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Discussion Starter #21
Erin, the purpose of this thread was to discuss the blanket statement that's always thrown around that a smaller box equals more cone control. Usually used when talking about IB, some people act as if the cone will just flop around uncontrollably if the box is taken away. I know Qts matters and Qtc is ultimately what matters but regardless of Qts, wouldn't you say that putting any sub into a smaller enclosure causes it to have less but not necessarily too little "cone control"?
 

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Thank you for the explanation Erin. There's so many factors to consider, and lots more reading to do :)

Also on a sidenote, going along with Spyke, what box building software do you recommend Erin? I notice you are using BassBox Pro on what you uploaded. And I guess from looking around PWK uses his own custom software to take into account cabin response and location correct? Just wondering what would be an all around good program to get a close approximation of performance in a car. I just fiddle with WinISD.

Oh and I posted in one of your threads, I was wondering if you could point me to a pic of the finished product of the kicks you showed in Bing's installer review subforum. Sorry for being off topic...
 

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The good thing is that it's all relative. If you put a woofer with a qts of 0.6 in a small sealed box, you might end up with a QTc of 1.2. But if you stick with a lowish qts, you won't get those obnoxious resonant beats.

Basically there's nothing wrong with small sealed boxes, as long as the final QTC isn't too high.
Agreed. I used to have 10" in a .63 sealed with a qtc of .7 and it sounded great, I kinda wished it was more boomy actually.
 

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So, for arguments sake (and hopefully this is enough information), lets compare a couple of scenarios (assume all have the same x-max and power available)....

1) a subwoofer, say 15" that has a QTC of .3 in infinite baffle and when tested in car, it has a final QTS of .35....what characteristics about how this setup should sound like should one expect?

2) the same subwoofer now put in an enclosure that models to a final QTS (in car for arguments sake) of .707. Is the cone experiencing more control from the enclosure? How does this sound as compared to the IB install?

3) Same as #1, except the sub has a QTC of .65 and a final QTS of .707 infinite baffle. Will this sub sound the same as the sub in scenario #2?

Furthermore is air spring represented in the QTS? If not, how would that further impact the sound?
 

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Discussion Starter #26
So, for arguments sake (and hopefully this is enough information), lets compare a couple of scenarios (assume all have the same x-max and power available)....

1) a subwoofer, say 15" that has a QTC of .3 in infinite baffle and when tested in car, it has a final QTS of .35....what characteristics about how this setup should sound like should one expect?

2) the same subwoofer now put in an enclosure that models to a final QTS (in car for arguments sake) of .707. Is the cone experiencing more control from the enclosure? How does this sound as compared to the IB install?

3) Same as #1, except the sub has a QTC of .65 and a final QTS of .707 infinite baffle. Will this sub sound the same as the sub in scenario #2?
Thanks, Jerry, those are the kind of questions I was trying to ask.
 

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I always thought the whole idea of using a qts .7 sub IB was because you ended up with a proper Q= .7. That was before everyone had unlimited EQ power, in fact hardly anyone had much EQ power so it sounded like crap if you did not tune the sub correctly. Yes some cars were different/etc, but it got you close. Today you can use about anything, subs are much better so even with bad tuning you can EQ out your odds of getting a sub that does something strange is pretty slim. That said I still like to error on install tuning, its way easier to tune and rarely does something I don't like....bigger drivers look cooler and are more efficient, etc. It often makes the install harder though.

The only cone control I know of, is with a cheap sub a smaller box will control it enough to allow it to handle more power. This will result in more spl in higher frequency if it does not blow up from thermal load. It will keep the cone from xmax as soon at low frequency you are not going to be hearing much of....lol. I don't know what this has to do with SQ so I never paid that much attention to it excepting some cheaper mids/woofers I installed AP to 'control' them more lol. If you don't have a real capable xover it can help you out, since I used AP more or less as a high pass.

Cone control, funny. Not much different than 1,000 watts which tells you nothing about sound quality or how loud it can get. I like IB because the cone does move, and makes me bass. No cone moving means no bass, excepting at port tuning of course if you have a vented enclosure. By far the cone moves where the amp tells it to, above anything else.
 

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Discussion Starter #28
That's just it, I was saying that a box does not control the cone, other than to reduce efficiency. My theory is that the box reduces the damping which I might be correctly or incorrectly associating with control.
 

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Dang, I was going to say that my experience with small, sealed box, 10" subwoofers were that they made great midbass drivers. I was going to go with the pre-fab Audio Integrations subwoofer enclosure for the WRX, but, I have yet to be wowed and amazed with the output from a single sealed 10" subwoofer.

I believe I would like 3 IB 10s better than a single sealed 10... Now to find 3 decent IB 10s. I need to remeasure because I may be able to do 3 12s IB without manifolding them.

EDIT: I almost forgot... If you want cone control, build a servo drive!
 

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Bigger sealed enclosure (lower Qtc) sound cleaner imo, they lose power handling but in a SQ oriented system that may not matter. Group delay is a derivation of frequency response, so if you EQ a bigger/smaller enclosure to produce the same FR I bet noone can tell the difference between them. Small enclosures should have higher non linear distortion. Qtc between 0,6-0,9 often work pretty good in a car. Go for a lower Qtc if you got the space and EQ down the extended lower response to decrease cone movement and you should have pretty clean sounding subbass. Combine low Le with low Qtc and transistant response should theoreticly be as good as possible. Then again, it's so hard to control the enviroment in a car so the small differences might not be noticable. Modes and resonances are the two most important factors for crappy response. A good parametric EQ can make lot of systems sound pretty damn good.

Ported might even be a better solution if you can EQ the peak created. I can't tell the difference between sealed/ported when FR is EQed to same curve.
 

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Discussion Starter #32

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I wouldn't use that as your rebuttal. There are too many glaring mistakes to believe anything in that article such as using a larger box decreases efficiency yet they also mention a larger box decreases power handling. Now which one is it? Every knowledgeable source seems to point toward a small enclosure decreasing cone control.
Air spring or air suspension, is control over the cone, there really is no debating this. The smaller the box, the stronger the spring. Its just logic. You know, I am at a loss for the losing efficiency part from JL's site, when they say make the enclosure too big. But JL has never put out wrong info for sales. Maybe whoever was typing that up made a mistake. But that is the only mistake on that page. I have yet to pull up one thing that says differently.

But here are some more links, all stating cone control in sealed enclosures by the air spring.

From kicker
Sealed Enclosure Pros and Cons | KICKER


Here is a link to a article that was copied to this the forum from the University of Michigans Engineering department. Only thing relavent to this discussion is the part about sealed enclosure or the acoustic suspension
Main Speaker Design Theory compared to Transmission Line - The Classic Speaker Pages Discussion Forums

Here is some info on Ebay among all places
eBay Guides - Ported vs Sealed Box Enclosure

also talks alittle about air spring
Speakers, Part 4: Enclosures | Frugal Home A/V



I can find tons more info, and it all says the same thing. Attack and decay are considered faster in sealed enclosures, thats because of the air spring bringing the cone back to its resting position faster.




The easiest thing for you to do, is take a subwoofer, make a super small enclosure and one that is considerably larger. Install said sub in each. Press the cone down. Then tell me which one returns to its rest point faster. This right here will show you the smaller the box, the more the air spring works. Which controls the diaphragm by pushing or pulling it.


I am talking about air spring and its effects on the diaphragm, not the frequency response of a sub in too small of an enclosure.

This myth section is retarded, its mainly just people spreading myths about myths or truths, and thats the truth :laugh:

Why do you think subs geared towards sealed enclosures have a softer suspension? Its because the air spring.
 

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Discussion Starter #34
Air spring or air suspension, is control over the cone, there really is no debating this. The smaller the box, the stronger the spring. Its just logic. You know, I am at a loss for the losing efficiency part from JL's site, when they say make the enclosure too big. But JL has never put out wrong info for sales. Maybe whoever was typing that up made a mistake. But that is the only mistake on that page. I have yet to pull up one thing that says differently.

But here are some more links, all stating cone control in sealed enclosures by the air spring.

From kicker
Sealed Enclosure Pros and Cons | KICKER


Here is a link to a article that was copied to this the forum from the University of Michigans Engineering department. Only thing relavent to this discussion is the part about sealed enclosure or the acoustic suspension
Main Speaker Design Theory compared to Transmission Line - The Classic Speaker Pages Discussion Forums

Here is some info on Ebay among all places
eBay Guides - Ported vs Sealed Box Enclosure

also talks alittle about air spring
Speakers, Part 4: Enclosures | Frugal Home A/V



I can find tons more info, and it all says the same thing. Attack and decay are considered faster in sealed enclosures, thats because of the air spring bringing the cone back to its resting position faster.




The easiest thing for you to do, is take a subwoofer, make a super small enclosure and one that is considerably larger. Install said sub in each. Press the cone down. Then tell me which one returns to its rest point faster. This right here will show you the smaller the box, the more the air spring works. Which controls the diaphragm by pushing or pulling it.


I am talking about air spring and its effects on the diaphragm, not the frequency response of a sub in too small of an enclosure.

This myth section is retarded, its mainly just people spreading myths about myths or truths, and thats the truth :laugh:

Why do you think subs geared towards sealed enclosures have a softer suspension? Its because the air spring.
You're spreading myths. Subs geared toward sealed enclosures don't always have softer suspensions. My IB specific subs have an extremely soft suspension to the point I thought John forgot the spiders.

The suspension seals the subs and centers the cone. The motor controls cone motion above Fs.

Making the diaphragm hard to move is not the same as cone control. Overshoot is a lack of cone control and the smaller the box, the more overshoot you get. I don't know about you but I would rather have the VC controlling the cone, not an air spring.

Attack and decay being considered quicker in a sealed box is not because of the air spring, that's your own assumption.

Lower Qts is more damping. Higher Qts is less damping. The smaller the box, the less damping.
 

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Control can be good and it can be bad. In this case the air spring effect is actually a resistance or limiting form of control. To me this is a negative form of control. I have always looked at this topic as you need more power to control the cone in a smaller box. I say it this way because you are fighting this air spring that is constantly applying an opposite force on the cone and suspension. With an opposing force you have a chance of causing the weakest part of the speaker to give a little. This can lead to non linear movement of the cone. Since the music signal is always changing direction fast the air spring is also changing in the opposite direction. With little power the spring might actually win. With more power you can more effectively push/pull thru this resistance (the air spring) and have better ability to prevent non linear movement i.e. more cone control.
 

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Control by the air spring resulting in better transient response is not a myth.

Nope. Damping is control. Springiness is the opposite of control. That's what the shock absorbers in your car do. When your shocks are bad, the car bounces around when you go over a bump. Drive over a big bump with no shocks and you may find yourself struggling to keep your car on the road.

The box stiffens the spring. Its effect is similar to the difference between dropping a ripe avocado on the kitchen floor and dropping a super ball on the floor. If "control" has anything to do with finding the avocado vs. finding the super ball after the experiment (and it does), then the air in a small sealed box reduces cone control.

The misunderstanding comes from the fact that the small sealed box reduces cone movement at low frequencies (and thus reduces output at low frequencies), but it raises the resonance frequency and raises the Q which is a measurement of overshoot at resonance (the opposite of damping). When you're talking about cone control, Q is the measurement. Any suggestion that Q isn't material in this discussion is completely wrong.
 

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You're spreading myths. Subs geared toward sealed enclosures don't always have softer suspensions. My IB specific subs have an extremely soft suspension to the point I thought John forgot the spiders.

The suspension seals the subs and centers the cone. The motor controls cone motion above Fs.

Making the diaphragm hard to move is not the same as cone control. Overshoot is a lack of cone control and the smaller the box, the more overshoot you get. I don't know about you but I would rather have the VC controlling the cone, not an air spring.

Attack and decay being considered quicker in a sealed box is not because of the air spring, that's your own assumption.

Lower Qts is more damping. Higher Qts is less damping. The smaller the box, the less damping.
This is exactly right and is expressed in the relationship between the various Q values in thiele and small parameters.

Qes is the amount of overshoot that the motor allows.
Qms is the amount of overshoot that the suspension allows.
Qts is the product of those two over the sum (same as resistors in parallel) and the fact that the result (Qts) is much closer to the Qes value than the Qms value indicates that the MOTOR provides more cone control.

So...when you put your woofer in a sealed box, Qts becomes Qtc. Qtc is the amount of overshoot that the system allows and it's higher than Qts and higher than Qms too. By the nuumbers, that means that the box increases overshoot.
 

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Things in subwoofer land have changed a lot since I've been in car audio... and that's only been about 5 years.

as some know i took a sabbatical for about the last 5-6 years and getting back into car audio it seem that subwoofers have made the most advancement and next to that power is cheap(probably because its made cheap :()
 
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