ok here is the big debate. How should i install my subs,
there are a few variations that i don't know what i should do,
Firstly is do i have a sealed enclosure or a properly ported box?
I know that i will get a higher spl at lower levels using a ported (tuned) box over a sealed enclosure, only setback is the larger size of a ported box.
A sealed box has a more linear range throughout the audio spectrum it needs to produce between 20hz and 100hz.

Next question is, as i'm going to have 2 12" subs and i going to have seperate boxes for each (which is much easier to tune the boxes to correct theil small parameters) or have one large box for 2 which seems dodgy to me but a number of ppl do it (doesn't mean its good i know haha people do heaps of crap things)

The last question is do i face the subs forward which seems like the most logical manner to have them setup. But installs rear facing have deeper bass but its more boomy and the delay is there even more evident than normal front facing. Also a rear facing looks better for a boot install...

Thanks for all your help cheers

Well as for front vs rear, you've pretty much told us what happens, it really now depends on what you prefer.

what subs do you have

i have 2 X 12" Orion cobolt subs that i was getting, they are 250watt rms dual voice coil i'll have them running at 2 ohms each total 4 ohms off a response 800watt monoblock i believe

ok i suggest2 seperate sealed boxes facing backwards

why backwards? is that just a matter of prefference or is there physics involved in the facing backwards as superior way. My HU also has a ****ion to change signal for rear facing subs?? wonder wat this does

in terms of the facing option my personal fav it front facing, I'm not a big fan of the rear facing subs though in the end its up to you. you could always keep the ski door? open so they're abit of both (if you keep the back of the open but I don't know how this would effect the sound), but thats just my opinion

well i have my single 12" JL sub facing forwards through the ski port at the moment and i like the idea of this, but its only a cealed box (which is too small for it) and the sub isnt enough power anyways at 150watt rms running off a 200watt rms amp.

any more suggestions with the sealed vs ported system?

why backwards? is that just a matter of prefference or is there physics involved in the facing backwards as superior way. My HU also has a ****ion to change signal for rear facing subs?? wonder wat this does
its just preferrence. If you like punchy bass face forward.

iv tried both and to me facing it in my boot is better. you get a deeper base and not as much rattle inside the cabin. but if you want deeper base face it inside your boot

I want as good frequency response through the lower range as possible with as lil peaking at specific frequencies as possible, i think i'm going to go from facing, how much space should i have between the boxes and the rear of the seat?

sealed or ported?

well, rear loading alwayse gives better bass reproduction, and why do you say one large box is a crap idea? ive got my 2 L7's in a box port tuned to 40hz and it sounds alot better than most sealed boxes/single boxes, and as for sealed /ported... does it say free air sub or suit sealed inclosures? and as for this function you claim your hu has, that just changes the phase of the subs, unless your actually talking about reverse mounting the sub onto the box, because then that might have some relevence, but if thats not the case it wont help.... your head unit cant tell which way your sub box is facing, im not to familiar with them subs, but just get the box made up with the dimensions suited to the subs, sealed, and dual box, because i dont know if you know this, but anyone that knows how to make a dual sub box properly will make seperat chambers wihin the box for each sub.
oh and also, if you go 2 seperate boxes, they will only be easy to tune if theyre ported, cos as far as i know you cant really tune a sealed enclosure? but i guess what im sayin is, just get the custom dual sealed box, save on money for labour cos it wont take as long, and its pretty much 2 boxes anyway (if you understood what was said before)

Bass frequencies are basically omni-directional, so it's not too important what direction you face your subs as long as they are not cancelling each other out (dont face them @ 180 degrees to each other unless you plan to have them wired push-pull). However you will want to locate the subs as far as practical away from the listening position (front seat) as very low frequencies can have quite long waveforms. Basically the closer your ear is to a speaker the less low frequencies you will hear. Of course you will hear the higher frequencies much louder. But what your aim will be is to create a flat as possible response at the listening position. This along with tuned boxes should make all frequencies that the subs are set up to produce, seem nice and loud.

just reading your above post, if thats what you want, get a custom made, ported, dual box, oh and unless theres something really wrong with your power supply to your amp or something, i highly doubt you will even be able to tell the difference between the box facing forwards or backwards in regards to lag

ok so a rear loading gives better bass reproduction but with the added delay...
The speaker i had a look at recommended box sizes and designs they are suitable for both free air and sealed enclosure, so its all a matter of preference.
The hu effect is just for reverse mounting the sub not direction of the sub that is correct thanks!
I am going to make a custom box with 2 seperate chambers for each of the boxes. just need to work out if i want a ported tuned box or a sealed box, i know it will be smaller if i make it a sealed box, but if i make it a ported box tuned to the optimum frequency that orion specify the result is a higher spl sub output at lower frequencies than the sealed design

TJae01: in response to what you said, so theoretically if i have the subs as close to the opposite end of my car (as far back as possible) its always better? so is it better to reverse mount the subs on the outside of the sub box, as close to the end of the car as possible? Thanks

i have my 3 15" subs facing towards the back. did have them facing forward
turned them around to see if there was a difference, when i put them
facing back there was a bigger bass output

YLD35L. thanks heaps, Still lost for what i'm going to do lol, reason why i want to know is i will make the box to fix the car in 1 direction, so ah well lets hope i come to a decision, thanks for everyones help,

one thing you gotta put out of your mind is this delay crap, its like 1 millionth of a second, it makes no differencs at all, my sub keep perfect timing with music that has 180-190bpm sections in it, it really makes no difference, so what you gotta ask your self is do you want the boot space? cos i garentee you it will sound just the same facing back or forwards, the only difference will be that you have a dirty great big sub box in the middle of your boot if you face the forwards like your thinking

I would recommend making a square box to start with and play around with placement. It is not expensive to make a box youself. Thats what I did. I had planned to have the box facing forwards but when I tested found that I liked backwards best.

You decision depends on what sound you are after. Sealed will be tighter and play more accuratly, but, like you said, ported will play louder.

I wouldnt think that ported would play lower though, if anything I would think the opposite.

In terms of placement you could also try in the rear corners of the boot, near the tail lights. This could possibly offer the best compromise between the two placements.

lmao thanks mate, boot space well i'd like boot space haha, and it will be easier to mount a sub facing backwards, ok i get the idea bout the delay ****e, anyways so now onto sealed or ported....i have designed home speakers that are ported and tuned, but how much different are subs? thanks for all your help its been very insightful! lol

In regards to which direction do you want to face your subs - Basically the main issue here is cancellation. Bass will travel in all directions from your sub. For simplicity focus on the primary wave (the wave directly from your sub to your ears) and the reflected wave (the wave that reflects off your boot and then goes to your ears.

Now if you look at the distance each wave takes to reach your ears it's obvious that the reflected wave is much longer.
Because of this the reflected wave is not in phase with the primary wave. If two waves are entirely out of phase then there is total cancellation at that frequency = not desirable at all.

On the other end if two waves are in phase then the amplitude doubles = good as our subs become louder with less power.

If you want to keep both waves in phase there are a few things you can do

Keep your subs as close to a corner as possible or as close to the rear of the car as possible. Which direction they face isnt that important as the wave will travel in all directions.

Also try reducing the low pass of your subs. (I run mine at around 40 hz as my fronts can keep up) But 80 hz is a good place to start.



In terms of ported vs sealed. Ported boxes are more efficient and louder upto their tuning frequency. But below that they suffer greatly.

So if you want low bass go for sealed :) Although most people get subbass confused with midbass. to me subbass extends below 20 hz. Midbass is more a kick in your chest.

Or go for ported with a very low tuning frequency. This wont be good for SPL as SPL is usually best at a higher frequency (like a box tuned to 40hz) but for music this isnt as good as everything below 40hz (quite a lot of spectral content there) is uncontrolled and usually requires a subsonic filter to make sure you dont place too much stress on your subs.

Sealed boxes are easier to get right and will have more low end extension and flatter response. But are not as loud as ported boxes can be at certain frequencies.

Peace

Tim

s_tim_ulate
thanks for that insightful post, I think i will go for the sealed low tuned sub, i don't want high spl, i want as linear range from say 80 hz to below 20hz, as i rather SQ over SPL any day ( my home system is onkyo preamp, rotel power amps and dynaudio home speakers) just wish i could get that quality in my car setup, but oh well
so if i don't need a boot rest the subs as far back as possible. i'll have them facing forwards i think, with 2 independant chambers ported. Thanks so much everyone for your help please add if you have any more ideas,

s_tim_ulate
thanks for that insightful post, I think i will go for the sealed low tuned sub, i don't want high spl, i want as linear range from say 80 hz to below 20hz, as i rather SQ over SPL any day ( my home system is onkyo preamp, rotel power amps and dynaudio home speakers) just wish i could get that quality in my car setup, but oh well
so if i don't need a boot rest the subs as far back as possible. i'll have them facing forwards i think, with 2 independant chambers ported. Thanks so much everyone for your help please add if you have any more ideas,
Ahh but you can have that in your car
Have a look at some dyn 3 ways :)

Are you looking to go sealed or ported? I got confused.

Hmm if you really want SQ I would go sealed. But thats me, not saying ported cant sound good, just it's much easier to get it right sealed. Sealed boxes are much tighter and have much better extension down around 20-40 hz.

I think the conclusion that i'v come to is i'll have 1 forward facing sub box with two cealed enclosures. I know it won't be as loud (or peak) at specific frequencies like a ported setup but i want a more linear drop off below the ported frequency.
Thanks for your help everyone. It has been very insightful

as to dynaudio tim:

I have some dynaudio tweeters and dome midranged (d-28 and d-52) and suitable covers so i can place them in my car but i would have to do some major modifications to the door linings to get them in place. Also the midranges are rather deep. also being 8 ohms is a bit of a drag.
Tweeter is 130watt rms 8 ohms 1000watt peak 93dB/1w/1m, and the midranges 200watt continuous power at 8 ohms 1000watt peak 93dB/1w/1m So extremely high power and very good sensitivity. Now for a matching woofer for these? also the size of the amp i would need to powere these alone at 8 ohms is extremely high, but think of the SQ spl that you would get haha!

if anyone lives in brisbane and know how to create custom door skins and are up for a challenge to install a 3 way dynaudio system in their doors, i sure as hell would enjoy some help lol :D

I'll get a mate to design the crossovers to the theil small parameters (he works for todds hifi).

I'm only currently using a set oj JL 75watt rms 2 ways, they have a drop off to 55hz-20,000hz, my HU has a low pass and high pass cut off filters at 50, 80, and 125hz, i'v been using them at 50hz which is just below the splits drop off of capabilities, it sounds a lot better (apart from not being able to crank it as much as at 80hz) but then isn't that what sq is about, focusing more on the quality rather than spl output (not saying sq setups can't be spl i know some that are running into the 130dB's) my home system has an extremely high spl and still good sq :D

I am running Morel Elate 9's in my doors (on a simple mdf baffle)
In the kicks I have just upgraded to Hybrid Audio Legatia 3" Midranges
And Morel supremos in the kicks as well.
Then I have two old school PG XMAX 12"s in the boot.

So it can be done.

Front stage is heaven... I run the fronts down to around 40 hz.

As for 8ohm drivers, get a nice 4x150 or 4 x 100 to run your fronts active. (Have you got passive crossovers?)

Do you have Esotars as well?:)

Tim,
I have 2 MTX Thunder 6000's 12 inch in a dual sub box, using the same air, will i benefit from seperating the subs (eg. Place a fitted piece of wood between them)?
They go really loud which is awesome, but it always seems the one sub is pumping out more than the other.

Tim: I don't have Esotars :cry: but your more than happy to donate some to the magma ;) haha, I have a passive cross over network, Is designing an active cross overnetwork or purchasing one easy as i know i will need one to bi-amp my speakers?
What woofer should i go for if i use these. I'm in need of installing an mdf baffle for my doors as i'm not happy with the frequency response and movement that the door trims give.
I have also looked into putting sound deadening because with the second gen there is a fair bit of vibrations from door trime and internal window handle, lock latch and inside door handle.
Whats your take on this?

Oh btw i just looked an a really good article on the benefits of the active crossover VS passive crossover http://sound.westhost.com/biamp-vs-passive.htm i think it was extremely interesting. I can see why a bi or tri amped speaker setup is so much better. I'm considering setting one up right now for my car as i'm not happy with my current setup which is
Jl 75watt rms 2 way (dome silk tweeter and 6.5" woofer) in a passive crossover network powered by a 2 X 150watt rms alpine amp.

I'm thinking of going the Dynaudio tweeter, dynaudio midrange, and ? for the woofer tri-amped with an active crossover network?
if so whats a good active crossover