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General => Car audio => Topic started by: Uku on 06 December 2006, 21:57
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ok did a search and found nothing useful , i want to put a sub in the spare wheel well , im running 17's so im gonna lose the spare wheel and live with tyre weld and a compressor , anyone know a good link for a build guide or a suggestion for the build id be greatful
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To be honest, the spare wheel well isn't big enough to get a good sound from - if space is an issue, a custom built side mount one by the suspension turrets will be the answer.
Is there a reason you want the sub in there? Or is it just a space saving issue?
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To be honest, the spare wheel well isn't big enough to get a good sound from
That's not necessarily true - it all depends on what driver you're using.
Some JL subs, for example, have an ideal enclosure size of less than 0.8 cubic feet.
The enclosure I have in my car (in which my JL sub sits) would take up approximately the same volume as the spare wheel well and it sounds awesome. (It's a JL designed enclosure).
Think about some of the 'pre-loaded' enclosures you can buy off the shelf - they're tiny, yet they can still sound great.
What I do agree with is that if you use a sub with a required enclosure size of, say, 4 cubic feet and you stuff it in the spare wheel well it will sound pap.
So, if you're hell bent on using this space, take some dims of the wheel well, calculate your available cubic space and buy a driver that will work on this space (most drivers will state the thiele parameters on the box, which will allow you to calculate the amount of space required/ideal space).
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I would have thought that the depth of the sub would be the real guiding factor.
Most really good subs are big front to back (ring to back of magnet) The wheel well wont be deep enough for some speakers!
Rough calcs I just did give just over 2 cu ft for that well. So a lot of speakers will suit but its that depth!
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Rough calcs I just did give just over 2 cu ft for that well. So a lot of speakers will suit but its that depth!
What did you estimate as the given depth Len?
When I think of my spare wheel well, the depth is massive (even bigger in the wife's A4 Avant - what did you guesstimate for a MK2? 10"?
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Yes Si my guess was 10". Thats what I based calcs on.
Was thinking of the tyre width. 185/195's as standard?????
So actually thinking about it again maybe that on the high side.
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Does the top of the tyre sit level with the boot floor on a mk2?
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That I dont know for sure, was guessing from the few I've seen.
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The tyre sits proud a few inches, so there's really not much room. Can't think of anywhere handier to put the sub than to the side of the boot TBH, especially if you're using fibreglass which I'd assume you would be for the spare wheel idea.
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aye im still in two minds about it , i was thinking of raising the floor though to make the volume/cubic space needed , if i used 2x2 (maybe bigger) wood to create a frame then mdf to make a false floor , cut out and router a hole to sink the sub into then use a perspex (prebought) cover to protect , surely that would give enough? especially with the tyre removed?
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You'd have to seal the gap between the bottom of the false floor and the boot floor surface, otherwise the cc calculation of the well would be incorrect.
So, if you're hell bent on using this space, take some dims of the wheel well, calculate your available cubic space and buy a driver that will work on this space (most drivers will state the thiele parameters on the box, which will allow you to calculate the amount of space required/ideal space).
Yeh, this is what I should have said :)
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possibly, sounds like a lot of work for very little benifit though.
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OK, I did a few quick calcs.
Assuming you can fit a 185/60/14 wheel/tyre in your spare wheel well then you have a spare wheel well of approximately 23" diameter:
Tyre depth (mm) = 185mm*60% = 111mm
Total wheel diameter (mm) = 111 + (14*25.4) + 111
Total wheel diameter (mm) = 111 + 355 + 111
Total wheel diameter (mm) = 577mm
Total wheel diameter (in) = 22.7" (say 23")
1 cubic foot = 1728 cubic inches (12*12*12)
Assuming you were running a JL8W3v2 with a required enclosure volume of 0.79 cu ft the enclosure volume, expressed as inches, would be 1728*0.79 = 1365 cu in
A slightly rectangular enclosure (totally square boxes are not as good as those which are not, as the sound can cancel intself out) of EXTERNAL dimensions of approximately 17" * 14" will fit snuggly in the spare wheel well (IE a rectangle within the circular spare wheel well).
Assuming you are constructing in 0.75in material, these dimensions are reduced to 15.5" * 12.5", giving an internal surface area of approx 193 square inches.
If we divide the required volume of 1365 by the surface area of 193 we arrive at the required INTERNAL height of the enclosure, which is 7" (will measure 8.5" externally). This figure should be increased slightly to make allowance for the volume displacement of the driver itself.
Now, obviously, if you aren't using a driver with such a low enclosure volume requirement you will need to increase the height of the box - all you need to do to achieve the look you want is to increase the height of your new false floor accordingly, so the enclosure top and the new boot floor are to the same level. The boot floor is then cut to go around the (rectangular) enclosure and the whole thing can be carpeted as one item - this saves all the hassle of trying to build a round box, or cutting a round false floor around it etc etc. It also means you do not have any sealing issues etc, as its a simple near-square enclosuredropped into the spare wheel well - which also means it will take 10 Min's to tally remove from the car and return it to standard.
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good thinkin, makin a square peg fit in a round hole! genuis!
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good thinkin, makin a square peg fit in a round hole! genuis!
I do my best :wink:
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Excellent S11EPS! Very well thought out!
Oh just a little tip - if you convert inches to a decimal of a foot then its easier to calculate cu ft!
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Excellent S11EPS! Very well thought out!
Oh just a little tip - if you convert inches to a decimal of a foot then its easier to calculate cu ft!
I chose to show it as that as few reading this would know what 0.24 of a foot looks like - expressing it all as inches is easier to relate to, for this purpose.
One calculation (12*12*12) gives you 1 cubic foot represented as inches and then you can continue to work in inches, which normal people will be able to understand.
Don't make me break out the yellow pad and go QS-style on your ass.
Inches are sh!t anyway, I'm a mertic boy - bring on the mm
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fair enough, it wasnt a critism just thought it would be easier for those that are not used to converting imperial to metric!
Personally I have always been versed in both but of course metric is far easier!
yellow pad? dim paper is usually blue! :wink: :grin:
I was appaulding you for doing all that work!
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aye cheers thats basically what i was thinking along the lines of. the bonus is you can hide the amps either side of the enclosure as well if you make a false floor in the exact shape of the boot, totally stealth then! , also im sure by having the sub centred and facing up (ported is a thought?) its going to have better acoustic propertys than one to one side. im going to go for this i think as i enjoy building my own stuff , i just obtained a perfect rear parcel shelf off ebay to replace mine which has 6x9's cut into it atm , which ill lose once i get a sub and amp , then also construct a set of door pods (that guide for custom doorpods is awesome and ill do that :p ) as ive already got top notch wiring for the 6x9's , when i remove them ill use that wire to power the door pod speakers :) just a matter of rewiring each ends.
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represented as inches and then you can continue to work in inches, which normal people will be able to understand
Finally! Someone who agrees with me! :laugh:
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(http://i24.photobucket.com/albums/c39/chris_wht/102_9369-1.jpg)
my old install. The whole boot was done in mdf and then carpeted, with 6x9's in the walls at the sides. sounded ok, but there was definitely not enough volume for the sub. it also rules out putting any luggage in the boot.
looked kinda cool tho.
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that amp probably didnt help , i had one of those a long time ago , they suck tbh , alot has to be said for a decent brand name amp , installs nice though , ur floor bit is how i want mine but with a perspec cover over sub :)
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Pardon my ignorance but does anyone know the ballpark Cubic feet measure of the Spare tire well of a Mk4 GTI?
I am a newby to all of this but I am willing to learn, I have a Near new condition Kicker Comp Vr that requires top-mount depth 5"
sealed box volume 0.8-3.0 cubic feet
Curious as if this could be done on one of these cars?
I have been reading and I am thinking about Trying to fiberglass the enclosure....
Any help or additional knowledge on this would be GREATLY appreciated!
Thanks.
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If you look at page 2 of this thread you'll see I did some rough calcs as to the volume of a Mk2 spare wheel well.
However, all of these measurements were guesstimates. If you want to take some dims of your spare wheel well I'll be more than happy to calculate the exact volume for you.
However, if you just want confirmation that your spare wheel well is somewhere between 0.8 and 3 cubic feet I can say catagorically Yes to that question.