Dammed

I have read it, and yes I have agreed to it. And yes I was misusing your definition of the terms. Which I find retarded, but yeah, not my forum. Everywhere else in the world SQ stand for Sound quality and SPL for sound pressure level, but apparently not here. You will not see me using those terms since they apparently are meant to be only used by people building SQ and SPL car audio systems for competition. If you want a better explanation without using the term SQ, """"SQL"""" or SPL here it is: I want my subwoofer to reproduce the bass in music correctly without any distortion or inaccuracy. I want them to sound good, not loud. As I said earlier my focus is sound quality. I want my system to sound good. Not to compete in SQ contests, but just plain and simple sound good. But I want to be able to turn the gain button all the way up so that my system can play loud. This is as I said not my primary goal. I like lots of bass at times, but I find myself more often turning the gain down and drive to school listening to music on a "normal volume". Meaning so low that you could talk to the person sitting next to you without any problems. And this would be SQ as you define it, to reproduce music as it was recorded as exactly as possible. Like I said earlier, still curious why I shouldn't use a tuning of 28hz? That was the idea, I was going to buy a amplifier that was much more powerful, and then I'll turn the gain down so that I can keep it cool, have enough headroom and be a bit future oriented so that if I find that I want it to be louder, which I really doubt, then I will be able to purchase some other subs and still use this amplifier to power them.

Will do. I'm thinking about making some sort of frame around it and then bolt it to my car, but I'll check around to see what other people have done as well. My questions was actually how big difference it is between sealed and vented if you want to subs to hit hard at low frequencies. Because if a sealed enclosure could make the subs hit hard at 25-30hz, I would of course built it then a vented one. Cause I'm not looking to have a lot of sound pressure, my goal is a good sounding system with the ability to hit hard at low frequencies. Since I'm gonna use a 3200W rms amplifier I'll get some sound pressure either way. So I wasn't having that as a primary goal. I started this topic becuase I was afraid that if I made a sealed enclosure that it wouldn't play well on low frequencies.

I read them a long time ago. I think you should check out the newbie forum as well, becuase you have a hard time staying on topic. And I knew what SQ and SPL stands for before I joined this community. Sound quality and Sound pressure level. SQ doesn't necessary mean as low DB as possible. That's bullshit and you know it. While SPL does mean as loud as possible without any consideration to SQ. Now, tell me this what's the problem with a system that sounds good and has a possibility to go loud, otherwise known as ""SQL"". Many HiFi brands have always been searching for ""SQL"", loudness without loosing sounds quality. You could argue that they are built for SQ and that they go loud. But many are trying to achieve just what I said loudness without loosing sound quality. And they state it in commercials and intros on their new catalogs. I have listened to HiFI speakers where your ears starts to hurt, but the mids and tweeters were still giving a really good SQ. Do you mean that's SQ or ""SQL"", ore even SPL since they get fairly loud? This discussion is fairly off topic, and has nothing to do with my thread. If you read the post here, less then 50% are on topic. The topic is even ridiculously easy, vented or sealed enclosure and how the subwoofers behave in each type of enclosure. Yet, many people including you are starting a stupid off topic discussion about my front stage and what SQ/""SQL""/SPL is, and some are even stating they know my car better then me and that I don't have room for a big enough ported enclosure. To return to the topic: I was gonna tune the enclosure to 28hz because: 1. Fi recommended it, and if someone knows the Fi products it should be them. I can't give any other reason, becuase I can only relay information I have read, and since it's not my own experience I can't thrust that information to be 100% correct. I could google "enclosure tuning" and write it down here like any other person what I read on the links, but I have no reason to do so. I have no reason to prove anything. This topic was created to seek information about this, and if you don't want to share information that's fine. But don't spam other questions instead of providing information. My questions still stands, why do you think that a 28hz tuning would be a bad choice?

It was a guess by eye that I have around 20-25ft3, I measured it now and I actually have room for a 30ft3 box (internal volume). Fi recommends 6-10ft3 per sub, so I should have more then enough room to build a 20ft3 box + port tuned to 28hz. So I'm going for a big vented box, wish me good luck, first time building a wall. I'll be posting a building thread in the future, have to wait a bit before I begin becuase it's -17/-25C here right now. thx for the replies. P.S. still a bit curios why M5 thinks a vented box tuned to 28hz would be a bad choice...

Yep, that's why the title is vented or backseats, like you said if I want to keep the backseats, I have to go with a sealed enclosure. So a vented enclosure plays better at 30-45hz, does music go much lower then 30hz? M5, why shouldn't I put them in a vented box tuned to 28hz?

Man this is such a stupid discussion, every time someone says they want SQ and a bit loudness you give almost the same speech. That it's impossible or that they really want loudness. There are many songs when the sub is louder then the mids, so I find that argument a bit strange. I want good sounding subs, I don't want a SQ setup. But I don't want a SPL setup. I want good sounding subs that can be louder then my front stage the times I want to be showing off or just crank them up a bit. But I want to have a sytem that can play with a nice sound at low volume. After all the gain remote to the sub amplifier is the thing that will be deciding if the sub are louder then the mids or not. And what has my fronts to do anything with this this problem. It's like going to a shop asking for good shoes and the seller says, forget the shoes, you need a better jacket? I understand that the front stage, subs, HU, deadening, etc etc plays together to make the system, but the question is still about two 18" Q's in a vented or sealed enclosure? And what I should expect from each choice.

It is a Celica. And with the back seats out I could have 20-25ft3 box. People underestimate how much room you have in a celica. The Q's are bought, so I'm using two 18" Q's, that's out of the question. And I was thinking about 28hz. I have only had a 12" in a sealed box, so I have nothing to compare to. The question still stands, big vented box or a 10.24/12ft3 sealed box. How big difference would it be?

Yeah, but then my car becomes a car audio car, not a car with a good car audio. If you know what I mean. And I won't have any space to put stuff to carry with me, like grocery bags. But I will have a pretty cool car... And how low can you tube the Q's, is there a limit, what's the gains/loses to tune really low? I was actually thinking about sending you a PM... Did you have the 18" Q in a sealed and vented enclosure or just vented? A bit curious regarding vented VS sealed and how they perform in those two types of enclosures.

it will be upfiring, As you can see in my first two pics the port is facing upwards and the subwoofers will be facing the same way. I have talked to some other people, and one of them has built a port that was 1,2" x 19,7" and he didn't get any noise. So I'm pretty sure it's doable without getting port noise, he said just flare the ends and build the bend with a PVC pipe and it should be fine. Then he said that a 133,9in2 port was way to much, since I had to build it 31,5" long to get a tuning of 28hz, he advised me to build a 77,5in2 that it would be enough for two 18" and 3000W rms.

I'm going to make a enclosure that will use almost all of my trunk space, so I'm going to make the bottom out of fiberglass so that I can use the space from the spare wheel well. The port have to be so long that it will close off 1/3 of the opening of the spare wheel well. Few pictures to illustrate the problem: from the side From above: Will this be a problem? And how will this affect the subwoofers?

school cop, hehe man that concept is lame. You discuss air movement and air characteristics with a Fluid Mechanical Engineer to find out if your port is good enough.

good to know. I'm going to power two 18" Q's with a Hifonics XX Colossus II that gives about 3200W rms. A bit overpowered but I'll just turn down the gain a little and be careful with the volume button. about the subs, what kind of music do you listen to? Are you planning on using a vented or sealed enclosure? I went with the Q's becuase I wanted something that has a nice sound to it. Because after all 3000W rms is loud enough IMO no mater what sub/subs you buy. The Q's are kinda like a Bently that drives like a Subaru rally car, best of two worlds, comfort, speed and handling, or in this case: loud and SQ. At least that's my impression after reading reviews and DB results.

check out the "Help Me End My Search!" topic in this forum for suggestions for new subs. A bit off topic, how much could the Q's handle with the BP power upgrade?

-forum error- please delete reply.

yeah a 13.5" square port would be best, but my problem is space. I could throw out my back seats to make a bigger enclosure and then I could have a more square like port, but I'll rather not do it. It's good to have back seats in the car. My space in the car (the measurements are in cm): The enclosure I was planning: (the wall in the middle will not be built, I'll use some threaded rods instead) As you can see the space is quite limited, are you sure that there will be port noise? What if I flared it at the openings and made the walls smooth with some filler and paint? I'm also open to suggestions on how I should build the enclosure, if someone has a tip or two.

a slot port and aeroport is different just like the resistance provided by a canal to water and a port to air is different considering the density of water and air molecules. (air travels much easier then water through tight gaps) But my point was if I made twenty 3" x 3" square ports witch has a area of 9in2 x 20 = 180 in2, how is that any better then a square port that is 3" x 60" with the same area? The space between the 60" sides is 3" same as the space between the sides in a quadratic 3x3" port, and even better, you have only 4 sides instead 80 sides. The air traveling through the 3x60" port must have a better air speed considering you have a lesser side area that contributes to slow down the air. Now if there are other factors that comes into play here like turbulence or something else then I would understand it, but if the only argument is the resistance the "tight" gap provides, then I'm unsure if the statement about the ratio is correct. I will ask my professor in fluid mechanics as well to see what he thinks, but this "rule" sounds a bit strange to me.

I found out that with a small redesign I'll have room for a 133.9 in2 port. (3.54"x37,8") in a 10.24ft3 box, that would be 13.08in2/ft3, which is within the 12-16in2/ft3 limit that people here and makers of subwoofers recommend. But regarding the ratio, which is still something I believe to be kinda strange, Since I can make a port that's more then 3" from side to side, why would it produce more noise then a 3" aeroport if I keep the air velocity low? And regarding the tuning, if I use fiberfill inside the box what volume should I use to tune the box, the physical volume or the volume I get after the fiberfill has been added? Could someone please help me out here, I don't have any experience with vented enclosure and I don't want to waste material making something that will not work.

hmm, I can make a 110 square inch port, would that be enough? If not, how big port opening should I have? I used this calculator: Public - Windows Live Made by a guy named Torres on the S_M_D forum. Data: height x width x depth 23.622" x 41.34" x 21.654" port: height x width x length 2" x 40" x 25 Subwooferne displacement: 0.5 cu ft This is a slot port and it has a bend and wood thicknes: 0,75" gives me 27.92hz edit; Regarding the 1:9 ratio: "The ratio of W to h should not be any more than 9 to 1 to prevent tuning shifts introduced by excessive friction between the rapidly moving air and the port's surface. It should be noted that this is not a hard-and-fast rule, merely a rule of thumb to help you prevent a mis-tuning. " source: http://mobile.jlaudio.com/support_pages.php?page_id=165

But why, if you increase the port area shouldn't it reduce the air velocity so that the air traveling through a tight gap will move slow enough so that it doesn't make any noise? Any way I can counter this effect? Make rounder edges / smoother walls? And how should I calculate the tuning or is it correct?

good. About the tuning, I used a program that calculated that I needed a port that's 25" long, when the opening is 2" x 40". But I have read a couple of places that the opening should not have a larger ratio then 1:9 between the width and height, and I have a ratio of 1:20. Is the tuning correct? The maximum size I can make the opening in the front baffle is 2,75" x 40" And regarding the air velocity through the port, how should I calculate it? Info about the system: two 18" Fi Q's powered by a Hifonics Colossus II amplifier that gives 3200W rms in a 10.25 cu ft enclosure filled with Fiberfill.

The bxi2010D should do around 1800-1850 true watt rms if I'm not mistaken. I had two Zeus amplifiers and they worked good, the new amplifiers coming this year are getting some upgrades, better cooling and maybe better power supply. I wouldn't hesitate buying one Brutus amp. But if you want true 2000W rms, then I would go for a 2610D, you should get at least true 2300W rms.

Metallica - That was just your life

I have a question that maybe that TS maybe is wondering about as well. Would a sealed enclosure be any good if you listen to mainly rap?

I would go for a Q over the BL, becuase I read the reviews of it, and it got loud and it was a nice thight sound from it. And for the Q 900W rms should be enough. It's rated to 1000W rms. I myself just ordered two 18" Q's.