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2 AQ HDC4 18"s

Quickbox questions

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14 replies to this topic

#1
ghostismyname

ghostismyname

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Alright so my hdc4s are on their way here, in the meantime ive been figuring out a design for my box, Measurements so far are H=25 W=40 D=25. This is going into a ford explorer 2 door. I dont know what will sound better port facing up(with the subs) or facing the rear hatch? Ive been working on trying to get the port on the top, but i want it tuned to 28-30hz and i cant seem to get it there, atleast on Chris Torres Box Calculator. it works in the calculator on The12volt. Either way i need help with this and on a second note sub displacement, ive never counted it in my builds because ive never had such big woofers before, on their site they list * V(as)= 48.450 liters (1.711 cubic feet) Under the hdc4 18"s specs, I only assume this is the displacement, so with two woofers thats 3.422 cubic feet, this drasticaly effects my tuning :( I need some help with this kinda stressfull. Further info depth and width of box cant be increased at all(it will fit snug this way as it is) height on the other hand has some roomi dont know exactly but id say atleast 10".Any help with this will be greatly appreciated.

#2
412 CVX

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It's late and i'm getting lost in your words, but from what i understand, V(as) is not displacement. i might reread this in the morning, but if i'm skimming it correctly now, the displacement of two HDC4 18's will not be over 1 cubic foot, i can almost guarantee that

Just say no to Ground Pounder Customs.

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some cars do over 170db with one sub, so clearly my two 12"s can do that in my car, with my knowledge too! look out bitches!

I'm with captain stupid.


#3
ghostismyname

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It's late and i'm getting lost in your words, but from what i understand, V(as) is not displacement. i might reread this in the morning, but if i'm skimming it correctly now, the displacement of two HDC4 18's will not be over 1 cubic foot, i can almost guarantee that

sorry for rambling on, but yes basically i need help getting my box tuned to 28-30hz, link for the hdc4 18 page is here http://www.audioque....1-A-_p_137.html incase you can find the displacement.

#4
412 CVX

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honestly when you can't find it, just guesstimate. unless you're chasing tenths on the meter it really doesn't matter as long as you're close. i would estimate the displacement per sub is around .25

if you need help with the design, feel free to PM me anytime.

Just say no to Ground Pounder Customs.

My temp system build log

More box builds

some cars do over 170db with one sub, so clearly my two 12"s can do that in my car, with my knowledge too! look out bitches!

I'm with captain stupid.


#5
ghostismyname

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honestly when you can't find it, just guesstimate. unless you're chasing tenths on the meter it really doesn't matter as long as you're close. i would estimate the displacement per sub is around .25

if you need help with the design, feel free to PM me anytime.

I will probably message you, any other input from people is stll welcome tho, ive decided ill go with the rear facing port and subs up.

#6
Joe X

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So ran some numbers, this a port up sub up configuration:

Enclosure Specifications:

Fb = 30.006 Hz
Vb = 9.049 ft^3

External Height = 25 in
External Width = 40 in
External Depth = 25 in

Port Width = 5 1/4 in

Cut List:

* All Dimensions in Inches.
* Wood Thickness is 3/4 for all Parts.

External Enclosure Parts:

2 x Top & Bottom (3 parts) = 40 x 25

Left & Right Sides = 23 1/2 x 22 3/4

Front & Back = 40 x 22 3/4

L Port Internal Assembly Parts:

Front to Back = 17 1/2 x 23 1/2
Extension = 4 x 23 1/2


Audioque recommends 5 cubic feet minimum per sub, the design above is a cube short, so you need to give up more space to have a working design, also is better to specify the minimum frequency you want to listen to (F3) than tuning itself.

For example a 28 inch depth will let you reach 5 cubes per sub.

#7
9515ROB

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Vas is not displacement. Vas is minimal CF that sub will actual work in. The stiffer the sub the lower the Vas and smaller of enclosure you need and the looser the sub is the higher the Vas will be and the bigger of an enclosure the sub needs

Edited by 9515ROB, 27 February 2012 - 02:09 AM.

- 1998 Ford Mustang - Time to rebuild. 4 15s and alot of power TEAM DTF

#8
9515ROB

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your going to have some fun getting a sub that has the free air response of 40hz to play in the low 30s and high 20s daily lol
- 1998 Ford Mustang - Time to rebuild. 4 15s and alot of power TEAM DTF

#9
ghostismyname

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So ran some numbers, this a port up sub up configuration:

Enclosure Specifications:

Fb = 30.006 Hz
Vb = 9.049 ft^3

External Height = 25 in
External Width = 40 in
External Depth = 25 in

Port Width = 5 1/4 in

Cut List:

* All Dimensions in Inches.
* Wood Thickness is 3/4 for all Parts.

External Enclosure Parts:

2 x Top & Bottom (3 parts) = 40 x 25

Left & Right Sides = 23 1/2 x 22 3/4

Front & Back = 40 x 22 3/4

L Port Internal Assembly Parts:

Front to Back = 17 1/2 x 23 1/2
Extension = 4 x 23 1/2


Audioque recommends 5 cubic feet minimum per sub, the design above is a cube short, so you need to give up more space to have a working design, also is better to specify the minimum frequency you want to listen to (F3) than tuning itself.

For example a 28 inch depth will let you reach 5 cubes per sub.

Thank you for the input, as for more space i can give up more height, atleast 10" more. And from what ive read after searching the forums apparently port firing to the rear is best in my application?

#10
ghostismyname

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your going to have some fun getting a sub that has the free air response of 40hz to play in the low 30s and high 20s daily lol

I never had any problem with my old aq's and playing 30hz and those were twelves? Not trying to give you a negative response, just in my case when i played low song that hit around 28-30 i still got the desired deep bass and solid rumble throughout my vehicle :( i may just not have heard enough really good builds to tell the difference. But i mostly plan on playing rap/dubstep/rock i want the lower tuning mostly for show i guess. I figure ill stick with 30hz like my last box, of course i never did displacement when i made it so that probably drasticaly changend my tuning. And thank you for the clarification on what Vas actualy is.

Edited by ghostismyname, 27 February 2012 - 02:29 AM.


#11
9515ROB

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your going to have some fun getting a sub that has the free air response of 40hz to play in the low 30s and high 20s daily lol

I never had any problem with my old aq's and playing 30hz and those were twelves? Not trying to give you a negative response, just in my case when i played low song that hit around 28-30 i still got the desired deep bass and solid rumble throughout my vehicle :( i may just not have heard enough really good builds to tell the difference. But i mostly plan on playing rap/dubstep/rock i want the lower tuning mostly for show i guess. I figure ill stick with 30hz like my last box, of course i never did displacement when i made it so that probably drasticaly changend my tuning. And thank you for the clarification on what Vas actualy is.


Its your box you can do what ever you want. Your best bet to figuring out what the displacement is, is trying to find the specs for subs that are around the same size and see what its displacement is.
- 1998 Ford Mustang - Time to rebuild. 4 15s and alot of power TEAM DTF

#12
ghostismyname

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Its your box you can do what ever you want. Your best bet to figuring out what the displacement is, is trying to find the specs for subs that are around the same size and see what its displacement is.


Yes ive already sent a email trying to contact Aq and see if they will tell me the displacement. But in the mean time i guess i could mock up some design with similar size woofers, ty

#13
9515ROB

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Here just to give you an idea. a DD 9518 with the 6 spoke basket has .33cf of displacement. So yours is probably a little over this but i cant imagine its over.5 each
- 1998 Ford Mustang - Time to rebuild. 4 15s and alot of power TEAM DTF

#14
ghostismyname

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alright thanks for your help, getting kinda late here so im gonna nod off. Thanks again and anymore help is appreciated.

#15
Joe X

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So here is what works out for a subs up/port back (all across the bottom) configuration:

Enclosure Specifications:

Fb = 30.15 Hz
Vb = 11.901 ft^3

Subwoofer Mounting = Flush Mounted

External Height = 29.25 in
External Width = 40 in
External Depth = 28 in

Port Width = 4 3/4 in

Cut List:

* All Dimensions in Inches.
* Wood Thickness is 3/4 for all Parts.

External Enclosure Parts:

2 x Top & Bottom (3 parts) = 40 x 28

Left & Right Sides = 26 1/2 x 27

Front & Back = 40 x 27

L Port Internal Assembly Parts:

Front to Back = 21 3/4
x 38 1/2
Extension = 4 x 38 1/2

As noted above though the 30Hz tuning is way below Fs, probably you should look into this.