I am looking to add a sub box to my 04. I have seen the under seat versions and the behind seat versions...what are the pros and cons of each?

I have been able to find the underseat boxes in the local stereo shops but am having a hard time finding a behind the seat style.

I have an under seat box that holds two tens, and I really like it. You do lose the fold flat rear seat function, however it is a truck and the bed is always back there to hold stuff;) . I have my Amp and Cap. mounted to the back of the 30% seat so a behind seat box would not work for me. You will probably only find a box for smaller speakers to fit behind the seat, as there is not enough space for a good size driver and the box behind it. FWW my box is from subbox.net, they have changed some since my purchase, but they have a few to choose from just for the HD CC. Goog Luck!

Probox has a single 10" ported sub box behined the rear seat. It sounds good!!
http://www.proboxrocks.com/chevy/01-03crew.shtml

Thanks guys. I already have 2 10's and an amp and everything from my ext cab 2000, so all I have to do is decide upon a box. I wonder if any behind the seat boxes will accomodate 2 10's?

I have also been looking around and came across this site http://www.subthump.com/silverado.htmHope this helps !

I have also been looking around and came across this site http://www.subthump.com/silverado.htmHope this helps !

Good info, thanks. I will have to measure the mounting depth of my speakers when I get home....speaking of which..

Does anyone know where to measure to obtain the mounting depth? I assume from the bottom of the mounting plate (the ring where the screws go in) to the bottom of the magnet?

mounting depth is measured from the mounting ring to the rear/bottom wall of the box. subtract the subwoofer mounting depth to obain sub excursion (movement) space

I GUARANTEE, that CC seat back box is nothing but distortion. I've done all the math, and several prototypes. The surrounds are going to beat the seat backs at 1W. It has to be shallower (as do the drivers). If it doesn't weigh in at 75 lbs, it's not braced correctly, the price usually says something about the quality also. The good news: it will work. But for a seat back sub to work well, it has to be recessed at least 3/4"

Guys I am sub stupid, as far as the technical terms...so I have a few questions.

Thanks for the info, ski1. What do you mean by your second sentence about "the sub excursion space"?

Masterp2, thanks for the reply. So I assume you are saying that all things equal, the underseat box will sound much better and with much less distortion than the behind the seat box?

By "surrounds" I assume you mean an underseat sub box, right?

What do you mean by "The surrounds are going to beat the seat backs at 1W"?


Is a seat back sub a different "sound" than a floor sub?

OK,

the seat back is the way to go IMO, for space considerations etc. I love all the room under the seat for tools, straps, etc. It's not easy to design a (10") box that will work well back there, because of space constraints. I have designed one that will. The surrounds are the foam or rubber rolls that form the suspension on the front of the driver, they protrude.

The trick is getting a 10" driver behind the seat, in the correct volume enclosure, that doesn't hit the seat back during big bass excursion. A tricky problem. But it has been done. BTW, 8" subs are more common because of this delemna. But like I said it has been done, usually by hacks, and often poorly executed.

I have 3 Jl 10w6ae behind the rear seat and it is a very tight fit but sounds good. I have speaker grills on them all because I was worried about the subs contacting the seats, and the speaker grills do leave a print in the back of the seats but better the grill than the subs. I will see if i have any pics for ya.

duckhunterintn, I had a box for four 8" subs that went behind the rear seat and it rocked, only reason took it was to goto a blowthru with three 15"s Still have the specs for it for the dimensions.

sub excursion is how far the cone center part of the sub will move in and out of the surround

surrounds are the rubber rings that are rolled that goto the cone or sub surface, this if not recesed will rub against the back seat and eventually wear. With the four 8"s it would rest on the seat back, didn't rub thru a sub in a years time and still have them going in another truck.

i know these aren't correct lingo but in the easiest terms that I know of to help break it down to somebody with out the tec lingo going on.

You can do 10"s as well, just need a shallow mount sub which is the mounting depth of the speaker, and a decent sized box.

I sell the peerless 10" XLS, that every bit of the performance of JL's with only 4.5" depth, expressly for this purpose. Optimum performance in the .7 cf enclosure.

chaps,
Some pics would be great. Thanks.

crewcab03,
Your definitions clear it up for me a lot. Thanks.

Masterp2,
I have a stereo shop locally that is going to take $30 and my ext. cab box in for a new crewcab box, so I don't really know what I will be able to get....I know they have an under seat box in stock. So is there no advantage of the underseat box over behind seat box, other than they are easier to make? Also, do you sell sub boxes? Where are you located?


And a question for whomever:

I already have a set of 10s with my previous system that I would like to use. I do not know their depth but I know they weren't any special "shallow" ones or anything. Would it be safe to assume that they would NOT work in a behind the seat box?

Probably safe to say. Unless they are low power drivers, not useable for good sub apps.

For $30, what do you have to lose?. Sounds like you are going to have a "retail" rubdown.

The underseat box can typically house subs that are a bit deeper, not an advantage to me, after considering the tradeoffs. Also, most sub enclosures are total crap, built out of whatever is laying against the wall. Carpet makes them all look the same.

Sub excursion is just the movement of the sub, usually nothing to worry about unless you have a "deep" subwoofer designed for an application with plenty of space, some JL drivers come to mind. you must have enough room (depth) to allow full movement of the sub without bottoming on the enclosure itself. if your sub is mounted below the surface of the enclosure (usually 1/2 to 3/4 ") your moutning depth will decrease by that much also. just something to watch for.

Uh, I've never heard of a retail rubdown? Doesn't sounds like a good thing, though.... :)

Well, I want to use the subs I have already bought (they are practically brand new), and if they won't fit in a behind the seat box, and the stereo shop dude acts like getting the behind the seat box will be a lot of trouble, then I might get the underseat box for $30 for now.....or I might do some measuring and see if my subs MIGHT fit in a behind the seat box if the guy can find one....


Do you happen to know offhand if an avalanche under seat box is the same as a crew cab box? He had one of them in stock but for some reason something looked different on it that gave me the impression that it would not fit...not sure though.

What subs do you have?

I take it my boston pro 12 probably isn't going to fit in a underseat box in a EX cab? :(

I take it my boston pro 12 probably isn't going to fit in a underseat box in a EX cab? :(

I had Two Boston Pro 12" under the seat of my EX cab.

Took to short pieces of 3"x 2" rectangular tubing and made lift blocks for the seat mounts. You do need to "knock off"the seat studs and use 4"Grade 8 bolts to replace the studs:ro)

Thanks ZR1150 I'll look into this :)

Yes you can get those under your seat, with an 8" deep box, but unless you are considering volume, they will sound like a boom box at 80HZ, and you'll get nothing audible under 40. They need much more volume. One would be better, for a cookbook design. You would need almost 3 cf (total) for 2 of them, and that would require seat removal I think. Would be a crying shame to do that to a Boston sub.

Masterp2 - I only have one boston Pro12 do you think i could do this without taking the seat out? I really do like the sub and hope I can use it but if the space constraints are too small you're right I'm not going to improperly mount a boston. I'll have to get some JL 10's or something if this doesn't work.

No. You need 8" of mtng depth, plus lumber thickness, plus 1" for seat clearance.

What subs do you have?

I have 10" MB Quarts...not sure if that helps or not. I'd need to look at them to get the specifics...

duckhunterintn, take and set the speakers magnet on a countertop and measure from the tops surface to the bottom of the speakers surround aka mounting surface, this will help with you mounting depth question to as how deep they are.

From what I've read on Cruchfield if you have a box that's not quite up to the exact deminsions you can use Poly fill http://www.crutchfield.com/S-Hu8NXvWeDEe/cgi-bin/ProdView.asp?I=027808 to make up for lost space. Maybe some of these audio pros can either confirm or deny that.

I plan on buying 1 Rockford 10" http://www.crutchfield.com/S-Hu8NXvWeDEe/cgi-bin/ProdView.asp?I=575P310D4 which requires 0.65 cu/ft (sealed box) and I plan on getting the box (single 10 with spacer) from the site I left a link for on my last post and use the poly fill so I think there are options if you can't get the box exact.

My box was a little short on air and I used a little poly-fill to help it out. :eek: I DIDN'T SPEND TEN BUCKS ON THAT STUFF!!:eek: Go to Wal-mart and get pillow stuffing, about $2, and pick up a twelve pack for the work ahead.:cool:

Dude i have 2 amps (a 1200 watt and a 900 watt) i mounted under the rear seat along with my flashlight and i put 3 10" JL Audio W3's behind the seat it sounds great there is pleanty of room and you still can put the seats compelty flat here are some pictures

In my 98 Chevy crew cab I just let my 10" solo-baric Kicker sit on the back seat in a box, I have two 800 watt amps under the seat for the sub and they are mounted on a piece of partical board that I covered with black material. Behind the rear seat I mounted a 4 way amp, a cross over for the sub, a 10 disc changer and the power blocks. See photo. I didn't want to drill holes in my truck so I custom fabbed a "L" shaped mount out of the same partical board and covered that too, attached with staples. It fits perfect and it doesn't rattle or touch the back of the seat. If you realy want your sub or subs to thump, I would sugest a cross over. Foundryworks1 I like your set-up too. It looks clean. :ro)


http://img.photobucket.com/albums/v608/SCE_T-roy/05113002.jpg

Foundryworks,

Nice job on the pics.

That looks like a late model CC, but you have no sig. Looking at those rings on the seat back, I am guess the seats don't go back to the original position? The depth of that box looks like the seat backs sit right on the drivers. Where does the sound go?

Palmvalley, you are right. Stuffing is a must in any box, but expect a 20% max apparent volume increase, for accoustical purposes. It is not a cure for undersizing boxes the a lot of people do. In actuality, few people plan volume correctly and end up with volume less than they planned, so planning an undersized enclosure with plans to fix it with stuffing is a poor idea. Optimizing a driver to a volume, using planning software (or manufacturers cookbook) is the right way to create something that does well with so many constraints as we have here.

If anyone thinks they have good quality bass, I invite one or 2 of you to get a radio shack SPL meter, and a test tone CD (I'll send you one for free if you like) and chart your "real world" response. It can be fun, and it is a useful tool to make refinements with x-overs etc. I can even send you a spreadsheet to chart the values on excel.

Create a sytem with flat 130 db to 20 HZ, not easy in a CC. Sure you can get 141 dB at 61HZ, that says little about quality, and usually indicates a proficiency at misaligning the driver (too small a box). Not poking at anyone here, just sharing.

My Boston Pro 12"s are a few years old, but the mounting depth is only 5-5/8 deep and the encloseure is only 1 cubic foot

http://www.bostonacoustics.com/support_car.asp then Pro Series Subwoffers

I only ran 150w brigde @ 4ohms to the 2- 2ohm subs and the shook the ground right down to 20hz):h

You have used test tones then?

Micheal, I PM'ed you a while back on these calculations that are a little over my head...at least for now. Anyway I am running two JL10W3v4's in a single enclosure behind the seat of my crew cab. I don't remember the exact volume I came up with without pulling my files, but I tried to acheive twice what JL recommended for a single driver. What is the best volume minus drivers to achieve a flat response in our crew cabs? I also have the ability to fine tune with the EQ on the JL 500/1 that drives the subs, as well as my Alpine deck that has EQ adjustments. So far it seems that I am getting the best sound with all that stuff off. As of yet I can't be sure if my enclosure is sized correctly, and it seems I am getting more of a one note bass hit rather than flat response. By the way I had to move my seat up 1" to clear my surrounds, (see pics). Thanks for any input on this.

What is the best volume minus drivers to achieve a flat response in our crew cabs? I also have the ability to fine tune with the EQ on the JL 500/1 that drives the subs, as well as my Alpine deck that has EQ adjustments. So far it seems that I am getting the best sound with all that stuff off. As of yet I can't be sure if my enclosure is sized correctly, and it seems I am getting more of a one note bass hit rather than flat response. The answer is dependent on the drivers, not our cab. The thiele/small parameters of the driver, plus your goals=box size. You need the spl meter and test tones.

I did a study on the 10" W3 JL's, it is charted here on this forum somewhere, a year ago. As I recall, I modeled them in .7 and that was "one notey". I think .9 or 1.2 cf was better, but as we have seen, very difficult to accomplish. An SQ driver that optimizes in a .7 enclosures seems to work best. The 10W3 does not. Understand, JL does not market to the SQ crowd. The smaller sizes they recommend are more for impressing the neighbors than listening to "music".

If you don't find it, I will do it again, later, I have to go play with my son

101: This picture tells the whole story. Keep in mind this is predictive software that denotes an anechoic response of the sealed box with a 10W3. The in-car response is dramatically different, as a result of "cabin gain", or "room lift".

The scale on the left is SPL (relative), along the Frequency axis (bottom). "one note bass" is denoted by the green .5 cf curve. The SQ curve will be somewhere between the yellow and red.

In a nutshell it says that to integrate with mains, for flat response, shoot for 1.2 (minimum) cf. I show the .7 curve to illustrate why it might be recommended for SPL freeks who like nosebleeds. (typical oem marketing is an attempt to satisfy the people buying these, the same people with hearing loss at the age of 20) The .5 curve shows how that quickly progresses with just a small math error in box size.

Me, I would go with 1.2 to 1.5 cf, if you want to hear reproduction below 50 HZ. This is why I can't use the JL in our application. Even the 1.8 curve, when integrated with mains has a good freq hump, this is where eq is usefull. Don't try to "gain" using eq at these freqs, it just eats up the amp headroom. "defeat" the humps.

MORE (http://dieselplace.com/forum/showthread.php?t=4975&page=3&pp=40&highlight=peerless) information here

That is what I need to digest.:) I will have to look at this more carefully when I'm not supposed to be working. Thanks Mike....more questions to follow I'm sure.

This one shows the W3 against the peerless, each in a .5 cf enclosure, a max SPL comparison this time. This is why I go with the peerless for the small volume SQ application.

When combined with the output of mains, add-in cabin gain, the JL needs a lot of EQ to tame the overall response for flat response, the peerless needs none (and it fits in a shallower enclosure).

My box is 43"x 13.5 x 8.25B x 6.5T. I calculated I have 1.56 cubes minus the driver volume...sound about right? If that's so I am about .78 each and would have the blue curve. What would be the best to do with the EQ to flatten this out.... I know I would like a bit more down lower than what I currently get. I did put in a fair amount of polyfill.

You will need test tones to make informed EQ tweaks. Our ears cannot do it without isolating the freq spectrum. If you get the spl meter ($30) and test tones, you will be amazed after you right them down and plot them to make your own curve, then you can play with many things to adjust the "quality". If you are interested in doing that I will run you through the process.

But if you are wanting deep bass to the lowest octave, the general idea is going to be to defeat much of the spectrum centered around 60-70, then turn up the amp gain. Remember that this works better than trying to pump up the lowest freqs, for reasons beyond the scope of this discussion. But you really have to test your own configuration to see where that center is.

BTW, if anyone is in the Phoenix area, you are welcome to come and play with mine and see what flat response can sound like.

Where is the best place to get a meter and test CD? What exactly am I looking for in case I run into less informed store help?

Radio Shack for the SPL meter, analog or digital, does not matter.

CD stores have some test tones, I know Bass mechanic has one or 2, get the one where 20 HZ is track 20, etc, if you see how that makes things much easier to keep track of.

Before you run out, let me see if I can upload this othe CD I made.

I work out of my truck daily so I have the need to keep the 60% side laid flat, I am looking at going with a box as small as it may be behind the 40% side and am interested in SQ not boom. Any suggestions would be great

Motovet, sorry the files are too large. Just go to a bid CD store. Bass Mechanik CD's are easy to find, just get track 20-99, 20-99HZ

I got an SPL meter and the test tones. Will play around with them tomorrow.

After you get familiar with the spl meter (including instructions on A vs C wt etc) Find a place on the center console or dash and leave it in one location.

Procedure for plotting overall response, decide if you want the truck running or not, (12V vs 14V) windows up, dont worry about the mains, you can do the test with them on. Also defeat any EQ, run the system "flat" and note your crosssover settings:

1. With a 50 HZ tone, set volume to around 100 dB, after this you will not touch the stereo volume.
2. Beginning with 20 HZ, write down the response of each tone, realizing that you may have to adjust the SPL meter down to around 70 or 80 dB
3. As long as you leave the volume constant, you can start and stop and repeat the test tones while you get accustomed to the SPL meter adjustments, kind of tricky at first.

Any luck?

I did get some numbers tonight. Roughly 102db @ 52-56Hz and 90db at either end. Do I need Excell to run these? E-mail sent.

Here is your plot. You mentioned this is with xo at 80. Blue line is what you measured. The yellow line is your true coorrected spl plot. These are the known correction factors for the spl meter at low freqs. I am assuming your mains are defeated. If not, you just have too much bass for a flat response.

This response is pretty much as expected.

To flatten this curve, defeat the 50-60 HZ area, and gain the 20-30 area. Trial and error, and you will get a flat curve. You then need to integrate with the mains by adjusting the gain of the sub amp. Let's see what you can come up with.

BTW, a 6 dB change give the ears an apparent doubling of volume, dont be fooled by the relative closeness of the values. There is a lot of improvement potential. Right now, 50 HZ is doubly loud compared to 20 or 70 (hence you can't hear those octaves, drowned out by the hump). This is where the terms "one-note bass" and "boom box" come from. Shoot for 3 dB or less across the spectrum. 3 dB is the "perceptible difference" threshhold, where we can discern a difference in level. The dB scale is a log scale.

Try the next iteration with the mains on, or if they were on, bring down the bass amp some. The idea is a flat curve over to 100 HZ, where the mains should be picking up some of the load.

Oh, wait, after looking at this again I see you did have them on, see the saddle at 80? Adjust the xo to 100 HZ and that should fill in some.

I will make a few adjustments and give it another shot tomorrow. Fun stuff.

pioneer makes a new 12 sub that is only 3 1/2 inches deep. i built this box under the seat and it works and sounds great.

Nice. What are the T/S parameters, Fs, VAS, etc? (or model number)

http://pioneerelectronics.com/pna/article/0,,2076_4057_104401920,00.html

Yes another picture. Anyone care to post actual tech specs?

oops...I posted the incorrect link.....
http://www.pioneerelectronics.com/pna/product/detail/0,,2076_4061_90400838_tab=B,00.html?compName=PNA_P roductDetailComponent

master2P, your box look KEWL...