Subwoofer enclosure building for 12" driver

[Howard]

Anybody see any glaring faults with this design? If not, I'm going to build it like this.

I think I'm going to extend the long pieces by a half inch or so and fill up the additional space with reinforcements at the butt joints.

 

[Howard]

Perhaps I'll replace the driver baffle with 1" MDF instead of 3/4". Then again, I don't want to spring for a whole sheet just to use so little. Any drawbacks to gluing a plywood panel to the baffle?

 

[Nutdotnet]

Does the box's cubic footage agree with the rec. cubic footage for the sub?

If so then go for it!

 

[ThisIsMatt]

Originally posted by: Nutdotnet
Does the box's cubic footage agree with the rec. cubic footage for the sub?

If so then go for it!

That, port lenght and port area. Do you know what you're tuning it to?

 

[Howard]

Originally posted by: ThisIsMatt

Originally posted by: Nutdotnet
Does the box's cubic footage agree with the rec. cubic footage for the sub?

If so then go for it!

That, port lenght and port area. Do you know what you're tuning it to?

The given value is 26Hz... Should I raise it?

Actually I should probably raise it, most of his music won't hit so low.

 

[Howard]

This is for my brother's car, and he's not really into classical or rock... Suffice to say most of his music is stuff that's played on radio.

 

[Nutdotnet]

Originally posted by: Howard
This is for my brother's car, and he's not really into classical or rock... Suffice to say most of his music is stuff that's played on radio.

So pop and rap?

 

[Howard]

Would it be better to use a circular (that is to say, cylindrical) port instead of the folded vent? It would be a lot easier to build.

 

[Howard]

Originally posted by: Nutdotnet

Originally posted by: Howard
This is for my brother's car, and he's not really into classical or rock... Suffice to say most of his music is stuff that's played on radio.

So pop and rap?

yar

 

[ThisIsMatt]

Originally posted by: Howard

Originally posted by: ThisIsMatt

Originally posted by: Nutdotnet
Does the box's cubic footage agree with the rec. cubic footage for the sub?

If so then go for it!

That, port lenght and port area. Do you know what you're tuning it to?

The given value is 26Hz... Should I raise it?

Actually I should probably raise it, most of his music won't hit so low.

Did you just find this box on the web, or does it actually correspond to the driver you have/plan to have?

 

[Howard]

Originally posted by: ThisIsMatt

Originally posted by: Howard

Originally posted by: ThisIsMatt

Originally posted by: Nutdotnet
Does the box's cubic footage agree with the rec. cubic footage for the sub?

If so then go for it!

That, port lenght and port area. Do you know what you're tuning it to?

The given value is 26Hz... Should I raise it?

Actually I should probably raise it, most of his music won't hit so low.

Did you just find this box on the web, or does it actually correspond to the driver you have/plan to have?

It's the manufacturer's blueprint for the sub I'm buying from nourdmrolNMT1 (Elemental Designs e12K.44 / 14).

 

[ThisIsMatt]

Originally posted by: Howard

Originally posted by: ThisIsMatt

Originally posted by: Howard

Originally posted by: ThisIsMatt

Originally posted by: Nutdotnet
Does the box's cubic footage agree with the rec. cubic footage for the sub?

If so then go for it!

That, port lenght and port area. Do you know what you're tuning it to?

The given value is 26Hz... Should I raise it?

Actually I should probably raise it, most of his music won't hit so low.

Did you just find this box on the web, or does it actually correspond to the driver you have/plan to have?

It's the manufacturer's blueprint for the sub I'm buying from nourdmrolNMT1 (Elemental Designs e12K.44 / 14).

Ok, that's good then...

 

[Howard]

Any input on switching the folded vent to a circular port? It would be much easier to build.

 

[ThisIsMatt]

Originally posted by: Howard
Any input on switching the folded vent to a circular port? It would be much easier to build.

You won't be able to fit a circular port of the proper size in that box.

 

[Howard]

Originally posted by: ThisIsMatt

Originally posted by: Howard
Any input on switching the folded vent to a circular port? It would be much easier to build.

You won't be able to fit a circular port of the proper size in that box.

Assuming I use a box of interior dimensions of 22.5cm x 36cm x 52.5cm which results in an interior volume of 1.5cf, a 3" port tuned to 30Hz will be 14.1"... Which is 35.56cm; < than 52.5cm.

I took the ratios from http://www.silcom.com/~aludwig/Room_acoustics.html - scroll down to optimum room dimensions. I used the third ratio, x(1.6x)(2.33x) and solved for x where the equation = 1.5 cubic feet.

Anything wrong with a 3" straight PVC port? EDIT2: I'll figure out a way to brace the end of it.

EDIT1: I used the port length calculator from http://www.the12volt.com/caraudio/boxcalcs.asp

Can a port be tuned to any frequency without SQ drawbacks (nothing too low, of course)?

 

[Howard]

Then again, http://www.diysubwoofers.org/prt/ported1.htm recommends a 2cf interior volume given the subwoofer's T/S parameters (from manufacturer). What do you suggest?

EDIT1: Using the above port length calculator and values of 3" port, 2cf box volume, and 30Hz tuning frequency, the length of the port will be ~10".

EDIT2: The interior dimensions with the 2cf box will be 9.75"x15.5"x22.75". Because the driver won't fit on the smallest face the port will be perpendicular to the driver. I'll probably brace the 22.75" length... If it's alright to mount the driver off-center, I'll use a single bracing panel perpendicular to the 22.75" wall (parallel to the 15.5x9.75 face), with a cutout to let air flow freely.

EDIT3: The port will probably have to go through the brace if I build it like that.

Jeez, this is complicated.

 

[95SS]

Dou you have WinISD?? If not, get it here for free(Use the PRO version). Play around with different enclosure sizes and tunig frequencies, and see what works. The enclosure you posted with the single 3" port has a little too much port velocity for my tastes, I like to be under 12-13 m/s. The manufacturer recommended enclosure seems like a good choice to me. How much power will the sub get, and does the amp have a high pass filter (aka subsonic filter) to filter out the low low signal, since excursion shoots straight up below tuning frequency.

 

[Howard]

Originally posted by: 95SS
Dou you have WinISD?? If not, get it here for free(Use the PRO version). Play around with different enclosure sizes and tunig frequencies, and see what works. The enclosure you posted with the single 3" port has a little too much port velocity for my tastes, I like to be under 12-13 m/s. The manufacturer recommended enclosure seems like a good choice to me. How much power will the sub get, and does the amp have a high pass filter (aka subsonic filter) to filter out the low low signal, since excursion shoots straight below tuning frequency.

Yes, it'll probably be crossed over at 60/80Hz. No idea about amp power yet.

 

[95SS]

Originally posted by: Howard

Originally posted by: 95SS
Dou you have WinISD?? If not, get it here for free(Use the PRO version). Play around with different enclosure sizes and tunig frequencies, and see what works. The enclosure you posted with the single 3" port has a little too much port velocity for my tastes, I like to be under 12-13 m/s. The manufacturer recommended enclosure seems like a good choice to me. How much power will the sub get, and does the amp have a high pass filter (aka subsonic filter) to filter out the low low signal, since excursion shoots straight below tuning frequency.

Yes, it'll probably be crossed over at 60/80Hz. No idea about amp power yet.

No, not low pass (lets freqs under through), high pass (lets freqs above through). A problem vith vented enclosures is that under tuning, the driver is unloaded, meaning it doesn't see the enclosuse at all, and there is no cone control. Your sub has a 16.3mm X-max (from vendor web site). Some music does reach low, and if those ultra lows get through to the sub, it has the potential to be very destructive to the sub.

 

[Howard]

Originally posted by: 95SS

Originally posted by: Howard

Originally posted by: 95SS
Dou you have WinISD?? If not, get it here for free(Use the PRO version). Play around with different enclosure sizes and tunig frequencies, and see what works. The enclosure you posted with the single 3" port has a little too much port velocity for my tastes, I like to be under 12-13 m/s. The manufacturer recommended enclosure seems like a good choice to me. How much power will the sub get, and does the amp have a high pass filter (aka subsonic filter) to filter out the low low signal, since excursion shoots straight below tuning frequency.

Yes, it'll probably be crossed over at 60/80Hz. No idea about amp power yet.

No, not low pass (lets freqs under through), high pass (lets freqs above through). A problem vith vented enclosures is that under tuning, the driver is unloaded, meaning it doesn't see the enclosuse at all, and there is no cone control. Your sub has a 16.3mm X-max (from vendor web site). Some music does reach low, and if those ultra lows get through to the sub, it has the potential to be very destructive to the sub.

Oh. I'm not sure if we have something that cuts out the lowest frequencies. We may end up building a crossover...

 

[Howard]

WinISD defaults to a box volume of 125L and a port tuned to 26.73Hz. Are these the recommended values?

EDIT: It also has values of 4" circular port and about 8" length.

 

[95SS]

Originally posted by: Howard
WinISD defaults to a box volume of 125L and a port tuned to 26.73Hz. Are these the recommended values?

EDIT: It also has values of 4" circular port and about 8" length.

That will get you the flattest response, but if you click on the ''l" for liters, you can change to cubic feet. Then you will see that's a 4.4 cubic foot enclosure. That's where the adjustments and compromises come in. Plot both the default enclosure, and the recommended from the web site. You'll see that they are pretty close down to about 53hz, with the 1.5cf about 1db higher. Below 53hz, the 1.5cf enclosure drops off, but that's where the car comes in, boosting low bass at about 12db/oct. I like the manufacturer recommended enclosure, just be careful with the power, at around 200w you're pushing Xmax @ 47hz.

 

[Howard]

Originally posted by: 95SS

Originally posted by: Howard
WinISD defaults to a box volume of 125L and a port tuned to 26.73Hz. Are these the recommended values?

EDIT: It also has values of 4" circular port and about 8" length.

That will get you the flattest response, but if you click on the ''l" for liters, you can change to cubic feet. Then you will see that's a 4.4 cubic foot enclosure. That's where the adjustments and compromises come in. Plot both the default enclosure, and the recommended from the web site. You'll see that they are pretty close down to about 53hz, with the 1.5cf about 1db higher. Below 53hz, the 1.5cf enclosure drops off, but that's where the car comes in, boosting low bass at about 12db/oct. I like the manufacturer recommended enclosure, just be careful with the power, at around 200w you're pushing Xmax @ 47hz.

So what power and tuning frequency do you recommend?

 

[95SS]

Originally posted by: Howard

Originally posted by: 95SS

Originally posted by: Howard
WinISD defaults to a box volume of 125L and a port tuned to 26.73Hz. Are these the recommended values?

EDIT: It also has values of 4" circular port and about 8" length.

That will get you the flattest response, but if you click on the ''l" for liters, you can change to cubic feet. Then you will see that's a 4.4 cubic foot enclosure. That's where the adjustments and compromises come in. Plot both the default enclosure, and the recommended from the web site. You'll see that they are pretty close down to about 53hz, with the 1.5cf about 1db higher. Below 53hz, the 1.5cf enclosure drops off, but that's where the car comes in, boosting low bass at about 12db/oct. I like the manufacturer recommended enclosure, just be careful with the power, at around 200w you're pushing Xmax @ 47hz.

So what power and tuning frequency do you recommend?

I like to tune low, for sound quality. Higher tunes are better for SPL. What is the maximum enclosure size you can go with?

 

[Viperoni]

Very very long port, and it's quite narrow. I woudln't be surprised if there was some port noise.

For the 1.5cf tuned to 26hz, under 250 watts would be ok with a 3inch port, otherwise above 300 I'd recommend a 4incher.
You probably wouldn't hurt frequency response by bumping the tuning frequency up to 30hz, and that'd reduce subwoofer excursion (IE: smaller chance of bottoming out) in the region where most bass happens as well.

You won't really need a 1inch baffle, but if you want to, you can always do small braces on either side of the sub... maybe ones that are 2-4 inches deep coming out from the front baffle.

95SS, are you *SURE* he'd be running out of excursion in that box @ only 200watts?
Remember that WinISD gives you a peak to peak excursion spec, while ED lists their Xmax spec (correctly) as a one-way spec... total Xmax would be double their listed one.