hey guys,

I've been planning on rear loading my sub, however after reading up on the CAA forums, it might be better for me to front load my sub (so the cone faces into the cabin).
This is only because i plan to have a wall of mdf spanning across the entire length of the boot to cover up the sub box.
So if i do rear load my sub, will this mdf wall stop bass getting into the cabin because it is pretty much sealing the boot??
Any help would be appreciated :)

cheers,

Sam

I tried both ways and found that rear loading gave better results. I have a a wall similar to what you are talking about and I have no problems. Mine is using pretty thin mdf, but I doubt thicker would be a problem.

Have a look at my boot here
http://www.caraudioaustralia.com/forums/index.php?showtopic=66758&st=0

you could also look at how this install has allowed bass to port through the wall
http://www.picturetrail.com/gallery/view?p=999&gid=1715113&uid=467659

i think he means not having a hole in the mdf like yours fats?

you would think it would have some effect but m....

If you're putting a wall there i'd front load, the walls gonna block air coming out of the sub and will severely limit the amount of bass you will get, not to mention the rattles.

Front loading - Good for fast beats eg. Techno, dance etc.
Rear loading - Good for continous bass eg. R&N, hip hop etc.

I prefer front loading as i listen to dance/techno mostly, but the way my box sits i get more boot space if i rear load, so thats why i've done it that way.

iv tried both and i say rear loading is way better. u still get a fair amount of base inside to get things pumping. but try different position and see which one you like.

MGNTZD, when your building the box, try it out in the car before you finally decide to stick it down in "x" position.

so basically, get everything wired up, and then for a few hours see how it all goes.
honestly ive never front loaded....the box is so big i just dont worry lol

one day i'll try it though

I've done both front and rear loading (with some experimentation) also...

Pushing the sub into the cabin in a sealed enclosure gives a definate sharp, tight snap to the chest whereas using a ported enclosure facing rearward tends to extend the bass (to the detriment of clarity) and give a lower, rumbling sound.

As a suggestion, I'd go front loading with a sealed enclosure for accurate bass, and rear loading with a ported enclosure to give a definate SPL advantage.

The best result I have had for SPL is to use the boots resonant freq (around 35-40Hz with undamped boots) toegther with a ported box at around this freq, mounted as far at the rear as possible facing upwards (firing up at the boot lid). This placement eliminates any cancellations the boot may pose as it is essentially corner loading the rear panel wave and uses the boot lid for an added harmonic in the lower freqs, forcing the pressure wave through the ski port and lessening the chance of over excursion to any parcel mounted speakers. It does shake the cr4p out of the boot lid however!!! The parcel mounted speakers tend to pose a phase cancellation and may need to be high passed to over 100hz for better results. For an example, I have increased my SPL at 40Hz by nearly 9dB using this setup compared to a cabin firing sealed enclosure with the same woofer and amp power. Other factors which may have helped were time correction to the sub and front splits, and high passing the rear 6*9s at 125Hz.

My present config has the sub in a sealed enclosure firing directly through the ski port. A definate increase in spl can be had by competly inhibiting the pressure wave into the boot by packing around the enclosure with foam, and also by negotiating the phase difference with the sub and the 6*9's.

Hmmm... maybe if I took some pics to help explain this?

ive got my sub firing straight through the ski port (ie the cone shoots thru the hole in the back seat)

sounds fantastic! cant stand it with the ski port closed tho, too muffled.

but yeah, as someone sed before, try diffrent positions before u stick her down (hey this could be advice for other elements in life!)

Ok, I misunderstood. If you are not going to have a hole in the board (like mine) then definately dont rear load.

I have to disagree that rear loading will result in slower rumblier bass. I spent several days trying different spots with a square box and found that rear loading was best. This came as a surprise to me but there was no doubting it. I listen to some system of a down and tool so there is no way I would settle for slow bass. Maybe it has more to do with the ported box benjames.

If you do fire it through the ski port, make sure that the front of the box is completely sealed from the rest of the boot. I was getting some very strange cancelation caused by waves bouncing around the boot before coming through the ski port.

Ok, I misunderstood. If you are not going to have a hole in the board (like mine) then definately dont rear load.

I have to disagree that rear loading will result in slower rumblier bass. I spent several days trying different spots with a square box and found that rear loading was best. This came as a surprise to me but there was no doubting it. I listen to some system of a down and tool so there is no way I would settle for slow bass. Maybe it has more to do with the ported box benjames.

If you do fire it through the ski port, make sure that the front of the box is completely sealed from the rest of the boot. I was getting some very strange cancelation caused by waves bouncing around the boot before coming through the ski port.
Rock/metal type music will benefit from rear loading, as the bass isn't "slow", its just not as punchy (but you dont need punchy with rock). Rear loading will give more bass, but wont be as punchy, will sound more continuous.

I disagree, kick drums do need punch, and fast kick drums need a sub that can keep up. I would not be using a sealed box otherwise

I have to disagree that rear loading will result in slower rumblier bass. I spent several days trying different spots with a square box and found that rear loading was best. This came as a surprise to me but there was no doubting it. I listen to some system of a down and tool so there is no way I would settle for slow bass. Maybe it has more to do with the ported box benjames.


:roll: LOL Oops!!! I think you'll find that you have accidentally misquoted me there fats... Slower and lower are 2 different words :bowrofl:

Essentially, I have to disagree to your disagreance and would argue to agree that we are indeed not disagreeing at all.

MGNTZD, I guess the next question to ask is wether you do intend to use a ported box or sealed as we have yet to establish this. If you were to use a ported design you would have to consider the placement of the port with as much importance as the sub.

With regard to the panel stoping low freqs passing through, I think the panel may have a small impact on the final resulting sound of the sub.

Fats, have you noticed a difference with the panel on to when its off with your setup?

MGNTZD, I guess the next question to ask is wether you do intend to use a ported box or sealed as we have yet to establish this. If you were to use a ported design you would have to consider the placement of the port with as much importance as the sub.


That's the other thing i'm not sure about either. I will be making a box for a DD 3512, and i was initially going to go with a sealed enclosure. However, most of the DD subs i've seen in enclosures are ported. If i do go ported i was thinking of just a basic setup like in the pic below. Would the position of the port be THAT crucial??

I disagree, kick drums do need punch, and fast kick drums need a sub that can keep up. I would not be using a sealed box otherwise


Yeah :think:... Although you can use time alignment to compensate if you want the best of both worlds... I managed to get a good overall sound with a ported sub that got 'close' to as snappy as a sealed setup but having the sub setup as it was became impractible.

To give more depth to what I spoke of earlier, using a sig gen with a CRO and cal'd mic you can clearly see that rear loading the sub results in a pressure wave that is slightly more out of phase with the reference than a cabin loaded sub.

http://www.lavendergreenooaks.com/BEN/Test%20equip.jpg

If you ever get the time,test it out for yourself. Get a signal generator (or maybe a test cd) and put out a low freq wave to the sub. Next, take a pick off of the sig gen wave and send it to a CRO. Put the calibrated mic in the cabin with you and send its signal to the CRO for comparison. The difference between the original wave and the mic's wave can even be measured in milliseconds. A big difference that I have seen with a ported design is that it tends to act kind of like a sealed box until it gets closer to its resonant freq (at which time it moves further and further out of phase). This is where a sub can become 'muddy', especially if the port freq is relatively high.

Now think of your entire boot as having a characteristic kind of like adding a port, which uses the reflected wave of the woofer hitting the rear of the boot to amplify the original wave, passing into the cabin...

That's the other thing i'm not sure about either. I will be making a box for a DD 3512, and i was initially going to go with a sealed enclosure. However, most of the DD subs i've seen in enclosures are ported. If i do go ported i was thinking of just a basic setup like in the pic below. Would the position of the port be THAT crucial??

I'd say putting the port on the same wall as the sub face will yield the best result... Just make sure that you avoid creating standing waves, which is eay to do when having ports n rear fill n subs all playing freqs every which way. The hardest thing I've ever had to grasp with low freq waves is the fact that they radiate in all directions (non-directional). The killer of bass is reflected waves that meet back and cancel the original wave node out. If you can sit there and look at a situation and nut out how all these factors come together then you are better than me :doubt:

Another trap I used to fall into was mistaking a reflected wave as a bigger bass hit... It definately "felt" louder, as I could feel my clothes n eyes n stuff moving more. When I checked it out with a sig gen and cro however, I could see that the SPL wasn't any higher, I'd just instead experienced the first wave and then the reflection and thought it was one BIG wave...

Cr4p, soz dude I'm going off topic!!!

haha that's ok mate!
Have you ever tried facing a ported box into the cabin?? or is that pointless??
I guess i mainly listen to dance/trance/techno music, but i like a bit of everything once in a while. Does this mean that it would be best to have a sealed enclosure? or would a ported one still be ok for this type of music?

haha that's ok mate!
Have you ever tried facing a ported box into the cabin?? or is that pointless??
I guess i mainly listen to dance/trance/techno music, but i like a bit of everything once in a while. Does this mean that it would be best to have a sealed enclosure? or would a ported one still be ok for this type of music?

Yeah.. Definately loved having a ported design that fired into the cabin.. I made sure that it was completely sealed from the boot with soft bedding foam packed around the enclosure and had the port and sub firing through the ski port. It would of destroyed the plastic seperator had I not taken it out, and whenever I turned it up the arm rest blew in and out (which was annoying) so eventually I just kept the arm rest down. Cause I have a small inquisitive kid, every time he got in the back seat he'd poke at it :angry:, and I decided that instead of killing him it would be best to change the setup of the sub instead :cry:

You've got basically the same tastes in music as I do... These command a seriously low and sharp bass response. With a Digital Design subby and a well thought out, bullet proof ported box tuned low, firing into the cabin (to keep relatively in phase) I reckon you'd be in aural heaven!!!

Some cons of having a DD sub firing into the boot would definately mean getting some sound deadening to help with rattles down the track, and you'd also have to worry about pressure waves affecting the rear speakers.
About the only con I found with the sub firing in the cabin is tha you'd need a perspex panel or glass rear to show off your ice :(

I'm probably a bit bias because my cabin setup with the ported box seemed quite good to me but from memory though, I think if you check out the Boot installs thread page 5 (http://www.aussiemagna.com/forums/showthread.php?t=20205&page=5) you can see alot of ported designs firing into the boot can look and sound awesome as well. It all comes down to the components, crossover freqs (which can change relative phase), box design...:blah:

If you have a DD sub you really must want to get loud so be a man and stick it in a big ported box and rear load. :D

If you have a DD sub you really must want to get loud so be a man and stick it in a big ported box and rear load. :D

haha, yeah i wanna get loud at times :P But remember, the DD 3512 has been used in many SQ comps and scored quite well (from what i've heard). So i'm wondering if i stick it in a ported box and rear load it, will it still produce good SQ??

sorry to jack the thread slightly. but what happens if you front load one sub and rear load the other?

so if we have a mid point

CABIN
.............._____
........|.../.........\.................................| < -- box
........----------------------------------- <-- this is the face of the box
...........................................\_____/

*IGNORE ALL THE FULL STOPS I HAD TO PUT THOSE IN FOR EDITING PURPOSE'S SO THE PIC WORKED*

you guys understand what i mean? what would happen? :D hahalol

I'd like to add that basically everything benjames has said as being correct. You should llisten to him :)

My personal favorite is to front load with as many blankets around the sub box as possible to seal it from the boot, thus sending as much bass through the ski post as possible, and negate interference from the sub bass to the underside of the 6x9 cones.

Rear loading is not usually meant by having the sub box between the rear struts and firing backwards either. It is more commonly associated with the bass box facing the rear of the boot AS CLOSE TO THE REAR OF THE BOOT AS POSSIBLE. This technique is commonly used in hatchbacks at the hatch acts like a horn, amplifying the sound naturally.

Best of luck with that system, should be awesome.

Ok first of all, your right benjames I did misquote you sorry. But I am still not sure about the "to the detriment of clarity" bit. However, I certainly dont have signel generators and CRO results to back me up, so I will have to take your word for it.

To wooley, I think that would sound bad. your bass would be out of phase with itself before you even worried about reflected waves. I dont really know, but some strange things might even be happening INSIDE the box with regards to back waves interfering with the other sub.

haha, yeah i wanna get loud at times :P But remember, the DD 3512 has been used in many SQ comps and scored quite well (from what i've heard). So i'm wondering if i stick it in a ported box and rear load it, will it still produce good SQ??

Ahhh yes but you can basicly use any woofer in those comps and get a decent score, the judges don't really care about sub bass. If it is there you will get 50% it seems. You will notice SQ cars have bass you can barely hear.... you don't need a 1000WRMS sub for that :bowrofl:

For respect however..... :D

Ok first of all, your right benjames I did misquote you sorry. But I am still not sure about the "to the detriment of clarity" bit. However, I certainly dont have signel generators and CRO results to back me up, so I will have to take your word for it.

To wooley, I think that would sound bad. your bass would be out of phase with itself before you even worried about reflected waves. I dont really know, but some strange things might even be happening INSIDE the box with regards to back waves interfering with the other sub.
You do lose clarity, thats what i was trying to say (couldn't think of the word lol).
Anyway each to their own, it really depends on what sound you prefer. I actually prefer front loading, but i get my boot space if i rear load (just the way the box was made).

Some cons of having a DD sub firing into the boot would definately mean getting some sound deadening to help with rattles down the track, and you'd also have to worry about pressure waves affecting the rear speakers.
About the only con I found with the sub firing in the cabin is tha you'd need a perspex panel or glass rear to show off your ice :(

I already plan to have a glass panel to show off my magnet, but i'm not sure how to attach it to the sub box. Do you just use a whole glass window as the entire back wall of the sub box?? Or do you cut a hole in the MDF, then glue a glass panel in, like so...

____________________________
MDF |__glass sits in here__| MDF
________|____________|______

Then you can view into the box from here


I would've thought that this would be more secure than just gluing a whole glass panel for the back wall to the rest of the box. But i really have no idea...... any help??

cheers,

Sam

I already plan to have a glass panel to show off my magnet, but i'm not sure how to attach it to the sub box. Do you just use a whole glass window as the entire back wall of the sub box?? Or do you cut a hole in the MDF, then glue a glass panel in, like so...

____________________________
MDF |__glass sits in here__| MDF
________|____________|______

Then you can view into the box from here


I would've thought that this would be more secure than just gluing a whole glass panel for the back wall to the rest of the box. But i really have no idea...... any help??

cheers,

Sam
I hope you mean fibre glass, as real glass would shatter from the pressure wouldn't it?
Yeh you just cut it out of the mdf however big you want it, make sure it's glued in ALOT.

I hope you mean fibre glass, as real glass would shatter from the pressure wouldn't it?
Yeh you just cut it out of the mdf however big you want it, make sure it's glued in ALOT.

No i mean real glass :P Apparently it doesn't shatter. You can just get it toughened, and it's cheaper and stronger than perspex, but don't quote me on that. I think you only need 12mm toughened glass and that should be thick enough to withstand the pressure. Can anyone verify this??

Yeah, glass is tougher than most ppl realize...

Of course you could get some of this bullet proof 12mm thick polycarbonate sheeting **** I gotz ere just to make sure!!!

http://www.lavendergreenooaks.com/BEN/CIMG1452.JPG

Costs a lil more than glass though :redface: ... I'm gonna use the long piece for showing the amp off, and the 2 other sheets mounted on top of each other (to make a slab of 24mm thick poly) in a box setup which will use them as one of the walls.

I don't see a problem with mounting the glass like you have stated in your diagram. Make sure you use the right adhesives and make sure all your screw holes through the glass have sufficient spacing for a rubber grommet, so you can buffer the screw through each hole in the glass. This will make sure the glass won't get stressed which can cause it to break prematurely.... Or just get some really really strong glue and #@$k the screws off altogether!!!

So where did you get this stuff from? Just a glass glazier place?
And if you don't mind me asking, how much did one of the sheets for the sub box wall cost?

I got some from work to muck round with....

It costs about $1200 for a sheet of 12mm by 1200 by 2400. It's getting hard to find plastic engineering mobs that will order it in smaller sheets :cry:

$1200!!!

well MGNTZD, there goes your sub and speakers, but at least you'll have alot of thick glass to show off your empty boot LOL

perspex is pretty cheap too...

bahahaha, ok i'll definitely be getting either 12mm toughened glass, or perspex.... Just don't know which one would be easier to mount. $1200 is a tad outta my price range for a little window to see the magnet :D

whoops....thats 1.2meter sheet by 2.4 meters.....a tad more then you'll need.

my mate got 2 sheets, about 50cm x 25cm for $22 each, made out of 22mm perspex, might be a better option

perspex will be easier to cut.

And you have more options with tricky lookin graphics with perspex too!!!:)

http://www.lavendergreenooaks.com/BEN/focal5.jpg http://www.lavendergreenooaks.com/BEN/focal4.jpg

Glass copes a lot better with scratches though....

And you have more options with tricky lookin graphics with perspex too!!!:)

http://www.lavendergreenooaks.com/BEN/focal5.jpg http://www.lavendergreenooaks.com/BEN/focal4.jpg

Glass copes a lot better with scratches though....

I've been wanting to get something like that done!!! Except with two big D's (DD audio logo)

Do you know where i can get perspex engraved in vic?? i'm really keen on this :D

Rear Loading for Sedans..
Upside:
Audible Bass is increased
Opened Boot Reveals a Sweet install
Having the Skiport down or Up is neglible to the Output
Less Damage From Drunk Passengers

Downside
Boot Vibrations are Increased
Damage to Subs without Grills from Dislodged Objects in the Boot
Cant Watch the Sub in Action inside the cabin
Sonically not as Accurate as there is a Slight delay


Front Loading
Upside
Sonically accurate
Bass is Felt more
Flipping down the ski port reveals Wicked Sub
No Damage to sub from Dislodged objects in the Boot.

DownSide
Bass out put is not as good as the Sub now fires into a Leaky passenger cabin instead of a well sealed Boot
Cone Noise is more Obvious
High Danger of Damage from Drunk mates
Reduces your Crusing capacity from 4 mates to 3.
Skiport must be down for maximum Impact
A Good Cross over low pass filter will be needed to block out lyrics from the sub..
Leave the ski port down when parking, Kiss good bye to your install
Open the Boot Leaving just amps and cables.. no Carpark Credit..


The Choices are Yours but I always Rear load and use a Ported Enclosure..
The Bass is soo good... Kidney stones are never a Problem as the Bass Shakes everything loose..

Also I haven't seen anyone mention phase as well, you can drastically change the way the sub sounds but adjusting the phase. Apparently at 100deg out of phase the bass sounds like it is in your face and is apart of your front stage. Add time alignment, I would definately rear load for more bass.... plus keep the ski port closed. :D

Hmmm... phase and time alignment kinda acheive the same thing, ... I wonder what relationship they have to each other?

For example, if a sub was 100 deg out of phase lagging, then what would the respective time alignment be in millisecond figures?

From my understanding, phase changes the wave to achieve minimal cancellation or more cancellation from a given point. If you adjust the time alignment of something you are only adjusting the point of time to which the wave is played but not how it is produced.

If you change the phase to make the sub sound like it is apart of your front stage, it still can lag...

I find that rear loaded subs that are at 0 degrees tend to sound like the bass is coming from the rear or out of the car behind. 180deg out of phase makes it sound like it is coming from the car in front when you rear load. If only I had adjustable phase control. :doubt:

I think what benjames is saying is that buy shifting a wave in time (with respect to all other waves in the system) you are also shifting its phase.

For example, a 50hz wave is 200ms long. By delaying your sub by 100ms you are shifting this waves phase by 180 degrees, and by delaying it by 50ms you are phase shifting by 90 degrees.

Tell me if I am wrong

sorry to revive an old thread but has anyone tried rear facing with a ported box and the ports being right behind the ski hatch? just looking for options to fix my system to the way it used to sound in the old falcon eb i had, i think the biggest thing is the 60 / 40 rear seats.