Ski hatch subwoofer install

[deshanv 0]

Hi guys,

I want to install a 10 inch subwoofer in the skihatch hole of my car. Some people say it will sound crap and I should put it in a big box facing the boot. I need space in my boot and I want a clean neat setup.

I need to know if anyone has tried to face the sub towards the drivers cabin, and how it effects the SQ of the audio. I have attached a picture of how I want it to look.

Please can you advise.

[_ethrty-Andy_ 2132]

i was looking at doing that back when i had my E30, but from what ive read its not a good idea if the armrest is up as the woofer is pushing air into a very tight space so it has to work harder. I went with a box in the boot setup instead. unless you plan to keep the arm rest down all the time, or are willing to rig a switch to the remote line on the amp so you can switch it off with the armrest up, i would suggest the same

[BM WORLD 1283]

have done a few like that in my e34's and other cars over the year works well enough , just tune in poperly with the correct crossover freq and level etc

[Neal 545]

My 10 cents worth.

I'm going to do a variation of this type of install in my M3

I've done this type of install this on three BMW's. (e21 + e30 + e36). All installs using the ski ports were using Subs designed to run infinite baffle (IB) so the bass ended up having a higher Q i.e. Bass sounded more like Night Club sound rather than tight hi end HiFi speaker sound. These installs all used 12 inch subs

You need less power than running a sub box in the boot as the BMW boot sound installation will drop volume by 8 - 10 db at lower volumes. With Boxes at higher volumes you get bass transfer occurring which the sub will transmit the sound via the vehicle structure so it's not quite linear in terms of bass drop verse volume.

In terms of cone excursion for the IB setups I mounted two 24mm MDF baffles back to back and shaped the second layer to the shape of the ski port on one side and rounded the corners on the inside. The forward excursion of the sub did not touch the baffle as a result. I didn't hear any untoward sounds such as huffing you sometimes get via ported boxes. The nice thing about running IB setups is that you lose very little of your boot space.

JL Audio makes some nice sounding IB subs and while some people rubbish IB setups they can be made to sound quite good.

I've also run sealed box subs in the boot (10 inch) and these have run lower Q's and produce fast tight bass notes with better timing. On this setup these I've run larger amps to make up for boot insulation but I’ve never been completely satisfied with running IB via ski port or sealed box in boot not firing through ski port.

What I’m planning for the M3 is to run a hybrid sub enclosure utilizing the ski port with a forward facing sub with custom baffle shaped from the sub into the ski port area. It will run a 1 cubic foot sealed box with a passive radiator running facing the boot. The Sub will be a 13x9 inch Boston SPG555 which matching Passive Radiator. The Passive radiator allows weights to be added so the box can be adjusted to give the desired Q . (e.g. boomy to tight bass)

I’ll post the build on here when I’ve got all the gear for the M3 build. I believe this will produce the best of both worlds in terms of direct cabin firing sub and running a smallish box but at the end of the day there are pros and cons to any setup.

Edited November 25, 2011 by Neal

[Neal 545]

BTW , here's a pic of a C110 as I mentioned in your other sub post. Great SQ and output for a small box sub. I've put it into the M3 so you can see size.

Edited November 25, 2011 by Neal

[rogan 7]

Forward facing won't effect sq, some reckon sq is better forward facing. You will probably get reduced actual volume.

I've always been happy with front facing subs. Yes you will lose some output with the arm rest up but it'll still be well audible

To Neal. I've had IB subs and they were crisp and clear. Have you considered a Fi IB3 sub. Not sure how you'd get one from the States but it's got an excellent reputation as an IB sub.

https://ssl.perfora.net/www.ficaraudio.com/...view.shopscript

[Neal 545]

interesting sub. Power is ip onthe IB's.

I like the idea of the boston as it almost mimics the shape of the ski port

Edited November 25, 2011 by Neal

[rjac001 0]

My Nephew did this to my old E30 and it looks good and sounds way better than having a box in the boot, you cant even really hear it if its in the boot and everything shakes and rattles people outside can actually hear it better if place in the boot, it also saves alot of room that a box takes up as this install is a 12" sub. You just have to take it out for WOF but it only takes 5mins. Basicly you just take out the armrest and mount the sub to some board or ply and mount the wood into the space...

[_ethrty-Andy_ 2132]

You just have to take it out for WOF but it only takes 5mins.

why? please tell me you/he didnt cut metal on the rear firewall?

[rjac001 0]

why? please tell me you/he didnt cut metal on the rear firewall?

Why, because it's classed as a 5 seater car and if you put a speaker where somebody is able to sit then I guess it becomes unsafe or something? thats what the VTNZ said. and No metal was cut it just sits in the space where he removed the fold out armrest.

[_ethrty-Andy_ 2132]

Why, because it's classed as a 5 seater car and if you put a speaker where somebody is able to sit then I guess it becomes unsafe or something? thats what the VTNZ said. and No metal was cut it just sits in the space where he removed the fold out armrest.

oh well that makes sence then! i was worried for a bit there ha. its communism to a certain extent isnt it

[deshanv 0]

thanks for all this guys,

I am planning on putting a kicker l7 solarbaric or a 10 inch rockford fosgate T1 power. The other option is putting a 12 inch where the spare wheel should sit, as the bmw e46 m3 convertible does not have a spare wheel, but has the space in there already.

[rogan 7]

Do you have any idea what you're talking about?

[E36 M 9]

Depends what your after, if your a young dude like me who loves bass, then forward facing is NOT the way to go, as the sub is not bouncing off anything and doesn't give any bass. But im sure your not after that. Have a 15inch in my wagon and it sounds bloody sweet/loud but the box takes up almost the whole boot because i wanted bass and quality. But my mate has a 10inch in his ute and that sounds pretty mint too, and thats facing the rear.

[rogan 7]

post then degenerates into obsession with fashion for ridiculously badly engineered speakers.

The link goes to an IB sub that handles 550watts

Lets look at it the speaker specs !!

The cone weight MMS is 250 grams , the efficiency is 83dB 1W/1m QMS is 4

What does this mean?

- The cone is so heavy you need a mack truck to move it - Hifi cone weights are around 50 grams for LF units

- The speaker is so inefficient it needs 1000 watts to produce 90dB SPl - a hifi speaker is typically 89 -91db - 1W/1m so for 1 watt in it will put out about the same acoustic power as this dog of a sub when it sucks a kilowatt.

- Qms is 4 which means the suspension is so stiff again you need a mack truck to move it.

So this heavy cone with stiff suspension is not going to move without some serious power it will be sluggish sound compressed and slurred and lack any detail because the detail will have come and gone before the cone overcomes its inertia.

Fashion is such a wonderful thing people will pay stupid money for flashy crap that doesn't deliver, or is it a penis extension ?

Part of my post was prefaced "to Neal" i.e. it was off the original topic. Maybe it would help if I write in crayon next time form those hard of reading.

Spl Efficiency - a very misunderstood rating. It is well known industry-wide that it's very inaccurate and speakers should not be compared on published efficiencies. There's no industry standard which is part of the problem. On paper the IDQv3 is less efficient than the IDQv2, but in reality that's because one of the parameters used to by Image Dynamics to measure efficiency was changed. Needless to say the IDQv3 is more efficient than the v2. To quote JL audio "Efficiency (1 W / 1 m) is not an accurate indicator of a subwoofer’s output capability and should not be used as a comparison to other subwoofers to determine which one is "louder"."

A pair of 86db (or thereabouts) efficient subs running off a total of 800rms made 139.9db in a spl comp a few years back. Hopefully this shows how over simplified your calcs were.

Mms and Qms. One of the most accurate sounding subs I've owned had a MMs of 174g and a Qms of 6.19, and it's used as a LF driver in home audio. Speaker design is about the whole picture; plucking out figures in isolation and then drawing conclusions off them is dangerous.

And what's this rubbish about fashion. I'm recommending a US$190 sub that very few people in this country (or worldwide) have ever heard of. I'm recommending it based on opinions of people I trust who know what they're talking about.

[deshanv 0]

HI guys, come now, back to helping me please on what I should do, I am thinking going with the Rockford fosgate Power series 10" or 12" sub. I have a 1000wDX monoblock kicker amp already. What do you guys think?

I had a kicker L7baric for a month an the voice coild blew, I gave it back and don't want to use a kicker sub again

[jcerecke 2]

HI guys, come now, back to helping me please on what I should do, I am thinking going with the Rockford fosgate Power series 10" or 12" sub. I have a 1000wDX monoblock kicker amp already. What do you guys think?

I had a kicker L7baric for a month an the voice coild blew, I gave it back and don't want to use a kicker sub again

I have two RF 10's. First had them in a really basic small sealed box and this was nice, and then swapped to a single one in the ski hole with a really whorey IF setup which wasn't really IF at all, it was more open baffle. With the RF, the second setup sucked big time compared to the sealed box. Probably because of how lazy I was with the second setup, and the fact that the driver specifically said not to use it in IF haha. I'll definitely be going back to sealed box when I start on a system for the e39.

EDIT: You can buy both my RF Power 10's if you want? Or just one. One's got a small dent in the metal cone. The other is in top condition.

Edited November 29, 2011 by jcerecke

[deshanv 0]

What RF 10's are they? and how old?

[Neal 545]

With an amp that size, get a heavy duty sub with a single voice coil with a similar or larger power rating to the amp and make sure that the box is of the right size so you don't mechanically overdrive the sub.

Seem strange to to do a voice coil if your putting clean and un clipped audio through, Do you like serious amount of volume ? What's the rest of your setup.

BTW, Looking forward to hear 3pedals car audio setup at the next SQ Car Stereo comp. I’m ready to be enlightened on quality car audio.

[rogan 7]

There are sq comps in NZ now? I thought the comps had completely died out.

But the comments remain valid: Overweight, inefficient and stiff suspension loudspeakers don't produce clean detailed and articulate bass and suck an inordinant amount of power to achieve a mediocre result.

Thank you for your opinion. Call me a fool, but I think I'll take the non-commercially motivated recommendation of the guy who has dominated the international car audio sound quality competition scene for the last 10 or 15 odd years including having the highest score ever recorded in any sound quality competition (irrespective of format or sanctioning organization), owns a successful car audio speaker company, tours the world giving workshops on car audio to industry professionals, and (according to a very reliable source) uses the Fi IB3 in his daily driver.

lol at Neal's pic. So true

Edited November 29, 2011 by rogan

[deshanv 0]

With an amp that size, get a heavy duty sub with a single voice coil with a similar or larger power rating to the amp and make sure that the box is of the right size so you don't mechanically overdrive the sub.

Seem strange to to do a voice coil if your putting clean and un clipped audio through, Do you like serious amount of volume ? What's the rest of your setup.

BTW, Looking forward to hear 3pedals car audio setup at the next SQ Car Stereo comp. I’m ready to be enlightened on quality car audio.

The L7 10 inch kicker is single voice coil isn't it?, it is a custom sealed box. I have the standard BMW headdeck with the harmon kardon speakers.

I am thinking of going for this setup

[Andre3000 55]

Just go and talk to the guys at rapid radio and tell them what you want, there is no-one else more helpful in akl. You could easily fit a 10" in the ski hatch hole and still have a folding armrest, which would retain the 5 seats and not void your warranty.

I'm not sure about everyone else but i'd rather have a spare wheel than doof doof...

[E36 M 9]

You wont be able to set up a sub with the standard BMW head deck though? I have put a iPod connection to my mothers car, but tried to install a subwoofer with the standard headeck and u couldnt, and it wouldn't do the trick like an aftermarket mp3 headdeck would

[Neal 545]

M3's have spare tyres ? Unfortunately they don't due to the smaller tyre well to allow M3 rear muffler. All you get is a compressor and tyre gunk and more room for car stereo's

Very nice tidy install. Was that a E46 m3 or a larger E46 boot well ? I'm planning on putting my amps in the same location. Also gives stealth install and retains full boot use.

I'm thinking that the depth of the tyre well will limit your sub to more shallow depth models. From memory there is a metal bracket that would need removing to allow enough depth smaller subs unless if you use super shallow subs (Like the 13 inch soundstream)

I do like the idea of the IB sub Rogan has talked about , sounds like they have come along way since the earlier Cewin Vega's , infinities or JL audio's

I wouldn't go with 2 x 17cm bass units suggested, you problably had the two 6X9 HK subs which would produce similar levels of bass and hardly any sub base. (These provide only mid bass really )

Rogan may be able to suggest a shallow mount sub that would go in M3 boot well. Your high powered amp is the issue and does limit choices somewhat.

In term of the audio feed to the sub amp, I'd look at modding the BMW tuner stage by adding RCA outputs to feed the sub amp rather taking a speaker type feed. That way you can get a cleaner unclipped feed into the sub amp and set it up so that it never has to clip the signal. BTW , did you earth the amp to the chasssi or take in back to the neg battery terminal.

Edited November 29, 2011 by Neal

[rogan 7]

Sorry I know nothing about shallow mount subs.

Neal, I was slightly wrong in my post above. Scott Buwalda doesn't just use that Fi IB3 sub in his daily, he also uses a custom version of it in the car that scored the highest ever. Interestingly it's mounted under the dash and vented into the transmission tunnel.

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