E30 Zone

Been looking at 8" subs circa 70 pounds on the ebay.

What i want is a box which has one port for the sound to come out and the sub is enclosed in it.

I would like the port tobe lined up with my 51/4 speaker grills in the parcel shelf so it will look oem.

I am willing to recloth the parcel shelf to to affix the enclore to it.

can anyone help?

looking for tight punchy basss sound not massiive low end,

possibilities;

http://cgi.ebay.co.uk/Focal-21H-8-Subwo ... 0030682482

http://cgi.ebay.co.uk/Elemental-Designs ... 0006841623

http://cgi.ebay.co.uk/JL-Audio-8-inch-J ... 0222463852

dont quite understand what you mean by recloth on the back shelf???

are you meaning to suspend the box underneath the rear shelf??

A fully enclosed box porting through the arm rest/Ski hatch would be easier and much cheaper than custom built thing to port on the back shelf

maybe you are right but i really want it affixed to the underside of the parcel shelf.
cal it an experiment.

At the risk of getting myself into trouble with the photoshop kings here is a 1 second mockup of what i want done on the touvhpad of the laptop so no laughing.

blue is the existing parcel shelf with oem grills
black is the box!
and you see the speaker on the left and the port on the right
to be honest it doesnt have to be 8" sub but my aim is to get the "X" value down to as little as possible -
if its possible to have it at 5 or 6 inches dep all the better -

according to http://www.bcae1.com/spboxnew2.htm you need .03ft of displacement if you click the link and scroll down to Enclosure Design Helper you can enter different dimension and it will give you the displacement values as well


Hope this helps

If you want tight punchy bass you would be a lot better off to build a sealed box,

Ported boxes are not as easy to get right as people think as the shape effects the way sound moves inside and a bad box can cancel out the desired fequencies. The lenght and diamiter of the port effect the frequencie's that can come through it, (generally sounds louder at a certain range, normally giving a deeper sound but you pay for this deepness through losing the tightness of the bass) just what you don't want.

Sealed boxes are a lot more forgiving to make as the main thing you have to get right is the internal volume, just dont make it dead square.

Liam
you should be able to knock something up for that as what pyros has said you can use the link to design something
i would think the main thing would be clearing all the bits and pieces for the boot mechanism to get a tight fit

remeber and cover everything with dynamat or something along that line

good to see you havent went down the 6x9 route

so with a sealed unit are you looking at one of the parcel shelfs having the sub under it and one of the grills having nothing?
and a sealed unit can cope with being shallow/having the ar$e of the speaker very close to the rear wall like abovee?

A sealed box will sound fine if it is shallow, (better than a ported one would). the other advantage is that sealed boxes need to be smaller than ported ones. (larger boxes sound deeper but smaller ones sound tighter).

Also just looked quickly at the subs you were looking at, to see what the recommended enclosure sizes might be.
and the JL one had this listed.

Sealed Enclosure Range: 0.30-0.60 cu.ft. (8.5-17.0 liters)
Ported Enclosure Range: 0.60-1.00 cu.ft. (17.0-28.3 liters)

so as you can see a sealed box can be considerably smaller than the ported design.

well here's the thing then,
seing as i am going with a sealed box i can use 2 subs can i?
to make the most of the two grills in the parcel shelf?
or would i be better off with using one good 10" sub - afterall no one will no that only one grill has aspeaker underneath it and i have read that you sacrifice alot of frequency/response with going with small as a 8".

getting a bit bogged down with the ammount of choice i think!

Hmmm? just thought if the speaker is facing the shelf their is two other problems you night encounter, 1 the excersion of the speaker (how far the cone move forward) and 2 all the air movement in front of the cone will be restricted by the small speaker hole (will effect the quality of the sound produced and volume levels).

got a few ideas floating around my head but not sure how they would suit, I take it you want the box to be subtle when the boot is open, also what sort of music do you listen to? and also how do you like it to sound?

mostly rock / metal / pop . very little dance very little reggae.

i like the low frequencies to be be very tight and punchy as opposed to pumping sub bass - i am not looking for a system setup that will turn heads accreoss the road at all at all.

All i want is to throw some bass into the cabin and be able to hear clearly the low spectrum of what i am listening too.

i had real properlook at the boot and parcel shelf today andi think my idea is maybe a bit silly.

maybe i will be best suited to the ski hatch open.

15" x 10" and 6" deep (maybe 7 but the les into the boot it is the better.

Personally I think a decent 8" will give you most of the sound that you require more mid-bass than the sub-bass you would get from 10", but some of the real low notes might be lacking a little.

The dimensions you have stated would give an internal capacity of 0.2999 ft3 if made from 3/4" mdf or equivelant so you have got that spot on, based on the JBL dimentions.

Once the sub is in the car you could experiment by adding some poly-fill to the inside of the box a few layers of this will stop any resonance in the box cleaning up the sound and will all make the box sound as if it is a little larger than it actually is (you may have noticed most high-end hifi speaker cabinets have fill inside them).

In fact you could get away with using poly fill to make the box slightly smaller than the stated dimensions which is what you want to acheive, but unfortunately I don't know how much by or the formula to work it out

I have been though loads of subs and the most musical one so far has been the Aliante 10".

I got this into a 4" deep cabinet and attached it to under the parcel shelf, then removed the rear speakers and put grilles into to let the bass come through.
You can pick these up used on www.talkaudio.co.uk for between £100-130.

They work best with a .6cuft sealed cabinet, and with at least 250w, even better with 350w.

Other option is to fit a couple of 8" infinite baffle subs in the parcel shelf in place of the rear speakers, by infinite baffle I mean a sub that doesn't need a cabinet at all, it uses the boot as the cabinet, these can work really well but need a decent amp to drive them.
I have a couple of Earthquake SWS8 subs that I was going to put in the stock locations of my E91, which is under the seats, but I am starting to think that these in the E30 would work really well.

I have an Audison SRx3 amp which is 2x65wpc to the fronts and will drive two SWS8 subs with 340w wired in series, this would work well with the subs as you can can't get much lower than 150hz from front speakers in an E30 without lots of fabrication, and the SWS8's can be driven from 150hz down to around 28hz which is plenty low enough.

A ported sub in the boot would have a pretty big peak somewhere between 40-80hz depending on the cabinet designed, which is the last thing you want when you are only getting the front speakers to drop down to 150hz or so.

So I think your choices really are sealed 10" sub, cabinet would be no bigger than an 8" and ceratinly shallower with the right sub, or a couple of infinite baffle 8" subs.


Genesis also do a 6x9 sub, Focal do a 6.5" mid bass sub and there are others out there worth looking at to sit in the stock locations.