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Sealed or Vented, What your take? - Click HERE for Original Thread
impsick
So whats everybodys preference when it comes to sub enclosures?

personaly i've always liked sealed boxes for the tight, and solid bass. to me it just sounds more natural, its not like it cant hit that low rumble down in the 30hz range it just doesnt exagerate it. At least thats how i always felt about ported or vented boxes.
so i'd like to see some other views, its not an argument just personal preference.

for the last four or five years i've had 2 dual voice coil 12 inch Comp-VR's in the back with 800watts @ 2ohm feeding them in there own seperate sealed boxes.
richie00boy
What it comes down to really is that given the small space available inside a car, it's often impossible to vent a decent high-excursion woofer, both in terms of available volume, and in terms of physically fitting the vent into a smallish box.

Also, with cabin gain, sealed boxes match up better with this natural boost.

Tight / solid bass IMO comes simply from the correct design of box, and implementation of crossover and integration, rather than box sealed vs vented per se.
Clipped
i think it depends on orientation of the box....i think sealed boxes sound best the farther away they are from you, crushing lows.

i always use vented boxes though, for me its easier to tune and tailor the taste to a customers liking. Alot of people dont listen to the kind of music that has alot of sub bass, and prefer strong midbass, starting in the upper bass region, just coming out of the sub bass region.....sub and port face are really important here.

you can tune a ported box to one octave above a sub bass frequency, and it will still play the low notes(just not as strong)....and not unload like most people think...depends on actual box volume.

i usually stay away from making bandpass boxes for customers because in the wrong hands they are sub killers.
FE3T
My personal preference here is sealed.

Mainly because i feel that a large woofer (15") in a sealed box x over`ed low (50-60hz) and in combination with dedicated midbass drivers (8") gives less mechanical noise from the vehicle and doesent give the subbox away as rear mounted.

My former setup with dual ported 10`s didnt give me as much satisfaction as my current solution.

More rattles, less deep bass, and much easyer to locate as a rear mounted box, and didnt even sound snappier than my current sealed 15"
audiobahnkid592
IMHO ported for all out SPL and noise and rattles, and sealed for clean cut bass
dangus
Sealed, for bass so low you can eat it with a fork.
impsick
ya a pitch fork
Clipped
thats pretty low... :cool:
impsick
:devilr:
Bad silver
What bothers me the most is that 95% of people install their subs in the trunk, completely isolated from cabin, and then talk about SQ bass when ALL they can hear is muddy superposition of sound waves and a lot of interference.

In my understanding, the perfect bass should punch you directly into the chest and take your breath away but it MUST NOT make your seats vibrate or make wowowowow –standing-wave like sounds of retarded rap music.

I tried building both vented and sealed enclosures but I was not satisfied with sound because as soon as I turned off my speakers to listen to the bass alone - it was horrible sounding. I experimented a lot with moving my sub enclosure and figured out that one of the best places was between the front seats oriented directly at the windshield. It minimized the amount of seat vibrations and gave me clarity that I was looking for. Also, ALL of the external car noises were gone. However, even though the bass became a lot clearer, it was less punchy compared to subs in the trunk, so I had to quadruple the amplifier power to get the clean, chest-pounding reflection off of the windshield that I was looking for.

I ended up using single JL 10W6v2 sub powered by JBL bpx1100.1 in 1.25 ft^3 sealed enclosure. ;)
impsick
i cant think of any time i listen to just the bass and thought it sounded good. from in my truck, to suv, and almost all the time when mixing on a cpu using a digital multiband compressor. Subs dont sound good alone. they never will. thats the beauty of having the highs and mids cut through and everything just mixes perfectly and those low subsonic sounds now only add to every part making it more intense and powerful. but once you cut all the highs from it its back to rumblerumblerumbleblahblah.
i agree positioning has a big impact, but if you got subs no matter what your seats are gonna rattle. if you got good subs, your seat is gonna rattle while it kicks you in the chest. ya know;)
i've always had my subs in the same cab as me. In my tacoma, and now in my 4runner. i must say nothing i've sat in beats a pick truck with the extra cab strapped w/ a couple 12's. God i miss it!
Bad silver
The SUVs are different form sedans, so I can’t comment on what enclosure design is going to work the best for you because I never experimented with SUVs. I spent a lot of time experimenting with enclosures in sedans though. Here is my most recent setup behind the front seats:






The theory behind my deign is that the bottom part of spherical audio wave gets slowed down by the MDF wall and the plastic pillow behind the front seats, so that distractive interference occurs at 60Hz while waves travel toward the windshield and your seats vibrate less. When waves hit the windshield, the glass starts flexing and sends back homogeneous punch at your chest. :lickface:
Clipped
hey i have the same car...your seats fold down?

these cars get loud, pretty easily. ;)

i ground strapped the hell out of my engine, now the voltage is stable and nothing dims with around 1000 watts total.

i'll get some pics up.
richie00boy
Sorry but your idea/theory is fatally flawed.
impsick
um ya i dont think you can slow down a sound wave:whazzat: . 60hz wave is a 60 cycle / sec. wave all the way till you cant hear it anymore.
so ya sound waves dont slow down they loose energy.

how did you end up with 60hz in your theory anyways? just curious.
Clipped
actually that board acts like a loading board.

similiar but not exactly the same as a bandpass box, a bandpass box combines the negative half as well as the positive half of a wave....giving output which is a combination of both.

part of the reason why a properly designed bandpass is louder.

the output is the combination of both halves of the wave. this is why speaker placement and distance is less dependent with a bandpass design.

so hes not slowing it, hes combining halves...

the angle of that board is also helping to aim the sound...dont believe me, try it for yourself...

as for 60hz :confused:


-------------------------------------------------------------
heres my ghetto ported box...and modified subs.



impsick
Really? See the way you explain that i dont see anyone being able to hear anything do to phase cancelation. right?
I thought bandpass boxes are sealed either from behind or in front of the cone and ported on the other side.

I always figured since doing this the two cones that are pushing against each other in the sealed part are creating pressure and basically bouncing off each other, which is like a natural energy causing the woofers to do less work and the need of a huge amp less needed.
like a passive bandpass, a woofer in a box with another cone type woofer (but w/ out a coil).

i was always under the impression that if you take ( + ) half of a wave and combine it with its ( - ) you hear nothing.

so now im even more confused because by simply putting a board in front of half a speaker doesnt block just a + or - half of the wave. WHAT I SEE THAT BOARD DOING IS BLOCKING HALF THE SUB CAUSING SOUND WAVES TO BOUNCE BACK INTO THE TRUNK PART OF HIS CAR BASICALLY USING HIS TRUNK AS A BOX. KIND OF LIKE A BANDPASS YOU COULD SAY. WHICH IRONCALLY lets call it PHASE CANCELS HIS POST ABOUT SUBS IN THE TRUNK AND DISLIKING THEM. :D

am i totally missing something here? cause im not trying to argue but i feel like understanding this needs to be handled. this is basic understanding of audio.
richie00boy
Impsick,

Bouncing a sound wave back into the car boot area, does not make that area act like a speaker box allowing more/deeper bass. The limiting factor is the air spring against the cone which will be what the actual box provides.

Clipped,

As for combining the waves in a bandpass box, either you meant something different explained it wrong or you just got it plain wrong. A vented box works by taking the rear (out of phase) wave, delaying it a bit then adding it to the front to gain some extra SPL.

In a bandpass box the front section merely acts as a low-pass filter by the same principle as a normal vented box being driven at resonance and below.

Bad Silver,

In any case, the point about bouncing a wave back from the windscreen to feel it in the chest is kind of moot when the dominant wave will be coming at you from the box. Remember this wave has to pass through you to hit the windscreen...
impsick
richie, i dont know man, i respect your knowlege but im gonna have to disagree.

example....
in a home set up, if you hang a speaker on the wall you in part get an added 3dB.
if you put it against the wall on the floor you will get an added 6dB.
and blah blah if you put it in the corner on the floor you will get an added 9dB.
(and we are talking ugly muddy decibell's that are added)

you agree?
me calling it a bandpass was nothing more then a joke but im positive that if he opened his trunk his bass would drop at least 9dB, there for the trunk does act like a box and does amplify the the sound.

ah i see his trunk part is sealed off pretty much so lets pretend its not.:D
richie00boy
What you are referring to there Impsick is what is called boundary reinforcement. This happens because the speaker if being driven into 1/2 space (first scenario), 1/4 space (second scenario) or 1/8 space (third scenario).

So I guess that it is right about you comment opening the boot lid to the outside world will lose sound, but not because the boot space is amplifying anything as such, just because you are now driving into (at least) twice the acoustic space.
mikee55
I don't understand what everyones going on about.I've heard T Lines slow soundwaves through their stuffing and I think 60 Hz is close to a Kickdrum at 65Hz, so the www says on music type sites, maybe at a high spl this frequency can be quite physical. Listen to Hardcore from say DJ Sharkey on Bonkers XI CD, its pretty kickdrum lead and although the beats per minute are turned up, you will get it in the chest anytime and most likely straight from the driver, not a reflection from the windscreen. Afterall, if the driver is in close proximity, ie behind the drivers seat, I'm pretty sure you'd feel the driver.

By the way, whats the Fs of your chest?:D

http://www.caraudiohelp.com/newsletter/cabin_gain.htm
Cheers mikee55

ps hello richie000boy, hope you're well, sir?
richie00boy
T lines don't slow the wave down, just gracefully attenauate them. Anything that slows waves down will introduce distortion. Also I'd imagine it would invole some rather strange physics.

Hi Mike, I'm ok just my PC is not liking the new hard disc at the moment, and I'm a bit stuck with it. So I have been offline at home for almost a week now with no access to my email.
Clipped
care to explain why im wrong?
with details please...

the front part of a bandpass box doesnt just act as a low pass filter....it does more than that.

it combines and concentrates the pressure in an enclosed space and releases it through one point.

contrary to popular belief, bass can be aimed.

if you have a home stereo with subs, take a piece of wooden sheet and angle it to the direction your aiming at, then walk to that spot and see for yourself....you must cover the top also...or else it will go in two directions.

im not just making this stuff up, if you actually tried it you would see for yourself.

mikee55
Yes T-lines attenuate, it was a decade ago that I was reading on them. As for steering bass, me thinks its over my head and I'm overloading my grey cells at the mo with the earth on my car.

Rich, I cleaned my CPU heatsink and fan last night and forgot to plug the fan back in after I stripped the dust.I'm so glad my bios set its siren off. I had fully booted and played an mp3 before the alarm. Oops:clown:
Bad silver
:confused: You are completely misinterpreting my design. :D


I have the theory written down on paper. My scanner is missing USB cable so I will post the scans of calculations after I buy new cable tonight.
impsick
i agree you can direct bass waves, so it would be louder in a general area.

the only way it is possible to slow down a soound wave would be ex.
on a digital audio software like cubase or nuendo, you can stretch the audio wave. so if you had a 65hz wave and took part of it and stretched it out to say 30hz. that in a sense would be slowing it down.
But Moch1 is the speed of sound. the only time that changes in the amount would be do to the atmosphere. of course you could put barriers up and the wave might take longer to get to a point but it is bouncing from point to point at the speed of sound.
Bad silver
My original theory and drawings are too messy so I had to erase a lot of stuff and some comments. I used Ti89 to substitute values into different equations and then link those equations to find out values for variables of interest. Most of it was calculated by playing with numbers and brute substitutions into linked equations that gave delta time of waves. The goal was to get delta time between wave 1 and wave 2 & 3 to as close as possible to 0.003412s to cancel properly in this car. Very long calculation was done over 3 day period to come up with something reasonable. :D :o






Bad silver
quote:
Originally posted by mikee55


By the way, whats the Fs of your chest?:D

hahahahaha lol. I dun't know, the windshield is an elliptical, porabolic disk with radius of about 50m. Without cylindrical coordinate system it is too difficult to find theoretical fs. ;)
mikee55
Hi, get an oscillator and frequency counter.Do a sweep till you find the frequency that vibrates your chest the most. This gives Fs of chest. Insert a 5 band graphic into your system which has Fs at the centre band. Push the centre slider up to +120db full boost, bring the remaining sliders down to get inverted smiley. This should make your sub pump your chest....

This is most unconventional, the theorey looks mad. Does it count for the shape of the glass?, and what would happen if the Transposistion thingy was the same shape as the windscreen?, amd where would I put my feet if I wanted a ride in the back? Where did you get your theorey? I'm terrible with math, but still can't understand why you minimize 60hz at the seat posistion?I found with, say, Wavelab, if you eq out 60hz and 120hz(1st and 2nd harmonic?),you can boost 30 hz fundamental by a massive amount. Used to do this to get more bottom end.:clown: Bit boomy though.

Cheers mike:confused:
Bad silver
quote:
Originally posted by mikee55
Hi, get an oscillator and frequency counter.Do a sweep till you find the frequency that vibrates your chest the most. This gives Fs of chest. Insert a 5 band graphic into your system which has Fs at the centre band. Push the centre slider up to +120db full boost, bring the remaining sliders down to get inverted smiley. This should make your sub pump your chest....

This is most unconventional, the theorey looks mad. Does it count for the shape of the glass?, and what would happen if the Transposistion thingy was the same shape as the windscreen?, amd where would I put my feet if I wanted a ride in the back? Where did you get your theorey? I'm terrible with math, but still can't understand why you minimize 60hz at the seat posistion?I found with, say, Wavelab, if you eq out 60hz and 120hz(1st and 2nd harmonic?),you can boost 30 hz fundamental by a massive amount. Used to do this to get more bottom end.:clown: Bit boomy though.

Cheers mike:confused:

I came up with this design by myself. When I built this box and started playing with sub’s elevation to change distance X and finely tune cancellation effect; I realized how much I don’t know about this box. :confused: The final result, though, is that bass pounds a lot harder in the chest than at your seats vs any conventional setup that I had before.

60hz is f –frequency of penetration and the center wave cancellation distribution at the surface of polypropylene pillow. I used this number because 60hz is the most annoying frequency of seat oscillation. At 35Hz or 100Hz the seat vibrations are unnoticeable with any box.

The rear seat was sacrificed for the sake of having minimum oscillation of front seats. I was trying to figure out the role of 3d shape of glass curvature by hand without success. You might be able to do it with cylindrical coordinate system. I just want to forget about it.:o


Here is a peace of old draft with an attempt using Cartesian coordinate system with a lot of partial derivatives :confused:

impsick
quote:
Originally posted by richie00boy
What you are referring to there Impsick is what is called boundary reinforcement. This happens because the speaker if being driven into 1/2 space (first scenario), 1/4 space (second scenario) or 1/8 space (third scenario).

So I guess that it is right about you comment opening the boot lid to the outside world will lose sound, but not because the boot space is amplifying anything as such, just because you are now driving into (at least) twice the acoustic space.
Richie YES! boundry reinforcement. but if you think about it, accoustic space or not, you've heard of an ampitheater right? designed to amplify sound waves. way back in the day, Romans, this is ancient technology.:D

and its not so much space its being driven in cause the room hasnt changed size. its the walls acting as reinforcement as you quoted
richie00boy
Amphitheatres work in the same way as satellite dishes - they focus the sound which can provide some gain. This is not the same as what happens with the truck rear space.

My second para in your quote is the reason it gets quieter when you open the rear door. Also when you open any door or window, the driving mode of the interior space will change from pressure mode to wave move, which basically takes out most if not all of the cabin gain (or room gain in a house).
impsick
ok, i'll stop here. cause we aint gonna agree, completely at least.

A natural amphitheatre is a performance space located in a spot where a steep mountain or a particular rock formation naturally amplifies or echoes sound, making it ideal for musical and theatrical performances

thats from wikapedia. not that wiki is correct 100% of the time but i agree with its statement, and if you cut the car in half and looked at a picture of the hollywood amphitheatre one could say they are closely alike. and i was thinking before i noticed the trunk was sealed that the sub was free air and just on a baffle that didnt cover the backseats.

anyways i'll end my debate right here. you feel free to put in your closing statement before the jury deliberates.:D
peace
beerman
I like the "slam" from ported enclosures. I'm still 17 in that regard.

Video of my PC sub. I couldn't find a small sub that did what I wanted it to do, so I built my own. It ended up a bit bigger than I initially wanted.

My current car sub, though not exactly ported:





It's quite forceful in the 40-45hz range.
impsick
classic Kicker right there.:D
calum112
I like ^^ :)

What are you powering that from?
beerman
Channels 3/4 bridged from a Phoenix Gold Octane R804. Roughly 225w.
calum112
Ah, about the same power I'm running at the moment.

I must get around to building a different type of box. I really want to try an internally ported, sealed box as I love sealed.
richie00boy
What on earth is an internally ported sealed box?
mikee55
Hi calum112, what type of box is that then? I'm curious too.

Cheers mikee55:D

Excuse-me, richie000boy, can I email you yet? Figure, if you got PC problems, you might have a back log of emails, I don't want to add to it and give you more to download!:D :)
calum112
An inusual design I've encountered recently...

The driver is mounted in to a ported enclosure, the ports vent in to a sealed enclosure. See my attachment for a (dodgy) pic. the effective box size varies with frequency, due to the vent tuning.
richie00boy
I'm wondering if he means a bandpass box with sealed rear chamber.

Of course you can email Mike, thanks for the patience. I was meaning to get back in touch with you to let you know that I got my system up and running again now.
beerman
quote:
Originally posted by calum112
An inusual design I've encountered recently...

The driver is mounted in to a ported enclosure, the ports vent in to a sealed enclosure. See my attachment for a (dodgy) pic. the effective box size varies with frequency, due to the vent tuning.
I think you'll be disappointed with that, only because of marginal gains from such a large enclosure. Your cars are smaller than ours.

If you have a trunk (or boot) you could build an aperiodic enclosure. It's basically the smallest possible sealed enclosure that vents through a mat. The vent does not play into the listening area.

It won't work with a hatchback, the vent needs to be isolated.

Many in the US use a section of yellow commercial insulation sandwiched between window screens to get the same effect that box purportedly has, but without the bulk. You need a driver whose Qts is less than 0.45 (the lower the better), and as much excursion capability as you're willing to pay for.

It's not a loud alignment by any means, but is the most accurate. Tuning is a major pain, you have to remove the mat and adjust the amount of material in it until you measure a flat impedance curve with a frequency sweep.

If you're still interested in trying it, here's a pictorial of one of the cleanest Aperiodic build ups I've seen, uses xtant subwoofers. His midbass up front also uses aperiodic mats.
richie00boy
quote:
Originally posted by calum112
An inusual design I've encountered recently...

The driver is mounted in to a ported enclosure, the ports vent in to a sealed enclosure. See my attachment for a (dodgy) pic. the effective box size varies with frequency, due to the vent tuning.

I can't see any real benefits of that design over simply making the box that big in the first place. It might get you a little more power handling in a smallish region above the vent tuning frequency, but this will be offset by the peaky response and shelving roll-off action.

Nothing more than a nasty boom box IMO.
calum112
quote:
Originally posted by beerman
I think you'll be disappointed with that, only because of marginal gains from such a large enclosure. Your cars are smaller than ours.

If you have a trunk (or boot) you could build an aperiodic enclosure. It's basically the smallest possible sealed enclosure that vents through a mat. The vent does not play into the listening area.

It won't work with a hatchback, the vent needs to be isolated.

Many in the US use a section of yellow commercial insulation sandwiched between window screens to get the same effect that box purportedly has, but without the bulk. You need a driver whose Qts is less than 0.45 (the lower the better), and as much excursion capability as you're willing to pay for.

It's not a loud alignment by any means, but is the most accurate. Tuning is a major pain, you have to remove the mat and adjust the amount of material in it until you measure a flat impedance curve with a frequency sweep.

If you're still interested in trying it, here's a pictorial of one of the cleanest Aperiodic build ups I've seen, uses xtant subwoofers. His midbass up front also uses aperiodic mats.
I've tried a few different ported and sealed boxes and I do prefer sealed however trying an aperiodic enclosure is attractive. I've got a hatchback so if/when I get something where I can make one ten I'll give it a shot, IB will also be on the cards.

quote:
Originally posted by richie00boy


I can't see any real benefits of that design over simply making the box that big in the first place. It might get you a little more power handling in a smallish region above the vent tuning frequency, but this will be offset by the peaky response and shelving roll-off action.

Nothing more than a nasty boom box IMO.
You can tune it such that it acts like a large box for low frequencies and a small box at highs.
I've yet to try it so cannot comment on output properly, two reviews I've read have both rated it very highly. On paper you can get it to have near enough the same response as a normal sealed enclosure however with exended reponse on the lower end. You do get a peak a bit above tuning however if you design t such that it's above 100Hz then it's not a problem.
All in all it doesn't hold anything over a ported box, on paper, but then neither does a normal sealed enclosure.

Worth a shot me thinks :).
richie00boy
I appreciate how it acts like different box sizes for different frequencies. What I'm getting at, is that is largely pointless.

The response will not be extended down below what a sealed box of the same size gives, nor will power handling be increased. And a bit higher up in frequency you get a peak that is not present with a sealed box of the same size. It all seems a bit pointless to my mind, then again I'd rather have SQ over boom.
calum112
quote:
Originally posted by richie00boy
I appreciate how it acts like different box sizes for different frequencies. What I'm getting at, is that is largely pointless.

The response will not be extended down below what a sealed box of the same size gives, nor will power handling be increased. And a bit higher up in frequency you get a peak that is not present with a sealed box of the same size. It all seems a bit pointless to my mind, then again I'd rather have SQ over boom.
Ah I see what you mean and I have to totally agree with you. I guess, as with all box designs, it's a trade-off.
I personally like the response of a large sealed box and that of a small sealed box; any chance to have a bit of both is a bonus. I appreciate what you're saying about the peak though.
I can't really argue further than the above as I haven't tried it, when I do I'll try to remember to post a review, which ever way it falls :) .
beerman
My thoughts on that box:

It will result in added group delay, resulting in a bit of an "echo" effect with the lower frequencies, like a ported enclosure.

Considering your small European hatchback and your love of sealed enclosures, it might be to your benefit to manipulate the signal to the amplifier as opposed to manipulating the air mechanics at the woofer side. I would prefer a linkwitz transform circuit to make the sub sound bigger while maintaining the sound quality you prefer and maintain a usable trunk, er, I mean boot. :D

Then back the gain off on the amplifier, so the LT effectively attenuates the signal to the woofer at higher frequencies.

Then again, cabin gain (car interior/woofer interaction) will have a much larger effect on what finally arrives at your ear. It's why many car-specific woofers result in 55hz F3 when Qtc=0.7, most cars begin "gaining" at 12db/oct in the 50-60hz range. Making a subwoofer with flat response down to 20hz in a large room makes a sloppy sounding box in-car.

In a nutshell, just build a bigger box (Qtc=0.577) and deaden the heck out of your up-front midbass installation, make it reach down to 60hz without rattling or popping.

Leave that snake oil box alone.
calum112
quote:
Originally posted by beerman
My thoughts on that box:

It will result in added group delay, resulting in a bit of an "echo" effect with the lower frequencies, like a ported enclosure.

Considering your small European hatchback and your love of sealed enclosures, it might be to your benefit to manipulate the signal to the amplifier as opposed to manipulating the air mechanics at the woofer side. I would prefer a linkwitz transform circuit to make the sub sound bigger while maintaining the sound quality you prefer and maintain a usable trunk, er, I mean boot. :D

Then back the gain off on the amplifier, so the LT effectively attenuates the signal to the woofer at higher frequencies.

Then again, cabin gain (car interior/woofer interaction) will have a much larger effect on what finally arrives at your ear. It's why many car-specific woofers result in 55hz F3 when Qtc=0.7, most cars begin "gaining" at 12db/oct in the 50-60hz range. Making a subwoofer with flat response down to 20hz in a large room makes a sloppy sounding box in-car.

In a nutshell, just build a bigger box (Qtc=0.577) and deaden the heck out of your up-front midbass installation, make it reach down to 60hz without rattling or popping.

Leave that snake oil box alone.
That is a fair point. I do much prefer good midbass upfront with the LPF to the sub set low. Ahh soo many variables to play with :D
richie00boy
From the sound of it you like a deep bass that is lean and tight, but also one that can be punchy. This kind of goes against each other.

My suggestion would be to build a (large) sealed box to get the lean and tight bit, then dial in a bit of punch with parametric EQ, and/or maybe a slightly peaking high-pass filter.

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