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View Full Version : Well/trunk box for '91 Camaro



vorgath
04-03-2006, 01:30 AM
Well I've been talked out of putting sub(s) in the backseat, seems like a really bad idea, cancellation etc involved.

So I'm going for a ported enclosure in the trunk. Here's my plan and also what I got so far:


Bought a 10 inch woofer, an Infinity Reference 1042W dual voice coil.
Got sound deadening material so I'll line the the trunk and especially rear glove compartment and spare tire compartment with it.

As far as amp goes, seems people here recommend a Directed Audio 250D ? Seems like a good deal, 49 bucks plus shipping, my question is though, if I run it at 2 Ohm, would it be too powerful for the 1042 ? The woofer can handle 250 RMS, 1000 W max.

I got the manufacturer spec sheet in front of me, the vented box volume listed is 1.75 cubic feet, port diameter is 3 inches, port length is 9 inches at 28.0 Hz. Can I run two ports rather than one ?


Could someone please explain this to me, the frequency etc etc, tuning etc ? I'd like to start this project asap, i.e. go and buy the MDF etc and build the box (does Home Depot or Lowe's cut the MDF for you or are you pretty much on your own ?)


Also, I won't always be driving with everything closed, once it gets warmer I'll probably end up driving more with my t-tops off.


Trying to use WinISD, but entering the parameters for the driver doesn't reall ywork, since my specs don't list the following:

Z
SPL
PE

vorgath
04-03-2006, 09:35 PM
When using the calculator, I should also remember to add extra space to compensate for braces, correct ? What about port though ? If I for instance go with a 3x9 port, should I add extra for the volume space lost there too ? I mean the port is after all .. hollow ... ?

vorgath
04-04-2006, 10:52 PM
Guess I'll just have to build the box and see what happens, hate to waste material, but ... *shrug*

2loud4u
04-04-2006, 11:02 PM
You will not need to brace that box.

Hook up with me on aim demon505hp and i can help you out with your box.

Lil Poot
04-04-2006, 11:11 PM
shouldnt be too difficult doing a ported box for a 10. theres a guy over on thirdgen.org forums that made one that only took up one side of his well, had the other side for storage still.

im almost done with my 4.2 cubic foot 30 hz box for my rl-p 12's in an 87 trans am. its been a trying build....

vorgath
04-05-2006, 01:23 AM
True, I mean I have the required/recommended volume, got the calculator at Rockford Fosgate's site, but I've been waiting and waiting since I didn't want to cut material until I figure out the size of the port.

Thirdgen's search is practically down, no reply to the post there and well I didn't get any replies here either.


OK, the recommended volume for a vented box, does include the driver/port displacement, but that's for 28.0 Hz. The port should be different for a slightly higher frequency, and I also wanted to go with two ports rather than one.

Trixter
04-05-2006, 01:20 PM
yes, you need to account for sub and port displacement. the recommended vol is the net volume. usually what i do is let's say....

the spec calls for 2cu'. add the sub displacement...like .1, or something, so you need a box that is 2.1cu'. use this number to calculate your port length. after you get the length, find the port's displacement, including the material it's made of. add this displacement to the 2.1cu' and do the calculation over. use this number for the port length. if your doing more than one port then divide the cu' by the number of ports and figure their lengths individually.

vorgath
04-05-2006, 04:13 PM
Here are the specs for my subwoofer, also volume require for box, volume does include driver and port volume. However anyway I can do with two shorter ports or something ? Nine inch long port is hmmm quite long.. and I'd like to go with two ports, and possibly tune it a litte bit higher ... maybe what .. 30 ... 32 Hz .. or something ?


http://manuals.harman.com/INF/CAR/Boxes%20and%20Parameters/1042W%20Tech%20Sheet.pdf


So a big no as far as putting poly fill inside the box, right ? Because that would make the woofer think the box is maybe even over 2 cubit feet ? Making a box smaller than 1.75 cubic feet, but filling it with poly fill is a bad idea right ?


The plugin "box", i.e. where you plug in the cords, where can I get one of those, so that I can cut a hole and mount that, rather than doing two cords out through a grommet thing ? Radioshack ... electronics store ?

Rasheedhos
04-05-2006, 10:41 PM
how is there cancelation on those cars? if your doing a wall?

Lil Poot
04-05-2006, 11:05 PM
its a hatchback. you put the subs behind the back seat, or in the back seat, its not going to sound good, i did it with my old camaro.

for example, in your home system, having the sub in the corner, sounds good. put it in the middle of the room, you'll barely hear it.

not trying to act like some audio guru, i dont know the science of why it is that way, i just observe and note results.

.::DuD3::.
04-05-2006, 11:09 PM
probably wouldn't need to sound deaden the trunk, i had absolutely no rattle in my maro, and didn't sound deaden a thing.

Lil Poot
04-05-2006, 11:12 PM
i had quite a bit of rattling after i put the rl-p's in. raammat took care of most of it.

Rasheedhos
04-05-2006, 11:21 PM
its a hatchback. you put the subs behind the back seat, or in the back seat, its not going to sound good, i did it with my old camaro.

for example, in your home system, having the sub in the corner, sounds good. put it in the middle of the room, you'll barely hear it.

not trying to act like some audio guru, i dont know the science of why it is that way, i just observe and note results.

what subs, box did you use? who installed it? still doesnt answer my question.

Trixter
04-06-2006, 01:27 PM
Here are the specs for my subwoofer, also volume require for box, volume does include driver and port volume. However anyway I can do with two shorter ports or something ? Nine inch long port is hmmm quite long.. and I'd like to go with two ports, and possibly tune it a litte bit higher ... maybe what .. 30 ... 32 Hz .. or something ?

the specified volume usually does not include the sub and port displacement. unless they give actual dimensions (ex: 12h x 16d x 24w), there is no way of knowing....but 99 out of 100 it is not included. the 9" for the port is what tunes the box to that specific freq. if you were to add 2 ports they would actually need to be longer, then you have to make your box bigger to make up the new port displacement. you can tune to what ever freq. you want. raising the freq. will shorten the port(s)



So a big no as far as putting poly fill inside the box, right ? Because that would make the woofer think the box is maybe even over 2 cubit feet ? Making a box smaller than 1.75 cubic feet, but filling it with poly fill is a bad idea right ?

poly fill is not a "big no-no". it will make the sub "think" it's in a larger box...which in turn will lower the tuning freq. as well as the power handeling. depending on your application, you use it or not...just make sure it doesn't blow out of the port.



The plugin "box", i.e. where you plug in the cords, where can I get one of those, so that I can cut a hole and mount that, rather than doing two cords out through a grommet thing ? Radioshack ... electronics store ?

i use 1/4" nuts and bolts....
http://img432.imageshack.us/img432/8132/nutandbolt2gk.th.jpg (http://img432.imageshack.us/my.php?image=nutandbolt2gk.jpg)

vorgath
04-07-2006, 11:13 AM
hmmmmm so what frequency would I get if I would shorten the port length to say 7.5 or 8 inches ?

On the spec sheet it says, includes driver and port volume.


When you guys use rammat or dynamat, where do you guys put it ? everywhere ??

Trixter
04-07-2006, 01:07 PM
hmmmmm so what frequency would I get if I would shorten the port length to say 7.5 or 8 inches ?

On the spec sheet it says, includes driver and port volume.


When you guys use rammat or dynamat, where do you guys put it ? everywhere ??

about 32-33hz...would sound nice...imo

i did it every where i could stick it...mainly in the trunk...like 2 layers. then spray glue that egg crate foam over it. also use the foam to stuff in the panels.

vorgath
04-07-2006, 02:07 PM
Good *L* because like I said before, 9 inch long port would create minor problems for me, I'm trying not to make the box too tall. 32-33 Hz would be perfect.

Yeah I put some rubber matting, kinda like dynamat, maybe bit more like thick industrial gasket material, but running out of it, and I have some places in the trunk where it would be really tough to attach it.

vorgath
04-07-2006, 02:31 PM
OK, used this link
http://www.linearteam.dk/default.aspx?pageid=ventcalculator
to calculate the port(s), however it doesn't seem quite accurate, maybe because my box volume is with and not without driver and port displacement.

http://manuals.harman.com/INF/CAR/Boxes%20and%20Parameters/1042W%20Tech%20Sheet.pdf

But am I thinking correct, when I say that I could go with two ports .. each 2 inches diameter .. and have them 8 inches long... I would get ... 33-34 Hz ?

Trixter
04-07-2006, 06:54 PM
yes, 2 2" ports 8" long will land you 32-33hz.

vorgath
04-07-2006, 10:23 PM
Awesome, ok I'll get some measurements for the build, and post it here before I run out and buy the MDF and PVC.

Oh, should I go with straight or flaired ports ?

Trixter
04-08-2006, 10:04 AM
flared ports wil provide less resistance resulting in less possibility of port noise, but they cost more than non-flared. if your going with flared, they also use a different formula to figure their length than non-flared.

vorgath
04-08-2006, 12:13 PM
Yes I believe they would end up being about an inch or inch and a half longer than non flared. hmmmmm two straight 8 inch long ports .. should I expect to run into port noise ??

Trixter
04-08-2006, 06:49 PM
well, 1 3" port (7sq") has more area than 2 2"ports (6.28sq"). they did recommend a 3" port...so really, i would go with at least what they say or more to be on the safe side. if you went with 2 3" ports, it would be nice, but then you would have to make them longer. 2 2" flared ports...i don't think you'd have a problem. if you can do it, 2 3" flared ports would sound nice. if you go with flared, remember to keep them (the edge of the flare) NLT the port's diameter from the box walls and NLT the port's daimeter away from the back of the box.

vorgath
04-08-2006, 11:39 PM
But I can most likely, not go with two ports, each 2x8 and have them straight, no flares ?