who knows about porting and band pass

[liam012]

who knows about porting and band pass cause i dont and i have an idea but not sure what my limitations are going to be as i am unsure of the science.
i want to but a bass speaker in the back - not killa watts but a good punchy low end, i am thinking one 8 or 10 inch sub in a very small enclosure i guees like a really long rectangle cube type thing under the rear shelf. i am hoping for their to be port hole or holes where the little grills are for the oem speakers in the shelf and seeing as thats the only hole in the enclosure all the bass willl come into the cabin.
so
how can i do this?
how should i design it? where should the port/s be?
is it even possible to do?
what is the smallest i can do my enclosure?

any answers welcome

thanks

[chu346]

If you want to bolt the enclosure up to the shelf you will have trouble using a normal port and a slot port will be needed which will be more difficult to build and angle through the grills. It can be done.

I'd go for a 10" sub, have you any ideas what sub? what is your budget? I should be able to design a box for you.

[dazleeds]

chu

dnt fancy designing me something for either 1x 15 or 2x 12s do ya

i have both above so dnt mind which i use even all 3

[chu346]

Need the specs of the subs, what subs are they.

[dazleeds]

jbl is a gt3 15" got book with full specs on this
the 12s are eminence but sound decent still not sure of specs on them will have o pull em out of the cabs to find out

[chu346]

Get me the full specs of the 12's and let me know what kind of box you want. Big/small, sealed/ported.

TBH it's alot easier to fit two 12's in rather than a 15 due to there only being 16inches of height in the e30 boot. It can be done but no room for error.

EDIT: give me the model number of the 12's as I already have some specs.

[dazleeds]

Get me the full specs of the 12's and let me know what kind of box you want. Big/small, sealed/ported.

TBH it's alot easier to fit two 12's in rather than a 15 due to there only being 16inches of height in the e30 boot. It can be done but no room for error.

EDIT: give me the model number of the 12's as I already have some specs.

these are the only no,s i can find on em fella
these are on a printed label on side of the magnets

eminence
me12-2008

121052 8ohm
67-95230062 G1

i know 8 ohms arent really ideal in a car but can be wired down to 4 ohm as a pair cnt they??

seems a shame for them to sit in my dj room as i always get grief when i turn em up lol

so would be put to better use in the car

as for box something that will sit at the back of boot between the rear shocks and leave me some boot space.
dnt mind of sealed ported etc
im after nice clear but hard bass rather than pure dbs and distortion

mainly listen to oldskool/jungle/d n b etc

have plenty of amps etc and a hefty 30band mtx graphics going in boot to control everything components front and rear in the near future
until then will run 2 pairs of mas audio coaxs rears on an mdf shelf etc

i basicly just want a nice sounding setup that can kick it out when the mood suits

not looking to blow out streetlamps etc been there done that lol

[chu346]

Bad news can't find any specs on them mate and won't be able to http://www.eminence.com/faq6.asp

[dazleeds]

oh well looks like a bodgit box for my boot then till i get round to blowing them or replacing them whatever comes first lol

cheers for looking mate

[liam012]

chu-
this is where i am stuck, i havent chosen the subs yet as there are so many to choose from.
Also i dont nkow what will be best for me so if you have suggestion that would be ace.
what i want is a good 60 to 80 hz punch, Not massive loud subbass. just something to counter the roadnoise so i can still here the kick drum and the bass lines in the tunes i listen too, this is in no way a show instsall or audio showcase!!
Also conserving bootspace is a priority,
I would have gone for a tube as they suit my priorities space wise but i dont want it in the cabin yet i want to here it in the cabin hence the dilema.
maybe i am being a bit unrealistic, with what i want to achieve with the space i am willing to use.
maybe really really good shelf speakers would be better for me, still they let all the sound in the boot and loose punch if not enclosed so thats probably pointless too.

[dazleeds]

i dnt pretend to know lots on this subject but have fitted a few mdf shelfs in the past and you can get really nice bass with the right speakers on a decent shelf

maybe a pair of decent 10inchers in a small box wwill give you what you need liam??

never underestimate a good pair of 10s

and modern componants are very good quality and sound
could also mount a sub in the centre of rear shelf too if you wanted to keep the full boot

im just being greedy and dnt need much bootspace so am happy to fill most of my boot

[chu346]

In one of my old e30's I use all four of the standard speaker from the e46 I had. Two in each door then ran them off the head unit. You would be suprised with the sound they made. Now if you buy some decent speakers and have an amp on them it might give you the punch that you want.

If you wanted to upgrade from there I have seen 6x9's in the rear panels. Never listened to it myself but may it sound good.

I think you should try the above first if space is the prority but if your sure you want a sub but you don't have an arm rest in the rear seats I would say you could try a single (or better two) 10" mounted up to the parcelshelf where the OEM speakers should be and totally sealed them to the metal. The only problem with that is the box isn't going to be resting on anything so gravity will be pulling on it.

As for which sub i'd recommend jbl gt4 or the newer version. I have had these before and will probably be getting some more soon. http://cgi.ebay.co.uk/JBL-GTO1002D-10-1 ... dZViewItem
I have seen these cheaper though.

[chu346]

I just remembered that pioneer make these free air subwoofers that you can fit right up to the shelf like I said but you won't need a box for them and won't have any problem with gravity due to less weight. http://www.mcs-direct.co.uk/acatalog/in ... 55F%2ehtml

TSW255F the F is for free air sub, don't buy the TSW255C's they are meant for enclosures.

Daz my way of doing things will keep the stock look.

im just being greedy and dnt need much bootspace so am happy to fill most of my boot

If thats the case this will be on of the best setups for you.

Make a box like this:

so having the rear of the box wedged against the rear of the seat and cut out the rear of the box where the ski hatch is. This should make the box just a holder for the subs and the boot will be the box now all the bass will go into the cabin. I did this on an e46 saloon and the sound was awesome, I used four cheap 12" jbls and it was so deep and clear with less vibration than normal setups.

or

an isobaric(sp) ported box where you have one (or in this case two) speakers on the front of the box with a big port in the middle the put two other speakers on top of the speakers already in the box, so you will see the rear of two speakers and the rear of the other speakers will be inside the box. This is something I tried in my first e30 five years ago. The sound is unbelivably clean due to one speaker pushing and another pulling which stops all the wobble wobble you get when pushing the speakers hard. You need to tune the box low though to compensate. Must also add that I didn't have an arm rest in this can because it was a 316i so the box was facing the rear of the boot, number plate side.

either way you will need four 12's and 800-1000wrms.

Providing you have an amp man enough I could build and fit either one for £260-£270 including all materials, cabling and speakers.

Daz have you ever done an MDF shelf in an e30?

[dazleeds]

Daz have you ever done an MDF shelf in an e30?


many years ago i did a full rear shelf that replaced the original and had 4x 8s on it and a decent amp
the sound from that was excellent
i had planned to do that again but as i have subs lying around have decided to just do a partial shelf this time
also this means i can keep the rear blind
my plan is to put a baffle board behind the blind and bolt and seal this to the metal undershelf and at most fit 1 pair of 8s but im leaning more towards a decent set of components on that and the subs in the boot now

am open to suggestions tho and as you say would like to keep it looking tidy and stock,ish

dnt wanna go as far as 4 subs mainly due to weight and the fact my cars so bloody low i already have major issues crossing anything more than the smallest of bumps