Hey guys, i'm really having trouble designing a box for my dads ML350.
At first i thought i can put 2 12 inch subs in a sealed, but then I decided to go for a ported for the extended low end (1 driver). The internal volume will be 2.87ft^3.
Everything I seem to try out in WinISD turns out to be very impractical.. When I tune to 30hz, the velocity just shoots up to 50m/s, and when i tune lower the port length gets crazy. I have seen 12 inch boxes with 3 inch ports and they didnt chuff a lot (if any at all)
Since the top of the enclosure will only be 3 inches thats kind of my diameter that I have to stick with.
I was thinking about an apline type R driver or a focal access 30a1 (dont know which one is better yet, WinISD shows some really bad responses for the focal)
Can anyone help out with the vent designing issue im having?
At first i thought i can put 2 12 inch subs in a sealed, but then I decided to go for a ported for the extended low end (1 driver). The internal volume will be 2.87ft^3.
Everything I seem to try out in WinISD turns out to be very impractical.. When I tune to 30hz, the velocity just shoots up to 50m/s, and when i tune lower the port length gets crazy. I have seen 12 inch boxes with 3 inch ports and they didnt chuff a lot (if any at all)
Since the top of the enclosure will only be 3 inches thats kind of my diameter that I have to stick with.
I was thinking about an apline type R driver or a focal access 30a1 (dont know which one is better yet, WinISD shows some really bad responses for the focal)
Can anyone help out with the vent designing issue im having?
A 3" port may be all that is required for a 12" driver with only a few mm excursion and a relatively high (45 Hz) tuning.
Long excursion requires big ports to keep the port velocity down and low tunings require the ports to be long.
Then there is the catch 22 that the large port volume has to be subtracted from cabinet volume, making the cabinet larger...
Ain't no free lunch, and no way around the issues, though you can fold the ports to fit inside (relatively) small enclosures.
so would it be better to just go with the 2 12s in a sealed? since if i would have to tune it higher (45hz) it would be missing the point of low end extension
How about if i used dual 3 inch ports? lets say the driver has an xmax of 11mm
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If money is no object, in general for home subs a pair of sealed will be preferable to one ported. A pair also gives you more options for placement.
Dual 3" ports are probably adequate for an 11mm excursion 12".
Ported cabinets drop off rapidly below Fb, but are louder around Fb than a sealed cabinet of similar size.
I use a pair of sealed 12" in my home stereo, but ported or tapped horns everywhere else where I am more concerned with output level and efficiency than ultimate sound quality.
Since you have WinISD, you can see the outcomes of your questions.
Well this would be for a car enclosure, not for home use. I usually listen to tech house and music that has tons of low bass in it, which is why i want to go for vented. I use WinISD to see the difference and it seems like the sealed cuts off at around 40hz which is less than preferable.
After many years in car audio, I'll second the notion that porting is just hard in small car enclosures. And I do NOT think a 3" port is adequate for a 12"-not even for a 10" actually. At least dual 3" or 4" minimum. And folding ports chokes the airflow. The one thing that *might* work is a shelf port.
However, ported boxes in cars typically need to be under tuned because of the cabin gain. You want a droopy response, slowly rolling off to a low tuning frequency. In the car, this will give a slowly rising bass response, which is what you want due to the road noise
Compensation for Road Noise in Automotive Entertainment Systems
Now if you WANT an exaggerated bump to your house music, that's a different story 🙂
Sealed will not really cut off at 40 Hz, again due to cabin gain. One advantage of sealed in your situation is you can make heavy use of stuffing to increase the apparent box volume, resulting in again a slow rolloff. You can't do that in a ported box because too much stuffing will block the port airflow.
As for the woofer, I'm highly partial to Alpine, I know the guy who designed that stuff and he is a very very smart cookie.
However, ported boxes in cars typically need to be under tuned because of the cabin gain. You want a droopy response, slowly rolling off to a low tuning frequency. In the car, this will give a slowly rising bass response, which is what you want due to the road noise
Compensation for Road Noise in Automotive Entertainment Systems
Now if you WANT an exaggerated bump to your house music, that's a different story 🙂
Sealed will not really cut off at 40 Hz, again due to cabin gain. One advantage of sealed in your situation is you can make heavy use of stuffing to increase the apparent box volume, resulting in again a slow rolloff. You can't do that in a ported box because too much stuffing will block the port airflow.
As for the woofer, I'm highly partial to Alpine, I know the guy who designed that stuff and he is a very very smart cookie.
I've seen a 6 inch driver cause unacceptable chuffing with a 3 inch port.
Driver - tang band w6-1139
Port was unflared on both ends and tuned around 30 hz or so
I don't remember any other details, the box was burned in shame by the guy that built it. He started with a 2 inch port (same tuning) and I told him it was going to chuff before he built it but he didn't believe me since the Cerberus sub uses a 1.5 inch port with the same driver and it's wildly popular on the Parts Express forum despite being the worst sub design and waste of a good driver I've ever seen. He replaced it with a 3 inch port (external due to the size) and it was still terrible.
So if it was up to you, would you get the dual 12 inch? ive never actually heard a sealed enclosure in a car which is why im so unsure about spending money on a type r alpine
Actually, tuning lower means you can use a smaller diameter port. So if he already tunes at 30Hz and gets chuffing it will be even worse if he tunes to 45Hz.
Although 3 inch diameter is not enough port for anything other than very low tuned 12 inch driver with low xmax. One of my early designs I had a 4mm xmax 12 inch driver in a 60 litre box tuned to 27Hz with a 4 inch port, it was OK but did have some port noise to the trained ear.
the internal box volume is 1.9 cubic inches without displacement of driver or ports. That is the largest i could build it because of where it has to be placed.
If i place 2 12 inch subs, will the low end response be enough to make a difference or should i try to port the box with 1 12 inch?
The ported box should be able to go lower. However, if you use some EQ then the overall performance of both designs should be similar. So you need to weigh up the costs and complexity of buying two drivers vs buying one driver and implementing EQ.
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