I've measured it all up and his custom box for the two 8"s will fit in my boot nicely (with spare tire still in), but it fits easier if I turn it upside down, so the subs face on an angle out of the boot. Will this give me horrible time delays? If they are on a funny angle? There's no time delay in his car with the subs facing away from the rest of the car.
I don't plan on modding it much, I'm gonna get all the wiring and stuff professionally installed, then fiddle around with how it looks/fits in the boot myself.
Monday, July 10, 2006 - 09:48 am, by: Shaun Stephenson(Neonasty)
You will get some time delays. Does your head unit has a function to control the delay?
The angle wont effect the delay, but you may get some cancelation. Have a play around with the box, and how it sounds. You will find a position that it sounds best. Bolt it down, and your done.
Why dont you do the wiring yourself? Its not hard, just time consuming. Would prob take you 3 hours max to run the wires, and you'll save yourself a couple of hundred dollers. (put that toward that exhaust you want)
Monday, July 10, 2006 - 05:55 pm, by: Mark Paddick(Sparks)
It all depends on the listening position. If inside the car then it will be horrible. If outside it will be good. If you want a good sound stage inside the car a parcel shelf sub or ported bandpass are the only real options unless you go for digital processing with time/phase delay compensation and a means of setting it up (budget $3k min for the digital processor setup). A transmission line with both ends terminating on the parcel shelf is another way that would work extremely well but the design and building is somewhat complex to say the least. Removing the rear seat entirely and mounting subs in the vertical section would work too. Getting subs in there with the fuel tank would be fun, a separate baffle spaced off that panel would be best.
Monday, July 10, 2006 - 07:38 pm, by: Tom Nicol(Goosemonger)
I've seen the words ported and bandpass come up a lot in reading the ICE posts, and forgive my ignorance, but could you please explain what it actually is in layman's terms? I usually figure this stuff out by researching it and stuff, but I can't find much.
I do intend on listening to all of my music inside the car. But in all the boot setups I see, the subs are facing anywhere but towards the inside of the car.
My empty parcel shelf is looking like a better idea, the only thing stopping me is that I will have 2 subs to play with, and obviously the shelf only holds one. Maybe I should stop being greedy and just install one sub in the parcel shelf and sell the other or whatever. The stock sub is 8" right?
And thanks for the feedback! helps me a lot seeing how I often don't know what I'm doing.
Hey tom you will have to come over to my house one day and we will work it out. I have nearly finished destroying my boot, excuse the dodgy phone photos.
Going to be great when finished, just need to BUY a head unit to run it all hahah, i am thinking the JVC avx2. Will get around to it.
Tuesday, July 11, 2006 - 12:56 am, by: Peter Nitschke(Pen)
Ported means a speaker box with a vent as opposed to a sealed box.
Bandpass means a filter to let certain stuff through and not others, eg let high frequencies through but not bass. A crossover in other terms. Used to separate the various sound frequencies to the appropriate speaker, very much needed as apart from sound quality, bass power will quickly kill tweeters for example.
Tuesday, July 11, 2006 - 07:52 am, by: Tom Nicol(Goosemonger)
Aaaaahhhh a crossover! Okay, it all makes sense to me now. Mickey, when I get all my gear (should be this week) I'll come by your place on a weekend and we'll see what we can do while I'm being jealous of your setup - that screen will look awesome!
Maybe if I pulled my finger out and actually bothered to put some work in, I could make some boxes to go on either side, like so many people seem to do. It would be horribly annoying to have to take out half your sound system just to change a tire.
My head unit isn't able to compensate for time delays unfortunately, so any ideas? Apart from the digital processor, which I can't afford.
Also does anyone have any pics of a ported boot setup?
Tuesday, July 11, 2006 - 11:18 pm, by: Mark Paddick(Sparks)
Except that in terms of speaker design a bandpass enclosure totally encloses the bass speaker and all sound exits the enclosure via a tuned port which can be tailored to end in the normal rear shelf position thereby giving the required spatial positioning and phase relationship to the rest of the system and also having the benefits of a boxed enclosure.
All speaker enclosures of any type can be likened to a crossover in some respects except that the speaker enclosure also tries to provide appropriate loading for the speaker driver and also can make some attempt at extending its' frequency response below the driver resonance in some cases. A bass reflex enclosure uses a tuned port to extend response about 1/3 octave below the driver resonance. A transmission line is usually tuned to 1/4 wavelength of the driver resonance and filled with sound absorbant material in such a way that only frequencies below the driver resonance exit the far end of the line. The transmission line can be folded back to arrange for the far end port to be on the same axis as the driver. In this way response can be extended a full octave below the driver resonance frequency and the driver is always nearly perfectly loaded.
Low frequencies are always somewhat omnidirectional i.e. it is not easy to tell where the sound is coming from. So subs don't have to face the intended sound stage like midrange and treble speakers have to. It is the distances that matter and the phase relationships associated with speaker placement.
Tuesday, July 11, 2006 - 11:28 pm, by: Mark Paddick(Sparks)
Not a very good pic but this is a bandpass box in place of the stacker and factory amps showing two tuned ports which end under the parcel shelf sub hole. For an idea of the size required this is an 8" sub enclosure using a very high end expensive driver and works down to 22Hz without loss. At 15Hz it is still only 3dB down. With the extra mid/treble speakers in the boot this setup has good spatial/phase performance both in the car and outside it. The mid/treble amps are switched between either the boot mounted speakers or the door speakers inside the car which are Boston Pro series splits driven with two Jaycar 2 x 150W Amps. The 8" square framed sub is a Kicker driven with 600WRMS.
Wednesday, July 12, 2006 - 10:07 pm, by: Sean Camelin(Krener)
No matter what you do you will always suffer time delay with mobile audio, unless you go to the big $$$$$$ extent like DSP's, acoustic deadening, super anal speaker alignment etc, it's a simple fact of life. The question is do you want doof doof, easy listening or sound quality? A sealed box is what most people opt for, it's simple and practical, the box can be made in an arvo with minimal effort, and is very forgiving of mistakes (but there is a limit!) Bass reflex (ported) boxes require a bit more effort for designing the port length and diameter if you intend to run from the box to the parcel shelf otherwise it simply won't perform well. Bandpass boxes require ALOT of design, and have minimal 'fudge' factor and are best left to people with alot more nouse for speaker theory (like Mark) otherwise you'll wind up with bass that sounds similar to farting in mud. If this is your first attempt at making sub boxes, go with the sealed version, but if you can spare some cash, get a decent mobile audio tech to do the hard stuff.
Thursday, July 13, 2006 - 10:22 pm, by: Tom Nicol(Goosemonger)
I'm after good sound quality, but occasionally I crank it up and put on some hardcore techers.
I think I'm gonna go with the parcel shelf, seems like the best and easiest solution. But my only problem then is that I have two subs. I know I probably only need one, but I want some decent sounding bass. Will one 8" sub in the parcel shelf be enough?
I don't spose there's any way to mount two 8" subs in the parcel shelf is there?
Friday, July 14, 2006 - 10:29 pm, by: Sean Camelin(Krener)
Not without some intense cutting of the rear shelf. And that is not advised at as it forms part of the vehicles structure. Might have to stick with one 8", or sell them both and purchase a Jaycar 10".
Friday, July 14, 2006 - 11:42 pm, by: Mark Paddick(Sparks)
An 8" sub will always give tighter, better controlled bass than a 10" or 12' given the same motor structure. With some creative cabinet work you could do two 8" bandpass boxes without cutting anything in the car. Or one 10". Or a 10" in the parcel shelf. Some 10" monsters like the Jaycar one will require a bit of thought but it can be done without cutting the shelf.
Of course you could go without the normal rears and put 8" subs in their place. The shelf is cut for 6.5" speakers but they are also spaced up so an 8" will go very close to fitting with an appropriate spacer. You could mount some sealed midrange/tweeters co-axially with the subs for rears even. If you were really, really, good with the cabinet work you could make both 8" subs transmission lines with the end ports in the factory sub hole. The transmission line is just a rigid tapered tube about 2 Metres long (for an 8" speaker) with a minimum cross-section of about 1/4 of the speakers' cross-section. It can be folded several times to get it to fit in the required space and is loosely filled with long fibre ultra-fine raw wool for best results. A single transmission line with just one sub would be much easier with the sub on one side and the port on the other although since the tube is tapered you could fit two in with a sub on each side along with the port from the other sub. You would need to be very good with the cabinet making stuff.
Saturday, July 15, 2006 - 07:03 pm, by: Sean Camelin(Krener)
You would want to be good with MDF to get those 8's to sit nicely without cutting the shelf. Mind you there is alot more room underneath the factory 6.5 holes than where the sub usually sits, and depending on the shape of the basket it could work without any cutting. Holding it in place would have to be a nut and bolt affair, not just screwing wood screws into the shelf like some I've seen. People seriously under estimate inertia when there is an accident. Maybe I'm just too safety conscious, but better to be safe than sorry.
Monday, July 17, 2006 - 10:52 am, by: Tom Nicol(Goosemonger)
Well well, don't I feel like a goose. I have no idea why, but I had it stuck in my head that the subs I am getting were 8". I just found out that they are 12"!!
I think sometimes I have a screw loose upstairs. Anyway, now I'm almost sure that I'll go with one sub in the parcel shelf. That is, if a 12" will fit. They are shallow mount (Cadence) speakers. Can I get a 12" spacer or something?
Thanks for all the feedback, I've finally learnt a lot about car audio and subs now.
Monday, July 17, 2006 - 03:45 pm, by: Mark Paddick(Sparks)
Just make an mdf spacer bolted in place to the original sub mount holes (6mm). If you don't mind it sitting up a bit then just about anything can be made to fit that way.
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helps me a lot seeing how I often don't know what I'm doing.
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