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Discussion Starter #1 (Edited)
I need to get a new enclosure for my Alpine SWR-1042D 10" subwoofer. The reason being is I now have a 147, and used to own a Fiat Seicento. In the old car the sub was in a box made to fit the exact contours of the car, and it's laying down in my 147 taking up most of the boot space, because of course it won't fit anywhere properly in this car.

I found the enclosure information chart for my sub, it says 0.5 to 0.8 cuft, but I was wondering are there any audio experts here who can advise me, as in the current box the sub goes loud enough, but seems pretty loud at certain (really low) bass frequencies but there is a lack of bass on a lot of music that plays really bassy on a friend's car who has a generic bass tube. I don't like the amount of 'fake bass' as I call it (where the bass tube makes it sound like there is tons of bass even on quiet passages of music) that his gives, but it does puzzle me why on some drum'n'bass and dance stuff even though my sub and amp are RMS500 and his is RMS150, his is a LOT louder on some tracks. Only certain tracks with really low and powerful bass on the recording sound louder through my system.

I don't want to lose the tight sound I have currently, as I listen to most genres of music from soft rock to easy listening to drum'n'bass and dance.

But I would like a bit more deep bass. I am told that if I get a ported box this will make more deep bass but lose the tightness of the bass.

So is there any mileage in increasing the (sealed) box size? The box it's in now (from the old car) is listed as 0.57cuft on the website I remember working it out manually aaaaaages ago at 0.64cuft though. Is there any point in getting a 0.8cuft box, will this make the bass deeper or just more muddy, as I definitely don't want muddy.

Any advice greatly appreciated!


AO Silver Member, 155 Lounge Winner 09
7,713 Posts
you seem to have a decent understanding which is good; but not knowing 'how much' you know ;) i'll recap some stuff.

the subbox design is crucial to the performance (sound) of the sub; as important as the sub itself. the design should be based upon the relevant electromechanical ('Thiele-Small') specs of the sub, in particular the Qts, Vas, and Fs. these can be modelled in box design software like WinISD and Bass Box Pro. though interpreting the results can be a bit of a black art, so some experience is useful. whether a sub will perform optimally in a 'sealed' or 'ported' box depends on these specs; some subs are biased towards one or the other, or something different again (eg: infinite baffle, aperiodic, other). some subs are designed to suit either.

the other factor that is more difficult to account for - yet also very important - is the acoustic effect of the car/cabin. 'transfer function' is the natural acoustic boost of low-frequency subbass. a small change in the direction the sub faces or its position in the boot can alter the results considerably. if you're limited to placing the sub in one particular part of the boot (eg: for practical reasons - which is fair enough!), this may be a compromise on performance. but so be it - however, it could also account for the differences between your sub/car vs your mate's sub/car.

ported boxes are more efficient than sealed, so the sub sounds louder and 'lower'. but the 'cons' are that a ported box is usually always bigger, more complex to build, and at the very low frequencies can sound less accurate (ie: group delay).

your mate's prefab tube sub/box is probably ported, and probably 'tuned' to be loud at around 60Hz, where a lot of music has most of its subbass.

the SWR-1042D suits either sealed or ported. the above caveats apply for a ported box: bigger box, higher group delay particularly below 40Hz (not much music plays below this though). my box design suggestions would be:

*sealed 0.8cuft nett internal volume: this models well, and is in keeping with the size discussed
*ported 1.2cuft nett internal volume, with port tuning the box to ~32Hz: will be louder and 'lower' for sure; can use a single cylindrical port 4" diameter x 22~24" long (probably need to use a 90 degree elbow bend to fit this port inside the box)

note that subbass compliments the midbass (and higher). so the perception of quality 'bass' that is 'tight and accurate' can depend much on your midbass too. this in turn is depending on having quality front speakers, properly installed (sound deadened/sealed doors), with good amplification.

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