17 replies to this topic

[storms]

Hi Everyone,

I have a 10 inch DVC [4+4ohm] Type R sub.
I used to use 2 of these babies in the back of my Impreza running at 220W RMS and found the sound lacked low end and was too boomy.

On the weekend I grabbed a ported box from my mates car, removed his sub and put one mine in and gave it a go running at 300W RMS. The single sub at higher power in the ported box sounded much better - better low end, more solid response (i expect my previous setup wasnt powering the subs enough for them to operate at their optimum and 2 drivers is overkill for the car), so now my question...

What is the correct specs for a ported box for a 10inch DVC Alpine Type R? in terms of box size, port diameter and port length?

[|OPEL|Astra]

i would like to know this aswell, i have my 2 type R's in a sealed box and it is abit too boomy for my liking but you see i am running about 618 RMS through each (with gain in 3/4 soooo i dunno i wouldnt mind hearing them in a propper ported box

[shiny_car]

state exactly what model type-R 10" you have so we can find the relevant specs. better still, check the manual and tell us the specs that we need to use box-design software to find something suitable:
*Fs (Hz)
*Qts
*Vas (L or cuft)

[storms]

OpelAstra, thats the same trouble I have, with 2 of these in my car running at 240W each it was waaay tooo boomy and taking up too much boot space. So I've gone to 1 sub running at 300W, tried it in a sealed and ported box and ported has better low end and not as boomy.

Shiny Car, the model is SWR-1040D

*Fs (Hz) = 30hz
*Qts = 0.41
*Vas (L or cuft) = 29L

Your help would be appreciated.

Also any idea why almost EVERYONE says you should put these in a sealed box? Is it just so you can pump the begeezuz outa em without a worry about SQ?

[shiny_car]

from the specs, ported should be the way to go, but sealed is fine too. what size have you been using?

*sealed: 0.5cuft each sub: should be fine
*ported: 1.5cuft tuned to 30Hz

a big problem with ported is fitting in the looong port. a 4" round port needs to be ~21" long (~55cm). that's do-able with a couple bend in it using 90 degree elbow sections of plumbing pipe. narrower port can be shorter but more turbulence through it, risking audible port chuff.

any idea what the ported box was that you experimented with?

[storms]

Shiny_car

The sealed box I was using was more like 1 cubic foot and they sound too boomy with not enuff low end. Box was obviousluy too big

THe ported box I tried was about 1.5 cubic foot with a 10cm port of about 1.5 inch diameter - so obviously too small a port.

I will have a look around, your help has been invalulable!

[shiny_car]

storms said:

THe ported box I tried was about 1.5 cubic foot with a 10cm port of about 1.5 inch diameter - so obviously too small a port.

that tunes it to ~25Hz, which would be excellent. but as you say, the narrow port would play havoc with audible chuff.

at lower volumes, i'm sure it sounded good. at higher volumes, with that port, probably would hear chuff. but if you don't then there's every reason to go with that design.

if you can find suitable piping that's, say, 3" in diameter, you could try that. will be less turbulence than a 1.5" port, but more than with a 4" diameter port, and would need to be (3"x) 45cm (or ~17.5") long.

[storms]

Hey Shiny,

I got a 1.4cubic foot box yesterday, port is about 3inches in diameter and it is 30cm long. Sounding good so far, what kidna frequency is that box gonna be at? Should I extend the port?

[shiny_car]

that'll be tuned to about 32Hz. there will be a bit of a boost down really low, around 20~40Hz, but probably not very noticable as not much music plays that low.

if you can extend the port, then worth trying. it would have to be ~52cm for tuning of 25Hz, so anywhere between that and what you have could be beneficial. but again, it really only flattens the very bottom end which is not a major feature in recordings, so you may not notice too much.

is port chuff a problem at higher volumes?

[storms]

no port chuff problems at all so far it doesnt port into the cabin, just into the boot so wouldnt be very noticable anyways..

my main problem now is i need a custom parcel shelf, the impreza standard one vibrates very badly so need to arrange that unless you have any recommendations for DIY fixes

[KLRBEE]

Sound deadening, sound deadening and sound deadening.

[storms]

KLRBEE,

where do i put it? on the underside of the exisiting shelf? do I remove the shelf first? what brand,etc?

[KLRBEE]

Generally the vibrating shelf is the shelf material buzzing against the metal. This is because there are numerous holes in the shelf letting the pressure waves from the sub come through. If you block these with sound deadening this will reduce this substantially. Similar principal to applying it to a door to stop the trim rattling. Try one sheet cut to size on top of the shelf under the trim material. Its is available in 4 square feet sheets (55x75cm) which is about $60. Stinger and Dynamat have the easiest to apply and are widely available. If it doensn't totally counteract your problem, do another sheet under the shelf. Best of luck.

[storms]

I looked under the parcel shelf the other day, it already has some type of thick material from the factory on it (i assume sounded deadening, was thick and looked like carpet underlay) - its an MY05 Impreza and brand new. The material would be about 1cm thick, should I remove the existing material and put on some new sound deadening material in its place, or add new sound deadening material on top of the existing material?

[storms]