I plan to build an MDF box with the internal dimension 10"x15.75"x23", with a 4" round port 16" long perpendicular to the driver, mounted on the smallest face. I think the walls will probably be 3/4", although for the driver baffle I may glue together 2 panels of 5/8".
Any errors in this design, or tips for building? I haven't decided whether this box needs bracing or not.
Any errors in this design, or tips for building? I haven't decided whether this box needs bracing or not.
I'm not experienced with vented box designs, but I would offer that the internal dimensions of the box and the dimensions of the port would depend to a great extent on the driver you choose. Can you let us know what you're planning on loading into the cabinet?
dooper
dooper
The driver is mounted on the 15.75" X 23" side, right?
Your box is probably okay but I would put a vertical brace on the back of the box. The driver can probably brace the front.
By the way, I calculate you have a 2.1 ft³ box tuned to 29 Hz, approximately. Were you planning to mount a 10" or 12" in there?
Your box is probably okay but I would put a vertical brace on the back of the box. The driver can probably brace the front.
By the way, I calculate you have a 2.1 ft³ box tuned to 29 Hz, approximately. Were you planning to mount a 10" or 12" in there?
Sorry, I meant to say that the driver is going to be mounted on one of the largest faces and I'm going to increase the dimensions by a bit to account for the volume taken up by the driver and bracing, which I didn't do earlier.454Casull said:
The driver is an Elemental Designs e12K.44 / 14, driven by an Avionixx 400.2 amplifier.
I don't know if this would be of any use to your enclosure... just be sure that the vent would be unhindered by any obstruction... but then you already knew that. 🙂
Well, the design seems to work out well enough Thiele-Small wise, anyway.
T / S Parameters
Qts : 0.41
Qes : 0.46
Qms : 4.50
Vas : 53.74 L
Sd : 0.0465 m^2
XMag : 16.3 mm
XSus : 18.3 mm
XMax : 16.3 mm
MMd : 199.97 g
Re : 1.44 ohm
Fs : 26.39 ohm
Bl : 10.38
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Physical Loudspeaker Data
Model : e12K.44 / .14
Mounting Depth : 5.70" (144 mm)
Mounting Diameter : 11.125" ( 282 mm)
Overall Loudspeaker Diameter : 12.5" (317 mm)
The vent I calculate as taking up only 3.25 liters, the speaker should take up maybe 4 liters, and the brace, assuming you use a 25" x 2" x 2" vertical brace, should be less than 2 liters. sio figure 10 extra liters.
T / S Parameters
Qts : 0.41
Qes : 0.46
Qms : 4.50
Vas : 53.74 L
Sd : 0.0465 m^2
XMag : 16.3 mm
XSus : 18.3 mm
XMax : 16.3 mm
MMd : 199.97 g
Re : 1.44 ohm
Fs : 26.39 ohm
Bl : 10.38
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Physical Loudspeaker Data
Model : e12K.44 / .14
Mounting Depth : 5.70" (144 mm)
Mounting Diameter : 11.125" ( 282 mm)
Overall Loudspeaker Diameter : 12.5" (317 mm)
The vent I calculate as taking up only 3.25 liters, the speaker should take up maybe 4 liters, and the brace, assuming you use a 25" x 2" x 2" vertical brace, should be less than 2 liters. sio figure 10 extra liters.
Looking at the website, the recommended value was 1.5 Ft³, I believe. This box will be 2.1 Ft³.
There will be no drawbacks to making it a little bit larger. 2.1 Ft³ is pretty close to the ideal volume for a box with those Thiele-Small specs-I am not sure why the manufacturer recommended a smaller box, other than to hook people who want a box no larger than 1.5 Ft³.
Although there is a theoretical ideal volume, woofers in both sealed and ported enclosures work very well in a large range of different volumes, and this woofer will be perfectly acceptable in a box both smaller than the 1.5 Ft³ recommended by the manufacturer or a box larger the 2.1 Ft³ that you are building.
As to what is going to happen to the response when you put the box in the trunk, I can only guess. However, I have seen people do this and they are happy with the sound, so what the heck.
There will be no drawbacks to making it a little bit larger. 2.1 Ft³ is pretty close to the ideal volume for a box with those Thiele-Small specs-I am not sure why the manufacturer recommended a smaller box, other than to hook people who want a box no larger than 1.5 Ft³.
Although there is a theoretical ideal volume, woofers in both sealed and ported enclosures work very well in a large range of different volumes, and this woofer will be perfectly acceptable in a box both smaller than the 1.5 Ft³ recommended by the manufacturer or a box larger the 2.1 Ft³ that you are building.
As to what is going to happen to the response when you put the box in the trunk, I can only guess. However, I have seen people do this and they are happy with the sound, so what the heck.
Thanks for the input, keltic. I'm really too tired to do more of the math which will calculate the volume of the bracing and then adjust the length of the port to fit... I think I'm just going to expand the dimensions just a tiny bit and leave the port the way it is. I don't really care if the tuning frequency drops by 1Hz.
Okay. If you really want to make the difference up, make the internal dimensions 10" x 15.75" x27" and you're covered.
Welcome to the world of car audio. There are a few things in car audio that would propel a manufacurer to suggest a smaller box.kelticwizard said:
One is small-box popularity. The trend in car audio is to design subs with huge mass that work well in tiny enclosures at the expense of sensitivity.
Second, is that most car audio buyers are kids that want to boom. Stuffing the subs in a box with a Q of .8 or higher gives a little more "thump" that kids like the sound of.
Whenever I build a box for the car, I make it around 20% or 25% larger than the manufacturer reccomends, and I haven't gone wrong yet.
You mean make the rear panel 1¼" thick? Dunno. Can't hurt. Considering that you can probably use even a ¾" thick back and get away with it, my guess would be-yes.
Oh, well. I'm not going to be building another one of these soon, so might as well make a hell of a tight box.
Incidentally, before you start, there is one possibility I would mention.
You said these are going in the trunk. I would imagine that would muffle the bass somewhat, even though low frequencies travel through various materials better than high frequencies.
One idea would be the bandpass box, fourth order. That is the box which has all the sound coming out of one single port. The port could be made of a certain length so that if an opening from the trunk to the passenger cabin can be made-perhaps only 4" round-the port could fit through there and the bass would pour directly into the cabin from the enclosure with no muffling whatsoever.
I have not built a bandpass box, but they can be modeled, and I believe that your woofer would model very well. The main trick is to be able to cutoff your main speakers to blend in with the bandpass box.
You said these are going in the trunk. I would imagine that would muffle the bass somewhat, even though low frequencies travel through various materials better than high frequencies.
One idea would be the bandpass box, fourth order. That is the box which has all the sound coming out of one single port. The port could be made of a certain length so that if an opening from the trunk to the passenger cabin can be made-perhaps only 4" round-the port could fit through there and the bass would pour directly into the cabin from the enclosure with no muffling whatsoever.
I have not built a bandpass box, but they can be modeled, and I believe that your woofer would model very well. The main trick is to be able to cutoff your main speakers to blend in with the bandpass box.
That sounds like a lot of work... I'm only going to be pouring in sound below 60/80Hz, and I don't think bass gets attenuated so much through such a thin rear deck.
Besides, I'd prefer to keep the woodworking to a minimum. If only Sonosubs were feasible for car audio. 😀
Besides, I'd prefer to keep the woodworking to a minimum. If only Sonosubs were feasible for car audio. 😀
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