Can someone help me model a sub Please?

[annunaki]

TLS thanks so much for taking the time to model these for me you are truly a stand-up guy in my book especially taking time around the holidays. I do have a question though it appears from your graph that the 10w3 has a vent velocity of 20m/sec at F3 is that acceptable? Is there anything I can do to combat this?

A slightly larger vent that is also bit longer would do well.

The 10W3v3-4 models very well in a 3.0ft^3 enclosure tuned to 24hz.

Using a 23"H x 17"W x 24.5"D enclosure with a slot vent at 2"H x 15.5"W x 43.5"L would yield -3db points at 21.9hz and -3db at 85.75hz remaining ruler flat in between at 111db simulated anechoic!! Vent velocity remains just below 17m/s over the entire range.

This alignment does assume a low-pass x-over at 80hz 2nd order and a high-pass (Infrasonic filter) at 20hz 2nd order.
The volume would account for bracing (window braces of minimal displacement) and driver displacement.

 

[Coheednme13]

that sounds pretty awesome should I build it sort of like the kappa design just with different measurments. I'm sorry I'm such a noob. LOL

 

[TLS Guy]

TLS thanks so much for taking the time to model these for me you are truly a stand-up guy in my book especially taking time around the holidays. I do have a question though it appears from your graph that the 10w3 has a vent velocity of 20m/sec at F3 is that acceptable? Is there anything I can do to combat this?

Just about. Since this was for a bedroom I made a reasonably small footprint box, and so I was concerned about fitting a longer port in the box. If you build the 3 cu.ft. box and the longer port you will solve it.

 

[Coheednme13]

it is for my soon to be dedicated HT but it is a small room so I don't want the sub to be huge but I think it will have to be so whatcha gonna do thanks for all the help

Do I need some rockwool or anything to line the enclosure

 

[TLS Guy]

it is for my soon to be dedicated HT but it is a small room so I don't want the sub to be huge but I think it will have to be so whatcha gonna do thanks for all the help

Do I need some rockwool or anything to line the enclosure

Yes, you will need to cover 50% of the interior surface with Mineral Wool, especially behind the driver. For smaller rooms like you describe the smaller box will work fine, and the vent velocity at the power you will use will be fine. The larger vent slows the air speed about 3 m/sec, for a vent velocity of 17 m/sec. I calculate the vent dimensions to be 2" X 13.25 X 43.5 for the 3 cu.ft box. You will need to add driver displacement and, bracing and amp volume to the 3 cu.ft.

 

[Coheednme13]

So for future reference when you build an enclosure- let's say you want it to be 3cub. ft. I know you have to add driver displacement and bracing to the enclosure size but do you also have to add the displacement of the wood making up the port?

 

[TLS Guy]

So for future reference when you build an enclosure- let's say you want it to be 3cub. ft. I know you have to add driver displacement and bracing to the enclosure size but do you also have to add the displacement of the wood making up the port?

Yes you do.

 

[Coheednme13]

Yes you do.

do you add the entire port volume as well as the wood used to make the port

 

[TLS Guy]

do you add the entire port volume as well as the wood used to make the port

Just the wood.

 

[annunaki]

The air in the vent cannot be included. The design I offered counts for ALL displacement.

 

[Coheednme13]

MDF suitable? Annunaki you have a single window brace? Does the design include displacement for adding some mineral wool or treatment?

 

[annunaki]

MDF suitable? Annunaki you have a single window brace? Does the design include displacement for adding some mineral wool or treatment?

I have not used just a single window brace in any of my designs. I typically use a bracing system which is a series of window braces tying all 6 panels together with no more than 7" of any one surface unbraced.

You will have no issue using 25% coverage in mineral wool along with some good bracing techniques in my suggested design.

 

[Coheednme13]

I have not used just a single window brace in any of my designs. I typically use a bracing system which is a series of window braces tying all 6 panels together with no more than 7" of any one surface unbraced.

You will have no issue using 25% coverage in mineral wool along with some good bracing techniques in my suggested design.

I was looking at your JL 13w1 build should I do a similar bracing technique? Will I need to add volume to your design or is the design assuming a bracing technique like the one you used?

 

[annunaki]

I was looking at your JL 13w1 build should I do a similar bracing technique? Will I need to add volume to your design or is the design assuming a bracing technique like the one you used?

You would probably want to add another .10-.15ft^3 if you added that much. I would suggest similar bracing, though you could get by with a bit less.

 

[Coheednme13]

now when measuring port length do I measure along the bottom and back of the port or do I measure the wood used to make the port? Trying to come up with a design. I wouldn't mind paying someone to come up wtih a cut list and design. I am glad that I'm learning though since you guys are helping. Let me know if you understand what I'm saying as far as the port goes.

 

[TLS Guy]

now when measuring port length do I measure along the bottom and back of the port or do I measure the wood used to make the port? Trying to come up with a design. I wouldn't mind paying someone to come up wtih a cut list and design. I am glad that I'm learning though since you guys are helping. Let me know if you understand what I'm saying as far as the port goes.

The length is calculated along the center line, including bends.

 

[Coheednme13]

So I have 2 different port options from you guys. So if TLS guy has the optimum port at 13.5 inches then what would be the difference in going with a port that is 15.5 inches annunaki suggests. Would the driver become sloppy?

 

[TLS Guy]

So I have 2 different port options from you guys. So if TLS guy has the optimum port at 13.5 inches then what would be the difference in going with a port that is 15.5 inches annunaki suggests. Would the driver become sloppy?

I was calculating on a final internal volume, and having you add the displacing addition of braces and wood for ports etc. Apparently Annunaki allowed for this.

I have looked at this closely. I think you will end up with around 20% of your final volume being braces etc. So if you have, an actual volume of air of 2.7 cu.ft. in your box the system tunes pretty much optimally. Your final volume will probably end up between 3.1 and 3.5 cu.ft, depending on your bracing and amp.

If that is the case the box tunes optimally with a vent of 2" X 12.5 X 45.75"

This gives you an F3 of 21.9 Hz and a vent velocity peak of 17 m/sec.

So that is my final calculation for you.

Name: 10W3v3
Type: Standard one-way driver
Company: JL Audio Inc
No. of Drivers = 1
Fs = 32.97 Hz
Qms = 7.027
Vas = 32.17 liters
Cms = 0.19 mm/N
Mms = 122.4 g
Rms = 3.61 kg/s
Xmax = 14 mm
Xmech = 21 mm
P-Dia = 209.6 mm
Sd = 345 sq.cm
P-Vd = 0.483 liters
Qes = 0.533
Re = 1.7 ohms
Z = 2 ohms
BL = 8.995 Tm
Pe = 500 watts
Qts = 0.495
no = 0.209 %
1-W SPL = 85.37 dB
2.83-V SPL = 92.07 dB
-----------------------------------------
Box Properties
Name:
Type: Vented Box
Shape: Prism, square (optimum)
Vb = 2.7 cu.ft
Fb = 22.94 Hz
QL = 6.68
F3 = 21.88 Hz
Fill = minimal
No. of Vents = 1
Vent shape = rectangle
Vent ends = one flush
Hv = 2 in
Wv = 12.5 in
Lv = 45.73 in

 

[annunaki]

I was calculating on a final internal volume, and having you add the displacing addition of braces and wood for ports etc. Apparently Annunaki allowed for this.

I have looked at this closely. I think you will end up with around 20% of your final volume being braces etc. So if you have, an actual volume of air of 2.7 cu.ft. in your box the system tunes pretty much optimally. Your final volume will probably end up between 3.1 and 3.5 cu.ft, depending on your bracing and amp.

If that is the case the box tunes optimally with a vent of 2" X 12.5 X 45.75"

This gives you an F3 of 21.9 Hz and a vent velocity peak of 17 m/sec.

So that is my final calculation for you.

Name: 10W3v3
Type: Standard one-way driver
Company: JL Audio Inc
No. of Drivers = 1
Fs = 32.97 Hz
Qms = 7.027
Vas = 32.17 liters
Cms = 0.19 mm/N
Mms = 122.4 g
Rms = 3.61 kg/s
Xmax = 14 mm
Xmech = 21 mm
P-Dia = 209.6 mm
Sd = 345 sq.cm
P-Vd = 0.483 liters
Qes = 0.533
Re = 1.7 ohms
Z = 2 ohms
BL = 8.995 Tm
Pe = 500 watts
Qts = 0.495
no = 0.209 %
1-W SPL = 85.37 dB
2.83-V SPL = 92.07 dB
-----------------------------------------
Box Properties
Name:
Type: Vented Box
Shape: Prism, square (optimum)
Vb = 2.7 cu.ft
Fb = 22.94 Hz
QL = 6.68
F3 = 21.88 Hz
Fill = minimal
No. of Vents = 1
Vent shape = rectangle
Vent ends = one flush
Hv = 2 in
Wv = 12.5 in
Lv = 45.73 in

Are you accounting for the volume displaced by the vent? All of the items I have ever encountered on vented enclosures states that the volume inside of the vent cannot be counted in the total volume, as would be the volume of the material used to construct the vent.

My design accounts for this and bracing. I always suggest a slot vent of a specified width as it is the same as the internal width as the enclosure, thus simplifying the construction process and adding additional structural integrity.

 

[Coheednme13]

Are you accounting for the volume displaced by the vent? All of the items I have ever encountered on vented enclosures states that the volume inside of the vent cannot be counted in the total volume, as would be the volume of the material used to construct the vent..

I need to know this answer so that I can begin designing the enclosure

My design accounts for this and bracing. I always suggest a slot vent of a specified width as it is the same as the internal width as the enclosure, thus simplifying the construction process and adding additional structural integrity.

I plan on making the width of the enclosure to account for this because I feel you state the bennefits of simplifying construction and adding strength. I'm trying to take Annunaki's enclosure dimensions and TLS's vent recommendations and blend the two to end up with a net enclosure size of 2.7 cubic feet


Again to both of you guys you are both really great treasures to this forum for helping me so much. I can not tell you how much I appreciate your help.

Matt