one of the birds I had back in the day had a custom box in the back that worked well and I was wondering if anyone has done this.

Go to the wood store. Ha Ha! and buy the thickest piece of plywood you can find.

cut it to fit over the rear well of the hatch. I did not ever bolt it down back in the day.

Cut holes for speakers and mount.

this provided me with unreal bass off the hatch. unfortunatly I mounted the amp under the speakers and burnt it up.

I was running MTX blue thunders 15in and I do not remember the amp brand.

this time I think I am going to seal the box with some type of glue and put a hole in it so the speakers breath and oh ya mount the amp so It can stay cool.

Let me know what ya think

 

Its called a Plate and its been done before, many times. Bluezee has one i believe. the problem is they leak air like crazy. you wont ever get the same sound quality as with a real sealed box. and even if u glue it down its gonna leak a bit. If your using ply wood to top it all off it will just be that much worse. Really the best thing to do is build a sealed enclosure to fit the well if thatswhat u want, good luck

 

dont they put holes in every box so that they can breath

 

Only "holes" I know about are ports or vents, and both are very strictly designed. If you're ports/vents are not correctly tuned to your speakers, sound will be poor and you play big odds of blowin the speakers.
Sub boxes need to be completely air sealed in order to seperate the front waves coming from the front of the speaker from the rear waves coming from the back of the speaker. If they are not seperated, the front waves and rear waves cancel each other out (due to the physical properties of waves).
Ports are tuned to delay the rear wave just enough so that it does not cancel the front wave, but actually boosts it.
Try the plate (or infinite baffle board) out again, I actually have that right now with two pioneer 12s. It sounds great at low to mid volumes, but at higher volumes I can sort of feel the cancelation and overall poor sound.

When I get the time, I'm building a full box, with ports designed according to pioneer's specs.

 

I had a plate as well, I will never to that again, as soon as I turned my system half way up th subs might as well just been off because they weren't making any noise due to the cancelation which was mentioned above. Just get a sub box made or make one and get it over with in one shot.

 

This is the graphs that came with my subs.
The first graph is a sealed box, the second is a ported box. You can see how the sealed box has smooth sound, and the ported one has a boost at the 50 to 100 hz range.
<img src="http://bellabrothersonline.com/thirdgen/subGraph.gif">

 

Plates suck.

 

Very Technical

 

The ported box they show has a tuning frequency that's way too high. This type of alignment is good for boomers who want retarded amounts of output and aren't concerned about sound quality. Move the tuning frequency down about 20hz and make the box bigger and chances are that sub will have smooth frequency response.

What sub is it?

 

cheapy ts-w300r, 150rms . cost $120 for both cus I bought one at best buy (55 on sale) and one at circuit city (60)
For that pioneer says to use a 3 inch by 9inch tube. How can I tune it to get a smoother response? 20 hz would be nice, 50hz seems little high.

 

Did the owners manual provide the t/s specifications, specifically the Qts, Vas and Fs? Pioneer's website doesn't give that information.

 

Yea, I had to download the manual from Pioneer as a PDF.
<list>
<li>Qts: 0.646
<li>Vas: 93.16 litres
<li>Fs: 29.5 hz
</list>

 

oi. I can see already from that Qts that this sub is going to requre a retardedly huge box.

Let's see here...


Yup. 5 cubes sealed, 12 cubes ported. For all intents and purposes, this is a free-air sub, and is not going to work all that well in any reasonably sized enclosure.

 

HOLD UP. So your saying I should keep it as a plate? Or even try to free it up more?
This may save me mucho trouble in the end.

No one tell me to buy other subs, I'm already planning on doing it later (after college).

ALSO, Jim, whats that program?

 

NO, PLATES SUCK.

The problem with a plate is that it does NOT provide a real free-air environment. A good free air environment is a car trunk. It's large enough that the subs can consider it an infinite volume, and most importantly, a properly constructed IB system has the rear chamber 100% acoustically isolated from the front. In a trunk this can be done by ensuring that the trunk area is 100% isolated and sealed off from the interior. THEN you have a good IB setup. In an f-body, you just can't do that unless you go to great pains to make sure the chamber below the sub is completely sealed, but doing that just means that you built a sealed enclosure with a volume way too small for an IB sub.

 

Poly-fill can't save this one eh.
I'm going to build the box anyways so I can use it later for other subs, but will this yield little improvement for the sound of these subs, maybe even hinder them?

Thanks.

 

They'll probably still sound better compared to a plate. Although not ideal, at least with a sealed enclosure, your effects are not as dramatic as the box size decreases. I would definately stick with sealed though. At least a sealed box will have a chance of working with your next set of subs, where a ported box is so application-dependant that it's unlikely that it'll be optimized for your next speakers.

Polyfill will help slightly, but will not provide a drastic change.

 

I am using 3/4 in plywood. Only one 12 that will be running about 300 watts rms. I can seal this area in the rear. I will use a dense foam between the metal bars the plate and bolt it down.

I do not see how this is bad thing if done well. I was a Seabee and can engineer just about anything if I put my mind to it.

 

I don't care if you make it out of cement, everybody who goes through all this work neglects the same thing: air leaking around the cheap ill fitting, thin, flexible plastic panels that help make up the "enclosure".

The amount of work necessary to properly seal the area off is greater than the work necessary just to build a damned box.

 

Leaks around the box top are fairly easily stopped with foam. The only problem is that there's nothing behind the plastic panels and there are plenty of gaps for air to get in meaning that the well will still vent to the rest of the car. You would have to seal everywhere plastic meets carpet and even then it still wouldn't be very air tight because the carpet would probably leak some air through it.

By doing this you would effectively destroy your hatch carpet and all panels involved. You're much better off just building a box. It will cost you about $25 for the sheet of MDF and a day of your time.

Also, you keep mentioning bolting it down. Where are you planning on bolting a piece of MDF that’s going to be floating about 16” off the floor?

Not trying to say that you can’t theoretically do it. It just doesn’t seem like the best course of action.

 

1. It can't really be done well.
2. Then engineering a box should be easy.
3. Instead of making use beat you up in a thread that has 100 post before you give up and make a box, then post back how much better it's is, just search for plates and read how we beat others into doing the same thing and how much better off they where. Much less typing for all of use.
IT'S A BOX! Calculate the volume (we will be more then happy to help you in the right direction), and whip some wood together. How is sealing the 'trunk' easier then a BOX. Your way, harder and will not work as well.

 

ok ok! I will build a box! You guys sold me.

what do you guys think about MA audio 12 in subs. I am only going with one. I have jbls in the front and alpine 6x9 in sail panels. sound so crisp.

The only problem is that it does not provide a lot of base but I love the sound so I am going with one amp driven sub for a little bass.

oh yeah never buy anything from Best Buy. My alpines were 64.99 on millionbuy.com and 125 at Worst Buy. You do the math

 

Sucess I especially liked NEEDAZs post because it's so painfully true

Anyway, I don't know about the sub personally but given your needs/other speakers it will probably work out fine for you.

 

I've not heard the MA Audio stuff personally, but my impression from seeing their designs is that it's a middle of the road type of sub. It's ok, and probably worth the money, but there are better subs for the same money.

 

<a href="http://www.pricegrabber.com">pricegrabber.com</a>
enter the product, do the search, enter your zip code, and price grabber gives you a list of usually twenty five merchants and shows you the absolute lowest price (with shipping and tax). Best buy has never been close to the lowest.

 

this plate vs box discussion reminds me of the fuel door discussion.

 

My friend has his subs upside down blowing into the box, is this better or worse?

 

it makes no difference.

 

The biggest diffrence is that no one is calling it hack job

Well, that and we have actual facts behind our arguments instead of opinions. If you're not a beleiver and have some time on your hands go out and buy a sheet of mdf. Try a baffle then make a box and report back which sounds better. Should cost you less than $30 and your time.

 

Should be a bit of time, but I'll be building a box soon for my retarded subs and I'l report back.

 

who said i wasnt a believer? i was just making an observation

 

What are open air subs?

 

Free-air or Infinite Baffle subs. They're designed to be used in applications where you don't use a conventional box, but instead utalize a big area as the "enclosure" such as a trunk in a sedan, or a basement or attic in your home theater room. However, you still need to completely isolate the rear wave from the front wave or you'll get cancellation.

A sub designed for IB usage has a high Qts and usually has a very stiff suspension since it won't have the air-spring effect from the enclosure. Using a sub like this in a conventional enclosure usually results in a terrible frequency response.

 

Thanks!

 

Sorry Jim I beg to differ with you on plates sucking. I have one in my car and I can tell you the sound is exellent. the boom from the subs is unbelivable, and the sound from the whole stereo in general is almost ear shattering. I am running a Panasonic head unit with two Punch P1's and a bazooka 500 watt mono amp and Cerwin Vega speakers in the stock locations. I have no problem with my plate I guess it's just preference though, or I might just be old.....

 

it seems to me that everyone tends to like what they have in there car presently and everything else is junk.

I never hear any real solid evidence on why the alternative sucks.

Everyone is entiltled to thier own opinion but we should not try to influence the actions of others based solely on preference

 

I've explained many times why plates suck. It's science, not opinion.

 

Well said.

 

DO YOU READ THE POSTS? It's been gone over 1,000 times. Plates are horible...

 

He's saying that calling plates horrible is an opinion. To an extent, I agree that horrible is just an opinion and not completely substantial. I will not say they are horrible because there are times it sounds nice. But I do understand plates have a huge flaw in that it doesn't isolate the front and rear waves.

And with most things on this board, it seems that plate or box is another preference. Some enjoy the sound from a plate, some hate it.

 

My apologizes. From now on, whenever you see me post "PLATES SUCK" please mentally replace it with "Plates provide a level of performance that is measurably substandard when compared to all standard enclosure types" so that I can remain politically correct.

 

2 more points goto Jim...

 

I think he's looking for that measurable proof, such as the measure of the frequency response for a standard enclosure being much smoother than the freq. response of a plate.

Then again I may have no idea what hes askin, or what I'm talking about
I know the plate can kick an enclosures a$$ for some songs, and sound absolutely horrible on others.

Call it political correct, I just want to seperate opinion (plates suck) from actuality (plates have wild, and potentially unpleasing freq. responses, but can still be good for listening to music).

UPDATE:
OOOPS. Sorry Jim, I missed that post earlier. I wouldnt have said all I said if I read that. The science IS the "measureable" stuff. Ma bad.

 

The problem is, people ASSUME that it's always opinion. Usually the only difference between opinion and fact is the person's level of experience.

If you just stop and think about how subs work and the role that an enclosure plays, it becomes completely obvious why they don't work well.

Every person that's ever had a hard-on for a plate on this site is somebody that never had a real enclosure in the same car, so they're making an apples to tailpipes comparison.

I don't think there's anybody on this site that's upgraded from a plate to a properly built box with no other change in equipment who didn't find it completely obvious how inferior a plate is.

 

I'm with Jim, I went from a plate to a not even properly built box, 2 small boxes that squeezed into the back of the firebird and it was a world of difference.

 

Sorry, I gotta jump in on this. I agree with Jim to a point, scientifically plates are bad. My disagreement is that their so inferior to plates. I have reason for this as well. I had an MTX factory box with 3 10's in it ( I cant remember the model number but it takes 1500 watts peak, has a plexi window in the back, and is wedge shaped) It fit VERY tightly into the well in my T/A and sounded just as good as it did in my 96 Z28. I didnt like the fit so I made a plate for them and they still sound great. They dont sound the exact same but they still play just as loud. Id say they play "boomier" They have more of a lower boom and dont play as tight. This is to be expected when the enclosure isnt sealed.

Something else that wasn't mentioned, or maybe I missed it, was the power input to any of these boxes. It takes less power to run a ported or free air sub than a sealed one at equal volume. This is scientific as well. It requires more energy to overcome the air pressure in the box increasing with movement of the sub moving in and the vacuum created by the sub moving out. I ran 700 peak to these subs sealed and now Im only running 300 peak and they sound nearly the same, just a little sloppier due to the freely moving air behind them. My car still plays loud enough that my ears ring and guys at work say holy **** thats loud. I guess if you want sound quality, sealed is the way to be. If you're on a budget like myself, a plate can get you by just fine.

 

same amp, same subs, same power, same car, I went from plate to sealed and it was louder and better sounding.

 

interesting, because thats what I did with this T/A, same amp, car subs just went from sealed to plate and it sounds fine to me. i had the bigger amp in the other car.

 

The one part of the "science" that you overlooked was the drastically lower output due to cancellation.

 

Ok I'm going to build a box this weekend using the specs on this board, but I still want to use the privacy cover over the enclosure. The way I see this enclosure, it looks like it will interfere with the cover. Right now it looks like I dont even have a system in the car it's all under the cover. Jim these questions are for you. Now I'm leaning on you for answers.

1. Can I use the cover over the box?

2. And if I do will the cover change the way the speakers sound?

3. If I modify the top of the box so that it sits lower in the well will the sound change?

Thanks