Where to port (Sub Box)

[john182rs]

I have an Alpine type R 10" sub but not got a scooby doo on where to cut in the port in the sub box that i have built to the measurements that came with the instructions.

Can some one answer these questions for me.

Does the port need to be angled or straight like in the pic marked A and B?
How big does the port in the box (marked with a ? mark) need to be?
How big should the actual port opening itself need to be width and height?

Measurements within the picture are all exterior with a 18mm mdf board, its all been sealed on all the joints by using no nails when fixing the box together screws to secure then caulk on the inside joints aswell as around the sub opening edge.

 

[Bennett]

Firstly let me say that is a quality drawing!

What are you looking to do with the port, are you wanting to tune to a specific frequency or simply for general music?

If you are looking to tune for a specific frequency i would suggest searching google for one of the many free box design applications.

Otherwise i would buy one of the generic port cones that are available from most audio dealers and build your port to that size. Unless your serious about your music then porting the box may not even be necessary, alot of the time a sealed box is best unless you are looking for SPL performance.

 

[john182rs]

I have it as a completly sealed box but at the lower levels i can not really hear much, at the higher volume say like 25% to 50% i can feel the bass and anything above 50% volume with the sub setting on 4 with bass on 0 and treble on +2 aswell as the amp being on roughly the 30% boost. The car shakes like bugger and you can hear it as but you cant really hear it, if you can understand that.

I know the volume inside is 1.31 cubic ft. My previous box was almost double in height with a stuffed up port but i had loads of bass on it at lower levels and not much at the higher levels and that was 2.65 cubic foot.
Alpine recommend 1.3C FT for this sub.

 

[john182rs]

No takers on this with all the audio people here?

 

[James28]

If you don't get an answer on here try talkaudio forum mate.
I'm sure someone will be along on here shortly though with an answer!

 

[john182rs]

I think i will have to try that matey, will be avoiding one or two of my mates on there tho as they talk more shet than a little. Both of them when looking at my old box told me where to put the port but didnt say the box was way too big for the sub when it had near to double the cubic volume it needed.

 

[Bennett]

It sounds like your last system did not have a good box at all. A port does not tend to alter the volume of a box unless your talking big numbers, i did a test at work a couple of months back, same sub, different boxes. The sealed box sounded better for all round performance whereas the ported box i used was tuned to 38hz and sounded better for dubbstep and bassline.

You could perhaps set up the sub a little better using the filters on your headunit and amp. Turning the bass boost up on the amp will be fine, just dont make the mistake of using the gain control to turn up the volume. On the head unit again turn your sub and bass up a little more if you want to hear the bass better at lower volumes.

The alpines are good subs but you are never really going to get the mental bass especially from a 10" unit. It may be that you would be better suited to something purely SPL based such as Rockford Fosgate, RE audio or Kicker.

 

[john182rs]

Its boxes ive built myself to the specs that some one has given me. The first box was huge and no benefit at all apart from the sounding of bass in some of it.

I do listen to alot of D&B, Dubstep, Garage, Rave, Hiphop, Rap genre type music.

I dont know if its SPL or not, I have looked in to buying the Pioneer speakers, one of these two.

10 Inch
http://www.pioneercaraudioonline.co.uk/products/47/391/pioneer_ts-w2501d4/

12 Inch
http://www.pioneercaraudioonline.co.uk/products/48/344/pioneer_ts-w3002d4/

Just found out the Alpine i have is max 600 rms.

The Alpine will do me for now but i might want to change some time in the near future for more gut rumbling oomph.

 

[Bennett]

Sounds like at the moment your sub might be putting out quite well for what it is.

If i were you id wait a little while till the alpine just does not do it for you anymore then look at getting a pair of REaudio SE 12" or possibly some Rockford Punch 12".

 

[Dink]

you can't just cut a port into a box and hope for the best

imho it just sounds like you need everything setting up right

 

[john182rs]

Dink, i know o can not just cut a port in to the box, this is why i am asking for measurements on how big and where to cut it with the ideal side panel to cover the hole/port and direct it to the front of the speaker.

I had the chance of getting a box made up by DBAudio but their prices start at £70 for the box, 70 quid to house a speaker that IF i could basically make myself saves me a packet is worth while in 'having a go' I got the MDF for free and the screws also for free aswell.

 

[Dink]

you need to know what you want to tune the ported box to.

this will then define the size and length of the port. (too big will act as if the sub isn't even in a box)

i'd just build a sealed box and shove a little more power into the sub

 

[Bennett]

There aint really any need to port a 10" sub unless its sumat crazy that can move a hell of a lot of air. Alot of the lower end 12" subs dont really benefit from porting.

£70 for a custom box is a really good price tbh. Our cost prices arent far off that and we consider our builder to be fairly priced!

 

[sideways danny]

that box looks huge for a 10. admitedly I dont know any of the manufacturers recommended volumes, but instinct says to me that you should roughly half the volume of that box, and keep it sealed. That should give you what a 10 does best and be nice and punchy rather than have a lot of depth.

 

[john182rs]

I have gone by what Alpine have said to do by box size for this sub. I just feel out done by some one else who has one of these all in one Juice packages yet it feels like he gets more bass and quality than what ive done.

I dont want a super huge box as i'd like the ease of removal should i decide to go racing one day out.

 

[TIG ACM]

best bet is to read the instructions for the sub, they will give dimensions and port size and ideal hz to tune it to.

I have a 10" Jl w3 in a custom ported box and it sounds so much better than it did in a sealed box

 

[Dink]

one other thing i've just noticed is that you need to slope the front or the back to stop any standing waves

 

[sideways danny]

I have gone by what Alpine have said to do by box size for this sub. I just feel out done by some one else who has one of these all in one Juice packages yet it feels like he gets more bass and quality than what ive done.

I dont want a super huge box as i'd like the ease of removal should i decide to go racing one day out.

what is the volume range they recommend? for both sealed and ported

 

[john182rs]

CFT for sealed is 0.8 to 1.1 and ported is 1.1 to 1.3.
Ive gone for ported measurements that are in the picture above, i know if you put them through a cubic volume calculater that it comes up more than 1.3 but the rear board is double thickness. So the depth is actually less internal, plus i allowed a small amount of room for the speaker to be sat inside the box.

This is what Alpines manual recommends.

I know if you look at the above numbers, it says the width needs to be 14.5, i had to make it wider so the amp has some thing to fit on and screw into.

I just do not understand the vent part. Is the vented length the total distance measured around the vent opening? Displacement?

 

[bozothenutter]

displacement is the amount of room the vent takes up inside the box.you have to subtract that from the internal box volume.
i'd go with a closed box anyway, as it gives a tighter faster response. Or maybe get a passive radiator aswell, i have this is a home setup and this allow your sub to go a bit lower without losing as much response as with a vent.