I have recently made a ported box for 2 10"s. the ports face up against the back seat with the subs. does having the back seat right up against the ports cause any problems such as sound diffence?
i was thinking of positioning the ports to go through and out the top of the parcel shelf straight into the cars cabin, would this work better then what i have?

Im not sure if i needed to be any more specific then this but if more info is needed i will post again later.

Thanks for any help or adive given.

We need as much info as possible to form a reasonable picture..

Hatch or sedan? (what car?)

Which way are the subs facing?

Do your back seats fold down at all?

Do you have rear fill? (or have you taken them out?)

How close is "back seat right up against the ports" - is it a port diameter or less?

Having the ports through the parcel shelf is not necessarily a good idea unless it is a bandpass box, or if the subs are facing forward and the back seats can fold down...

Also, how much room is there around the box? (give measurements in all directions to give others an accurate picture)

1990 VQ statesman(sedan)

The subs are in a retangular box but with a slant angle the same degrees as the back seat. The subs are mounted in the mounted on the angle baffle which face towards the seats. The rest pretty much right up against the seat. also the subs are closed off from another with a internal middle panal in the enclousure.

The middle part of the seat folds down. When down half of each sub is in view but the ports are higher then the opening leaving it 30mm at the most of space between the port and back seat. Its deffinately less then the port diameter. the ports are 66mm

Im not sure what you mean but rear fill but im gonna guess speakers. I have 6.5 2ways.

As for room around the box. No space between top and botto. the back is closed off by a panal that conves on end of the boot to the other side, top and bottom. The only room at all is the sides and thats only halfway up the box. its about 300-400mm to the edge of the boot with around 200mm in hieght. When i made the box i measured it to just fit in between everything.

another thing is i didnt partically want the middle seat being open all the time if thats what helps.

i think thats all info given you asked for, cheers

Ok, when designing a box to go behind the back seat, I would normally suggest at least 15cm between the subs/ports and the back seat.

Folding down the middle part of the seat is preferable in terms of SQ and SPL...
Obviously you can fold it back up when you park the car (so people can't see your subs...) - yes it may take a little bit of time, but if your priorities are good sound quality then it should be worth it.


If there is very little room between the ports and the back seat, then this will certainly alter the sound - even with the middle part of the seat folded down, since the output of the port will be significantly damped, the box will sound more as if it was sealed (or tuned very low).

In this case, since the subs face forwards, having the ports positioned to go out the top of the parcel shelf can work ok, but you will still want to fold the middle part of the seat down - much of the output comes from the subs rather than the ports, so it certainly won't sound as great if you were to fold it back up..

Ok thanks for clearing that up. I tested out the sound after i put the subs in positioned to see what the differnece was like between the seat fold up and seat folded down. I couldnt really tell much of a differnce between it up or down it terms of sound but it sounded good enough for me either way. The only other problem im worried about now is if it will effect the subs in any way such as damage to them. i hear if ported enclosures arnt designed properly damage can occur to the subs. this will be my last question, but would you think will the short distance between the ports and seat that i may get this problem?

It is rather rare that a ported enclosure contributes to the risk of damage to the subs
(if the ported enclosure contributes to the damage, it is normally caused by too much power sent to the subs significantly below the tuning frequency and mechanical damage may result)

Since the short distance between the ports and seat actually reduce the effect of the port so there won't be any real risk in damaging the sub.

Making sure there is enough room between the subs themselves and the back seat is more important - so the subs can reach full excursion and not hit the seats at all.