I'm working on a tiny sub to blend in with cabin gain in a car. The perfect option is a 6th order BP rolling off at 24dB/oct from 70Hz down (vehicle has a 20dB boost at 42Hz)
However, I'm thinking the cone will unload below 70Hz and may be a problem so was wondering if I could replicate a 6th order BP with a pair of 4th order boxes, with tiny sealed back chambers. (sealing them will prevent them from over excursion below tuning)
I've attatched a pic to show what I'm trying to achieve.
I guess the pair of 4th order subs would be wired out of phase to act like the 6th order one ?
Thanks,
Rob.
However, I'm thinking the cone will unload below 70Hz and may be a problem so was wondering if I could replicate a 6th order BP with a pair of 4th order boxes, with tiny sealed back chambers. (sealing them will prevent them from over excursion below tuning)
I've attatched a pic to show what I'm trying to achieve.
I guess the pair of 4th order subs would be wired out of phase to act like the 6th order one ?
Thanks,
Rob.
Attachments
Hi, i see what you're trying to achieve by using 2 x 4BP
I think you mean rolling off from 70Hz up
No - I mean rolling off from 70Hz down - take a look at the graph I posted
Why do you think the cone will unload below 70Hz ?
It's in a vented alignment - below tuning they are unloaded.
Can you provide the driver Make/Model # & TS
Elemental designs 7kv 6" subwoofer. Too late to post all the specs. tbh my question is generic and will apply to all drivers / boxes.
Why do say they are or would be wired out of phase ?
Because in a 6th order box the 2 chambers are driven out of phase to one another.
Ahh, right you want 60/70Hz - 100Hz
Ok, not much bandwith there, but sure it'll make a difference to having none
It will be flat in car from 40Hz - 150Hz. That's not a bad bandwidth
If you have a HPF in place @ 60/70Hz you'll be fine
If I use a HPF it will change the response and not blend in with the cars cabin gain
But they will be tuned to different Frequencies, so add rather than cancel
I'm perfectly aware of how a 6th order bandpass box works thanks.
Measure the t/s parameters of that eD driver before you commit to any design, particularly one that's quite sensitive to t/s parameter variations.
I'd try them wired in phase then out of phase. One will likely sound better than the other. I would be interested to know which one it is (in or out of phase).
It is an interesting question, nothing like what I've seen before. Go for it, and if it doesn't work out, you could always use a generic sealed box (but where's the fun in that?)
Chris
It is an interesting question, nothing like what I've seen before. Go for it, and if it doesn't work out, you could always use a generic sealed box (but where's the fun in that?)
Chris
I'm not really an authority on bandpass designs, so can't really comment, but I completely understand your worries about unloading. In my limited experience I would really recommend a high pass filter if you're running them that high. Have you thought about a three chamber fourth order bandpass? That might be easier to get working, and sound more musical than the sixth order.
Hi Al,
I don't have software to model a 3 chamber 4th order box unfortunately..
I posted the 6th order plot to give an idea of the response I want. As I said before I can't run a HPF on the sub as it will stop the bottom roll off from integrating with the cars cabin gain.
Which is why I'm asking if it's possible to replicate a 6th order box with a pair of 4th order boxes.
It's looking like I'll just have to start building and measuring. I was hoping someone here would be able to give me a simple 'yes it's possible' or 'no it's been tried and failed' type answer.
Cheers,
Rob.
I don't have software to model a 3 chamber 4th order box unfortunately..
I posted the 6th order plot to give an idea of the response I want. As I said before I can't run a HPF on the sub as it will stop the bottom roll off from integrating with the cars cabin gain.
Which is why I'm asking if it's possible to replicate a 6th order box with a pair of 4th order boxes.
It's looking like I'll just have to start building and measuring. I was hoping someone here would be able to give me a simple 'yes it's possible' or 'no it's been tried and failed' type answer.
Cheers,
Rob.
It didn't appear that way from what you asked, that's why i provided those links
In essence yes, as you've already shown with your 2 4BPO WinISD designs
As you could be using 2 drivers, have a look here
Tri-Chamber Bandpass System - The Subwoofer DIY Page - Tr-Chamber Bandpass Systems
Hi,
I'm lost as to how a car can exhibit a 24dB/octave gain from 70Hz down to
40Hz, you probably wouldn't need a subwoofer at all if that was the case.
Your average in-door decent sized speakers would be bass monsters ......
Putting a series capacitor on those might even help if its true ......
rgds, sreten,
I'm lost as to how a car can exhibit a 24dB/octave gain from 70Hz down to
40Hz, you probably wouldn't need a subwoofer at all if that was the case.
Your average in-door decent sized speakers would be bass monsters ......
Putting a series capacitor on those might even help if its true ......
rgds, sreten,
Hi Sreten,
The last time I messed about with this project I measured the car with a sealed sub. I'll attatch a groundplane (outside) measurement of the 12" sub versus the same sub measured in the vehicle (test mic at head position on front seat)
To get round the cabin gain I tried a 6th order box tuned with loads of boost at 75Hz but it didn't work out too well as it didn't roll off enough. I'll post plots of this bandpass box too for you, with the winISD screen to show sim versus built box.
The boost is why nearly every sub install sounds boomy in a car. (huge 40Hz, no midbass output)
Thanks for looking in,
Rob.
The last time I messed about with this project I measured the car with a sealed sub. I'll attatch a groundplane (outside) measurement of the 12" sub versus the same sub measured in the vehicle (test mic at head position on front seat)
To get round the cabin gain I tried a 6th order box tuned with loads of boost at 75Hz but it didn't work out too well as it didn't roll off enough. I'll post plots of this bandpass box too for you, with the winISD screen to show sim versus built box.
The boost is why nearly every sub install sounds boomy in a car. (huge 40Hz, no midbass output)
Thanks for looking in,
Rob.
Attachments
The reason I started toying with running subs above the cabin boost is that a friend at work has a new mini with a harmon kardon system. He was going on about how low his stereo went with the tiny sub in it and I was saying that he'll only be getting down to about 40Hz and that they probably use dynamic limiters to cut the bass at higher volumes.
This made me realise that sub 40Hz probably isn't too important in a car as it sounded 'good enough' in the bass. This project is for my 4x4 where most of the space is taken by camping gear etc..
This made me realise that sub 40Hz probably isn't too important in a car as it sounded 'good enough' in the bass. This project is for my 4x4 where most of the space is taken by camping gear etc..
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