Help with Tuning a Type R?
08-01-2003, 01:14 PM
#1
0 Watt CAFz'r
Thread Starter
Join Date: Apr 2003
Posts: 28
HEy.. I'm about to build my own Ported Box.. and I need someone to help me out with the Calculations.
My Box is going to be 22 x 13.5 x 15 inches.. I'm looking to tune to 36hz. Unless someone recommends another frequency.
Any help would be awesome!
BTW.. I'm using a JBL 600.1 and I have a 2 ohm DVC Type R running on it.. I'll be running it at 4 ohms.. so only 300 watts going into it.
Thanks in advance!
My Box is going to be 22 x 13.5 x 15 inches.. I'm looking to tune to 36hz. Unless someone recommends another frequency.
Any help would be awesome!
BTW.. I'm using a JBL 600.1 and I have a 2 ohm DVC Type R running on it.. I'll be running it at 4 ohms.. so only 300 watts going into it.
Thanks in advance!
08-01-2003, 01:58 PM
#3
0 Watt CAFz'r
Thread Starter
Join Date: Apr 2003
Posts: 28
Hey! Thanks
Do you mind me asking you what program you used to do that? BTW.. it's the outer dimensions.
Would you recommend a bigger enclosure? Because my trunk certainly has room for it.
Also.. when you said gross volume.. does that include displacement for the sub and port?
[ August 01, 2003, 03:01 PM: Message edited by: Gabe ]
Do you mind me asking you what program you used to do that? BTW.. it's the outer dimensions.
Would you recommend a bigger enclosure? Because my trunk certainly has room for it.
Also.. when you said gross volume.. does that include displacement for the sub and port?
[ August 01, 2003, 03:01 PM: Message edited by: Gabe ]
08-01-2003, 01:59 PM
#4
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Join Date: Apr 2003
Posts: 48
Hrm, I'm building a sealed box (Ext. 16" x 13" x 10.75") which is 0.8ft^3 (recommended).
I'm running same setup except I've an Alpine
amp (MRP-M350) pushing 350W @ 2ohm.
Will find out how it sounds in a couple days
when evertyhing gets put together
I'm running same setup except I've an Alpine
amp (MRP-M350) pushing 350W @ 2ohm.
Will find out how it sounds in a couple days
when evertyhing gets put together
08-01-2003, 02:04 PM
#5
0 Watt CAFz'r
Thread Starter
Join Date: Apr 2003
Posts: 28
Right now I have it in a 0.9 cubic foot sealed box.. well.. not really sealed. It's just a spare box my friend had laying around.. it leaks.. so I decided it's time to build my own.
Might as well try ported.. I'm starting to think my box is too big? 1.75 was the recommended max for ported boxes.. any suggestions? [img]graemlins/dunno.gif[/img]
Might as well try ported.. I'm starting to think my box is too big? 1.75 was the recommended max for ported boxes.. any suggestions? [img]graemlins/dunno.gif[/img]
08-01-2003, 05:05 PM
#6
500 Watt CAFz'r
Join Date: Jan 2003
Posts: 575
Thickness - 0.75" MDF
Dimensions - 22 x 13.5 x 15 inches
Gross volume - (22-1.5)(13.5-1.5)(15-1.5)/1728 = 1.921875 ft^3
Driver displacement - 0.128 ft^3
Port diameter - 4"
Port length - 12" (11.25" internal)
Port displacement - (3.14159*2^2*11.25)/1728 = 0.0818123 ft^3
Net volume - 1.921875 - 0.128 - 0.0818123 = 1.712062691 ft^3
Tuning - (Using diysubwoofers.org formula)
(k*Dv)+Lv = (23562.5*Dv^2*Np)/(Fb^2*Vb)
Dv = 4*2.54 = 10.16
Vb = 1.712062691*28.319 = 48.4839
Np = 1
Lv = 12*2.54 = 30.48
k = 0.614, 0.732, 0.85 (See http://www.diysubwoofers.org/portcal.htm)
For k = 0.614 (i.e. PVC piping), Fb = ...
(0.614*10.16)+30.48 = (23562.5*10.16^2*1)/(Fb^2*48.4839)
36.71824 = (2432253.2)/(Fb^2*48.4839)
36.71824 = (50166.20363)/(Fb^2)
Fb^2 = (50166.20363)/(36.71824)
Fb = Sqrt(1366.247501)
Fb = 36.963 Hz
For k = 0.732, Fb =
(0.732*10.16)+30.48 = (50166.20363)/(Fb^2)
37.91712 = (50166.20363)/(Fb^2)
Fb^2 = (50166.20363)/(37.91712)
Fb = Sqrt(1323.048893)
Fb = 36.374 Hz
For k = 0.85 (i.e. Aeroport), Fb =
(0.85*10.16)+30.48 = (50166.20363)/(Fb^2)
39.116 = (50166.20363)/(Fb^2)
Fb^2 = (50166.20363)/(39.116)
Fb = Sqrt(1282.498303)
Fb = 35.812 Hz
If you build the box correctly (no leaks), it should be fine ...
[ August 01, 2003, 06:08 PM: Message edited by: Jmac ]
Dimensions - 22 x 13.5 x 15 inches
Gross volume - (22-1.5)(13.5-1.5)(15-1.5)/1728 = 1.921875 ft^3
Driver displacement - 0.128 ft^3
Port diameter - 4"
Port length - 12" (11.25" internal)
Port displacement - (3.14159*2^2*11.25)/1728 = 0.0818123 ft^3
Net volume - 1.921875 - 0.128 - 0.0818123 = 1.712062691 ft^3
Tuning - (Using diysubwoofers.org formula)
(k*Dv)+Lv = (23562.5*Dv^2*Np)/(Fb^2*Vb)
Dv = 4*2.54 = 10.16
Vb = 1.712062691*28.319 = 48.4839
Np = 1
Lv = 12*2.54 = 30.48
k = 0.614, 0.732, 0.85 (See http://www.diysubwoofers.org/portcal.htm)
For k = 0.614 (i.e. PVC piping), Fb = ...
(0.614*10.16)+30.48 = (23562.5*10.16^2*1)/(Fb^2*48.4839)
36.71824 = (2432253.2)/(Fb^2*48.4839)
36.71824 = (50166.20363)/(Fb^2)
Fb^2 = (50166.20363)/(36.71824)
Fb = Sqrt(1366.247501)
Fb = 36.963 Hz
For k = 0.732, Fb =
(0.732*10.16)+30.48 = (50166.20363)/(Fb^2)
37.91712 = (50166.20363)/(Fb^2)
Fb^2 = (50166.20363)/(37.91712)
Fb = Sqrt(1323.048893)
Fb = 36.374 Hz
For k = 0.85 (i.e. Aeroport), Fb =
(0.85*10.16)+30.48 = (50166.20363)/(Fb^2)
39.116 = (50166.20363)/(Fb^2)
Fb^2 = (50166.20363)/(39.116)
Fb = Sqrt(1282.498303)
Fb = 35.812 Hz
If you build the box correctly (no leaks), it should be fine ...
[ August 01, 2003, 06:08 PM: Message edited by: Jmac ]
08-01-2003, 08:09 PM
#7
0 Watt CAFz'r
Join Date: Apr 2003
Posts: 48
Gabe, why would you build the box bigger then the
recommended spec for sealed?
Anywho, mine is just over 0.8ft^3 (0.80061429 to
be exact) and I already had my wood cut and paid
so I'm not turning back.
Crossing my fingers this sounds good [img]smile.gif[/img]
recommended spec for sealed?
Anywho, mine is just over 0.8ft^3 (0.80061429 to
be exact) and I already had my wood cut and paid
so I'm not turning back.
Crossing my fingers this sounds good [img]smile.gif[/img]
08-02-2003, 06:43 AM
#8
Guest
Posts: n/a
I'm impressed that diysubwoofers actually uses the end correction factor. Nobody ever thinks of that. 
BUT then you can see the minimal difference in length it makes and you can see why it is often ignored. Real world - you'll never hear it.
When at work or not wanting to open a full box designer at home I like to use http://tools.autoaudio.com/ventcalc/ for a quick port length number.
I used a calculator for the volumes as shown above and I used an allowance for driver displacement based on similar drivers I am more familiar with.
BUT then you can see the minimal difference in length it makes and you can see why it is often ignored. Real world - you'll never hear it.When at work or not wanting to open a full box designer at home I like to use http://tools.autoaudio.com/ventcalc/ for a quick port length number.
I used a calculator for the volumes as shown above and I used an allowance for driver displacement based on similar drivers I am more familiar with.
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