22 replies to this topic

[Callan Fraser]

So my mind is made up, 4th order bandpass is what I want.
I understand I probably won't get it right first time, but I intend on working on it heaps to get the desired sound.
Will be building the boxes over sized to shrink as we need, and thinking a removable port for future tuning purposes.
Any ideas would be appreciated. Thanks

[Lunchbox.inc]

1st up, when going with a bandpass enclosure it's not just a choice of 4h order or 6th order, each has a certain type of sub that suits the application... a 4th order suits subs that work best in sealed enclosures, where as a 6th order suits subs that work best in ported enclosures, as the rear chamber of each box is either sealed or ported....

what subs will you be using...? as that'll help with any advice we may be able to give...

[Callan Fraser]

I'm using the type R 15's which have a EBP of 51 just verging on wanting sealed,

on that note I have generally liked the sealed sound, but wanted to be able to tune the box as well.

I have made a few Sealed and Ported boxes, nothing special tho. I just feel 4th order is a nice challenge but also feel anything more complicated may be too much of a challenge at this point.

I have three which may make for a weird install with a bandpass box, but I'm sure it'll be worth while, and its all going in a Magna wagon.

[Tiger]

Have you got the Fs, Vas and Qts handy on them subs?

[Lunchbox.inc]

Have you got the Fs, Vas and Qts handy on them subs?

from my little collection...


Type R 15” (dual 2ohm)

FS – 22hz
QTS – 0.41
QMS – 8.57
QES – 0.43
VAS – 100l
RMS – 750rms
XMAX – 20.7mm (one way linear)
SPL – 87db 1w/1m


Type R 15” (dual 4ohm)

FS – 23hz
QTS – 0.45
QMS – 7.17
QES – 0.48
VAS – 100l
RMS – 750rms
XMAX – 20.5mm (one way linear)
SPL – 87db 1w/1m

[Callan Fraser]

sorry yeah, they're the dual 2's

[Lunchbox.inc]

sorry yeah, they're the dual 2's

i thought so but couldn't remember, so i posted both, only had to copy/pasta it so wasn't an issue... lol

i might have a play around and see what they like interms of 4th order a little later if i get a chance, hopefully some other will chime in with some advice before that...

[Callan Fraser]

So Winisd is giving me 7.165 ft^3 rear chamber and 4.273 ft^3 front chamber, This is calculated with 3 subs. However I've read that putting the magnet in the front chamber can help reduce out of band noise. Would I just subtract the drivers displacement from the rear volume and add it to the front chambers volume?

Also I want to be hitting around 20hz through to roughly 50-60hz, which winisd is saying a 10x3inch port 25 inches long. This peaks at 19.7 hz and drops quickly after 50hz

I felt the port was a bit small, and was intending on making the boxes and port slightly larger

[SQXPRT]

According to my calcs, that sub's better for sealed only application.

any "reasonable" sized box looks terrible for 4th order.

[Callan Fraser]

But if I went sealed it won't be as loud

Edited by Callan Fraser, 13 April 2012 - 10:36 PM.

[Lunchbox.inc]

well i've had a bit of a play, and 4th order actually looks quite nice, at least to my eyes, i have no doubt Pulse-R and myself look for different things and have different tricks when it comes to bandpass... i tend to design mine from my own experience, and my designs tend to differ a little...

BUT for 3x woofers, i found tha (after displacement)t 3.5cf rear chamber, 9.6cf front chamber with around 170-200sq inch of port tuned @45hz should be quite nice indeed...

feel free to whack those demensions into WinISD/BBP6 and see how you go...

[SQXPRT]

Yeh, I was looking at a smaller box, only about 2 cubes per woofer.

maybe have a look at the "Wicked One" design - for a 3x "1/2 chamber" idea. It's been thrown around but no-one has stepped up yet to try it.

[Callan Fraser]

maybe have a look at the "Wicked One" design - for a 3x "1/2 chamber" idea. It's been thrown around but no-one has stepped up yet to try it.

The wicked one seams like a great option, but to put a 3rd sub into the equation could really make things tricky. You say its been thrown around abit, do you know where I might find some info on using three drivers in this config? I can only seem to find dual boxes.

well i've had a bit of a play, and 4th order actually looks quite nice, at least to my eyes, i have no doubt Pulse-R and myself look for different things and have different tricks when it comes to bandpass... i tend to design mine from my own experience, and my designs tend to differ a little...

BUT for 3x woofers, i found tha (after displacement)t 3.5cf rear chamber, 9.6cf front chamber with around 170-200sq inch of port tuned @45hz should be quite nice indeed...

feel free to whack those demensions into WinISD/BBP6 and see how you go...

That bandpass box looks like a great option for spl, and still gives me a kinda nice freq range, but its a little too high for my likings, and as I drop the tuning it becomes very messy and much quieter ..

[SQXPRT]

you make 3x "half boxes" with a woofer in each

[Lunchbox.inc]

That bandpass box looks like a great option for spl, and still gives me a kinda nice freq range, but its a little too high for my likings, and as I drop the tuning it becomes very messy and much quieter ..

4th order bandpass are tuned high, because the port is actually tuning the high frequency cut off, not the low frequency cut off that you would generally associate with a standard ported enclosure, that is handled by the sealed chamber.... 45hz is actually quite a low tuning... generally a typical 4th order tuning is around 65hz....

remember that altho you can model enclosures till your blue in the face, that graph means absolutely nothing once you put it into a car.... modeling enclosures/woofers should only really ever be used to make sure the woofer itself will work in a given enclosure, and not to actually replicate the in car response, as every car is different, you deal with different cabin gains, different frequency response, and so on... some people can adjust for cabin gain in their modeling, but 90% of the times its little more than a rough guess...

[RAD]

I'm gonna go with steve on the 3.5cuft rear/sealed chamber, but maybe shrink it down to about 4-5cuft if you actually intend to play music with it. 9cuft would be good, if it were a burp car or chasing numbers.

I know the 2.5:1 ratio works GOOD for spl, it creates efficiency near the the tuning frequency need for SPL, but closed to a 1:1 ratio is better for music, and playing lower bass.

EDIT: just modelled the sub, 4cuft sealed, 5cuft ported @ 45hz should drop off past 55hz, give enough output for the odd fling at an SPL comp, while still playing strong down to 30hz.
It all depends on the height and dimensions of the box, but 70 square inches of port area, coming to 10" long seems good.

[Callan Fraser]

Might it be worth using roughly these specs in a wicked one design, or just keep it simple?
I have been looking at the WO and seams legit, and very intersting, might just have enough space to pull it off and I'm pretty sure a few ppl would like to know to how it goes scaled up.
Then again I don't want to waste any time

[Callan Fraser]

4th order bandpass are tuned high, because the port is actually tuning the high frequency cut off, not the low frequency cut off that you would generally associate with a standard ported enclosure, that is handled by the sealed chamber.... 45hz is actually quite a low tuning... generally a typical 4th order tuning is around 65hz....

remember that altho you can model enclosures till your blue in the face, that graph means absolutely nothing once you put it into a car.... modeling enclosures/woofers should only really ever be used to make sure the woofer itself will work in a given enclosure, and not to actually replicate the in car response, as every car is different, you deal with different cabin gains, different frequency response, and so on... some people can adjust for cabin gain in their modeling, but 90% of the times its little more than a rough guess...

I agree and I'm certainly no pro on winisd I think I was hoping it would magically spit out the perfect box somehow .. I'm designing and planning now and probably will be for a week or so, but will certainly post a build thread as we're re-doing the entire car, although we're still looking at walling with a bandpass box I'm sure I'll come across heaps of questions.

[RAD]

There is a certain percentage to use for scaling up a wicked one. Correct me if i'm wrong anyone, but it's an additional 2" higher for a 12" sub, but two fifteens i'm not sure of. Given a 12" will want to use 1cuft in a sealed enclosure, or larger, two would roughly work out to 1.8cuft or larger.

Myself, i'd use the specs i gave you, to design a 9-10cuft TOTAL 4th order, 4cuft sealed, 5cuft ported.

[Callan Fraser]

I'll have to do the math but I'm looking at 1/2 WO boxes placed vertically and strectched to fit three 15's, I'm sure I can tweak it to get the specified sizes or atleast close to.
I know the general box is designed to use one port for two subs to reduce space but I'm pretty sure at this moment space isn't a problem.I've drawn up a simple pic but can't upload atm due to technical difficulties..

Edited by Callan Fraser, 16 April 2012 - 07:51 AM.

[SQXPRT]

just scale it - all dimensions.

important is the throat (the narrow part) - scale the area, not the dimensions of it. Try to keep it still about 2" or so, or 2.5" with round-overs.

To fit 15" into the original baffle won't go either, so you need to make the sealed section larger, wider, taller to accommodate the bigger woofer.

[Callan Fraser]

we've scaled the height to a reasonable working size, but will have to re-look at the throat due to that info.
due to the way it will be installed we'll have a removable panel to fit the subs and check on them, fitting them in should also be covered by this

[KungFucius]

I would love to see someone here build an 'Auto Tuba'.

Sadly the design dictates the vehicle it goes into. It needs to be in a van