I need help / advice finishing my system!

[ramos 5,000+ posts]

Wow.... awful lot of assumptions being made itt //content.invisioncic.com/y282845/emoticons/frown.gif.a3531fa0534503350665a1e957861287.gif

 

[CamJ256 10+ year member]

Also, I have been doing research...as much as possible for a student at the moment. I did know that sealed enclosures were less efficient. The EBP made it look like this sub could go both ways. I looked to see what other people were doing with this sub but I mostly found home audio people. A few guys on youtube with ported enclosures in their cars.

If the research I have done (thus far) has taught me anything its that I won't be designing a 'perfect' enclosure by myself anytime soon. Especially since I am just using google and and sifting through forum posts. I find there is a ton of misinformation as well. (if you have any recommended reads please share) I have an undergrad in Computer Engineering (not comp sci!). I have been able to pick up quite a bit pretty fast but I don't kid myself that I'm going to understand it like an acoustical engineer or even someone who has been doing this for many years. I think acoustical engineering is one of the more difficult subjects to study. Its crazy how some people can take something as simple as a subwoofer box inside an SUV and turn it into a "masterpiece" of engineering with perfect frequency response for their application.

This afternoon I took my car to the local audio shop looking for feedback on the sub and a possible enclosure. Unfortunately, they said they don't build boxes. The guy working was busy and basically wrote me off after he realized I wasn't going to be buying anything. The next nearest place is about an hour away and I've never been there.

Anyway. I'd just like to buy something online. And soon. I'm not looking for perfect by any means. I just want to get the most out of my money....and make sure it doesn't sound like a turd by putting it in the wrong box.

Perfect size for my car would be 36x24x18. (LxWxH)

 

[FtheNutHuggers]

My recommendation in most cases is to take the enclosure blueprint to a local cabinetry shop. Express the extreme importance of surgical precision of dimensions, cuts and assembly; that nothing can be off by even a fraction. See if they are willing to take that extra time to do precision work. Most of the time, they seem to be less expensive than a local car audio shop, which has one goal.......make as much money as fast as possible. So precision is not normally the goal, but selling you "carpeting" or "bedliner" sure is! (The kind that covers up all the oopses and mistakes.)

Again, you can choose to go wherever for a design, but unless you know what to ask, you'll never know their level of qualification/ proficiency. I've got a lot of friends that can BUILD a box beautifully....masterfully even. Gorgeous cuts, perfect seams. Artists if you will that pour their soul into each piece. If it was a turd in the performance category, it'd still be the most beautiful turd known to man. Case in point: look at 99.9% of the fiberglass enclosures out there. Extremely rare is the one that has been precision designed based on anything beyond the simple "can it fit and will it look good" mentality.

Just as QTS numbers 10+ years ago were the determining factor for what type of box the sub HAD to go in, based on a history of misinformation and a lack of serious engineering in the field at the time, EBP has taken on the same role. It is still wrong. If you pay close attention, you'll see that most would-be gurus will still say that a sub has to be either in a sealed enclosure or a ported alignment. Simple questioning would quickly chop the legs out from under that table. There are so many factors that go into the determination of which alignment will yield results closest to the purchaser's request that none of those gurus would know where to start. So, it may take another 10 years before common knowledge says that EBP is not the determining factor......and when I say "common", I simply mean the time when most enthusiasts know that. But the same 50+yr old misinformation keeps circulating and the average knowledge barely goes up. When someone comes in with provable data, they are beaten with flip-flops by everyone who believes they know better or are scared sh!tless that they will no longer be the one to go to. Being rendered obsolete is a fear of almost every human being is it not?

Now that we have YOUR max dimensions, that's great......but does DC have T/S parameters listed for the inbred baby you have there? An engineer cannot use "X motor and Y soft parts". Those soft parts have no value until they are put into the motor, just the same as the motor has no real value until soft parts help define it. A battle axe looks kick @ss on the wall, but you'd hate to pull it down for a fight to find out that you are to be pitted against 3 midgets on 4 wheelers all armed with automatic shotguns and M134's. An engineer needs those parameters to be able to model anything. If they are not available, the sub is just a paperweight that moves back and forward with AC voltage.

 

[FtheNutHuggers]

Also, remember to change the dimensions to W x D x H.......in whatever order, but when Length is a substitute measurement, it can confuse people. Width, Depth and Height are nearly impossible to misunderstand. The Width is always side to side in the vehicle, no matter which way the sub faces, the Depth is always front to back and the Height.....impossible to screw up.

Another Also; why must the sub fire up? That is another massive blow to the design, essentially tying an arm behind the back of an MMA fighter. Where the sub faces is an aesthetic request, which is totally opposite of a performance request. Sometimes the optimum design ends up matching an aesthetic wish, but requiring that is totally handicapping the potential performance.

Hit the link here: HexiBase's Channel - YouTube

It describes how the subs location on just the same axis changes audible response at the headrest. Fire the sub off axis by 90 degrees and you shift the response heavily. Sometimes it is required to reach the goal, same as moving a port or waveguide to a different plane. Everything changes if anything changes. You know this by taking your box and sticking it in your buddy's SUV.....sounds TOTALLY different, yet the sub didn't change, the box didn't and you could have been running it on a long wire off your amp! Why does it sound totally different? Cause the shape and integrity of the vehicle is the last chamber of the box and the test mic (your ears) is in a specific spot INSIDE that chamber. Move the listener, the sound changes.....you know this by listening at the driver seat, then hopping in the back seat and listening....different sound. Roll a window down and you change the alignment again by adding a passive radiator to the final chamber. All those things are calculated and every spec of the sub helps determine what enclosure it will take to make your request a reality.

 

[FtheNutHuggers]

Oops, wrong video.....but a good explanation none the less. The correct one is here: HexiBase's Channel - YouTube.

 

[CamJ256 10+ year member]

Well I didn't know it would make THAT big of a difference to have it fire up. I said that because I want to actually be able to use the other half of my trunk and not have to worry about driving around with a few folding chairs touching the woofer. Almost every weekend I have a car full of friends out to the lake I live by for the night.... Usually just a bonfire and drinking. I would not be happy if some drunk person threw a cooler or chair in there fast and it caught the woofer and tore it. (myself included)

 

[FtheNutHuggers]

Ok, handicap noted. Dimensions noted.....where is this shape's proposed positioning? Is the box all the way against the driver side or passenger side? All the way against the rear seat or butted up against the back hatch?

 

[CamJ256 10+ year member]

I am surprised at how much I've overlooked. That video was great by the way. I've been just f5'ing here and watching his vids since the first you posted.

Ummm. If I use the full dimensions I listed it will go entirely from the rear seat to the rear hatch. If the box ends up being smaller it will be pushed to the rear seat.

I'd like to keep the box on the passenger side.

 

[FtheNutHuggers]

Ok, now just to make sure, at the height you gave (18"), did you measure your depth (front to back) at that height? Many mistakes are made when folks don't measure at their max height, not accounting for the angle of the rear seat reducing depth as the height increases. If so, just for sake of laziness on my part.....can you re-post the maximum dimensions......if you didn't account for the tapering depth.....then give the new dimensions.

Next question: What system have you heard in the past that you thought would be a great performance (volume) level for your preference? We already know you need something that plays relatively flat between 35Hz and 70Hz.....maybe extending to 80Hz if it does not significantly decrease output in the lower octave. Did you hear two Kicker 12L7's in a big ported box in the trunk of a cadillac or an 18" Solo X in the back of a Tahoe? This gives me a reference for expectation.

 

[FtheNutHuggers]

I am surprised at how much I've overlooked.

You shouldn't be............look at how many "professionals" have been surrounded by the facts for decades and didn't see it. Look at how many now know that they are doing nothing close to what it takes to professionally design an enclosure and choose not to increase their repertoire. "It's all done through trial and error" should be your first red flag to cancel the conversation and kick rocks in the opposite direction. LOL.

I practiced what I had been told by those that knew something more than I did in some category or another. The more I practiced acoustic theories passed down by these guys, the more I noticed they were not correct and that they, like everyone else I've met were trying to cover everything with a blanket statement or blanket recommendation. Every real variable is easily proven by even a kindergartener to have an effect on audible response. Why then does EVERY manufacturer still say that X sub needs to be put in Y box? They know with a 20 second test that their theory can be shut down. Fear of the unknown? Fear of losing face? 20 year old mistakes are still being practiced today and the blind who would lead the blind keep selling the bs. How else do religions still have steam?

 

[Nut Hair Trick 10+ year member]

FtheNuthuggers is probably one my favorite and most knowledgeable posters on this board. I have tons of questions to ask him but hell, I have no clue on how to go about asking. As far as taking cabin space into consideration in respect to the sub you are running and it's parameters.... is it total cuft of space in the cabin that you look at? I noticed you mentioned in someone else's thread about them having 4 doors vs 2. How do you take listening distance, cabin space, and God knows whatever else, and come up with specific enclosure type, size, and orientation? How do you put these things together, because I would like to know?

 

[CamJ256 10+ year member]

Yes I did take the seat into account. (it actually makes a 4 inch difference.)

So its still 24x36x18 (W x D x H)

 

[CamJ256 10+ year member]

fthenuthuggers is probably one my favorite and most knowledgeable posters on this board. I have tons of questions to ask him but hell, i have no clue on how to go about asking. As far as taking cabin space into consideration in respect to the sub you are running and it's parameters.... Is it total cuft of space in the cabin that you look at? I noticed you mentioned in someone else's thread about them having 4 doors vs 2. How do you take listening distance, cabin space, and god knows whatever else, and come up with specific enclosure type, size, and orientation? How do you put these things together, because i would like to know?

same

 

[FtheNutHuggers]

I appreciate the remarks and regards. But I request that you never take anything I type as the rule of thumb either, otherwise you've just swung to the other side of the pendulum. Look for yourself, read up and educate yourself as far as you want to. If it's not your cup of tea, that's absolutely cool.....but think about what someone is saying and if it does not make sense (because you've applied their logic in your head and are questioning it)....then by all means say something. But.....as credit to what I've learned over years of thinking on the wrong path and then pointing in the correct direction......you won't catch me saying something incorrect. If I don't know something I won't comment. If I cannot prove that misinformation spread by someone else is just that, then I won't comment until I can prove it. It's not to vulch and it's not to gain recognition anymore and it's not to troll, it's to raise the average knowledge base of enthusiasts and industry members alike....simultaneously stomping bad information. It may hurt egos temporarily, but people get over that if they really want to learn. I share and teach to learn, not just to be a soapbox hero to a group of 3-5 at a time...lol.

 

[FtheNutHuggers]

@BlackFx3inTN: Those factors and how to calculate them are not MY specialty. Knowing about their effects and making folks aware that they exist and dictate what you'll audibly experience is my goal. I learn more daily, but I'm honestly not interested enough to go jump into that field. It's too damned boring for me. The math is friggin endless. I don't enjoy math that much. When I came across PWK after being introduced by a mutual friend, I quickly recognized how firm of a grasp.....no.....rear-naked-choke he had on the physics/ science behind acoustic design. Shortly thereafter, I found out that his system is infallible, it can only spit out incorrect data if incorrect data is put in. He has to model each specific vehicle by its unique geometry and apply measured losses for each panel. Geometry makes just as large a difference in the design as number of doors, total cabin volume, seat position, accessibility or lack thereof to the cargo/ trunk area....etc. Think about this as a simple analogy:

You put an enclosure (pick a type, size "tuning frequency LOL" whatever) in the front of a 53' tractor trailer.....in one of the corners. Throw a thousand watts on it....stuff your favorite subwoofer (for whatever reason LOL) in it and let it rip. Play sweeps like 100-20Hz...over and over. Start by standing right in front of the sub....then every sweep, move two feet further away. You'll definitely notice a difference in output or intensity at different frequencies as you get further away from the enclosure. Now that particular environment has an unchanging cross sectional area......it's the same shape all the way down. That is sort of the same thing as a big pvc pipe in front of your mouth....you know if you shorten the pipe, it will sound different to the listener, even if they are the same distance from the end of the pipe. What if you change the shape of the pipe....the cross sectional area? What if it starts small at the source and gets gradually bigger? Sound like a hatchback? Sounds like an SUV too...oh....and a Sedan, Coupe etc. Each internal cabin geometry acts as a unique waveguide. Only a real acoustic engineer can calculate those shapes using @yss loads of math to determine their unique effect on sound waves as they move down the length of that waveguide. Calculate the effects of a window being rolled down or a door opening up......or the listening position leaving the car and transplanted 10' outside the driver door. You definitely know the sound changes, it is usually way less intense....but more than that, it shifts what frequencies become louder than others. And all the while, the box never changed, the sound played does not change, the amp gain setting is unchanged etc. Shape of environment means just as much for the design as the parameters of the subwoofer. It's not 10% this and 80% that....NOTHING is accurate unless you have all the information. So in effect, every individual component of the system has a 100% value. Take any single gear out of a watch and the BEEEITCH don't work, does it?