# Smaller than optimum Sealed enclosure



## Spyke (Apr 20, 2012)

This has been bugging me. Anyone know or have any opinions on why manufacturers always suggest a smaller sealed enclosure than is optimum? By optimum, I mean what modeling software such as winisd will tell you. 
I have 2 8's in my truck in an enclosure that is built to mfg specs(.23cu per chamber). Optimum (according to winisd) is .56cu and mfg is .23cu. They sound great with some polyfil and get quite loud. I also have a single 10 in my car in a .6cu(optimum) but the mfg tells you to put it in a .4cu. The 10 sounds good and gets loud but seems a little boomy on the low low end, almost like it would do better in a smaller enclosure. My best guess is that all of this has to do with cabin gain. Idk. But then again I always hear about how bad small enclosures are. Any opinions are appreciated, thanks.


----------



## Spyke (Apr 20, 2012)

bump


----------



## jim walter (Apr 10, 2010)

Post up T/S parameters of each and we can compare them. 

The issue with "optimum" is that it varies in performance from one manufacturer to another. There is no standard here, so it is difficult for customers to really compare. 

Jim


----------



## Spyke (Apr 20, 2012)

I understand that each manufacturer has a different view as to what they consider optimum. For example, Rockford likes to have a qtc in the .9's. When I say optimum, I am using modeling software and trying to get a .71 qtc.

Just for fun: here are the t/s parameters for my dayton
Qts: .44
vas 1 cu ft
fs 29.6
re 3.3
le 3.09
xmax 18.7
znom 4
qms 7.34
qes .47
spl 85
pe 400w
bl 14.25
dia 10"
sd 330cm2

Plugging these in gives a box size of .63 with an f3 of 47 and a qtc of .71

In a .4cu (as suggested by the mfr) it has an f3 of 48 and a qtc of .82

This isn't much difference but why wouldn't they just tell you to put it in a .63? A .63 will give about 2 more db at 30hz and doesn't leave any hump. I may just be thinking too much about this.


----------



## Patrick Bateman (Sep 11, 2006)

I've been ranting about this for years. Here are some reasons to ignore the 'optimum sealed box'

1) QTC is only relevant if you're listening outside or in a very large room. In a living room or in a car, cabin gain will have a much larger affect on frequency response than QTC. I've used some enclosure sizes that some would consider absurdly small, with QTCs that exceeded 2.0

2) this isn't 1962. Nowadays maximum output is generally limited by xmax. And a small box takes more power than a large box, because small boxes reduce excursion below FB better than large boxes. 

3) there's one compelling reason to use a large sealed box. Small sealed boxes have more group delay because the resonant peak is larger, and it's more audible because it's higher in frequency.


----------



## thehatedguy (May 4, 2007)

And that big peak makes it seem like you have a lot more bass than what is there.

And some take into account the transfer function of the car to flatten things back out.


----------



## [email protected] (Jun 12, 2008)

Modeling software does not take into account any cabin gain of the car like Winslow said. If you dont take that into account, your gonna have a really fat bottom. Car audio specific manufacturers do when giving you enclosure suggestions. There is a thread on here where Andy from JBL posted a graph of several different cars cabin gain. Some cars had 20db gain.


----------



## thehatedguy (May 4, 2007)

And given enough excursion, power, and eq you can tailor the response to what you want it to be.


----------



## FG79 (Jun 30, 2008)

Manufacturers often (correctly) assume that the end user likes a peakier response. 

Unfortunate, but that's the way it is.


----------



## Spyke (Apr 20, 2012)

Patrick Bateman said:


> I've been ranting about this for years. Here are some reasons to ignore the 'optimum sealed box'
> 
> 1) QTC is only relevant if you're listening outside or in a very large room. In a living room or in a car, cabin gain will have a much larger affect on frequency response than QTC. I've used some enclosure sizes that some would consider absurdly small, with QTCs that exceeded 2.0
> 
> ...


I've started taking numbers less seriously recently.(power handling, freq resp, xmax...) I guess Qtc is another one I can put on the shelf. I took one of those 8's and built a much larger enclosure for it with amazing results. It isn't as loud, but it sounds huge and i'm much happier with it. I'm gonna try something similar with a single 12 for my car.


----------



## Spyke (Apr 20, 2012)

thehatedguy said:


> And that big peak makes it seem like you have a lot more bass than what is there.


And this is fine if you like blowing your eardrums out at 50hz. 


thehatedguy said:


> And some take into account the transfer function of the car to flatten things back out.


This was what I thinking originally. Makes sense in theory until you realize that they have no clue about the final environment and listening preferences of the user. Kind of like designing a crossover for a set of components.


----------



## Spyke (Apr 20, 2012)

cajunner said:


> from a business perspective, fewer returns on product (reliability goes up), and smaller box volume requirements mean more people can fit them into their limited space, therefore more sales


True and true.


----------



## jeepguy_1980 (Dec 3, 2011)

I have a JL 10W6V2-D4, which recommends an airspace of 0.625ft³. It is powered by the 500W channel of the JL HD900.5 The sub is enclosed in an AudioIntegrations sealed enclosure for my car, which claims an internal airspace of 0.7-0.75ft³. It is also filled with pollyfill.

In my house I have a Klipsch SW-450 subwoofer, and the bass it produces blows away the sub in my car. There isn't really a comparison.
This sub is in a ported enclosure that I estimate to be 2.6ft³​
Is the reason that this sub sounds so much better because it's in a larger box? Would increasing my car's box size improve the sound?


----------



## Spyke (Apr 20, 2012)

jeepguy_1980 said:


> I have a JL 10W6V2-D4, which recommends an airspace of 0.625ft³. It is powered by the 500W channel of the JL HD900.5 The sub is enclosed in an AudioIntegrations sealed enclosure for my car, which claims an internal airspace of 0.7-0.75ft³. It is also filled with pollyfill.
> 
> In my house I have a Klipsch SW-450 subwoofer, and the bass it produces blows away the sub in my car. There isn't really a comparison.
> This sub is in a ported enclosure that I estimate to be 2.6ft³​
> Is the reason that this sub sounds so much better because it's in a larger box? Would increasing my car's box size improve the sound?


The obvious difference is that the klipsch is ported. This is tricky because porting a sub won't make it louder but it will sound different. The klipsch prob has more low rumble to it right? This is comparing apples to oranges though. A 2.6cu ported enclosure in a house and a .6cu sealed enclosure in you car are about as opposite as you can get.

Increasing the size of the box of the jl will change the sound but not the total output. A larger box will give more of a ported sound, in that it will emphasize the lower freq more. A smaller enclosure will give more thump but less lowend. 

At the beginning of this thread I stated that my dayton 10 in a sealed .63 sounded like it needed a smaller enclosure. I was wrong. I am changing to a 12 in a 2cu sealed but if I were to build a new box for the 10 it would prob be around 1-1.2cu. I'll put it this way,(this is in my truck) I am happy as **** with that single 8 in about 3x the manufacturers suggested box size.

Just remember. The larger the enclosure the less power it will handle. This is not a bad thing and it'll still get plenty loud but you need to be careful.


----------



## [email protected] (Jun 12, 2008)

Spyke said:


> The obvious difference is that the klipsch is ported. This is tricky because porting a sub won't make it louder but it will sound different. The klipsch prob has more low rumble to it right? This is comparing apples to oranges though. A 2.6cu ported enclosure in a house and a .6cu sealed enclosure in you car are about as opposite as you can get.
> 
> Increasing the size of the box of the jl will change the sound but not the total output. A larger box will give more of a ported sound, in that it will emphasize the lower freq more. A smaller enclosure will give more thump but less lowend.
> 
> ...


Porting a sub makes it 3 db louder than if it was in a sealed enclosure. And how does making a sealed enclosure larger make it sound like a ported enclosure?


----------



## Spyke (Apr 20, 2012)

BeatsDownLow said:


> Porting a sub makes it 3 db louder than if it was in a sealed enclosure. And how does making a sealed enclosure larger make it sound like a ported enclosure?


True that it will give more output for a given input. If you mean louder overall, I guess that depends on the passband.
I meant that it emphasizes the lower freq more.


----------



## [email protected] (Jun 12, 2008)

Spyke said:


> Nope. A sub can only move so much air. How would porting it make it louder? True that it will give more output for a given input. Max output would be the same though.
> 
> I meant that it emphasizes the lower freq more.


A ported enclosure will only play lower if the box is tuned lower. Below a ports tuning, the freq response drops off drastically where a sealed enclosure rolls off more gradually. You need to run some more simulations in WinIsd it seems. Do alittle reading about how a port actually works. A ported enclosure is louder than a sealed given the same wattage is applied to both.


----------



## BuickGN (May 29, 2009)

Whoa, I thought it was common knowledge that porting a sub makes it at least 3db louder, sometimes more. How it sounds is determined by the tuning frequency. Higher tune= more output and peakier. Lower tune= less output (but more than sealed) and a flatter more musical response. A properly tuned ported enclosure is better than sealed in every way possible other than size. 

Going to a large sealed will make the sub more efficient down low. While power handing is reduced because the sub will hit it's mechanical excursion limits easier, this is a very good thing. Output in sealed is solely determined by excursion (and cone area) so the less power it takes to hit full excursion, the less power it takes to hit max SPL, the better. The SPL potential between small sealed, large sealed, or even IB is the same but IB and then large sealed will take the least amount of power to get there. Response will be flatter as well.

Going too small sealed makes the sub very inefficient down low, cutting low end response. I would much rather throw it in a larger enclosure and if excursion needs to be limited to prevent damage, do it electronically with the crossover (subsonic), greatly reducing your power requirements rather than physically making it inefficient. You gain damping and cone control when you put it in a larger box or no box at all.

I've tried several popular subs, most notably the JL 12W6 in the factory recommended size sealed box, large sealed, ported, bandpass, and infinite baffle. They sounded the worst in the factory sized sealed and required every bit of power my 1,000w amp could put out, headlight dimming and all. With the large sealed that was less of a problem. In IB I had to cut the gain way back for the same output and the response was so smooth. They were punchy yet had low end for days. The boominess of the small sealed box was gone and replaced with an efficient all around better sounding in every possible way sub setup.


----------



## BuickGN (May 29, 2009)

BeatsDownLow said:


> A ported enclosure will only play lower if the box is tuned lower. Below a ports tuning, the freq response drops off drastically where a sealed enclosure rolls off more gradually. You need to run some more simulations in WinIsd it seems. Do alittle reading about how a port actually works. A ported enclosure is louder than a sealed given the same wattage is applied to both.


And a ported setup will have much less excursion around the tuning frequency, cutting down on distortion over sealed.


----------



## Spyke (Apr 20, 2012)

BuickGN said:


> Whoa, I thought it was common knowledge that porting a sub makes it at least 3db louder, sometimes more. How it sounds is determined by the tuning frequency. Higher tune= more output and peakier. Lower tune= less output (but more than sealed) and a flatter more musical response. A properly tuned ported enclosure is better than sealed in every way possible other than size.
> 
> Going to a large sealed will make the sub more efficient down low. While power handing is reduced because the sub will hit it's mechanical excursion limits easier, this is a very good thing. Output in sealed is solely determined by excursion (and cone area) so the less power it takes to hit full excursion, the less power it takes to hit max SPL, the better. The SPL potential between small sealed, large sealed, or even IB is the same but IB and then large sealed will take the least amount of power to get there. Response will be flatter as well.
> 
> ...


Makes sense. I always thought that it had more to do with overall driver displacement. I had it in my head that what you gain down low(say30) is lost up higher(say80) I guess that would apply to differently tuned ported or different sized sealed but not between ported and sealed?


----------



## Spyke (Apr 20, 2012)

BeatsDownLow said:


> A ported enclosure will only play lower if the box is tuned lower. Below a ports tuning, the freq response drops off drastically where a sealed enclosure rolls off more gradually. You need to run some more simulations in WinIsd it seems. Do alittle reading about how a port actually works. A ported enclosure is louder than a sealed given the same wattage is applied to both.


Learn something new everyday.


----------



## [email protected] (Jun 12, 2008)

BuickGN said:


> Whoa, I thought it was common knowledge that porting a sub makes it at least 3db louder, sometimes more. How it sounds is determined by the tuning frequency. Higher tune= more output and peakier. Lower tune= less output (but more than sealed) and a flatter more musical response. *A properly tuned ported enclosure is better IMO than sealed in every way possible other than size.*
> 
> Going to a large sealed will make the sub more efficient down low. While power handing is reduced because the sub will hit it's mechanical excursion limits easier, this is a very good thing. Output in sealed is solely determined by excursion (and cone area) so the less power it takes to hit full excursion, the less power it takes to hit max SPL, the better. The SPL potential between small sealed, large sealed, or even IB is the same but IB and then large sealed will take the least amount of power to get there. Response will be flatter as well.
> 
> ...


I fixed the bold part for you  There is no consensus for the best enclosure, only what the listener prefers and what their needs call for.


----------



## BuickGN (May 29, 2009)

BeatsDownLow said:


> I fixed the bold part for you  There is no consensus for the best enclosure, only what the listener prefers and what their needs call for.


It sounds like an opinion when you first read it but other than size, name one way a sealed box is better. Ported has less distortion all else being equal, additional free output, is just as "quick", and has more output potential. Assuming it's carefully designed, I can't think of a single way a sealed box can outperform ported. I think it was proven a while back that transient response can be just as quick when ported and group delay, when eq'd for the same response as sealed is about the same as well.


----------



## Libertyguy20 (Jun 6, 2012)

You all are arguing for the pre-made, vehicle specific tuned JL stealthbox....all the guesswork has been done and the enclosure is mfg....from an SQ standpoint...why not? Thinking I'm gonna pull the trigger finally for one.


----------



## [email protected] (Jun 12, 2008)

........


----------



## Hanatsu (Nov 9, 2010)

Experimented with enclosures in my last build. Sealed enclosures at Qtc 0.5 / 0.7 / 1.2. The sub I tested had pretty non-optimal specs for low end extention in sealed enclosures (Qts .3/Fs 40Hz/Vas 40lit), but even with the sub in a small enclosure at Qtc 1.2 the cabin gain pushed the response flat down to 20Hz (this is a pretty large car). So Qtc won't matter that much, idk about audible group delay with higher Qtc. Not a major concern imo. If you have the space you can build larger enclosures and EQ down the extended FR for less power requirement. Same with ported, they have less excursion than sealed box around the tuning frequency and have the potential to have greater low end extention, which you can EQ down in the car later on. Less current draw, less distortion with less excursion. With less excursion T/S parameters are also closer to small signal measurements (which we model our "optimal" enclosures after).

Sent from my Samsung Galaxy 3 via Tapatalk.


----------



## Orion525iT (Mar 6, 2011)

Hanatsu said:


> Experimented with enclosures in my last build. Sealed enclosures at Qtc 0.5 / 0.7 / 1.2. The sub I tested had pretty non-optimal specs for low end extention in sealed enclosures (Qts .3/Fs 40Hz/Vas 40lit), but even with the sub in a small enclosure at Qtc 1.2 the cabin gain pushed the response flat down to 20Hz (this is a pretty large car). So Qtc won't matter that much, idk about audible group delay with higher Qtc. Not a major concern imo. If you have the space you can build larger enclosures and EQ down the extended FR for less power requirement. Same with ported, they have less excursion than sealed box around the tuning frequency and have the potential to have greater low end extention, which you can EQ down in the car later on. Less current draw, less distortion with less excursion. With less excursion T/S parameters are also closer to small signal measurements (which we model our "optimal" enclosures after).
> 
> Sent from my Samsung Galaxy 3 via Tapatalk.


Thanks for returning to the subject. I didn't think this was a ported vs sealed discussion .

QTC is something I have struggled with for a bit. I have tired to get as close to the .7 as possible, but after doing modeling on multiple drivers, it appears it may not be worth it you are sacrificing space, placement, or even aesthetics (gasp). After going through endless failed configurations trying to meet the "ideal" QTC, I decided that it was not the most important parameter in the face of all the other considerations. The 1-2db hump from QTC >.7 does not seem to be too difficult to eq out. Both my sub (also used for lower mid bass) and midrange are in the .8-.9 range. It just seems that cabin gain and the acoustical environment likely play a much bigger role.


----------



## DAT (Oct 8, 2006)

Yeah ,

Smaller boxes handle more power and are a tad more upper freq "boom" and a larger than *recommended* with be flatter and extend lower.

I have a program that helps figure out cabin gain, so I design all my boxes for that and what the customer desires. 

90% of the boxes i build are never the "optimum" size the company says to do.


----------



## Hanatsu (Nov 9, 2010)

Orion525iT said:


> Thanks for returning to the subject. I didn't think this was a ported vs sealed discussion .
> 
> QTC is something I have struggled with for a bit. I have tired to get as close to the .7 as possible, but after doing modeling on multiple drivers, it appears it may not be worth it you are sacrificing space, placement, or even aesthetics (gasp). After going through endless failed configurations trying to meet the "ideal" QTC, I decided that it was not the most important parameter in the face of all the other considerations. The 1-2db hump from QTC >.7 does not seem to be too difficult to eq out. Both my sub (also used for lower mid bass) and midrange are in the .8-.9 range. *It just seems that cabin gain and the acoustical environment likely play a much bigger role.*


Indeed. Cabin gain is very strong in a small "room" as in a car. 20dB boost at 20Hz are not uncommon. Qtc 0.707 is the best compromise between low end extension (-f3 point) and transient response in an anechoic environment. WinISD, Bassbox and such programs do not take the room response in account, therefore is Qtc 0.7 a pretty meaningless value. I doubt anyone can tell the difference between an EQed Qtc 0.5 enclosure and a non EQed Qtc 1.0 sub if the frequency response is the same. The big enclosure would have less power handling (reaches Xmax easier) than the small one, however it requires less power to move and therefore less current draw from the car's (already strained?) electrical system. 

Fsc (resonance of the sealed enclosure) moves up in frequency as the enclosure gets smaller. The impedance peak might therefore end up higher in frequency than the area we intend to use the sub for, this makes the system inefficient. Impedance will not change inside the car and will end up pretty close to the modeled impedance graph if we assume the manufactures T/S parameters are correct (which they almost never are completely, for some reason...). Temperature is another factor and will affect the response, Fs increases, Vas decreases with less temperature which means = Less low-end extension... Let's stop there now before this get OT


----------



## ToBiN! (Jun 3, 2009)

Sorry Ive been out of this game for quite a while but have recently picked up a new extended cab whip all inclusive of some Earthquake 5.25s in the doors, 4x6s in the back, RF 4 channel amp for the highs (not sure the model) and an Earthquake 2 channel for the Kenwood 10" flat subs in a prefab box. 

This thread interested me because the 10" flats are just not giving me the low end that I love so much about 12s, however I have heard the flat subs just can't do what a regular basket sub can, so I am contemplating upgrading and using two of my JL12W6s and this thread has been very informative and helped me dust off things I used to know.

IIRC, WRT cabin gain, we used to measure from the firewall to the back of the cabin, punch that measurement into a formula to figure out what the lowest Hz rating of the car was, e.g. the length of your cabin can produce a 25% of a Hz wave, what is that Hz wave? We did this with my 93 S10 Blazer and noted the blazer was capable of reproducing a 23Hz wave, therefore we port tuned two 12s to 23-25Hz and were able to produce 148Db using Orion Reds (of all things) and one Orion 225HCCA down to 1 ohm mono.

I am finding it hard to locate the formula to figure out what wave my 99 Silverado extended cab can produce so I can try and port tune the JL12W6s I plan on sticking in there. Also, can anyone lead me to the graph on port tune vs box enclosure? Again, IIRC we did a 1.75 - 2.25 cuft enclosure with a 3" x 7" port per sub enclosures in separated airspace. But I know my Silvarado won't be able to produce a 20Hz wave like my blazer but I should be around the mid to high 30s.

Thoughts?


----------



## sameoldme (Jun 26, 2012)

DAT said:


> Yeah ,
> 
> Smaller boxes handle more power and are a tad more upper freq "boom" and a larger than *recommended* with be flatter and extend lower.
> 
> ...


+1 Cool what's the program?


----------



## sameoldme (Jun 26, 2012)

Man, all great responses, I just have to add that published T/S are generally NOT accurate at all. Lately I've been designing my boxes with the real T/S previously extracted for a specific sub. Music listening is so subjective that manufacturer suggested boxes are what they like, not you... To properly get a box for your listening taste will take some R&D from your part, model with Winisd, look at the curve, make the box, "listen" for the curve you modeled and go from there, at least 2 boxes would need to be made or a ported one that you can alter the tunning with the same volume... Just my 2 cents.


----------



## The Baron Groog (Mar 15, 2010)

Patrick Bateman said:


> 3. there's one compelling reason to use a large sealed box. Small sealed boxes have more group delay because the resonant peak is larger, and it's more audible because it's higher in frequency.


True, though you can tune the enclosure so resonance is above the crossover point of the driver. Fb of my 0.126cf enclosure (housing an Aliante 10") is >75Hz, sub crossed at 50Hz. Dry bass in a Mini


----------



## subwoofery (Nov 9, 2008)

jeepguy_1980 said:


> I have a JL 10W6V2-D4, which recommends an airspace of 0.625ft³. It is powered by the 500W channel of the JL HD900.5 The sub is enclosed in an AudioIntegrations sealed enclosure for my car, which claims an internal airspace of 0.7-0.75ft³. It is also filled with pollyfill.
> 
> In my house I have a Klipsch SW-450 subwoofer, and the bass it produces blows away the sub in my car. There isn't really a comparison.
> This sub is in a ported enclosure that I estimate to be 2.6ft³​
> Is the reason that this sub sounds so much better because it's in a larger box? Would increasing my car's box size improve the sound?


Did you install the Klipsch behind you while having your front main speakers 5 feet from you? <-- phase integration
Do you have stuffs rattling in the back when the Klipsch hits some low notes? 

Lot's of reasons why it sounds better in home environment  

Kelvin


----------



## subwoofery (Nov 9, 2008)

ToBiN! said:


> Sorry Ive been out of this game for quite a while but have recently picked up a new extended cab whip all inclusive of some Earthquake 5.25s in the doors, 4x6s in the back, RF 4 channel amp for the highs (not sure the model) and an Earthquake 2 channel for the Kenwood 10" flat subs in a prefab box.
> 
> This thread interested me because the 10" flats are just not giving me the low end that I love so much about 12s, however I have heard the flat subs just can't do what a regular basket sub can, so I am contemplating upgrading and using two of my JL12W6s and this thread has been very informative and helped me dust off things I used to know.
> 
> ...


Which shallow sub did you use? Am asking coz lot's have an FS above 35Hz and are sensitive = need a much bigger box than what the manufacturer recommends... Those shallow subs are mostly oversized midbass IMO  

Get a real shallow with an FS below 30Hz + a good and strong motor to allow for a small enclosure 

Kelvin


----------



## thehatedguy (May 4, 2007)

Linkwitz transform is for this very thing.

There is a thing called ACE bass which you can use with ported enclosures.


----------



## BuickGN (May 29, 2009)

DAT said:


> Yeah ,
> 
> Smaller boxes handle more power and are a tad more upper freq "boom" and a larger than *recommended* with be flatter and extend lower.
> 
> ...


What good is handling more power when you've made it require more power by making it less efficient for the same spl? The less power it requires for full excursion the better. It's a good thing that power handling drops in a larger sealed box.


----------



## Spyke (Apr 20, 2012)

subwoofery said:


> Which shallow sub did you use? Am asking coz lot's have an FS above 35Hz and are sensitive = need a much bigger box than what the manufacturer recommends... Those shallow subs are mostly oversized midbass IMO
> 
> Get a real shallow with an FS below 30Hz + a good and strong motor to allow for a small enclosure
> 
> Kelvin


True. I had a rockford p3 shallow 12 with an fs of 43, yikes. IIRC, the final qtc was over 1 and had a huge peak around 80hz. I steer clear of shallow subs in general. However the kenwood shallows have a low fs, the 12 was I think 25ish.


----------



## Spyke (Apr 20, 2012)

The Baron Groog said:


> True, though you can tune the enclosure so resonance is above the crossover point of the driver. Fb of my 0.126cf enclosure (housing an Aliante 10") is >75Hz, sub crossed at 50Hz. Dry bass in a Mini


Only problem is that you'll run out of excursion in a hurry. That's a good solution if you listen at normal levels.


----------



## subwoofery (Nov 9, 2008)

Spyke said:


> Only problem is that you'll run out of excursion in a hurry. That's a good solution if you listen at normal levels.


Or have an upfront Aliante like him 

Kelvin


----------



## Spyke (Apr 20, 2012)

If anyone is interested, the 12 in the over sized enclosure works awesome. It sounds like the 8 in my truck but just louder deeper awesome. The odd thing is that i'm able to keep the level lower, and it still seems louder, but everything rattles less. If a large sealed is anything like IB then I can see what everyone is on about.


----------



## thehatedguy (May 4, 2007)

Not that an aliante 10 has a lot of excursion...I had a pair.


----------



## Cancerkazoo (Jul 21, 2006)

I have an old RF spp-158 in a 6 cuft box tuned to 25hz in my work van and it sounds great with any genre of music. My amp only pushes 75w to 8ohms, but it sounds great and it's not so loud that people call into my work complaining about me


----------



## Brian Steele (Jun 1, 2007)

IMO the manufacturer's suggestions for a "smaller than optimum" enclosure (sealed or vented) seem to more about providing a good compromise between output, thermal power handling and excursion limitations than anything else. 

If you know something about t/s parameters, or, better yet, you can do some experimenting with a test box, you can probably come up with a better alignment (box size, tuning) that meets your listening preferences. 

For example, concerning my current subs, Infinity 122.7Ws, Infinity recommends 1.2 cu.ft. sealed per sub. I'm using them in 1.6 cu.ft. sealed per sub with very good results, because I like a little extra low end and I'm not driving them at any power level that results in them exceeding Xmax. 

Finally, concerning the debate between sealed and vented alignments, a vented alignment is the more efficient use of a given driver, but a sealed alignment is typically a more efficient use of the space allocated (e.g. given the box size requirements for a vented 10", one easily could fit a sealed 12" in the same space, or even two sealed 10"s, and not have to worry about port nonlinearities, "organ-pipe" resonance effects caused by the vent, and of course greatly reduced power handling below Fb. And there's also less of a risk of burning out the voice coil at higher power levels (I'll leave that for another thread to discuss ).


----------



## Patrick Bateman (Sep 11, 2006)

Hanatsu said:


> Experimented with enclosures in my last build. Sealed enclosures at Qtc 0.5 / 0.7 / 1.2. The sub I tested had pretty non-optimal specs for low end extention in sealed enclosures (Qts .3/Fs 40Hz/Vas 40lit), but even with the sub in a small enclosure at Qtc 1.2 the cabin gain pushed the response flat down to 20Hz (this is a pretty large car). So Qtc won't matter that much, idk about audible group delay with higher Qtc. Not a major concern imo. If you have the space you can build larger enclosures and EQ down the extended FR for less power requirement. Same with ported, they have less excursion than sealed box around the tuning frequency and have the potential to have greater low end extention, which you can EQ down in the car later on. Less current draw, less distortion with less excursion. With less excursion T/S parameters are also closer to small signal measurements (which we model our "optimal" enclosures after).
> 
> Sent from my Samsung Galaxy 3 via Tapatalk.


Yep.

Put the subwoofer in a smaller than optimum box, and apply some EQ to flatten it out. I know a lot of you guys thing EQ is A Bad Thing, but you really gotta get over that, in a small room or a car there are so many peaks and dips it's basically impossible to get flat-ish response without an EQ.

Also, keep in mind that if you have enough power, your output will be limited by xmax. Therefore, if you have enough power, a small box will improve dynamics my maximizing output by the reduction of excursion that occurs in a small box.

If you don't have enough power, then none of this applies. But power is cheap these days, I don't know why you wouldn't be running a few hundred watts to your subs.


----------



## BuickGN (May 29, 2009)

Patrick Bateman said:


> Yep.
> 
> Put the subwoofer in a smaller than optimum box, and apply some EQ to flatten it out. I know a lot of you guys thing EQ is A Bad Thing, but you really gotta get over that, in a small room or a car there are so many peaks and dips it's basically impossible to get flat-ish response without an EQ.
> 
> ...


Why wouldn't you rather do that electronically with a highpass rather than relying on the box to make it inefficient down low?


----------



## Topdown (Aug 12, 2009)

Why would a mfg say to put a sub in a smaller than optimum enclosure:

Power handling and as with anything/everything meant for the consumer market, there is a compromise between the "best" that this subwoofer can perform and what consumers perceive as the "best" performance.

That fact that most of us use modeling software and/or tunable enclosures puts us in the "extreme minority". Knowing how to set your gains properly alone puts us in the "minority". Think of how many times you have heard of or seen someone go to a local car stereo shop where they added 2 12's and a 1000w amp to a stock stereo system? The consumer is looking for "1000 watts of power" and "boom". The recommendations by the mfg are the "best compromise" to make a happy consumer (90%, not the 10% of us).

get into nice high quality gear, HT gear especially since they are 99% of the time completely manufactured with enclosure (versus us buying drivers and making enclosures) and things change dramatically. the MFG can build for the driver, and so the enclosures are "more optimum".

So like I said... its less about optimum and more about happy customers. Dumb your question down and think like your 16yrs old. ever heard of WinIsd? Know how to set gains yet? Understand the difference in "Q"? Know what cabin gain is? Have any idea that getting 3db additional output is a HUGE difference? Probably not.

Know that when you have the loudest car in the school parking lot when playing the latest popular song that has a steady and heavy (40hz for example) bass-line it gets the attention of the smokin hot piece of tail you have been chasing? Probably... 

Know that having a 10,000 watt system when your buddy, or the other putz that is chasing the hot piece of tail only has a 1,000 watt system makes you "better"? absolutely.

So, IMO - I wouldn't worry about the MFG recommended enclosure, if you ever were, sounds like you were just curious more than anything. Work with the space you have available and if you have "enough", then I try and shoot for "more" than optimum so that I can put in green foam to tune the enclosure to the specific car. If at that point I want to rebuild the enclosure, I can/do.


----------



## DAT (Oct 8, 2006)

Another option is build the box the size you want and just run your subs 50hz or below like me , no worries about peaks and such, maybe even 60hz and below... running 70 or 80hz you get those peaks and such... unless you really want them.


----------



## Spyke (Apr 20, 2012)

DAT said:


> Another option is build the box the size you want and just run your subs 50hz or below like me , no worries about peaks and such, maybe even 60hz and below... running 70 or 80hz you get those peaks and such... unless you really want them.


I think that's what Baron was talking about. I have tried it myself with mixed results. It sounded great but when pushed it eats up power and excursion. It def works and is a good compromise if space is limited.


----------



## Hanatsu (Nov 9, 2010)

Peaks doesn't matter much as long as you got EQ. Cabin gain extends our frequency response and with EQ you can make almost any enclosure to sound good (well at least sealed boxes, vented can sound crappy if not tuned correctly even with applied EQ). A rise of 6-7dB from 50Hz to 20Hz sound good and natural to me. Imho, Qtc does not matter much at all, it's the frequency response which matters. FR and group delay are related.


----------



## adrenalinejunkie (Oct 17, 2010)

Good read. Sorry, carry on.


----------



## Spyke (Apr 20, 2012)

Hanatsu said:


> Peaks doesn't matter much as long as you got EQ. Cabin gain extends our frequency response and with EQ you can make almost any enclosure to sound good (well at least sealed boxes, vented can sound crappy if not tuned correctly even with applied EQ). A rise of 6-7dB from 50Hz to 20Hz sound good and natural to me. Imho, Qtc does not matter much at all, it's the frequency response which matters. FR and group delay are related.


This is true. The nice thing about a larger sealed enclosure is that the group delay is usually lower making it less audible.


----------



## BuickGN (May 29, 2009)

Hanatsu said:


> Peaks doesn't matter much as long as you got EQ. Cabin gain extends our frequency response and with EQ you can make almost any enclosure to sound good (well at least sealed boxes, vented can sound crappy if not tuned correctly even with applied EQ). A rise of 6-7dB from 50Hz to 20Hz sound good and natural to me. Imho, Qtc does not matter much at all, it's the frequency response which matters. FR and group delay are related.


But can you tune out the cone ringing from having a too high Qtc due to too little damping from too small of a box?


----------



## Hanatsu (Nov 9, 2010)

Spyke said:


> This is true. The nice thing about a larger sealed enclosure is that the group delay is usually lower making it less audible.


Yeah, but once again. Everything changes once the enclosure is inside the car. Measure your FR with REW/RoomEQ and watch group delay, won't look pretty. Irregular FR is distortion, linear distortion. If you match the frequency response of two enclosures, small or big, I doubt there are any audible differences. High Qtc increases non-linear distortion, perhaps HD-IMD. Never measured that, but HD/IMD isn't THAT important with subs. The audibility threshold of GD can be debated over and over, I've heard that if you keep GD below ½ cycle at a specific frequency it will be inaudible. 50Hz is 20ms, if GD is below 20/2=10ms then it will not be audible. Group delay is frequency dependent and it can be calculated from measured FR. 

The "slow bass" thing is most likely caused by other issues than GD, but this has been discussed in countless threads now 

This is modeled group delay vs measured inside car (without EQ). 40ms at 40Hz ain't very nice. The modeled vented enclosure looks much better than the measured sealed box. The GD peak can be fixed more or less with EQ. This enclosure measured have a Qtc of 0.8 fyi.

Sealed=yellow // Vented=white


----------



## Hanatsu (Nov 9, 2010)

BuickGN said:


> But can you tune out the cone ringing from having a too high Qtc due to too little damping from too small of a box?


Imo. <<

Frequency response and non-linear distortion caused by high Qtc are different things and they are not perceived in the same manner. Imo linear frequency response is more important/audible, rather trade linear response to a increase of HD/IMD in the usable range of a sub. The answer to your question is yes, it's possible to do.


----------



## Patrick Bateman (Sep 11, 2006)

BuickGN said:


> Why wouldn't you rather do that electronically with a highpass rather than relying on the box to make it inefficient down low?


Due to cabin gain, it's trivial to hit 20hz in a car. I would rather put a large woofer in a small box than go the other way. The large woofer in a box thats too small will still have higher power handling, higher efficiency, and lower compression.

The main reason to use a large sealed box is to improve low frequency efficiency, but that isn't a problem in a car.

Big sealed box has superior GD tho.


----------



## Spyke (Apr 20, 2012)

Patrick Bateman said:


> Due to cabin gain, it's trivial to hit 20hz in a car. I would rather put a large woofer in a small box than go the other way. The large woofer in a box thats too small will still have higher power handling, higher efficiency, and lower compression.
> 
> The main reason to use a large sealed box is to improve low frequency efficiency, but that isn't a problem in a car.
> 
> Big sealed box has superior GD tho.


I guess it comes down to listener preference. I listen to some pretty bass heavy music sometimes(not rap). I tried small enclosures but I felt they really let down the low end. Using larger enclosures really helped. Music gained more of a visceral feeling and everything feels "more involved".

As far as efficiency, I always thought small sealed were the least efficient?
What's GD btw?


----------



## Hanatsu (Nov 9, 2010)

Patrick Bateman said:


> Due to cabin gain, it's trivial to hit 20hz in a car. I would rather put a large woofer in a small box than go the other way. The large woofer in a box thats too small will still have higher power handling, higher efficiency, and lower compression.
> 
> The main reason to use a large sealed box is to improve low frequency efficiency, but that isn't a problem in a car.
> 
> Big sealed box has superior GD tho.


Hm higher efficiency... You're talking about the Q bump right? Resonance peak increases in frequency with high Qtc, ain't it less efficient using the sub below the resonance but more efficient through and above the peak?


----------



## Hanatsu (Nov 9, 2010)

Spyke said:


> I guess it comes down to listener preference. I listen to some pretty bass heavy music sometimes(not rap). I tried small enclosures but I felt they really let down the low end. Using larger enclosures really helped. Music gained more of a visceral feeling and everything feels "more involved".
> 
> As far as efficiency, I always thought small sealed were the least efficient?
> What's GD btw?


GD - Group delay.

Low end extention depends much on the car as well. Larger cars have less boost generally.

Sent from my Samsung Galaxy 3 via Tapatalk.


----------



## thehatedguy (May 4, 2007)

Large cars have more boost down low.


----------



## Topdown (Aug 12, 2009)

build the box you can fit, adjust the volume to meet your listening needs/taste.

After having used new school/old school, big, small, slim, high excursion, high power, multi-VC/single VC... I think too much emphasis and concern is put into which subwoofer should I choose. Best SQ I have ever had has been out of a free pair of 8" 8-ohm drivers in a large ported enclosure, about 1.7 cubes (cant remember the exact dimensions), 1lb of poly and tuned low.


----------



## Spyke (Apr 20, 2012)

Hanatsu said:


> Hm higher efficiency... You're talking about the Q bump right? Resonance peak increases in frequency with high Qtc, ain't it less efficient using the sub below the resonance *but more efficient through and above the peak*?


Ahh, efficient where it doesn't count.


----------



## Spyke (Apr 20, 2012)

Hanatsu said:


> GD - Group delay.
> 
> Low end extention depends much on the car as well. Larger cars have less boost generally.
> 
> Sent from my Samsung Galaxy 3 via Tapatalk.


Group delay...right. :blush:


----------



## BuickGN (May 29, 2009)

Patrick Bateman said:


> Due to cabin gain, it's trivial to hit 20hz in a car. I would rather put a large woofer in a small box than go the other way. The large woofer in a box thats too small will still have higher power handling, higher efficiency, and lower compression.
> 
> The main reason to use a large sealed box is to improve low frequency efficiency, but that isn't a problem in a car.
> 
> Big sealed box has superior GD tho.


But a too small sealed box is LESS efficient down low where the sub generally requires tons of power so making it more efficient in that range is the most important, at least to me. The too small sealed box is no more efficient up high. The rise is distortion, cone ringing. It is output, I'll give you that, but it's not the kind of output I would prefer. You also end up with less cone control.

I've been in way more cars that will not hit 20hz, many not even audible than I've been in that will hit 20hz flat. Some of my old systems would not hit that 18 or 16 hz note in "put on", just silence, you wouldn't know there was supposed to be anything there. In fact, my 12W6s would not hit that note at all in the small sealed. Once they went IB they hit it with authority. My current dual 15" IB system hits 20hz just as well as any other sub frequency. Dubstep on my friend's system is missing a ton of low frequency information as he found out when he played it on mine. The best thing is I'm running 250w to each sub for ridiculous low frequency output due to my 20 ft^2 "box". 

I think reproducing the lowest audible frequencies is a big problem in most car subwoofer setups. 

I just can't wrap my head around your statement that the large woofer in a box thats too small will still have higher power handling, higher efficiency, and lower compression. If anything it's the exact opposite. Mechanical power handling goes up because you have this air spring resisting cone movement. Efficiency where it counts goes down and does not go up anywhere. If anything you can argue that the thermal power rating goes down in a very small sealed box due to less excursion at a given power level and less important, a smaller volume of air that will rise in temperature quicker. Are you speaking of lower power compression when you mention compression? Because that's going to be higher as well when you have to pump 4-16x the juice on the low end for the same output as the same sub in a large sealed or IB setup. What am I missing?

No one has really answered the question of why higher power handling is considered a pro when you do so by making the sub less efficient, when it now requires additional power for the same output. I still can't see a single reason why you would want to put a sub in a small sealed over a large sealed or IB enclosure other than space savings.



Spyke said:


> I guess it comes down to listener preference. I listen to some pretty bass heavy music sometimes(not rap). I tried small enclosures but I felt they really let down the low end. Using larger enclosures really helped. Music gained more of a visceral feeling and everything feels "more involved".
> 
> As far as efficiency, I always thought small sealed were the least efficient?
> What's GD btw?


I fully agree. This is what I've been saying all along. If you like the changes when you went to your large sealed, you'll really love IB.


Last, I can't understand how you can eliminate the cone ringing and lack of control associated with too small of a box with EQ or whatever. It seems like a mechanical problem to me, how do you fix it without changing the enclosure volume?


----------



## Patrick Bateman (Sep 11, 2006)

Spyke said:


> Ahh, efficient where it doesn't count.


uh uh










Here's a spectrum analysis of a bass heavy track. See what's going on below 40hz? There's basically nothing there. That's why I keep arguing for efficiency where it counts, which is 40-80hz.

I know that there's a natural tendency to design your system so that it's flat from 20hz to 20khz. That's great if you have an unlimited budget, unlimited space, and unlimited power.

But here in the real world, I'd argue that you can basically write off the octave from 20-40hz. Due to cabin gain, you really don't need much power or efficiency to generate big bass at 30hz in a car. *The hard part is generating big bass where it counts, which is the two octaves from 40 to 160hz.*

And 20hz? Forget about it. There's nothing there, unless you happen to watch movies in your car.


----------



## BuickGN (May 29, 2009)

Patrick Bateman said:


> uh uh
> 
> 
> 
> ...


That's the thing, I thought the same until I had a system that would easily reproduce it. There's not a lot of it by any means but once you have it you feel like you're missing something when it doesn't want to do 30hz and below. There's some "normal" music (non dubstep and rap) that goes surprisingly low. 

But again, how does any sealed enclosure give a bump in efficiency that's not distortion? Cone ringing is distortion. Backwave making it's way back through the cone is distortion. A large sealed gives you the low end efficiency without hurting the other ranges. 

If you have a trunk car and can do IB you don't need much money or space or power to get low and loud. My pair of 15s cost $333 shipped to my door brand new. About $30 in materials for the baffle. 250w to each give big bass at 20hz, what I suspect would require thousands of watts with your average sub in a small sealed enclosure. Add in the better than average efficiency and ultra low Le and these things play the 40-160 with authority in addition to the 15-30hz range with very little power.


----------



## Hanatsu (Nov 9, 2010)

I agree that not much mainstream music have information below 40Hz or so, even less below 30Hz. Below 30Hz is practically meaningless, while we are driving we need an insane boost below 30Hz to even hear it since most of that get drowned by road noise, exhaust noise etc. For efficiency in a ported enclosure, you could tune in the 33-35Hz area, it will still reproduce 30Hz and the peak created can be pulled down with EQ. The problem is that many use big midbass drivers that essentially are used as mini subs, playing down to 50Hz or so. Those people don't care about the sub being efficient at 50Hz and above since they lowpass around there. But if you using a higher crossover like 80Hz, then by all means a small sealed will have better output "better hit" as some call it with mainstream music as well as most rock/metal. These type of enclosures/subs tend to subjectively sound more punchy than IB/large sealed/low tuned ported because of the increased output in 50-60Hz.

I usually aim for good efficiency 35Hz and up. Imo, vented enclosures is the way to go. Small sealed/large sealed/IB also have their uses. All have pros and cons, compromises like with everything else in this hobby.


----------



## Hanatsu (Nov 9, 2010)

BuickGN said:


> But again, how does any sealed enclosure give a bump in efficiency that's not distortion? Cone ringing is distortion. Backwave making it's way back through the cone is distortion. A large sealed gives you the low end efficiency without hurting the other ranges.


Much of bass we hearing is distortion. Just doesn't know it. Our ears have a really hard time perceiving distortion with bass notes and we just sum it together with the fundamental as more bass. There are limits of course but there's no reason to stress over distortion in the lowest 2 octaves. The arguably most audible form of distortion, peaky -Frequency Response- can be fixed with EQ


----------



## Brian Steele (Jun 1, 2007)

BuickGN said:


> That's the thing, I thought the same until I had a system that would easily reproduce it. There's not a lot of it by any means but once you have it you feel like you're missing something when it doesn't want to do 30hz and below. There's some "normal" music (non dubstep and rap) that goes surprisingly low.


Agreed. Look up "Yaar Anmulle (g-ta's dubstep remix)" for an example. Down to 18 Hz, and a lot of it too. There's also a remix of Rob Dougan's "Clubbed To Death" that goes down to single digits. You can't hear it, but you can certainly FEEL the pressure changes in your car, if your sub is capable of producing these frequencies.


----------



## Spyke (Apr 20, 2012)

Patrick Bateman said:


> uh uh
> 
> 
> 
> ...


There is a lot of sub 40 information in a lot of electronic music. And if you aren't into that type, there are a few standard instruments that reach that low.(Pipe organ, harp, bass, bassoon...) It's just as important to get 40-80 as it is to get 20-40. More important to get 20-40 (maybe) since our hearing is less sensitive down there. Imo


----------



## Hanatsu (Nov 9, 2010)

Barefaced Bass - What is bottom?


----------



## Patrick Bateman (Sep 11, 2006)

Spyke said:


> There is a lot of sub 40 information in a lot of electronic music.


Can you post some examples?

Over on the thread 'bass - how low can you go?' I've posted spectral analyses of a few 'bass heavy' tracks, and the one thing they have in common is that the bass is predominantly at 40hz and up.

I'm not saying that it's *impossible* to find tracks that go to 20hz.
I'm saying that 98% of the music out there doesn't need efficiency at 20hz. (IE, there's a little bit of output at 20hz, but the output level is so far below 40hz, that any sub that can get to 40hz can reproduce 20hz at levels that are satisfying.)

Which is a long-winded way of saying: when it comes to subs, focus on getting satisfying output to 40hz, *maybe* 30hz, and don't sweat anything below that.


----------



## BuickGN (May 29, 2009)

Hanatsu said:


> Much of bass we hearing is distortion. Just doesn't know it. Our ears have a really hard time perceiving distortion with bass notes and we just sum it together with the fundamental as more bass. There are limits of course but there's no reason to stress over distortion in the lowest 2 octaves. The arguably most audible form of distortion, peaky -Frequency Response- can be fixed with EQ


I agree but why would you purposely increase distortion with too small of a box? People spend thousands of dollars on low distortion subs that will remain low distortion over a healthy range of excursion but others will throw subs in a very small box and greatly increase distortion. IMO, I would rather feed it more power or more cone area or whatever to get more output. Why not just take all the sound deadening out of the car and let the rattles contribute to SPL as well? Extreme example but I think it makes my point.


----------



## BuickGN (May 29, 2009)

Hanatsu said:


> I agree that not much mainstream music have information below 40Hz or so, even less below 30Hz. Below 30Hz is practically meaningless, while we are driving we need an insane boost below 30Hz to even hear it since most of that get drowned by road noise, exhaust noise etc. For efficiency in a ported enclosure, you could tune in the 33-35Hz area, it will still reproduce 30Hz and the peak created can be pulled down with EQ. The problem is that many use big midbass drivers that essentially are used as mini subs, playing down to 50Hz or so. Those people don't care about the sub being efficient at 50Hz and above since they lowpass around there. But if you using a higher crossover like 80Hz, then by all means a small sealed will have better output "better hit" as some call it with mainstream music as well as most rock/metal. These type of enclosures/subs tend to subjectively sound more punchy than IB/large sealed/low tuned ported because of the increased output in 50-60Hz.
> 
> I usually aim for good efficiency 35Hz and up. Imo, vented enclosures is the way to go. Small sealed/large sealed/IB also have their uses. All have pros and cons, compromises like with everything else in this hobby.


That's just the thing, in an IB setup where you can use a lot of cone area/displacement and with the proper subs, they require zero boost below 30hz. Actually mine have 1.25db boost at 20hz, flat at 25 and 32hz to make them flat but that's probably due to my hearing, there's a ton of pressure even with a little 1.25db boost. I have 250w each with practically zero boost required and I can hear 20-25hz just fine going down the freeway. In fact I was demonstrating some dubstep to a co-worker that dropped to 18hz while on the freeway. He's an SPL guy but all he could talk about is how low it goes. Insane boost is only required when your subs roll off too early and that's usually from a very small box. 

I absolutely do not agree that small sealed is more punchy than IB or large sealed. That's in the tuning and the subs. Sure, if you remove the 40hz and below by choking the subs with a small box and all you have left is the 50-80hz, the perception might be that there's more punch but that's not the way I want to attain a punchy sound. I like to have my cake and eat it too and that means flat to 20hz, very punchy, and the option to lowpass at 200hz if I want to. The right subs in a very large box will do this and they will do it with very little power. I can hit xmax with only 200w each due in part to the very large box. With a sub stage that can play everything well, not just punch or 20hz or 120hz, the bass is more involving, more realistic, just better all around. 

As I've said before, if I had the room I would probably go ported but IB with lots of cone area gets the job done well and most importantly, small sealed would be dead last in my enclosure choices because it presents the most compromises. Subs might play a relatively narrow range but there's a lot of weight in that range and a bad sub setup can easily make the whole system sound like garbage. When the material calls for it I want to feel the subs but I want them to disappear when they're supposed to. Having a peaky setup makes this much harder to do.


----------



## [email protected] (Jun 12, 2008)

Its all about air spring for the punch that a sealed enclosure is always said to have over other alignments.


----------



## Hanatsu (Nov 9, 2010)

BuickGN said:


> Why not just take all the sound deadening out of the car and let the rattles contribute to SPL as well? Extreme example but I think it makes my point.


Well, that would most likely decrease output. Flexing panels act as a enormous speaker out of phase with the music, canceling out bass instead. Not the best example perhaps, but I understand what you mean. Distortion is unavoidable with any speakers in any enclosure. You just trade one form for another. We want to go with the one least audible. IB, Sealed, Vented all have different pros and cons. What is comes down to is when and where to use it, some cars may not be able to even use IB setups. Low frequency material are easy to reproduce in a car, much easier than in a large room in a home environment. It's all about moving air, IMHO subwoofer drivers doesn't sound that different from each other (there are exceptions, crappy exceptions). How often have you seen HD/IMD testing on subwoofers btw?


----------



## BuickGN (May 29, 2009)

BeatsDownLow said:


> Its all about air spring for the punch that a sealed enclosure is always said to have over other alignments.


But that's a myth. The air spring reduces cone control. How can something that restricts cone movement help with punch? The air spring reduces low end, making it seem like there's more punch. I invite anyone to take a listen to my IB15s for an example.


----------



## Orion525iT (Mar 6, 2011)

BuickGN said:


> I agree but why would you purposely increase distortion with too small of a box? People spend thousands of dollars on low distortion subs that will remain low distortion over a healthy range of excursion but others will throw subs in a very small box and greatly increase distortion. IMO, I would rather feed it more power or more cone area or whatever to get more output.



I think you are making your point that everybody should IB with 15" or larger drivers. But not everybody can do that or wants to do that. Does the amount of money they spent make any difference to reality? That seems to be your major point. Maybe spending thousands of dollars on low distortion subs for car audio is money not well spent? 



BuickGN said:


> Why not just take all the sound deadening out of the car and let the rattles contribute to SPL as well? Extreme example but I think it makes my point.


No, I don't see how that correlates at all. However, that is a good example of logical fallacy, a bit straw man.


----------



## BuickGN (May 29, 2009)

Orion525iT said:


> I think you are making your point that everybody should IB with 15" or larger drivers. But not everybody can do that or wants to do that. Does the amount of money they spent make any difference to reality? That seems to be your major point. Maybe spending thousands of dollars on low distortion subs for car audio is money not well spent?


My point went right over your head. You fail to see where I mentioned my subs cost $333 shipped to the door brand new for the pair. They happen to have outstanding Le performance and are a great value. But yeah, for low distortion with lots of excursion you generally have to spend more. 

Where did I say everyone should go IB with 15" or larger drivers. This is what I hate about this forum, people coming in here that either don't read or make assumptions and it goes from information sharing, a good discussion to ugly. 

IB with the right subs is an example that subs can get very low and loud without a ton of power and boost down low. It is a very good solution to a lot of problems. Not the only solution but a good one. 

What I said (previously) is the last setup I would go with is small sealed. As I also said earlier I would go with ported first and foremost even over IB if I could give up the space. My argument is why on earth would anyone ever go "too small" sealed when you have other options. There are too many downsides and few upsides unless you only care about bass frequencies. 


Orion525iT said:


> No, I don't see how that correlates at all. However, that is a good example of logical fallacy, a bit straw man.


As I said when I first posted that sentence, it's an extreme example meant to illustrate a point. Again, do not assume. As I explained previously, what I meant was some people see no problem with boosting distortion via a small sealed box to increase SPL. Where do you stop increasing distortion for free output? An extreme example is allowing rattles. My point as I also stated previously is I would rather increase power or efficiency or cone area, there are many better ways to increase output without increasing distortion.


----------



## [email protected] (Jun 12, 2008)

BuickGN said:


> But that's a myth. The air spring reduces cone control. How can something that restricts cone movement help with punch? The air spring reduces low end, making it seem like there's more punch. I invite anyone to take a listen to my IB15s for an example.


 An air spring does the same thing your spider does, just on a larger scale. Do you go around saying a spider "fights" a cones movement?


----------



## Spyke (Apr 20, 2012)

Patrick Bateman said:


> Can you post some examples?
> 
> Over on the thread 'bass - how low can you go?' I've posted spectral analyses of a few 'bass heavy' tracks, and the one thing they have in common is that the bass is predominantly at 40hz and up.
> 
> ...


Pucifer - The humbling river , Combichrist - Dawn of man, actually about half of combichrist's discography. Industrial in general seems to have some pretty low bass in it. (nine inch nails, kmfdm)

I get your point. I just don't agree with a sub alignment that has a peak around 60-80.


----------



## [email protected] (Jun 12, 2008)

Spyke said:


> Pucifer - The humbling river , Combichrist - Dawn of man, actually about half of combichrist's discography. Industrial in general seems to have some pretty low bass in it. (nine inch nails, kmfdm)
> 
> I get your point. I just don't agree with a sub alignment that has a peak around 60-80.


It may have an initial peak, but after EQ is applied, no more peak. Thats what they have been saying.


----------



## WTF1978 (Apr 12, 2012)

I would love to try an IB set up but my crew cab truck is not up to the task but i do have a question that fits right in to this discussion: If sealed box size is limited would a person be better off putting a 10 in a slightly larger box or a 12 in a slightly smaller box? Goal of system being SQ with output a close second.


----------



## subwoofery (Nov 9, 2008)

WTF1978 said:


> I would love to try an IB set up but my crew cab truck is not up to the task but i do have a question that fits right in to this discussion: If sealed box size is limited would a person be better off putting a 10 in a slightly larger box or a 12 in a slightly smaller box? Goal of system being SQ with output a close second.


An 18" in an absurdly small box  

Kelvin


----------



## BuickGN (May 29, 2009)

BeatsDownLow said:


> An air spring does the same thing your spider does, just on a larger scale. Do you go around saying a spider "fights" a cones movement?


A spider has several important functions. The air spring does fight cone movement and at the same time reduces cone control. What possible good can come from restricting cone movement and making it less efficient assuming the user knows to keep an eye on excursion and will take the proper steps to protect ot from over excursion. Why rely on the airspring to do this, take the training wheels off lol.

I keep asking what good comes from an airspring?


----------



## Spyke (Apr 20, 2012)

BuickGN said:


> My point went right over your head. You fail to see where I mentioned my subs cost $333 shipped to the door brand new for the pair. They happen to have outstanding Le performance and are a great value. But yeah, for low distortion with lots of excursion you generally have to spend more.
> 
> Where did I say everyone should go IB with 15" or larger drivers. This is what I hate about this forum, people coming in here that either don't read or make assumptions and it goes from information sharing, a good discussion to ugly.


If someone doesn't want to take the time to read the *entire* thread, they shouldn't get involved.


----------



## Spyke (Apr 20, 2012)

BeatsDownLow said:


> It may have an initial peak, but after EQ is applied, no more peak. Thats what they have been saying.


But why do that? Sure you will save some power at those freq, but if you want to hit the low low's then you need to add boost down low. Assuming you want more than what cabin gain will provide. And now you need a ton of power and excursion. It depends on what you are going for. If you just want something for a little low end at normal volumes a small sealed will be fine. I used small sealed for years and it sounded good to be honest. It was just *my* preference that wanted more.


----------



## Spyke (Apr 20, 2012)

WTF1978 said:


> I would love to try an IB set up but my crew cab truck is not up to the task but i do have a question that fits right in to this discussion: If sealed box size is limited would a person be better off putting a 10 in a slightly larger box or a 12 in a slightly smaller box? Goal of system being SQ with output a close second.


How bout a blow through? Seal the bed and mount 3 15's in the back wall. J/K

You should read this thread. 10" in a larger box.


----------



## Brian Steele (Jun 1, 2007)

Hanatsu said:


> How often have you seen HD/IMD testing on subwoofers btw?


Well, here's a full-range distortion test on my system, played a few dB lower than my usual listening level. Of note is that, while there seems to be a 10dB rise in distortion below 200 Hz, it is still at a very low level, and even dips near the subwoofers resonant frequency, even though the subs are set about 9dB higher than the rest of the system. The peak @ 700 Hz is caused by something on the front doors that starts audibly buzzing at much higher levels.

The test is easy to run if you've got access to a decent measuring system (HolmImpulse, which I used for the measurement, is freeware).


----------



## Hanatsu (Nov 9, 2010)

Brian Steele said:


> Well, here's a full-range distortion test on my system, played a few dB lower than my usual listening level. Of note is that, while there seems to be a 10dB rise in distortion below 200 Hz, it is still at a very low level, and even dips near the subwoofers resonant frequency, even though the subs are set about 9dB higher than the rest of the system. The peak @ 700 Hz is caused by something on the front doors that starts audibly buzzing at much higher levels.
> 
> The test is easy to run if you've got access to a decent measuring system (HolmImpulse, which I used for the measurement, is freeware).


Yeah I've tested a few subs for subs for HD. They were clearly different when I measured them, hard to do A/B/X testing with subs inside a car but I've tried a few and idk if there's much audible difference really after applied EQ. My ears might suck though.

Btw the THD rise at 700Hz are most likely caused by panel resonance, I had one in my door at 500Hz, really annoying one. Got rid of it after 3 layers of dampener... I usually measure with aRTA, Holmimpulse looks complicated in comparison. My point was that lot of DYIers test midbass/midrange/tweeter drivers for HD/IMD but almost never you see plots over subwoofers. I believe it's because it's not very important down the last two octaves, buuut I don't know......
-----------
Tried a few bass heavy tracks in the spectrum analyzer of Audacity. Some were even higher than I thought, lot of Infected Mushroom had peaks around 45-55Hz, Deadmau5 had several centered between 38-45Hz, tried a few dubsteb songs, found one that stretched down to 28Hz but that one was kinda rare. Lots of random bass heavy Rap songs (Lil Wayne etc) peaked around 34-40Hz. Tried Yello as well, the songs from their latest album centered around 35-45Hz. Eagles - Hotel California (unplugged) had a slight peak around 28Hz and a larger at 44Hz. I stand by what I said, below 30Hz is basically a waste of power to reproduce, make due with what cabin gain provides down there, which btw is a lot. There is no need to boost anything down there imo.

Below is a plot and measurement of a sub in a small sealed enclosure (18lit) with a measured Qtc of 0.94 with DATS. WinISD model vs in-car measurement in a large car (VW Passat B6 wagon). Not trying to argue here, just showing an example how much cabin gain raises the response.

(It's lowpassed at 55Hz/24dB)


----------



## BuickGN (May 29, 2009)

No one has argued that cabin gain is not a huge factor and that's why car subs usually roll off much sooner than HT stuff. However, the vast majority of the car setups I've heard, cabin gain or not, have a hard time with the really low stuff. I'm not happy with a system that can't produce the whole range now that I have had it. Whether or not there's a lot of material down there is irrelevant to me, if it's there in 1 out of every 20 songs I listen to I want my system to be able to reproduce it. There's something awesome about being able to drop down to 20hz.

Again, it's very easy to reproduce this range and do so without a ton of power with the right setup. If subwoofer distortion is so unimportant, why have an xmax rating, why not just rate every sub at xmech instead. At some point it is important and I still don't see the point of adding distortion on purpose.

More importantly and on topic, and the question no one has answered, why would you not go with the larger enclosure and eq out the bloated low end (if there is one) and enjoy the greater efficiency rather than doing so mechanically? The only valid reason I can see for the small box argument is if you have no eq. 

There are a couple Dubstep songs I need to run through Audacity. Anyone know the low note in "put on"? My old system was pretty much silent on that note, new one hits it with authority and little power. If I remember right it's 27hz.


----------



## Brian Steele (Jun 1, 2007)

cajunner said:


> here's the answer:
> 
> it's because road noise masks and actually "stutters" the wave in the region of 40-65 hz. To hear it distinctly the box has to have a peak in response to "cut through" and manufacturers find that people who install peaky small boxes are happier with the sound because of it.
> 
> ...


IMO it's more likely because most people simply haven't heard what music sounds like on a system that's flat down to single digits, so when they do hear it, it doesn't sound "right". 

I'm going to bet that most music isn't mastered on systems that go down to single digits either.


----------



## Brian Steele (Jun 1, 2007)

BuickGN said:


> There are a couple Dubstep songs I need to run through Audacity. Anyone know the low note in "put on"? My old system was pretty much silent on that note, new one hits it with authority and little power. If I remember right it's 27hz.



Here's Yaar Anmulle (g-ta's dubstep remix). The lowest peak is at 18 Hz. 

Note: the FFT size has to be set quite high for good resolution at these low frequencies. 8192 is not going to cut it.


----------



## Spyke (Apr 20, 2012)

cajunner said:


> here's the answer:
> 
> it's because road noise masks and actually "stutters" the wave in the region of 40-65 hz. To hear it distinctly the box has to have a peak in response to "cut through" and manufacturers find that people who install peaky small boxes are happier with the sound because of it.


It's a good theory and I can almost get it to work in my head. What manufacturers and who are the people they are asking? Manufacturers have never and will never recommend a box that's too large.(as far as I know) They do this for a couple reasons. 

1. 98% of consumers would kill the subs due to over excursion. 

2. You sell more subs by making them "stealth" which is another word for "You are sacrificing performance so that your wife lets you get a sub". *or* You can buy more subs because you can fit 2 12's instead of 1 12". 

3. You need to buy a bigger amp because now you need 500w instead of the 250w which would have made this sub sound better in a bigger box.


----------



## FG79 (Jun 30, 2008)

Interesting thread. The good news is that both sides of the argument have legit points!

The argument that you need full extension (or as much as possible) is correct for two reasons:

1. There is some music with information that low (not a ton, though)
2. Most music has "fundamental harmonics" which indeed is deep.

The second one is critical. It is like high frequency harmonics in reverse. There is not much musical information past 4-5 kHz but try listening to a system that cuts off there or even 10-12khz. You will get a lot of glare , and it won't sound right.

Even if your analyzer says a song has nothing below 60 hz , you still want extension down low. Doesn't mean you need it flat to 110 db at 20 hz, lol. Just something.

I'll give some examples in real life where this is proven over and over :

I once built a sealed enclosure in my doors for my woofers. Thought it was a bright idea. At first it sounded nice, more punch in the midbass but upon further listening it sounded hollow. Car didn't sound as full. Nothing changed in crossover frequency, and still had subs playing . By killing the woofers ability to play deep it was very audible. I wound up cutting a hole into it to bring it back to normal. An expensive lesson but worth it for others. 

Second example is my home setup. Studio monitors, 8" woofer in small cabinets . Goes down to 48 hz.

Music is enjoyable but the lack of full range is usually apparent. It can still be very enjoyable but if songs have a lot of bass content you can tell. Sometimes songs are mixed in a certain way that makes up for lack of low bass but you know it's missing.

Btw, PA systems that go down to 35-40 are not a whole lot better. You can hear the missing octaves. Thank car audio for that education. LOL.

Finally a counterpoint to all of this. While important to have the entire frequency range covered , the bottom octave is still the least important. 40-80 is more important than 20-40, and 80-160 even more important than that. Try listening to a system that has the midbass selectively filtered and the bottom intact and report back how it sounds!!

Listen to these amateur car booming systems that high pass the woofers high so the system can play loud. Horrible.


----------



## subwoofery (Nov 9, 2008)

cajunner said:


> you're right.
> 
> I was being facetious, albeit with a little cunning involved.
> 
> ...


Manufacturers need to allow some for of "headroom" for their subs coz 90% of the end users WILL USE the infamous "Bass Boost"  

Kelvin


----------



## Spyke (Apr 20, 2012)

subwoofery said:


> Manufacturers need to allow some for of "headroom" for their subs coz 90% of the end users WILL USE the infamous "Bass Boost"
> 
> Kelvin


I like to call that the remote sub destruct knob.


----------



## The Baron Groog (Mar 15, 2010)

Spyke said:


> I think that's what Baron was talking about. I have tried it myself with mixed results. It sounded great but when pushed it eats up power and excursion. It def works and is a good compromise if space is limited.


Works well in my car, flat sub to 20hz-can eq in more low end, no excursion issues to date. Reading about Linkwitz Transform gave me the idea to try it.


----------



## Spyke (Apr 20, 2012)

After a lot of playing and box building I have decided to agree with Baron and Mr. Bateman, and anyone else who had the same idea(I don't feel like reading the whole thread) Basically saying that IF you decide to go sealed AND ignoring all of the shortcoming attributed to a sealed enclosure of ANY size. The size and qtc is pretty irrelevant as far as sound goes. I can get the same "sound" (curve) from pretty much any enclosure/sub combo I can put in my car by using xo point/slopes or eq. Given that there are obvious limitations on low output based on the size of the sub, I have found that you can get the sound you want out of anything really. Bigger subs are still better though, imo.


----------



## Spyke (Apr 20, 2012)

Agree/disagree?


----------



## Hanatsu (Nov 9, 2010)

As I said. Q does not matter, frequency response in-car and efficiency does.

Sent from my Samsung Galaxy 3 via Tapatalk.


----------



## Orion525iT (Mar 6, 2011)

Spyke said:


> After a lot of playing and box building I have decided to agree with Baron and Mr. Bateman, and anyone else who had the same idea(I don't feel like reading the whole thread) Basically saying that IF you decide to go sealed AND ignoring all of the shortcoming attributed to a sealed enclosure of ANY size. The size and qtc is pretty irrelevant as far as sound goes. I can get the same "sound" (curve) from pretty much any enclosure/sub combo I can put in my car by using xo point/slopes or eq. Given that there are obvious limitations on low output based on the size of the sub, I have found that you can get the sound you want out of anything really. Bigger subs are still better though, imo.


Pretty much what my idea was too. Not my idea really, but the conclusion I drew from information and multiple other posts given by those, like Patrick, who have far more knowledge and real world experience than I. It was an education process. 

If you happen to be able to IB, then do it. If you have space for a large ported, and you like that, then by all means....but that isn't the point here.

The issue I ran into was that sealed was the most practical for my goals and my vehicle. But I found that trying to achieve "optimal" Qtc forced me to consider physical placement and design that was less than optimal. In the face of that, Qtc fell off the list of major considerations. This is not to suggest that it should be ignored completely, just that there are tools to deal with sonic issues introduced by less than "optimal" Qtc. These are simple tools that are already at disposal, and should be in the kit if you have any real desire to have a SQ system; EQ.

By ignoring Qtc to some degree, I was able to stuff 8" subs, 5" mids and tweeters into my kick panel area without major intrusion into the foot well. With that, many, many other issues became non-existent.


----------



## ChrisB (Jul 3, 2008)

cajunner said:


> here's the answer:
> 
> it's because road noise masks and actually "stutters" the wave in the region of 40-65 hz. To hear it distinctly the box has to have a peak in response to "cut through" and manufacturers find that people who install peaky small boxes are happier with the sound because of it.
> 
> ...


This is what my WRX 1,500 to 2,000 RPM exhaust drone looks like on the Studio Six iPhone 4S RTA:









I learned a very valuable lesson and that is I tuned my enclosure WAY too low. I have deep bass out the wazoo, but my sub starts to lose steam near 60 Hz. I'm going to try tuning the next enclosure between 40 and 45 Hz to see if I can overcome the exhaust drone.


----------



## BuickGN (May 29, 2009)

Spyke said:


> After a lot of playing and box building I have decided to agree with Baron and Mr. Bateman, and anyone else who had the same idea(I don't feel like reading the whole thread) Basically saying that IF you decide to go sealed AND ignoring all of the shortcoming attributed to a sealed enclosure of ANY size. The size and qtc is pretty irrelevant as far as sound goes. I can get the same "sound" (curve) from pretty much any enclosure/sub combo I can put in my car by using xo point/slopes or eq. Given that there are obvious limitations on low output based on the size of the sub, I have found that you can get the sound you want out of anything really. Bigger subs are still better though, imo.


But again, why would you purposely make it super inefficient for no apparent reason (unless space is that bit of an issue). If Qts doesn't matter and you don't mind using a ton of eq, go with the large enclosure, run half the power and use the eq to CUT the bottom end instead of running 4-16x the power just because you can. You've got some of the same people in this thread saying it's perfectly acceptable to run a tiny enclosure with a ton of power to bump up the bottom end while saying in another thread the power compression is an issue in IB if you run a .3qts vs a .7 qts which is a minor difference in power. 

If space is a huge issue, I would find a way around it. You can do IB or you can go with a smaller sub but in a ported enclosure. Both will be MUCH more efficient than running a sub in a too small sealed enclosure.

What happens when it's in a tiny enclosure and you hit the thermal limits before you can hit xmax? You just left a lot of output on the table not to mention all of the other negatives. IMO, you should always be able to at least hit xmax.


----------



## Wesayso (Jul 20, 2010)

You are aware that some run small sealed and are perfectly happy with it, right? 
I'd love to run a 15" IB but where to put it (lol). Maybe the vifa LAT as Highly suggested would be an idea. 
But with small cars comes insane cabin gain. My 8" sub is flat to 20 Hz (not exactly flat as my radio shack SPL meter isn't able to accurately measure the output at low frequencies and shows lower numbers at 20 Hz than the actual output) at and above my listening level. Now tell me why I should be able to hit xmax if it has more output than I need as is.

My box is a hair over the suggested size from JBL @ 10 liters and I filled it with polyfill. Sounds great to me with maximum of 290 watt RMS available and never needed.


----------



## Spyke (Apr 20, 2012)

BuickGN said:


> But again, why would you purposely make it super inefficient for no apparent reason (unless space is that bit of an issue). If Qts doesn't matter and you don't mind using a ton of eq, go with the large enclosure, run half the power and use the eq to CUT the bottom end instead of running 4-16x the power just because you can. You've got some of the same people in this thread saying it's perfectly acceptable to run a tiny enclosure with a ton of power to bump up the bottom end while saying in another thread the power compression is an issue in IB if you run a .3qts vs a .7 qts which is a minor difference in power.
> 
> If space is a huge issue, I would find a way around it. You can do IB or you can go with a smaller sub but in a ported enclosure. Both will be MUCH more efficient than running a sub in a too small sealed enclosure.
> 
> What happens when it's in a tiny enclosure and you hit the thermal limits before you can hit xmax? You just left a lot of output on the table not to mention all of the other negatives. IMO, you should always be able to at least hit xmax.


I agree with this but at the end of the day if my sub is less efficient it really doesn't matter if they sound the way I want. I have a large sealed in my car and a small sealed in my truck, both 12's of about the same eff. I prefer the out of the box(no pun) sound of the large sealed hands down. But, I can get them both to sound they way I want. The small sealed requires more power and doesn't get as loud and like you said, I prob left a few db on the table, but It was out of necessity.


----------



## Hanatsu (Nov 9, 2010)

It's more interesting to see where Fsc ends up than if the enclosure is big/small whatever. We want it around 40-50Hz generally if we care about efficiency. The speaker have the highest amount of excursion around this point, it's the other way around with vented. I prefer those over ib or sealed actually.

Sent from my Samsung Galaxy 3 via Tapatalk.


----------



## Wesayso (Jul 20, 2010)

cajunner said:


> when the car is rolling the added boost that makes things out of whack in the driveway, e.g. too much bass, is just fine, I'm sure many of you can vouch for that, and not just the ones with tuned exhaust notes.
> 
> Road noise/tire rumble is insidious, it's also going to have "cabin gain" and find the transfer function of the small enclosed space a suitable environment for competing sound waves.


One more advantage for me. My engine is in the back and my sub is up front. While I still experience a difference it is still quite good at driving conditions. So tuning ~50 Hz a bit above normal at stand still will sound pretty good on the road. 2 layers of mlv (one from factory) with open cell foam between it and the original sound deadening under the mlv and a sound deadening mat on the inside of the firewall help too .
I haven't treated the wheel wells yet but I'm sure there's something to be had there too. I do think an up front sub has advantages. It doesn't have to be a big one to help out with a bigger sub in the back.

But for pure sound quality? I'd rather have a bigger car (space).


----------



## Orion525iT (Mar 6, 2011)

BuickGN said:


> But again, why would you purposely make it super inefficient for no apparent reason (unless space is that bit of an issue).


Nobody is suggesting this. That is not the point being made. What is "super inefficient". Again, you may think I am being nitpicky, but I feel this is similar to your sound deadening fallacy. 



BuickGN said:


> If Qts doesn't matter and you don't mind using a ton of eq, go with the large enclosure, run half the power and use the eq to CUT the bottom end instead of running 4-16x the power just because you can.


You say 1/2 the power but then 4-16x times the power in the same sentence? Which is it? The issue with enclosure size universally trends in the other direction. Most have a hard time finding the space. But compare the space of a 200 watt class D to a 400 watt class D and the ability to mount the amp in a location separate from the sub.




BuickGN said:


> If space is a huge issue, I would find a way around it. You can do IB or you can go with a smaller sub but in a ported enclosure. Both will be MUCH more efficient than running a sub in a too small sealed enclosure.


Again, the pros and cons need to be weighed in the face overall design considerations. We all know that each situation must be considered individually, or else we would not need this forum because all installations would be identical. My initial belief that Qtc was a primary concern led me to too many design compromises, it wasted time, and it wasted money.

In my situation, by setting aside optimal Qtc, I was able to front mount my subs in the kick panels. I can run them higher to augment the much sought after and difficult to attain mid-bass punch, all without issues of localization that come from rear mounted subs. I can then use a dedicated mid-range and a tweeter. Done! All of this runs off a single multi-channel amp. This would not be possible if I was obsessed with optimal Qtc of the subs. The final Qtc is a bit over .8

If you want to discuss over all system efficiency, I don't think I have lost anything here. Consider that I run my subs, mids and tweeters off a single amp. The mids and tweeters run off a whopping 60 watts max per channel, and at that point they are louder than I would ever care to listen. Sure, I could mount the subs in the rear, taking up more space, to hit .707 or go ported. But that means I would have to add dedicated midbass plus another amp. So, in my case, the system efficiency issue is a wash, and the system cost and equipment factors far outweigh the optimum Qtc argument. I can see this being a good argument for those doing subs in door pods or floor/under seat locations too.


----------



## Wesayso (Jul 20, 2010)

cajunner said:


> you'd be pleasantly surprised what changing your car's tires can do to make your system sound better, even better perhaps, than adding 100 pounds of damping/bloc/foam/mlv techniques.
> 
> that rumble coming into the cab can differ by 12 db or more, easily just by changing tread patterns, it's ridiculous.


I am aware of that! I had awefull tyres for a while. When they were older I thought I had bad cvjoints! The ones I have now are pretty good but my summer tyres are even better.


----------



## BuickGN (May 29, 2009)

Wesayso said:


> You are aware that some run small sealed and are perfectly happy with it, right?
> I'd love to run a 15" IB but where to put it (lol). Maybe the vifa LAT as Highly suggested would be an idea.
> But with small cars comes insane cabin gain. My 8" sub is flat to 20 Hz (not exactly flat as my radio shack SPL meter isn't able to accurately measure the output at low frequencies and shows lower numbers at 20 Hz than the actual output) at and above my listening level. Now tell me why I should be able to hit xmax if it has more output than I need as is.
> 
> My box is a hair over the suggested size from JBL @ 10 liters and I filled it with polyfill. Sounds great to me with maximum of 290 watt RMS available and never needed.


If I had an old aircooled Porsche I wouldn't care about the system, I would want to hear the engine.

I'm not saying there's anything wrong with a small sub in a small box but this whole discussion so far has been about putting a fairly large sub into a "too small" box. My point is why? Why limit yourself if box size is not an issue? If you have the room for a 3 cube box but put your 12" sub in a .3 cube box, why? I can't think of a single pro for that setup.


----------



## BuickGN (May 29, 2009)

Orion525iT said:


> Nobody is suggesting this. That is not the point being made. What is "super inefficient". Again, you may think I am being nitpicky, but I feel this is similar to your sound deadening fallacy.


Model a 12" sub in a 2 cube box. Model the same sub in a .3 cube box. That is "super inefficient". What's this sound deadening fallacy you speak of?




Orion525iT said:


> You say 1/2 the power but then 4-16x times the power in the same sentence? Which is it? The issue with enclosure size universally trends in the other direction. Most have a hard time finding the space. But compare the space of a 200 watt class D to a 400 watt class D and the ability to mount the amp in a location separate from the sub.



It's very simple if you read. You can use 1/2 the power in a very large sealed box or IB. In a very small, too small sealed box it can require 4-16x the power to get the same low end as IB or large sealed.



Orion525iT said:


> Again, the pros and cons need to be weighed in the face overall design considerations. We all know that each situation must be considered individually, or else we would not need this forum because all installations would be identical. My initial belief that Qtc was a primary concern led me to too many design compromises, it wasted time, and it wasted money.


No **** every situation should be considered individually. The argument is what can you possibly gain by putting a sub into too small of a sealed box when you have the option of a large box. My argument has never been that everyone must run a pair of 15s IB or in a large box. My argument is why would anyone put any sub regardless of size into a box that's way too small on purpose when they have other options. I can't think of a single benefit. As I've said many times I would go ported if I could give up trunk space, then IB, then large sealed and small sealed would be the absolute last resort if none of the others were possible.



Orion525iT said:


> In my situation, by setting aside optimal Qtc, I was able to front mount my subs in the kick panels. I can run them higher to augment the much sought after and difficult to attain mid-bass punch, all without issues of localization that come from rear mounted subs. I can then use a dedicated mid-range and a tweeter. Done! All of this runs off a single multi-channel amp. This would not be possible if I was obsessed with optimal Qtc of the subs. The final Qtc is a bit over .8


And I bet those kick panel subs have a ton of bass. My 9s in the doors have adequate sub bass, likely more than some kick panel subs but I'm after realism and dynamics and sometimes that means feeling the bass. I have great punch from the subs and they're flat with authority to 20hz and they are glued to the dashboard. I can flex the dash when I want and mine also run off of a 5 channel amp with a 500w sub section, each 15 getting 250w. I also have an ideal Qtc in the high 5s. So tell me, how is your setup better or more efficient than mine?



Orion525iT said:


> If you want to discuss over all system efficiency, I don't think I have lost anything here. Consider that I run my subs, mids and tweeters off a single amp. The mids and tweeters run off a whopping 60 watts max per channel, and at that point they are louder than I would ever care to listen. Sure, I could mount the subs in the rear, taking up more space, to hit .707 or go ported. But that means I would have to add dedicated midbass plus another amp. So, in my case, the system efficiency issue is a wash, and the system cost and equipment factors far outweigh the optimum Qtc argument. I can see this being a good argument for those doing subs in door pods or floor/under seat locations too.


No space taken up by my subs either. I also have the option of running my 9s as subs and they sound pretty good doing so but again I like to feel the bass and play flat to 20hz and 9s or kick panel subs just aren't going to cut it. I have 3x the power to the front stage than I do to the subs because I like dynamics. I doubt the system uses 1/4 of that on average but it's there for the dynamic peaks. The sub system is so efficient that 500w is more than adequate while taking up no trunk space and with an optimum Qtc requiring no eq. 60w will get very loud on a front stage but if you have it cranked and your using say 40w average, what's left for those dynamic peaks that can use up huge amounts of power? Plus there's the fun factor. Most people around here, whether they admit it or not like to crank the system, specifically the bass once in a while.


----------



## Spyke (Apr 20, 2012)

cajunner said:


> here's the answer:
> 
> it's because road noise masks and actually "stutters" the wave in the region of 40-65 hz. To hear it distinctly the box has to have a peak in response to "cut through" and manufacturers find that people who install peaky small boxes are happier with the sound because of it.


I disagreed before but now after some building, swapping, and listening I will have to agree with this.:blush: A smaller enclosure *does* seem to "hit"...i'll say differently. Though a large sealed will go lower a small sealed will have more punch. This observation is with no eq. So with a large sealed you will have to add some 50-80 and with a small sealed you will have to add some 30-50. So you mind as well use 2 small sealed in the space it would take to do 1 large sealed.(assuming you have enough power) My final conclusion is that with eq you can make anything sound however you want. And that there are pros and cons for each. Power is cheap.


----------



## ChrisB (Jul 3, 2008)

While power is cheap, EQ does bring into consideration another detriment. You are limited by the mechanical capabilities of your subwoofer. I learned that the hard way when I ran a pair of 10w3v2s in JL Audio's recommended sealed enclosure. They hit 60 Hz to 100 Hz like you wouldn't believe, but fell on their face rather quickly below 50 Hz. At the time, I had more amplifiers than I knew what to do with, so I wired them to 1 ohm and nearly tripled the power going to them so I could equalize the spectrum below 50 Hz. Then they started hitting their mechanical limits because they ran out of XMax. Long story short, they hit the low notes much better on 500 watts RMS in a ported enclosure than they did with 1,500 watts RMS with .65 cubic feet per 10 sealed.


----------



## Spyke (Apr 20, 2012)

ChrisB said:


> While power is cheap, EQ does bring into consideration another detriment. You are limited by the mechanical capabilities of your subwoofer. I learned that the hard way when I ran a pair of 10w3v2s in JL Audio's recommended sealed enclosure. They hit 60 Hz to 100 Hz like you wouldn't believe, but fell on their face rather quickly below 50 Hz. At the time, I had more amplifiers than I knew what to do with, so I wired them to 1 ohm and nearly tripled the power going to them so I could equalize the spectrum below 50 Hz. Then they started hitting their mechanical limits because they ran out of XMax. Long story short, they hit the low notes much better on 500 watts RMS in a ported enclosure than they did with 1,500 watts RMS with .65 cubic feet per 10 sealed.



I'm not comparing sealed to ported. The difference between large sealed and small sealed is non existent if you are looking solely at output. If you eq'ed both large and small to sound the same they would both give the same output. The difference being, that the small sealed would take more power to reach full output.

Comparing sealed to ported: A ported enclosure will give about 3 more db than the same sub in a sealed. Doubling the number of sealed subs will give 3 more db as well. So it's your choice. Single ported or dual sealed, both will give the same output and can be eq'ed to sound exactly the same. So, by porting your jls, you gained 3 db and made them more efficient. If you had been limited by space them you wouldn't have been able to make them louder because you would have only had room for 1 sub. So going from 2 sealed to 1 ported would have been a lateral move. But at the same time you could have doubled the number of subs(sealed) and gotten the same results in the same amount of space. The drawback is that it would obviously cost more.


----------



## BuickGN (May 29, 2009)

Spyke said:


> I disagreed before but now after some building, swapping, and listening I will have to agree with this.:blush: A smaller enclosure *does* seem to "hit"...i'll say differently. Though a large sealed will go lower a small sealed will have more punch. This observation is with no eq. So with a large sealed you will have to add some 50-80 and with a small sealed you will have to add some 30-50. So you mind as well use 2 small sealed in the space it would take to do 1 large sealed.(assuming you have enough power) My final conclusion is that with eq you can make anything sound however you want. And that there are pros and cons for each. Power is cheap.


That's not exactly true. A small sealed will have less down low so while it might "hit" harder, it's only perception since the bottom is missing. Take a large sealed, eq out the bottom, it will sound like a small sealed. Large sealed will have the same output at the same power level as small sealed at 50-80hz. Small sealed is not more efficient in that area, it's more inefficient down low making the 50-80hz stand out more. The only real difference here is with one you might have to cut the bottom end to suit your tastes. With the small sealed you will have to boost the range that consumes the most power. If space is not an issue there's just no reason to run small sealed. It's much better to cut than to boost.


----------



## BuickGN (May 29, 2009)

Spyke said:


> I'm not comparing sealed to ported. The difference between large sealed and small sealed is non existent if you are looking solely at output. If you eq'ed both large and small to sound the same they would both give the same output. The difference being, that the small sealed would take more power to reach full output.
> 
> Comparing sealed to ported: A ported enclosure will give about 3 more db than the same sub in a sealed. Doubling the number of sealed subs will give 3 more db as well. So it's your choice. Single ported or dual sealed, both will give the same output and can be eq'ed to sound exactly the same. So, by porting your jls, you gained 3 db and made them more efficient. If you had been limited by space them you wouldn't have been able to make them louder because you would have only had room for 1 sub. So going from 2 sealed to 1 ported would have been a lateral move. But at the same time you could have doubled the number of subs(sealed) and gotten the same results in the same amount of space. The drawback is that it would obviously cost more.


Adding a second sealed sub with the same power will give a 3db bump. Double the power since you're running 2 subs you get a 6db gain from the extra sub. 100w to a single, add a second for 50w each and you get 3db. 100w to 2 subs gives 6db. 

Porting a sub does more for SQ than just adding output. Excursion is considerably less meaning less distortion. It also requires less power for a given SPL, farther lowering distortion and power compression. The 3db gain from a ported enclosure is just a quick rule of thumb, you can get considerably more gain near tuning frequency. Of course, somewhere above, probably far above tuning frequency you're basically back to sealed box output but luckily at those frequencies excursion is not an issue.


----------



## Spyke (Apr 20, 2012)

BuickGN said:


> That's not exactly true. A small sealed will have less down low so while it might "hit" harder, it's only perception since the bottom is missing. Take a large sealed, eq out the bottom, it will sound like a small sealed. Large sealed will have the same output at the same power level as small sealed at 50-80hz. Small sealed is not more efficient in that area, it's more inefficient down low making the 50-80hz stand out more. The only real difference here is with one you might have to cut the bottom end to suit your tastes. With the small sealed you will have to boost the range that consumes the most power. If space is not an issue there's just no reason to run small sealed. It's much better to cut than to boost.


The fact that a large will output more lowend than a small will at a given power level has to do with efficiency. The large may produce more 20-50 with less power but it will reach excursion limits with less power as well. 
I understand the perception part of this. That's why I said "with no eq". We *perceive* that large sounds more efficient down low and vice versa. My point was that both large and small will have the same overall output. To achieve this output the small will require more power and will have higher distortion levels. I like a little inaudible distortion in my bass.


----------



## Spyke (Apr 20, 2012)

BuickGN said:


> Adding a second sealed sub with the same power will give a 3db bump. Double the power since you're running 2 subs you get a 6db gain from the extra sub. 100w to a single, add a second for 50w each and you get 3db. 100w to 2 subs gives 6db.
> 
> Porting a sub does more for SQ than just adding output. Excursion is considerably less meaning less distortion. It also requires less power for a given SPL, farther lowering distortion and power compression. The 3db gain from a ported enclosure is just a quick rule of thumb, you can get considerably more gain near tuning frequency. Of course, somewhere above, probably far above tuning frequency you're basically back to sealed box output but luckily at those frequencies excursion is not an issue.


Ok, so wouldn't going ported be the same as doubling the surface area, since you are using both sides of the cone instead of just 1? I'm asking,btw. If that were true then there would be no way to gain considerably more at the tuning freq without losing it higher up in freq. Therefore wouldn't 2 sealed give exactly the same output as 1 ported? Maybe more since you need to subtract the area of the back of the cone that is taken up by the vc former. Ok that made me :laugh:. I get your point and agree with you btw. I get that it isn't all about extracting every sq inch in order to get max deebeez.


----------



## Hanatsu (Nov 9, 2010)

BuickGN said:


> Large sealed will have the same output at the same power level as small sealed at 50-80hz. Small sealed is not more efficient in that area, it's more inefficient down low making the 50-80hz stand out more.


Not correct. Efficiency is determined by the impedance peak. It peaks around Fsc, resonance of the closed box. If it occurs between 50-80hz it will be more efficient there, a larger box will with the same driver have a lower Fsc, pushing the resonance lower. Therefore the larger will be more efficient down lower and the small efficient up higher. With IB the speaker's Fs will be the highest efficiency point.


----------



## Hanatsu (Nov 9, 2010)

Vented enclosures are more complicated to understand fully than a simple sealed enclosure or IB for that manner. We can't generally say that a vented enclosure have +3dB efficiency, around tuning frequency the port gain might be a lot higher. Depends on port tuning and enclosure size. 

If power remains the same we gain 6dB with two subs if they are within 1/4 wavelength generally. Two drivers with the same cone area increase output by 3dB if power is lowered by half by adding a second speaker.

And smaller enclosures with higher Fsc, are efficient higher in frequency. It's that simple.


----------



## Orion525iT (Mar 6, 2011)

Bottom line, there is no free lunch. Nothing new here. 

IMO, IB and ported shouldn't be part of the discussion really, as this is not the title of the thread.

Obviously, box size is an issue one way or another for everybody. If you don't want to sacrifice trunk space, or have to remove your sub(s) to use the trunk, then you are often stuck pushing the subs into corners. If you want to have front mounted subs, then door panels, floor mounting, and if your car is genetically gifted , kick panels. In all of those cases, box size is a serious concern, and will generally be limited. 

In my case, I could maybe find some 6" subs that would allow me to reach lower Qtc or ideal Qtc (.707). But I can also use 8" subs, with the penalty of slightly higher than optimal Qtc. So what is the best choice?

Modeling the 8" at Qtc .707 vs Qtc .8, I lose about 1.4 db at 30hz, 1 db at 40hz, and .3db at 50hz. Keep in mind that Qtc of .707 requires a box that is .22 ft^3 larger than than Qtc .8 (.58 ft^3 vs .35 ft^3). *That is a huge difference in box size just to gain 1.4 db at 30hz*. Now compare the graph of the 8" sub with a Qtc .8 against a 6" sub with optimal Qtc .707. I am willing to bet the 8" puts out more below 50hz watt per watt. -This is my argument as succinct as possible


----------



## Spyke (Apr 20, 2012)

Orion525iT said:


> Bottom line, there is no free lunch. Nothing new here.
> 
> IMO, IB and ported shouldn't be part of the discussion really, as this is not the title of the thread.
> 
> ...


Eggs act lee. Qts, or more importantly, Qtc does not have an impact on the sound the sub will produce nor the max output. I don't think there is a better way or a worse way. It just depends on how you want to achieve the same end result. High power, low power, multi sub, single sub, ported, sealed, ib, iso, bp, pick one that suits your situation.


----------



## Hanatsu (Nov 9, 2010)

Spyke said:


> Eggs act lee. Qts, or more importantly, Qtc does not have an impact on the sound the sub will produce nor the max output. I don't think there is a better way or a worse way. It just depends on how you want to achieve the same end result. High power, low power, multi sub, single sub, ported, sealed, ib, iso, bp, pick one that suits your situation.


Indeed.

Sent from my Samsung Galaxy 3 via Tapatalk.


----------



## Orion525iT (Mar 6, 2011)

Spyke said:


> Eggs act lee. Qts, or more importantly, Qtc does not have an impact on the sound the sub will produce nor the max output. I don't think there is a better way or a worse way. It just depends on how you want to achieve the same end result. High power, low power, multi sub, single sub, ported, sealed, ib, iso, bp, pick one that suits your situation.


I meant Qtc not Qts :blush:, fixed in original post.


----------



## The Baron Groog (Mar 15, 2010)

BuickGN said:


> But again, why would you purposely make it super inefficient for no apparent reason (unless space is that bit of an issue). If Qts doesn't matter and you don't mind using a ton of eq, go with the large enclosure, run half the power and use the eq to CUT the bottom end instead of running 4-16x the power just because you can. You've got some of the same people in this thread saying it's perfectly acceptable to run a tiny enclosure with a ton of power to bump up the bottom end while saying in another thread the power compression is an issue in IB if you run a .3qts vs a .7 qts which is a minor difference in power.
> 
> If space is a huge issue, I would find a way around it. You can do IB or you can go with a smaller sub but in a ported enclosure. Both will be MUCH more efficient than running a sub in a too small sealed enclosure.
> 
> What happens when it's in a tiny enclosure and you hit the thermal limits before you can hit xmax? You just left a lot of output on the table not to mention all of the other negatives. IMO, you should always be able to at least hit xmax.


For me space was that much of an issue and having a hatch back an IB set up would be out of the mix. I cannot think of any readily available 6-8" sub that would give me the same output with the depth available in the footwell of my mini. Loud enough for me on 500w and 90mph with a decat SS exhaust


----------

