Enclosure for deep bass.

[Witty690 10+ year member]

Everything you want, you will get with a low tuned ported enclosure.

Sealed wont cut it, but i wish you luck anyway.

 

[SubsonicSounds 10+ year member]

I'm not telling you not to use the type r... I'm just simply stating.. go ported.
... I calculated...

(1) 10" Alpine Type R in a 20cuft. enclosure SEALED ( WOW! )... would be 30.88hz capable.

... Have fun with that.

* 666 post ... That's not a good number *

I think you are trying to get me a resonant frequency. Resonant frequency is more important in a vented enclosure, as the port lenght causes an inherent steep roll off below that frequency. Out of phase sound wave cancellation is a killer.//content.invisioncic.com/y282845/emoticons/tongue.gif.6130eb82179565f6db8d26d6001dcd24.gif

Don't let that above number mislead you. I promise that in my current sealed 1.06 cubic ft. enclosure, I can produce enough sound pressure at 18Hz to make it clearly noticeable. I have had 20Hz prompt people to say, "what the heck?" But outside of getting a meter right now at 3am, I cannot make you see that these frequencies are possible from this sub. Granted they are not loud, it is enough to make trunk panels move.

You may still be thinking that this is minimal sound, and compared to your system, im sure it is. But getting the bass to extend low is interesting to say the least.

 

[SubsonicSounds 10+ year member]

Everything you want, you will get with a low tuned ported enclosure.
Sealed wont cut it, but i wish you luck anyway.

I agree with you on the first part. However, in creating a very low tuned vented enclosure, you need to create a vent that is long enough to support the incredibly long wavelengths (that I am for some strange reason going for), by keeping "out of phase waves" from the rear of the speaker from negatively interacting with the "in phase" waves coming from the front.

From my understanding, this is only done by allowing enough time to pass for the "in phase" wave eminating from the front of the speaker to oscilate and become better aligned with the wave coming from the port.

The only way to do this that I can presently concieve of is to create a vent long enough for these long wavefronts to better align themselves, i.e. T-line.

I can see how certain types of more conventional ports could increase internal air pressure by restricting the flow of molecules, thus creating a higher velocity, and shortening the time elapse requirements of the rear-of-cone wave front. But I believe that this would add a variable that might be incredibly difficult to analyze by increasing back pressure on the cone. Anyone well versed in fluid dynamics?

 

[Rashaddd 5,000+ posts]

OP, go with a sealed box.

1. its clearly what you want, so just do it, its easier to mess with anyway than a ported one. You can even build a big one and fill it with solid objects to adjust box size and figure out what kind of differences in freq response you get depending on box size

2. I'm pretty sure I know what you're talkin about with the low "earthquake" type feeling you get from 15hz-25hz, and it seriously can be sick

3. Yes he can get a ported enclosure, but its not going to do what he's looking for very efficiently unless he tunes it to ~20hz

4. I was able to get some serious lows (20-30hz) with a couple sony xplods in just 1.15 cubes each sealed...I'm sure you can do it with some nicer subs, but seriously...just buy an mj 18 or a cheap 15 or somethin. I don't see any reason to attempt it with a single not-so-great 10" sub...thats like trying to use a bicycle to break the world record for land speed. You might as well start with an advantage at least.

(video of some of the lows ur talkin about with my old xplods, now sold and gone)

 

[helotaxi 5,000+ posts]

I agree with you on the first part. However, in creating a very low tuned vented enclosure, you need to create a vent that is long enough to support the incredibly long wavelengths (that I am for some strange reason going for), by keeping "out of phase waves" from the rear of the speaker from negatively interacting with the "in phase" waves coming from the front.
From my understanding, this is only done by allowing enough time to pass for the "in phase" wave eminating from the front of the speaker to oscilate and become better aligned with the wave coming from the port.

The only way to do this that I can presently concieve of is to create a vent long enough for these long wavefronts to better align themselves, i.e. T-line.

I can see how certain types of more conventional ports could increase internal air pressure by restricting the flow of molecules, thus creating a higher velocity, and shortening the time elapse requirements of the rear-of-cone wave front. But I believe that this would add a variable that might be incredibly difficult to analyze by increasing back pressure on the cone. Anyone well versed in fluid dynamics?

You are only partially getting how a ported enclosure works. There is no reason to consider a T-line or any 1/4 wave design. The resistance of the port and the effect of that resistance from a given area and length relative to a given enclosure volume is very predictable and well modeled by the standard enclosure calculations. But I still agree with you that a sealed enclosure is the way to go for the really low stuff.

NissanKicker obviously has no idea what you're talking about, nor how to properly model a sub system for use in a car. He seems to not understand the effects of cabin gain and why an F3 of 50hz in no way keeps the system from reproducing frequencies well below that with authority from a sealed system while the same cannot be said about most ported setups below tuning.

Since you really just want to hear the low stuff and not really be abused by it, a decent sized sealed box with moderate power should get you where you want to be or at least as close as you'll get with that sub. More cone are or excursion capability or both would help you out a lot towards your goal, though.

Really like the choice of music. I listen to everything (almost) as well and I really like Techmaster P.E.B. and have for years.

 

[Krown 10+ year member]

Don't forget that using enough polyfil will basically "enlarge" the enclosure.

 

[NissanKicker 10+ year member]

Helotaxi:

... for one... I do know what he's talkin' about and tryin' to accomplish.

Quote:

" I don't see any reason to attempt it with a single not-so-great 10" sub...thats like trying to use a bicycle to break the world record for land speed. You might as well start with an advantage at least. "

BINGO! - the note to going to be faint. only thing that was mentioned was, I wanna hit the LOWS!.... earthquaking effect bass... go ported... Easiest way.

NOW!

... As far as a sealed hitting lows, that's no doubt. sealed has a fuller range on music OVER port-tuned enclosures. I had 4 cvx 12s and you felt 15hz like a 30hz note. I'm not denyin' nor taken anything away from a sealed enclosure nor his ideas. I'm just simply stating " if you feel it can be done, do it. I showed him the enclosure needed... If not, I'll tune it to 20hz ( for a 10... I don't know why but ok ).

As for as a T-line box, there's no need and I don't have to speak on that ( that's been taking care of - Helotaxi )... ALL & ALL, there's a simpler way to do it. But as you stated - Just for knowledge and a better understanding.

GoodLuck Bro.

 

[SubsonicSounds 10+ year member]

You are only partially getting how a ported enclosure works. There is no reason to consider a T-line or any 1/4 wave design. The resistance of the port and the effect of that resistance from a given area and length relative to a given enclosure volume is very predictable and well modeled by the standard enclosure calculations. But I still agree with you that a sealed enclosure is the way to go for the really low stuff.

You are absolutely correct. I think i am only partially understanding how a ported enclosure works (i do mean in relative terms). That is one of the reasons why at this point I am opting to avoid the ported enclosure. I'm somewhat concerned with the effects on the waves during the compression and subsequent decompression processes through the restrictive points encountered while exiting the enclosure. I know that there is research out there, and I know that many on this forum can help me understand, but that is for another day. I'm hoping to go that direction after I have a sealed setup completely figured out.

Really like the choice of music. I listen to everything (almost) as well and I really like Techmaster P.E.B. and have for years.

P.E.B. was a talented composer, with unmatched mixing abilities for his time. Some of his work was capable of putting me in a dreamlike state LOL.

Nissan, I do believe that you understand what I am interested in accomplishing, and I thank you for wishing me luck. I think it will be needed in finding someone to construct my enclosure around here where I live. //content.invisioncic.com/y282845/emoticons/smile.gif.1ebc41e1811405b213edfc4622c41e27.gif

 

[helotaxi 5,000+ posts]

Helotaxi:... for one... I do know what he's talkin' about and tryin' to accomplish.

If you're recommending a ported box tuned to the high 30's, ummm, no, you obviously don't. Even Alpine recommends a lower tuning, and my experience has shown the manufacturer spec enclosures are usually a little small and tuned a little high. Better SPL, which is what most people want. Tuning higher than that is only going to make the response peak bigger and steepen the rolloff below that. The effect would be to cut the lows even more, which is definitely not what he was looking for.

There's no reason that sub shouldn't be able to go well below the audible spectrum in-car in a sealed box. It isn't going to really take your breathe away because it's still just a 10, but it'll still ba able to get down there. Cabin gain will help it out a lot in that regard. Pretty much any sub will be able to go below the audible range sealed in a car.

 

[BEAVER.989 10+ year member]

I also recommend a low tuned ported enclosure. The problem with building a larger sealed box with q approaching .5 is that you'll quickly run out of excursion while trying to reproduce the lowest octaves.

With a ported enclosure excursion is significantly reduced near the tuning frequency which allows you to apply more power. This, along with the increased efficiency of the ported design is going to best accomplish what you're after, IMO.

 

[SubsonicSounds 10+ year member]

... Even Alpine recommends a lower tuning, and my experience has shown the manufacturer spec enclosures are usually a little small and tuned a little high. Better SPL, which is what most people want. Tuning higher than that is only going to make the response peak bigger and steepen the rolloff below that. The effect would be to cut the lows even more, which is definitely not what he was looking for.
There's no reason that sub shouldn't be able to go well below the audible spectrum in-car in a sealed box. It isn't going to really take your breathe away because it's still just a 10, but it'll still ba able to get down there. Cabin gain will help it out a lot in that regard. Pretty much any sub will be able to go below the audible range sealed in a car.

You have seemingly pinpointed exactly what i am trying to accomplish and why I would attempt it. I thank you for taking the time to evaluate what I am attempting, and acknowledging it pheasability. I agree with your theory on manufacturer recommendations. The are most likely trying to "impress" the customer, rather than prompting the flattest possible frequency response without rolloff.

 

[SubsonicSounds 10+ year member]

***New Question*** In a rectangular enclosure, is there a problem mounting the driver closer to one end of the enclosure, or does it need to be centered to eliminate uneven pressure on the back of the speaker? In other words, will I cause unwanted damage or distortion by having the speaker close to one end of the enclosure?

 

[BEAVER.989 10+ year member]

I recommend that you download WinISD (it's free) and model the sub in a variety of enclosures to see for yourself exactly what you can expect to get out of a given enclosure.

 

[BEAVER.989 10+ year member]

***New Question*** In a rectangular enclosure, is there a problem mounting the driver closer to one end of the enclosure, or does it need to be centered to eliminate uneven pressure on the back of the speaker? In other words, will I cause unwanted damage or distortion by having the speaker close to one end of the enclosure?

Stuff the sub all the way to one side. How else are you going to have enough room for that port? //content.invisioncic.com/y282845/emoticons/wink.gif.608e3ea05f1a9f98611af0861652f8fb.gif

Seriously, it won't hurt anything to do it that way... even if it's sealed.

 

[SubsonicSounds 10+ year member]

I'm not doing the ported. Im actually doing the sealed, and my current drawing has it all the way to one side for better in vehicle location. However, it seems that on the rear of the cone (the part exposed to the inside of the box), the side that is close to the side of the box will not recieve as much reflected wave energy as the side that is more open to the bulk of the enclosure.

Im afraid this may cause lateral movement of the cone, which would cause voice coil deflection, and therefore causing a decrease in motor efficiency, and possibly some rubbing issues between the voice coil and magnet. It would be like putting your hand on one side of your cone and pushing it back. The uneven push causes lateral movement that causes an audible scratching sound between your v.c. and magnet. This is damaging the coil, and if the speaker were playing, temporarily destroying the overall geometry of the motor structure.

I have already ordered the box, so i guess im just hoping that I am wrong.

Maybe the air inside the box will do its job of equalizing in air pressure causing a balanced push from all directions. Yes/No?

Maybe the pressure will be low enough not to significantly effect cone movement.

Maybe I think too much. Anyone in the know?