Ok thanks Rob.
Is removing the spare tire an option? I'm thinking not since you'd use it for camping. If it is you could build a box into the well for the two 12s.
The issue I have with bandpasses is that they take up a large amount of volume before they can compete with a simple ported box.
Isobaric is a great technique to get around needing large chambers. But I wonder, if you used passive radiators how much space you could save.
The thing I like about them is they are very easily tuned. Add or remove some weight...as opposed to cutting down a port.
This is my girlfriends set up, its a 15, with a 15" passive radiator. Heres a pic. (Wow it looks cramped in there, but it actually doesn't take up that much room. Thats a bad camera angle, and the sub isn't mounted to the seats in that pic.) It is a very narrow box, infact the magnet of the sub is 1" away from the back of the box. Anyways if you did something like that with your 12s it would take up very little space I think. You can buy grills to protect the subs. You could considder running just 1 sub and one 12" radiator(I'm sure you know you'd need one that has a hefty amount of xsus if its the same size as the active driver)
I think the tapped horn is a great idea, it could be built in such a way that it would be very tall, but not too deep, so it could be placed against the back seats and leave plenty of room for gear.
I wouldn't do a 8" sub in the glove box, I don't think you'll get satisfactory results. The box would be difficult to build and you won't get nearly as much gain having the sub mounted there...I think. What about under the seats?
What about putting a 8" sub on the passenger and driver side, in the kick(Essentially where you rest your feet, away from the gas and brake.)
This may be useful.
This is usually done for midbasses, but it could work with subs...albeit without as much gain as if it were in the back.
Something else to considder would be building a false floor with the subs flush mounted, with a protective grill over them. You could do it in such a way that they vent outside, and would thus be infinite baffle...netting you a nice in car response.
Or you could mount them agaisnt the back seat, in a narrow, tall box, and fire the subs back, and ports up...this is often done at SPL competitions, since hittin the front wave off the hatch delays it enough to be in phase with the port wave when it gets up to the front of the car.
Anyways, how goes the progress with the bandpass?
Is removing the spare tire an option? I'm thinking not since you'd use it for camping. If it is you could build a box into the well for the two 12s.
The issue I have with bandpasses is that they take up a large amount of volume before they can compete with a simple ported box.
Isobaric is a great technique to get around needing large chambers. But I wonder, if you used passive radiators how much space you could save.
The thing I like about them is they are very easily tuned. Add or remove some weight...as opposed to cutting down a port.
This is my girlfriends set up, its a 15, with a 15" passive radiator. Heres a pic. (Wow it looks cramped in there, but it actually doesn't take up that much room. Thats a bad camera angle, and the sub isn't mounted to the seats in that pic.) It is a very narrow box, infact the magnet of the sub is 1" away from the back of the box. Anyways if you did something like that with your 12s it would take up very little space I think. You can buy grills to protect the subs. You could considder running just 1 sub and one 12" radiator(I'm sure you know you'd need one that has a hefty amount of xsus if its the same size as the active driver)
I think the tapped horn is a great idea, it could be built in such a way that it would be very tall, but not too deep, so it could be placed against the back seats and leave plenty of room for gear.
I wouldn't do a 8" sub in the glove box, I don't think you'll get satisfactory results. The box would be difficult to build and you won't get nearly as much gain having the sub mounted there...I think. What about under the seats?
What about putting a 8" sub on the passenger and driver side, in the kick(Essentially where you rest your feet, away from the gas and brake.)
This may be useful.
This is usually done for midbasses, but it could work with subs...albeit without as much gain as if it were in the back.
Something else to considder would be building a false floor with the subs flush mounted, with a protective grill over them. You could do it in such a way that they vent outside, and would thus be infinite baffle...netting you a nice in car response.
Or you could mount them agaisnt the back seat, in a narrow, tall box, and fire the subs back, and ports up...this is often done at SPL competitions, since hittin the front wave off the hatch delays it enough to be in phase with the port wave when it gets up to the front of the car.
Anyways, how goes the progress with the bandpass?
A conventional ported enclosure gives you efficiency between 30Hz and 60Hz. According to measurements and experience, this is exactly where you don't need that much efficiency, at least not for listening to music. Bandpass allows to boost the 60Hz to 120Hz range, which usually becomes quite weak (resulting in rumbly bass with a complete lack of fast "kick"), while still providing cone excursion control between 30Hz and 60Hz.
Hi Judtoff,
The spare tyre is outside the cabin so not an option..
About passive radiators you said
"The thing I like about them is they are very easily tuned. Add or remove some weight...as opposed to cutting down a port."
The thing I don't like about them is you have to pay for them whereas a port for me is free... Building prototypes out of scrap wood at work costs me nothing but time..
I have no problem doing the box in the glovebox - I'm pretty good at making stuff like this.
Re: 8" in the kicks. I originally bought a set of dls r4's to go in the kicks with some midbass 6" drivers in the doors...... Problem being even the 4" ers would not fit in the kicks, let alone 8" drivers.....
Thanks for thinking about this install,
Rob.
The spare tyre is outside the cabin so not an option..
About passive radiators you said
"The thing I like about them is they are very easily tuned. Add or remove some weight...as opposed to cutting down a port."
The thing I don't like about them is you have to pay for them whereas a port for me is free... Building prototypes out of scrap wood at work costs me nothing but time..
I have no problem doing the box in the glovebox - I'm pretty good at making stuff like this.
Re: 8" in the kicks. I originally bought a set of dls r4's to go in the kicks with some midbass 6" drivers in the doors...... Problem being even the 4" ers would not fit in the kicks, let alone 8" drivers.....
Thanks for thinking about this install,
Rob.
Your DLS mids should be able to play down to 80Hz no problem. The sub only needs to cover from 80 down. I think using the bandpass to boost the upper bass will make the sub much more noticeable. It won't be omni directional, and unless you have a brick wall filter it'll play up past 80Hz. Sealed may be best, it rolls off at 12db/octave and thats what cabin gain is, netting you a pretty flat response. A 4th order bandpass could be used to physically protect the subs, while retaining a decent amount of flatness.(well I guess it wouldn't have to be flat, but I'd aim for 0dB of passband ripple.)
Hmm model this in WinISD:
4th order BP
Rear chamber:1.5cuft
Front chamber:1.3
Front tuning:51.7Hz
0dB ripple, and 0dB gain.
It looks good to me.
Its down 3dB at 95Hz and 31Hz, it should be relatively flat in car. The DLS should be able to cross over at 80Hz and pick up where it leaves off.
Hmm model this in WinISD:
4th order BP
Rear chamber:1.5cuft
Front chamber:1.3
Front tuning:51.7Hz
0dB ripple, and 0dB gain.
It looks good to me.
Its down 3dB at 95Hz and 31Hz, it should be relatively flat in car. The DLS should be able to cross over at 80Hz and pick up where it leaves off.
judtoff said:
Sorry, this will result in the usual void between 60Hz and 200Hz. There are too many acoustical phenomena taking place inside cars and neither being modelled by WinISD nor by your brain.
The first wrong assumption is that a 6,5 inch speaker bolted to the door of a car can produce good SPL down to 80Hz.
The second wrong assumption is that 80Hz bandwidth at both upper and lower ends is enough for a 80Hz crossover to sum properly. Even LR24 (24dB/oct Linkwitz-Riley) requires 1.5 octaves of overlap, and LR-12 requires 3 octaves.
But the major mistake is to suggest tuning a bandpass box in the frequency range of maximum cabin gain...
Just got to say Judtoff there's plots earlier on in this thread of sealed subs measured in my car and they are way from flat....
I'm more home audio based so am trying to get my head round the 'tricks' the car audio guys use to deal with the cabin gain problems of the vehicle.
For example I've seen it written loads of time to set a gap in the xo points - ie use a 50Hz low pass on the sub and a 90Hz high pass on the mains. This creates a dip to eq out the cabin gain.
I'm just weighing up my options right now - haven't been able to test any more as the vehicle is playing up a bit...
Rob.
I'm more home audio based so am trying to get my head round the 'tricks' the car audio guys use to deal with the cabin gain problems of the vehicle.
For example I've seen it written loads of time to set a gap in the xo points - ie use a 50Hz low pass on the sub and a 90Hz high pass on the mains. This creates a dip to eq out the cabin gain.
I'm just weighing up my options right now - haven't been able to test any more as the vehicle is playing up a bit...
Rob.
In the end I decided I needed the space too much to go ahead with a large sub. I ended up buying a pair of 6" subs and building a tiny ported box for one of them. This has been 'not terrible' but I'm looking at using both drivers now and concentrating on the 40Hz - 100Hz range to keep good output.
I started a thread here about the 2 6" subs and have ended up building a test box for a 4th order BP box.
I'll post some initial measurements on that thread soon.
I started a thread here about the 2 6" subs and have ended up building a test box for a 4th order BP box.
I'll post some initial measurements on that thread soon.
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