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Porting parcel shelf 

 

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 Post subject: Porting parcel shelf
Posted: Wed Apr 04, 2012 9:47 pm 
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I have JBL 6.5" 3 ways and an Alpine 8" sub in my Ef's parcel shelf running off a Weconic 85w rms ch amp. I get good deep bass but I was thinking about running 2X 2" ports at each end of the shelf, would that make a difference? The JBL's are bolted direct to shelf if that helps
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 Post subject: Re: Porting parcel shelf
Posted: Wed Apr 04, 2012 9:53 pm 
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79raven wrote:
I have JBL 6.5" 3 ways and an Alpine 8" sub in my Ef's parcel shelf running off a Weconic 85w rms ch amp. I get good deep bass but I was thinking about running 2X 2" ports at each end of the shelf, would that make a difference? The JBL's are bolted direct to shelf if that helps


Ports won't do much, also it will be illegal to cut the metal in the parcel shelf due to changes to structural integrity.

If the 8" sub is meant to be enclosed...I suggest you build a box underneath the parcel shelf and seal it off, then port the enclosure later on if you want to change the bass/design.

 

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 Post subject: Re: Porting parcel shelf
Posted: Wed Apr 04, 2012 9:58 pm 
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I'm with Phong...

My shallow mount pioneer is meant to be enclosed and I know the bass would be much tighter if had the proper volume behind it... The entire boot makes the bass a bit flat... But I am not really interest in trying to box it in so I make do... I think you'll find most small subs which seem to have less surface area work better in small sealed enclosures... Tighter bass and better pronounced...

Plus, what you wanna do is illegal...

 

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 Post subject: Re: Porting parcel shelf
Posted: Wed Apr 04, 2012 10:14 pm 
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It would not be illegal to port if I mount them in the holes already made from factory, and if 2" was too big I could go smaller ports. I know about boxing the sub too, would be nice and tight boxed but with the mrs and 3 kids s**t in the boot I have not much room. It also does sound a bit flat, but tweaking the crossover on the amp helped to almost sound like the bass is bouncing round the boot with no escape.
I know the 6.5" with no spacers is illegal, but I could not stand them on spacers anymore. Got a bloke who I have been told does pink slips and wont be bothered with a clean cut 6.5" hole instead of a 6", so hopefully should be right there
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 Post subject: Re: Porting parcel shelf
Posted: Wed Apr 04, 2012 10:20 pm 
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As you say... Comes down to whether you can find someone willing to break the law to pass your car...

As far as the engineers at the RTA are concerned... As soon as you drill any hole, be it a 1mm hole or a 2 inch hole... The car is structurally unsafe to drive with an engineers cert saying it is indeed still safe... I sure as hell done remember seeing any "spare" 2 inch holes in my parcel tray that your saying exist? Unless of course EF's have them and ED's done but I didn't think the body changed that much...

 

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 Post subject: Re: Porting parcel shelf
Posted: Wed Apr 04, 2012 10:26 pm 
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I think some ef's had tweeters in the shelf.... but I could be wrong. There is 2 lengths each side that from memory that are around 1.5 to 2" wide on each corner and also in front of the restraint bolts
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 Post subject: Re: Porting parcel shelf
Posted: Wed Apr 04, 2012 10:31 pm 
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Cool...

Learn something every day... I don't it'll make much difference either way... I know where you're coming from... I have a shallow mount sub and it still gets in the road sometimes depending what I'm trying to squeeze into my boot, but I think you'd make best sound out of some kind of sealed enclosure... Other thing to maybe try, for the sake of trying it... A speaker box has dampening inside it to absorb the bouncing sound... Trying loading you boot up with rags or old clothes or something... Try to cover the steel surfaces in there... Maybe this will stop the bounce you're hearing? Can't hurt... May work, may not... If it does you may be able to get some spray adhesive and some cheap carpet and line the steel surfaces in your boot?

Cheers,
Tim

 

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 Post subject: Re: Porting parcel shelf
Posted: Wed Apr 04, 2012 11:42 pm 
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yeah was thinking that too, pulled apart some old speakers over the past months and taken the sound deadening sheets out of them, should be enough to cover the major bits. I know its going to weigh the car down, but the sheets I have are quite thin and light so shouldnt be too bad. Going to do that this weekend. Also noticed Jacar have silk dome tweeters in Penrith, 120 watters for $25. Thinking about grabbing those soon and repacing stock tweeters. Response s**t is normally good and for that price I cant compain.
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 Post subject: Re: Porting parcel shelf
Posted: Thu Apr 05, 2012 12:16 am 
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...I managed to fit 8" speakers on my parcel shelf with a custom parcel shelf spacer...the magnet itself is nearly as big as the 6" hole. This makes it much simpler to revert back to stock if ever need be. Also for more bass without compromising boot space, you can always mount a large free-air sub on a baffle board behind the folding seats. The only downside to this is you lose the ability to store long items poking through the rear seats...so boot/cabin are now totally separate.

Here is a picture to illustrate what I have done...

Image

 

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 Post subject: Re: Porting parcel shelf
Posted: Thu Apr 05, 2012 12:49 am 
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I actually mounted a 10" sub behind the seat of an Nc I had, turned out the padding on the back of the back seat absorbs that much of the bass it was a waste of time. The thing with the 6.5" speakers being mounted direct to the dash is by adding a spacer your restricting the air flow from the side of the speakers. By adding spacers you should really take into account this air flow and make the internal section of the spacer large enough to allow enough air flow, so say for a JBL 6.5" titanium 3 way with 125w rms out the space would have to take up most of the shelf. Not to mention when they were on spacers they didnt look like they belonged to me.
I know I am doing the wrong thing by not having a free air sub, but the Alpine 8" sub cost me $5 on Gumtree so I made do. It pumps hard, I just thought maybe giving the air somewhere to go instead of bouncing round the boot would be benificial. I think deadening the boot would be the best bet and I had planned it but just forgot when I was writing my to do list this arvo. Having 3 small kids leads to no sleep leads to mind f**k leads to dim lights in the brain leads to me being confused and I think I should lay down
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 Post subject: Re: Porting parcel shelf
Posted: Thu Apr 05, 2012 1:44 am 
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my first car (XF) i had i didnt know it was illegal to cut the partial shelf.. :? :?

i spent a whole day with tin snips and a angle grinder it get the holes big enough for some 6x9s :lol: :lol:

had the car for a while and was pulled by cops and never has a issue??.. :shock: :o

o well you live and you learn i suppose. . hahaha :wink: :twisted: :twisted: :mrgreen:

 

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 Post subject: Re: Porting parcel shelf
Posted: Thu Apr 05, 2012 7:49 am 
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phongus wrote:
...I managed to fit 8" speakers on my parcel shelf with a custom parcel shelf spacer...the magnet itself is nearly as big as the 6" hole. This makes it much simpler to revert back to stock if ever need be. Also for more bass without compromising boot space, you can always mount a large free-air sub on a baffle board behind the folding seats. The only downside to this is you lose the ability to store long items poking through the rear seats...so boot/cabin are now totally separate.

Here is a picture to illustrate what I have done...

Image


that's really neat phong... A+ there... That's a complete custom carpet is it? Looks like the brake light is gone? And you just made it out of ply or carboard and carpet?
79raven wrote:
I actually mounted a 10" sub behind the seat of an Nc I had, turned out the padding on the back of the back seat absorbs that much of the bass it was a waste of time. The thing with the 6.5" speakers being mounted direct to the dash is by adding a spacer your restricting the air flow from the side of the speakers. By adding spacers you should really take into account this air flow and make the internal section of the spacer large enough to allow enough air flow, so say for a JBL 6.5" titanium 3 way with 125w rms out the space would have to take up most of the shelf. Not to mention when they were on spacers they didnt look like they belonged to me.
I know I am doing the wrong thing by not having a free air sub, but the Alpine 8" sub cost me $5 on Gumtree so I made do. It pumps hard, I just thought maybe giving the air somewhere to go instead of bouncing round the boot would be benificial. I think deadening the boot would be the best bet and I had planned it but just forgot when I was writing my to do list this arvo. Having 3 small kids leads to no sleep leads to mind f**k leads to dim lights in the brain leads to me being confused and I think I should lay down


i have never heard of this issue... Air has to be the most free flowing fluid... I honestly thought having a 1/2 inch gap around a basket would be ample... Air moves so easily... Mounting it on a spacer may have reduced vibration transfer to the parcel tray... But i can't see truth in your air arguement yet? :/
Benny D wrote:
my first car (XF) i had i didnt know it was illegal to cut the partial shelf.. :? :?

i spent a whole day with tin snips and a angle grinder it get the holes big enough for some 6x9s :lol: :lol:

had the car for a while and was pulled by cops and never has a issue??.. :shock: :o

o well you live and you learn i suppose. . hahaha :wink: :twisted: :twisted: :mrgreen:


yeah, like the firewall it is deemed a structural part of the car... No extra holes allowed... No making holes biggger allowed... I doubt a copper would know the law or to look for that... They are only police remember... ;) some clever rule writer for the rta is the clever nugget that came up with it... :roll:

cheers,
tim

 

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 Post subject: Re: Porting parcel shelf
Posted: Thu Apr 05, 2012 8:37 am 
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There is a formula to work the size of an enclosure needed for each speaker, but I cannot remember how it goes. A speaker designed for a parcel shelf means the makers have put into account the general size of a boot and made the speaker to produce the best sound with that sized enclosure ( boot size). If you look at your speakers, the air flow is produced on the sides of the speakers basket and by putting a spacer around that area it strangles the air flow. You will still get low end bass as that wave will pass through almost any surface and if anything it will push harder on the shelf as its trying to exit through the stock 6" hole ( thats actually smaller due to the magnet obstructing the hole).
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 Post subject: Re: Porting parcel shelf
Posted: Thu Apr 05, 2012 11:09 am 
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79raven wrote:
There is a formula to work the size of an enclosure needed for each speaker, but I cannot remember how it goes. A speaker designed for a parcel shelf means the makers have put into account the general size of a boot and made the speaker to produce the best sound with that sized enclosure ( boot size). If you look at your speakers, the air flow is produced on the sides of the speakers basket and by putting a spacer around that area it strangles the air flow. You will still get low end bass as that wave will pass through almost any surface and if anything it will push harder on the shelf as its trying to exit through the stock 6" hole ( thats actually smaller due to the magnet obstructing the hole).


From what I know, enclosures are only really important when it comes to large woofers to produce low frequency more accurately. Mid and high frequency don't require a precise sized enclosure to work as effectively, unless you want to enter SQL comps. My 8" speakers are only used for mid and high, no low frequency passes through them...which makes them redundant since I have a sub.

Regarding bass being absorbed in the seat, I will agree with you there...hence I am wanting to upgrade to a high quality 8" sub for the parcel shelf, however that might grab attention of opportunistic thieves and cost more than my 2 x $50 subs.

You're not doing anything wrong by using 8" sub, but to get the full potential, I'd say build an enclosure for it. An 8" sub shouldn't have a big enclosure? Not sure on your model sub, but the JL 8W3v3 8" sub only needs a 8.5L sealed enclosure or 9.9L ported enclosure...that's the size of a standard bucket. Can be fitted under the shelf (without blocking the 6.5" speakers) and high of the ground enough to still use the cabin/boot length for awkwardly long luggage.

Honestly, I don't think anyone will spot the difference between a 6 and 6.5" hole, so nothing wrong with that, I just don't see the point to needing to port the sub when the boot space is most likely too large for it (assuming it isn't a free-air sub).

TimmyA wrote:
that's really neat phong... A+ there... That's a complete custom carpet is it? Looks like the brake light is gone? And you just made it out of ply or carboard and carpet?


Thanks, yeah made it at home with mostly items I found in my parents garage at the time. Carpet cost me like $40 I think and a pieces of MDF maybe another $50ish. I used packing foam for the smoothing out of the spacers. I have a factory fitted spoiler which has the upper brake light...actually when I pulled the brake light out, there was no wiring or globe in it so would have been disconnected from factory.

Here is the build thread for it. ford-audio-visual-f5/seat-belt-blocking-speaker-set-up-new-install-pg3-t24001.html

 

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 Post subject: Re: Porting parcel shelf
Posted: Thu Apr 05, 2012 11:37 pm 
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FYI,

Adding ports, is not something you 'just do'.

A port is a properly designed tube to control air flow. To design it properly you need to calculate the size of the 'box' used (in this case the whole boot), the properties of the sub woofer, and what frequency you want to accentuate (or not).

Just adding two 2" ports will - unless via some weird coincidence - do more harm than good.

Don't waste your time.

 

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