*r>>>
> 
> Now...if you look at the parameters for 99% of the speakers that are available you'll see that the Qms is always MUCH higher than the Qes. That means that the suspension allows MUCH more overshoot than the motor. Thinking a little further, you'll discover that what that really means is that the MOTOR controls the motion of the cone and the suspension contributes very little control. Both the motor and the suspension work to overcome the inertia of the moving MASS. The motor does a better job than the suspension. essentially, the suspension screws things up. The suspension is there mostly to keep the coil from leaving the gap and should be designed to apply very little force until that is about to happen.
> 
> Resonance is the point where the motor and suspension make the hand-off. Above resonance, the motor provides nearly all the control and below resonance, the suspension does more work. Above resonance we say a speaker is mass controlled and below we say it's stiffness controlled. Above resonance the motor overcomes the inertia of the moving MASS and below resonance the motor overcomes the COMPLIANCE of the suspension.


This may help


----------



## Jaredturp

Oliver said:


> This may help


If I knew more about what resonance means it probably would


----------



## Gary S

Everything else being equal, more cone area = more SPL for a given input. In extreme cases though, an array of smaller subs, like 10", could have more output than an equal array/cone area of bigger drivers, say 15" - simply because the smaller woofer cones are more rigid (due to Physics). But you would need thousands of watts to see a noticeable difference.

In some cases, smaller subs, perhaps some 8" or smaller, could have trouble reproducing the lowest frequencies due to their typically higher resonate frequency. But this can vary widely depending on the woofers and the system.


----------



## speakertime

It's not about size, it's how you use it  But I think you can see by the specs that a 12 or 15" speaker actually has a lower frequency range than a 10"...so it would depend on what you're listening to. I personally like a 12", but I am sure that is because that was in the system my buddy had when I fell in love with bass. But I think a high quality 10" speaker will sound better than a low quality 15" in either SPL or SQ. To me it's about quality as opposed to price.


----------



## sqshoestring

I don't know what slower bass is, but larger similar subs in general will play lower at a marginal tuning for each size. Sure you can make an 8 play flat to 30Hz, but the SPL may be so low you can't hear it in a loud car. Larger 15 will push more air for more SPL, be more efficient, and be much better at the job of making sub bass. In addition the larger cone will tend to have a lower Fs and thus be more capable at low frequencies. If you can tune them right (larger sub certainly will take more room) the larger sub will go deeper and be louder there.

How deep/low/tight/etc you want it is up to user preference, as well as how much room out of your vehicle you want to sacrifice to subs. That is exactly why I run a pair of 15s IB and lose about 6" behind my back seat, in usable trunk room its less than a .8cf box. It can hit 25Hz.

I had quad 12s IB before that, they were not tuned (the driver) as low. I had to EQ them hard to stop the huge boom at 50Hz. Yes they would put out at 30Hz too because of the cone area, but tuning was not very good. If someone liked big boom at 50 they would have been ideal. Those were 1252w infinity subs. The 15s have qts .7 and Fs 20, about perfect for IB flat response I want. The 12s had qts .46 and Fs 24. You will have a hard time finding a 12 with the same T/S as the 15. But like I said it depends on how you like your bass as to what you will prefer. I like flat and low mostly.


----------



## BuickGN

sqshoestring said:


> I don't know what slower bass is, but larger similar subs in general will play lower at a marginal tuning for each size. Sure you can make an 8 play flat to 30Hz, but the SPL may be so low you can't hear it in a loud car. Larger 15 will push more air for more SPL, be more efficient, and be much better at the job of making sub bass. In addition the larger cone will tend to have a lower Fs and thus be more capable at low frequencies. If you can tune them right (larger sub certainly will take more room) the larger sub will go deeper and be louder there.
> 
> How deep/low/tight/etc you want it is up to user preference, as well as how much room out of your vehicle you want to sacrifice to subs. That is exactly why I run a pair of 15s IB and lose about 6" behind my back seat, in usable trunk room its less than a .8cf box. It can hit 25Hz.
> 
> I had quad 12s IB before that, they were not tuned (the driver) as low. I had to EQ them hard to stop the huge boom at 50Hz. Yes they would put out at 30Hz too because of the cone area, but tuning was not very good. If someone liked big boom at 50 they would have been ideal. Those were 1252w infinity subs. The 15s have qts .7 and Fs 20, about perfect for IB flat response I want. *The 12s had qts .46 and Fs 24*. You will have a hard time finding a 12 with the same T/S as the 15. But like I said it depends on how you like your bass as to what you will prefer. I like flat and low mostly.


I'm going through this delima right now. I'm doing two Tempest 15s. With two of them, the overall Q is .7 on the dot. With one it's .45. Not sure what would sound better. I know the W6 sounds great IB with a .45 but if I had one complaint it would be a little light up top. I'm wondering what the Q was with all 4 12s. It might have been higher than with the two 15s.

It's so confusing that I'm trying not to think about it until I can actually try it out.


----------



## sqshoestring

BuickGN said:


> I'm going through this delima right now. I'm doing two Tempest 15s. With two of them, the overall Q is .7 on the dot. With one it's .45. Not sure what would sound better. I know the W6 sounds great IB with a .45 but if I had one complaint it would be a little light up top. I'm wondering what the Q was with all 4 12s. It might have been higher than with the two 15s.
> 
> It's so confusing that I'm trying not to think about it until I can actually try it out.


Model it! In general if you stay over Vas in your IB with a low Q the bottom will roll off, meaning you get more highs like 50Hz. Unless your trunk is really small, or tons of sub to get to Vas or smaller, that will raise the Q and you might be better with a lower Q than .7 (.7 is flat IB). The .7 Q providing you are over Vas and its a low Fs (so the Q is high down at low frequency, such as a 20Hz Fs 15 or similar) will be flat almost down to that Fs. A high Fs and high Q would be a super boomer, the .7 boosts the curve down to Fs so the Fs has to be low to make it work IB (if you want it flat). Typical you will not get much under Fs at all. Again it depends on where you want it to hit. A lower Q will have less output, at least down low. If you have lots of power and xmax you can get around that with EQ. I only ran 420rms on four 12s and it was gobs of bottom for me, if I let it the 50Hz would have been much louder than ED'd flat like I ran it. I had two LP at 50 and 50 was cut on the EQ 3db or something plus 30 and 20 were boosted some. Huge difference. The way I see it I can get rid of low bass with the touch of a finger on the sub gain or EQ, but making it by boosting is not so nice....so I go for more bottom. Another thing is pair of subs will have more output, you get less xmax for more SQ, less nodes, etc., unless you are on a budget or the install will be difficult.


----------



## BuickGN

sqshoestring said:


> Model it! In general if you stay over Vas in your IB with a low Q the bottom will roll off, meaning you get more highs like 50Hz. Unless your trunk is really small, or tons of sub to get to Vas or smaller, that will raise the Q and you might be better with a lower Q than .7 (.7 is flat IB). The .7 Q providing you are over Vas and its a low Fs (so the Q is high down at low frequency, such as a 20Hz Fs 15 or similar) will be flat almost down to that Fs. A high Fs and high Q would be a super boomer, the .7 boosts the curve down to Fs so the Fs has to be low to make it work IB (if you want it flat). Typical you will not get much under Fs at all. Again it depends on where you want it to hit. A lower Q will have less output, at least down low. If you have lots of power and xmax you can get around that with EQ. I only ran 420rms on four 12s and it was gobs of bottom for me, if I let it the 50Hz would have been much louder than ED'd flat like I ran it. I had two LP at 50 and 50 was cut on the EQ 3db or something plus 30 and 20 were boosted some. Huge difference. The way I see it I can get rid of low bass with the touch of a finger on the sub gain or EQ, but making it by boosting is not so nice....so I go for more bottom. Another thing is pair of subs will have more output, you get less xmax for more SQ, less nodes, etc., unless you are on a budget or the install will be difficult.


I appreciate it. I need to start over researching this. I thought the low QTS meant more bottom end. It does make sense, I needed just a little EQ at 50hz to get rid of the peak with the 12W6's .45 QTS. It has a ton of bottom end, very smooth and not muddy but it doesn't like anything above 75hz. 

Modeling the single Tempest vs the W6 shows more bottom end from 30hz to 100hz. Doing two of them shows a boost between 45hz to 65hz. I'm honestly not sure which one is the better setup.

I think I'm getting more confused by the hour lol. I'll re-read your post a few more times and maybe it will make more sense. Thanks.


----------



## sqshoestring

Just remember Q .7 is flat, 1 is bumped up in higher bass and .5 is a slow roll off that goes deep. With IB if you are over Vas the Qts is your Q (or close); you have no box to change it. So .7 will give flat response to near Fs. Low Q drivers are made to have a box to push the Q up, turn it from Qts .4 to Q .7 in the box, or where ever you want to tune it to. You might use the sub IB and get it to work of course, with EQ, and will need power reserves to boost. The fudge factor is your cabin gain, some say you don't need to get low because of it while others (like me) say with .7 you will have bottom and can easily get rid of it. I have .7 subs and they are pretty neutral with no EQ and roll off under 30 like the model shows, maybe this car has no cabin gain who knows, I would say it has little under about 40Hz (the hardest bass to get).

How well a sub plays above 80Hz is up to the sub, a lot of heavy duty high power subs don't like that.

Don't forget tuning and capacity are two different things. You can get a qts .7 and Fs 20Hz sub and not EQ much at all....or you can get a qts .4 that handles double the power with more xmax and EQ it and it will work too; it might even have a higher SPL because peak output is going to be xmax related no matter what SQ it has. You want to get low you need xmax or more cone area you can never get around that. I don't care so much this pair of cheap pyle 15s make plenty for me at low xmax (is fair amount of cone area), I like them tuned right because EQ causes more problems IMO I'd rather have no EQ at all for the perfect system.

Whatever the case I'd recommend you model them at least in winISD its not hard to do there are posts here about it. If you look at the xmax and SPL curves you will see big xmax sub can put out more, the transfer curve will show the response if thats off you will need EQ. I only use the previous post explanations to choose subs to model, and it explains how the Q works or is affected. Also when I get a new car I toss a sub box in the back and play it, EQ it, and then model that for a baseline. I add my EQ to that curve to give an idea of what my new sub needs to be....and start searching. Because you have to know what sub you like, if you want it to hit at 40 or 50, or 30, or very flat everywhere, whatever it is you can make it closer to what you want.


----------



## Face'

sqshoestring said:


> Don't forget tuning and capacity are two different things. You can get a qts .7 and Fs 20Hz sub and not EQ much at all....or you can get a qts .4 that handles double the power with more xmax and EQ it and it will work too; it might even have a higher SPL because peak output is going to be xmax related no matter what SQ it has. You want to get low you need xmax or more cone area you can never get around that. I don't care so much this pair of cheap pyle 15s make plenty for me at low xmax (is fair amount of cone area), I like them tuned right because EQ causes more problems IMO I'd rather have no EQ at all for the perfect system.


Sorry to bring up an old thread, but what about EQ'ing in the opposite direction? I have a pair of woofers calling for a large sealed enclosure. If I were to build box that would fit in my application, get rid of the 60hz bass hump and add some gain to the bottom end, as long as I don't surpass x-max would sound quality suffer? 
Thanks!


----------



## sqshoestring

Face' said:


> Sorry to bring up an old thread, but what about EQ'ing in the opposite direction? I have a pair of woofers calling for a large sealed enclosure. If I were to build box that would fit in my application, get rid of the 60hz bass hump and add some gain to the bottom end, as long as I don't surpass x-max would sound quality suffer?
> Thanks!


That is what most people do now, to get a small box to work. You will need a sub that can take a lot of power and a large amp. The issue is you have to double power to get 3dB, so just how much dB boost do you need on the bottom end and that equals how many watts...

You can stuff the box maybe even try an AP vent, if you can get close enough then some EQ to flatten it out...sure it will work fine. That is why there are so many subs that handle tons of power and fit a small box. Though a sub made/tuned for a small box tends to have lower efficiency it has to make up for with power anyway.

Certainly with EQ power you can get today you can make some ugly tuned subs work great.


----------



## divvide

Im doing some catching up with this threadso bear with me. I find the myth to be true and heres why.

A 10 versus a 12 (same subwoofer model, same wattage and recomended optimum airspace for each sub) has a smaller enclosure requirement vs the 12 but will be able to match the 12 down low if it is put in a larger box. However, the 12 put in a larger maximum airspace enclosure will be able to play slower than the 10 which is already in maximum airspace and indeed produce lower frequencies better than the 10. The extra cone area is able to resonate with more lag. Now if you put that 10 in the same airspace as the 12s largest airspace requirements, It would simply bottom out and we would be unable to hear/feel the depth of the lower hz spectrum. 

So in conclusion... the bigger the cone size the lower you can play the bottom end. The myth of the 12 being able to play the lower end louder than the 10 is true. Given you have the space to generate resonance and cabin gain.


----------



## subwoofery

divvide said:


> Im doing some catching up with this threadso bear with me. I find the myth to be true and heres why.
> 
> A 10 versus a 12 (same subwoofer model, same wattage and recomended optimum airspace for each sub) has a smaller enclosure requirement vs the 12 but will be able to match the 12 down low if it is put in a larger box. However, the 12 put in a larger maximum airspace enclosure will be able to play *slower* than the 10 which is already in maximum airspace and indeed produce lower frequencies better than the 10. The extra cone area is able to resonate with more lag. Now if you put that 10 in the same airspace as the 12s largest airspace requirements, It would simply bottom out and we would be unable to hear/feel the depth of the lower hz spectrum.
> 
> So in conclusion... the bigger the cone size the lower you can play the bottom end. The myth of the 12 being able to play the lower end louder than the 10 is true. Given you have the space to generate resonance and cabin gain.


EEEEEEEEEEEEEERRRRRRRR!!!!! Wrong answer... 

Kelvin


----------



## TrickyRicky

All I can say is that square subs put out squared frequency waves. Triangle woofers (Bazooka) put out triangular frequency waves. Also notice that my xtant x2 (hexagon shape) woofer puts out honey combs waves which sound very sweet just like the real thing (honey). 











................................jk.


----------



## sqshoestring

What shape sub makes cherry flavor?

How to simplify.....For low bass a sub cone is like an airplane wing; the larger it is the more lift you get, because it can grab more air. You can't say speed/fast/slow because the frequency dictates cone speed. The lower the frequency the slower the speed the harder it is to grab the air, just like the slower a plane flies the closer it gets to not flying...


----------



## BuickGN

sqshoestring said:


> What shape sub makes cherry flavor?
> 
> How to simplify.....For low bass a sub cone is like an airplane wing; the larger it is the more lift you get, because it can grab more air. You can't say speed/fast/slow because the frequency dictates cone speed. The lower the frequency the slower the speed the harder it is to grab the air, just like the slower a plane flies the closer it gets to not flying...


I wish I had the knowledge but I wonder how the velocity of the cone changes with frequency at the same SPL. For example 25mm of excursion 20 times a second vs 1mm of excursion 500 times a second. Wouldn't the cone be moving at the same "speed" just switching directions quicker and moving less each way?


----------



## cmayo117

BuickGN said:


> I wish I had the knowledge but I wonder how the velocity of the cone changes with frequency at the same SPL. For example 25mm of excursion 20 times a second vs 1mm of excursion 500 times a second. Wouldn't the cone be moving at the same "speed" just switching directions quicker and moving less each way?


The equation for maximum particle velocity of a wave is just angular frequency * amplitude. Angular frequency is 2Pi * frequency. So yes, the maximum velocity of the cone wold be exactly the same in those two cases. Any change in frequency or amplitude will result in a proportional change in the maximum velocity of the cone. So, if you double the amplitude(excursion) and keep the frequency the same, you double the maximum velocity of the cone.


----------



## chris2013

Cone area is plenty important when converting electrical signals into sounds. What is important here is transferring power from an electrical domain into an acoustic domain. When anyone is trying to maximize the transfer of power bet ween two things what is important is impedance matching. If there is a mismatch you'll get reflected power in the system. Ever wonder why ittakes 1000's of watts to make some decently loud sound? It's because of the enormous impedance mismatch between the hard cone of the sub and the air! All of the acoustical power is reflected at the cone and never leaves it! If the cone is exposed directly to the air, the larger the cone area is the better! An avg speaker maybe passing 3% of its electrical input power into acoustical power!most times ur only hearing a few acoustical watts. a couple thousand acoustical watts will make prestressed rebarred concrete wave like water!


----------



## chad

ohshit, here we go.....

Someone's brain melted somewhere.


----------



## mizatt32

A guy who built high end home audio speakers explained to me years ago, and I don't know how true this is, that you can compare speakers to a rubber band...if you pull the rubber band tight it makes a higher tone because it has less width just like when you aren't pulling it tight it makes a lower tone and it has more width.


----------



## tornaido_3927

^^ Doesn't that have to do with the tension of the rubber band causing the oscillation of the rubber band to be faster (or at a higher frequency/hertz, if you will) rather than having _anything_ to do with the width?


----------



## subwoofery

mizatt32 said:


> A guy who built high end home audio speakers explained to me years ago, and I don't know how true this is, that you can compare speakers to a rubber band...if you pull the rubber band tight it makes a higher tone because it has less width just like when you aren't pulling it tight it makes a lower tone and it has more width.


Most bigger cone have more Xmax in the same family range... So I don't really understand you're statement  

Kelvin


----------



## sqshoestring

I would think a string/rubber band/etc would have moving mass and the tension against its movement as major tuning factors....just like a sub does. Width would equate to cone area, but is that small change in area really going to matter much. Changing to a larger sub can add 50% more area with likely a higher transfer efficiency to the air than a string/etc has. Is a 50% wider rubber band going to have the SPL increase a 50% larger sub cone has? I guess I don't know off the top of my head lol. A lower tone should be a factor of more mass causing it to be tuned lower, not area.


----------



## squeak9798

mizatt32 said:


> A guy who built high end home audio speakers explained to me years ago, and I don't know how true this is, that you can compare speakers to a rubber band...if you pull the rubber band tight it makes a higher tone because it has less width just like when you aren't pulling it tight it makes a lower tone and it has more width.


No, that's nonsense.

Relating this to a speaker; it vibrates faster when pulled tighter because it's compliance (the inverse of stiffness) decreased, increasing it's resonant frequency. It's the same reason that the Fs on a speaker increases when a stiffer suspension is used.


----------



## SilkySlim

chad said:


> This can easily be solved with testing say, a 10" driver and a 18" driver with the center of the VC's on the same plane.
> 
> I can assure you that the impulse arrival time will be tits on, the same. Thus negating one driver being slower than the other.


How can you assure us? Have you done a test with high speed cameras? I would love to see the results. I have always wanted to do one. I would also like to see the test with multiple impulses to see recovery time and see how they stand up.


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## GLN305

SilkySlim said:


> How can you assure us? Have you done a test with high speed cameras? I would love to see the results. I have always wanted to do one. I would also like to see the test with multiple impulses to see recovery time and see how they stand up.


I can back Chad up on this one as he uses a software package called SMAART where you can run a comparison loop and measure impulse response. In my experience, the only drivers that need tremendous consideration of impulse response are tweeters and other drivers that play higher.


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## subwoofery

SilkySlim said:


> How can you assure us? Have you done a test with high speed cameras? I would love to see the results. I have always wanted to do one. I would also like to see the test with multiple impulses to see recovery time and see how they stand up.


Just wondering if you know how a 50Hz note is being produced by a transducer... You know? 
Now my question is if you play a 50Hz test tone through a 10" driver and then through an 18" driver - what happens if the 18" driver really is slower than a 10" driver? 

Crap... I'm turning into a Lycan 
Kelvin


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## sqshoestring

Inside the abilities of a sub and the amp, how can it not play 50Hz? Is not the signal sent to the sub far, far more dominant than any other effect that might move the cone? 

Unless I am not understanding the terms here, if a cone were off time to the signal sent to it then it would quickly be cancelled by the signal. What happens if you hold the cone of a sub, it still tries to make the same sound even with massive force intervention on the level of 1,000X the mass of the cone. So exactly how could it do this on its own.

Oh wait, maybe VBA?:laugh:


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## subwoofery

sqshoestring said:


> Inside the abilities of a sub and the amp, how can it not play 50Hz? Is not the signal sent to the sub far, far more dominant than any other effect that might move the cone?
> 
> Unless I am not understanding the terms here, if a cone were off time to the signal sent to it then it would quickly be cancelled by the signal. What happens if you hold the cone of a sub, it still tries to make the same sound even with massive force intervention on the level of 1,000X the mass of the cone. So exactly how could it do this on its own.
> 
> Oh wait, maybe VBA?:laugh:


What? Your subs aren't evil enough to play by themselves even with your system turned off?  


























 

Kelvin


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## sqshoestring

subwoofery said:


> What? Your subs aren't evil enough to play by themselves even with your system turned off?
> 
> 
> 
> 
> Kelvin




Crap! I'll have to print some little :devil: on them, and they already have baskets made of flames.


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## cleansoundz

Subscribed.


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## captainscarlett

Sorry for skipping from page 1, straight to page 6. I've been worrying about xmax, as i prefer my bass to be low/deep rather than a matter of being to hit SPL levels. 

The jl audio 'Daytona beach' training video suggests that xmax allow a sub to hit lower and louder. As i design mainly for 8's (currently have my jl audio 8W3v3 in a tapered t-line) i've been furiously searching for an SQ sub with decent xmax. 

Quick newbie question; *Linear Xmax *... what does that mean please?

As for my narrow understanding of sine waves, regardless of the size of the cone, a cone at 50hz oscillates 50 times, from a tiny 5" sub to a 22". So where does the BL product and CMS or MMS?? come into play?


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## Victor_inox

what everyone should be looking for in a search to faster driver is VC inductance . lower inductance- faster sub, it has nothing to do with frequencies it plays.
SmallerVC usually has lower Inductance, smaller VC usually attached to smaller cone, that's where myth came from.bigger cones with more mass can play as fast as small subs if VC inductance is the same. Lower RF doesn't mean that sub will be slow.


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## chad

well not really, a single layer edge-wound 4" VC has a pretty low inductance


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## Victor_inox

chad said:


> well not really, a single layer edge-wound 4" VC has a pretty low inductance


That's why I said Usually. still low inductance means faster driver. probably why they did edge wound VC, to lower inductance.


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## subwoofery

Victor_inox said:


> That's why I said Usually. still low inductance means faster driver. probably why they did edge wound VC, to lower inductance.


If you're thinking about Adire Audio tech paper, the low inductance = faster transient has been contradicted by Lycan - well not really contradicted but inductance doesn't tell the whole story... 

Kelvin


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## Victor_inox

subwoofery said:


> but inductance doesn't tell the whole story...
> 
> Kelvin


Just like there no single solution to every task. whole story is complicated, to many critical components involved.


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## BuickGN

Victor_inox said:


> what everyone should be looking for in a search to faster driver is VC inductance . lower inductance- faster sub, it has nothing to do with frequencies it plays.
> SmallerVC usually has lower Inductance, smaller VC usually attached to smaller cone, that's where myth came from.bigger cones with more mass can play as fast as small subs if VC inductance is the same. Lower RF doesn't mean that sub will be slow.


Cool. So my 15s are likely the "fastest" automotive sub out there? I did not know it was that simple.


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## chad

the lower inductance the higher it plays... especially higher it plays without phase shift that inductors cause... If it were moving slower there would be shifting of pitch.


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## chad

BuickGN said:


> Cool. So my 15s are likely the "fastest" automotive sub out there? I did not know it was that simple.


Check out old JBL GTi series, they have a pretty damn low inductance, it's going to be the same as the VGC series of pro drivers... Morel should be pretty low too as Dyn also.


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## Victor_inox

BuickGN said:


> Cool. So my 15s are likely the "fastest" automotive sub out there? I did not know it was that simple.


Sarcasm, huh? it`s only simple if you understand how complex electromechanical things(such as speakers)works and how each element affect the outcome, and you don`t because there not a single person alive who does , otherwise we would have a perfect drivers by now.


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## BuickGN

chad said:


> Check out old JBL GTi series, they have a pretty damn low inductance, it's going to be the same as the VGC series of pro drivers... Morel should be pretty low too as Dyn also.


My sarcasm didn't make through over the Internet lol. 

Whether or not inductance means a sub is faster, I don't know but I'm sure it's not the only factor if its a factor at all. They are pretty darn low, the same as my midranges. I was just showing it off to a board member last night with the subs playing full range coupled to the tweeters. They easily play female vocals and they're reasonably detailed up there but I was being sarcastic about them being the quickest. For what its worth I believe Le is about .18 mh but I'll look it up.


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## chad

I think my sarcasm receptors did not make it past post this morning.


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## BuickGN

Victor_inox said:


> Sarcasm, huh? it`s only simple if you understand how complex electromechanical things(such as speakers)works and how each element affect the outcome, and you don`t because there not a single person alive who does , otherwise we would have a perfect drivers by now.


Lol. You got it. Maybe Le has an effect, I always thought the Mms vs Bl might matter. I guess a definition of fast is in order because obviously cycles per second is cycles per second, any change quicker or slower would be a different frequency. 

I've often wondered if a light coned speaker might possibly be more detailed or have a chance of being more detailed or even "quicker". My 15s do have a very low Mms for a car sub at 152g and they are pretty articulate despite having a relatively average or even lower than average Bl. Since I didn't know for sure I went ahead and tried to find a midbass with a reasonably low Mms just in case when I was going larger. I just don't hear a lot of people talking Le when selecting midbass for some reason.


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## Victor_inox

BuickGN said:


> Lol. You got it. Maybe Le has an effect, I always thought the Mms vs Bl might matter. I guess a definition of fast is in order because obviously cycles per second is cycles per second, any change quicker or slower would be a different frequency.
> 
> I've often wondered if a light coned speaker might possibly be more detailed or have a chance of being more detailed or even "quicker". My 15s do have a very low Mms for a car sub at 152g and they are pretty articulate despite having a relatively average or even lower than average Bl. Since I didn't know for sure I went ahead and tried to find a midbass with a reasonably low Mms just in case when I was going larger. I just don't hear a lot of people talking Le when selecting midbass for some reason.


Light coned speaker will be more detailed. carbon and kevlar use is not for exotics only. People not talking LE because importance is underestimated. Cone stiffness sometimes more critical.


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## captainscarlett

Lower inductance - VC? So what am figures am i looking for in the T/S parameters? Sorry for being such a newbie, but i gotta learn!

http://www.morelhifi.com/wp-content/uploads/2012/04/Ultimo.pdf


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## squeak9798

Inductance is usually listed as "Le", but in the case of the Ultimo it's listed as "Voice Coil Induct. @ 1khz (MH)".

One thing to keep in mind is that inductance as an absolute value is less important than the inductance in relation to the voice coil resistance (Re), and the resultant corner frequency. You can determine the corner frequency with the formula;

f = Re/(2*Pi*Le) 

[Le needs to be in H, typically manufacturer's rate it in mH so you'll have to convert it first]

According to basic crossover theory you want this corner frequency to be an octave above the intended lowpass crossover frequency. As long as it's an octave above the intended lowpass frequency then the lowpass crossover is going to be the limiting factor in the "quickness" of the driver, so at that point inductance becomes moot.


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## BuickGN

squeak9798 said:


> Inductance is usually listed as "Le", but in the case of the Ultimo it's listed as "Voice Coil Induct. @ 1khz (MH)".
> 
> One thing to keep in mind is that inductance as an absolute value is less important than the inductance in relation to the voice coil resistance (Re), and the resultant corner frequency. You can determine the corner frequency with the formula;
> 
> f = Re/(2*Pi*Le)
> 
> [Le needs to be in H, typically manufacturer's rate it in mH so you'll have to convert it first]
> 
> According to basic crossover theory you want this corner frequency to be an octave above the intended lowpass crossover frequency. As long as it's an octave above the intended lowpass frequency then the lowpass crossover is going to be the limiting factor in the "quickness" of the driver, so at that point inductance becomes moot.


Very informative, thanks


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## captainscarlett

Life seemed so much more .. uncomplicated when the simple answer was; i've got a 200 watt amp, i'll go buy a 200 watt sub! Knowledge can get you into a lot of deep water .. and i'm out of my depth ... but i've gotta learn!


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