15" alpine type R -port tuning frequency?
03-10-2011, 06:03 PM
#1
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15" alpine type R -port tuning frequency?
diagram of the box with all the numbers in inches
i used this website http://www.the12volt.com/caraudio/boxcalcs.asp#por
to calculate the volume and go around 4.1 ft^3
what LP and HP Frequency should I set my amp on?
i used this website http://www.the12volt.com/caraudio/boxcalcs.asp#por
to calculate the volume and go around 4.1 ft^3
what LP and HP Frequency should I set my amp on?
03-10-2011, 06:33 PM
#2
Don't use .6" MDF or it will most likely fall apart. Go with .75" or 1". The port only takes up .04 cubes and the displacement should be around .1-.15 cubes. Brace it with some 2x4's etc too. 4.1 is ideal, hopefully the driver displacement is .1 cubes.
Set the LP about 5 Hz above the port tune, and don't go under the port tune. Set the HP to where your mids or speakers are low passed at - around 60, 80, 100 Hz.
Is that all of the space you have?
Put the sub on the far side and put the port on the far side.
What year is the sub?
... and I almost forgot - that is not enough port area.
Use at the least 8 square inches of port area per cubic foot, even that's pushing it so shoot for 10-12 inches of port area per cubic foot - try a flared 8" aeroport from prescision ports, with 4 cubes it's 12.56 square inches of port area per cubic foot. You're currently planning for 3.14 per cube and you'll hear a lot of port-noise, you'll be choking the sub.
What's with the .4 measurements, are you afraid of .5 or do you just not have it?
Can you do 29 x 24.5 x 17 x 15 / .75" MDF - 8" aeroport that is 22" long, have the port going inside the box 6.25" (as in 15 height minus the backwall .75" minus the diameter of the port, leaving 8" from the back wall) - the port would stick out 15.75" for a tune of 34.87 Hz.
Set the LP about 5 Hz above the port tune, and don't go under the port tune. Set the HP to where your mids or speakers are low passed at - around 60, 80, 100 Hz.
Is that all of the space you have?
Put the sub on the far side and put the port on the far side.
What year is the sub?
... and I almost forgot - that is not enough port area.
Use at the least 8 square inches of port area per cubic foot, even that's pushing it so shoot for 10-12 inches of port area per cubic foot - try a flared 8" aeroport from prescision ports, with 4 cubes it's 12.56 square inches of port area per cubic foot. You're currently planning for 3.14 per cube and you'll hear a lot of port-noise, you'll be choking the sub.
What's with the .4 measurements, are you afraid of .5 or do you just not have it?
Can you do 29 x 24.5 x 17 x 15 / .75" MDF - 8" aeroport that is 22" long, have the port going inside the box 6.25" (as in 15 height minus the backwall .75" minus the diameter of the port, leaving 8" from the back wall) - the port would stick out 15.75" for a tune of 34.87 Hz.
Last edited by Lord Huggington; 03-10-2011 at 06:51 PM.
03-10-2011, 06:46 PM
#3
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Thread Starter
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Don't use .6" MDF or it will most likely fall apart. Go with .75" or 1". The port only takes up .04 cubes and the displacement should be around .1-.15 cubes. Brace it with some 2x4's etc too. 4.1 is ideal, hopefully the driver displacement is .1 cubes.
Set the LP about 5 Hz above the port tune, and don't go under the port tune. Set the HP to where your mids or speakers are low passed at - around 60, 80, 100 Hz.
Is that all of the space you have?
Put the sub on the far side and put the port on the far side.
What year is the sub?
... and I almost forgot - that is not enough port area.
Use at the least 8 square inches of port area per cubic foot, even that's pushing it so shoot for 10-12 inches of port area per cubic foot - try a flared 8" aeroport from prescision ports, with 4 cubes it's 12.56 square inches of port area per cubic foot. You're currently planning for 3.14 per cube and you'll hear a lot of port-noise, you'll be choking the sub.
Set the LP about 5 Hz above the port tune, and don't go under the port tune. Set the HP to where your mids or speakers are low passed at - around 60, 80, 100 Hz.
Is that all of the space you have?
Put the sub on the far side and put the port on the far side.
What year is the sub?
... and I almost forgot - that is not enough port area.
Use at the least 8 square inches of port area per cubic foot, even that's pushing it so shoot for 10-12 inches of port area per cubic foot - try a flared 8" aeroport from prescision ports, with 4 cubes it's 12.56 square inches of port area per cubic foot. You're currently planning for 3.14 per cube and you'll hear a lot of port-noise, you'll be choking the sub.
my question is how to calculate the tuning frequency of the box so i can adjust accordingly the amp HP and LP Freq.. cuz right now i dont know what the port tune is
the sub is brand new, just got it like a week ago. it Alpine Type R 15 inch 4 ohms subwoofer. my amp is JBL GTO7001.
i got the box ready like this from some guy.. he said he made the box
Last edited by Slimsta; 03-10-2011 at 06:49 PM.
03-10-2011, 07:01 PM
#4
NET space is 4.25 cubes.
The port tune is 29.97 Hz.
I can tell you right now that the box is CRAP! so toss it!
You might as well use it sealed, cover up the port and you'll like it a lot more.
2.4 cubes sealed = QTC .707 (flat response) with roll-off @ 36.16 Hz.
4.15 cubes sealed = QTC .6122 w/ roll off @ 31.29 Hz.
... and usefull up to 15 cubes (.5 & 25.56)
With newer specs: QTS .45 F/S 23Hz VAS 100L/3.5cuft.
The guy who made that box is an idiot.
The port tune is 29.97 Hz.
I can tell you right now that the box is CRAP! so toss it!
You might as well use it sealed, cover up the port and you'll like it a lot more.
2.4 cubes sealed = QTC .707 (flat response) with roll-off @ 36.16 Hz.
4.15 cubes sealed = QTC .6122 w/ roll off @ 31.29 Hz.
... and usefull up to 15 cubes (.5 & 25.56)
With newer specs: QTS .45 F/S 23Hz VAS 100L/3.5cuft.
The guy who made that box is an idiot.
03-10-2011, 07:10 PM
#5
Build something like this, it's roughly the same size just better. Have the magnet and port outside of the box - what vehicle?
12 volt calculator/29 x 24.5 x 18 x 14.5 / .75" = 4.08601 cubes.
8" aeroport x 22" long
34.5 Hz
12 volt calculator/29 x 24.5 x 18 x 14.5 / .75" = 4.08601 cubes.
8" aeroport x 22" long
34.5 Hz
Last edited by Lord Huggington; 03-10-2011 at 07:14 PM.
03-10-2011, 07:19 PM
#6
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i have a 2010 honda civic LX
the roof of my trunk is almost touching my sub so i cant flip the sub (from the floor to the highest area a box could fit is around 16", the box is 14.4" + 1" for the sub sticking out, so it's really tight in there)
you'll need to speak with me in simpler terms since im having hard time following "QTC .707 (flat response) with roll-off @ 36.16 Hz."
i cant change the box now.. i mean its already built and is in the car.. you want me to take it out and put more wood to the walls to make it thicker? and make the port bigger somehow?
the roof of my trunk is almost touching my sub so i cant flip the sub (from the floor to the highest area a box could fit is around 16", the box is 14.4" + 1" for the sub sticking out, so it's really tight in there)
you'll need to speak with me in simpler terms since im having hard time following "QTC .707 (flat response) with roll-off @ 36.16 Hz."
i cant change the box now.. i mean its already built and is in the car.. you want me to take it out and put more wood to the walls to make it thicker? and make the port bigger somehow?
Last edited by Slimsta; 03-10-2011 at 07:37 PM.
03-10-2011, 07:33 PM
#7
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Join Date: Feb 2011
Posts: 127
Did he make that box for that sub, or was he using it for a different sub? Poorly designed if made for your sub, imho. I suppose it doesn't really matter if that's the box you're going to use and aren't planning on having a decent one built (or building one yourself).
As for your crossover, set it wherever you want your sub to drop out. I usually set mine 90-120hz depending on how it sounds in any particular box.
Box tuning more has to do with how your sub sounds (whether it's a fairly consistant volume throughout a range of tones with a gradual drop off - generally what you want - or peaks at a certain tone and then drops quickly) than where you should set your crossover imo. Simpler terms for what huggington said, your box will peak and drop off instead of being steady with a gradual drop, making it a poorly designed box for your sub.
As for your crossover, set it wherever you want your sub to drop out. I usually set mine 90-120hz depending on how it sounds in any particular box.
Box tuning more has to do with how your sub sounds (whether it's a fairly consistant volume throughout a range of tones with a gradual drop off - generally what you want - or peaks at a certain tone and then drops quickly) than where you should set your crossover imo. Simpler terms for what huggington said, your box will peak and drop off instead of being steady with a gradual drop, making it a poorly designed box for your sub.
03-10-2011, 07:43 PM
#8
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Did he make that box for that sub, or was he using it for a different sub? Poorly designed if made for your sub, imho. I suppose it doesn't really matter if that's the box you're going to use and aren't planning on having a decent one built (or building one yourself).
As for your crossover, set it wherever you want your sub to drop out. I usually set mine 90-120hz depending on how it sounds in any particular box.
Box tuning more has to do with how your sub sounds (whether it's a fairly consistant volume throughout a range of tones with a gradual drop off - generally what you want - or peaks at a certain tone and then drops quickly) than where you should set your crossover imo. Simpler terms for what huggington said, your box will peak and drop off instead of being steady with a gradual drop, making it a poorly designed box for your sub.
As for your crossover, set it wherever you want your sub to drop out. I usually set mine 90-120hz depending on how it sounds in any particular box.
Box tuning more has to do with how your sub sounds (whether it's a fairly consistant volume throughout a range of tones with a gradual drop off - generally what you want - or peaks at a certain tone and then drops quickly) than where you should set your crossover imo. Simpler terms for what huggington said, your box will peak and drop off instead of being steady with a gradual drop, making it a poorly designed box for your sub.
my main concern is this, is there any chance of damaging the sub using this box? i dont care about the details of the bass as long as its loud and doesnt damage the sub..
what do you mean by "crossover" and "sub to drop out" i dont get that.. sorry im a noob.. i bought this sub cuz i know its a good brand and i've used one before for a year with my amp settings on max before i blew the cone out.. then i sold it and got this brand new one. i got it cuz i know its reliable and loud haha
03-10-2011, 07:50 PM
#9
Do nothing to the box, I was suggesting you throw it out because it's dog . The best thing that you can do now is plug the port-hole with a towel and call it a day, make sure there isn't air coming out of it. It's a real mess of a box for your sub.
A sealed box is tuned too, but it depends on the specs of the driver (QTS, FS, and VAS) and how much space it's in (obviously you can only change the tune by changing the space). A sealed sub with a QTC of .707 will yield a flat frequency response from where it'll start rolling off at around -10 decibels per octave (an octave is 10 Hz) and on up. If the roll off is at 30Hz than at 20hz it should be at -10dB compared to 30hz. A ported box rolls off at 24db per octave, which means if it was tuned to 30hz than at 20hz it would generate 24 db less than 30hz. This is why sealed boxes are better for low end repsonse, say below 25hz they'll be louder than ported (in theory anyway). The reason a ported box can have such a loss at only 10hz below the port tune is because there isn't enough cone control/back pressure, which can allow for over-excursion of the cone. This is why you have a lowpass filter in the first place. An amp isn't sending much power to a sub when it's playing below the port tune because below the port tune the cone movement takes over. Amps recognize when this happends.
For instance a sub in whatever space with FC (roll off) at 30 Hz will be flat from 30hz on up when it has a QTC of .707. QTC is frequency response, the shape of the line if you were to graph the decibals per frequencies. Useable QTC ranges from .4 to 1.2.
.4 is better for extended low end but it starts to drop (decibels) on the higher end.
.707 is flat
1.2 will sound peaky
If you aren't going to fix your box by going by my or anothers suggestion, complaining that it's already in your car (big deal) than you have come to the wrong place because that's just viewed as lazy. You're going to break your brand new sub.
A sealed box is tuned too, but it depends on the specs of the driver (QTS, FS, and VAS) and how much space it's in (obviously you can only change the tune by changing the space). A sealed sub with a QTC of .707 will yield a flat frequency response from where it'll start rolling off at around -10 decibels per octave (an octave is 10 Hz) and on up. If the roll off is at 30Hz than at 20hz it should be at -10dB compared to 30hz. A ported box rolls off at 24db per octave, which means if it was tuned to 30hz than at 20hz it would generate 24 db less than 30hz. This is why sealed boxes are better for low end repsonse, say below 25hz they'll be louder than ported (in theory anyway). The reason a ported box can have such a loss at only 10hz below the port tune is because there isn't enough cone control/back pressure, which can allow for over-excursion of the cone. This is why you have a lowpass filter in the first place. An amp isn't sending much power to a sub when it's playing below the port tune because below the port tune the cone movement takes over. Amps recognize when this happends.
For instance a sub in whatever space with FC (roll off) at 30 Hz will be flat from 30hz on up when it has a QTC of .707. QTC is frequency response, the shape of the line if you were to graph the decibals per frequencies. Useable QTC ranges from .4 to 1.2.
.4 is better for extended low end but it starts to drop (decibels) on the higher end.
.707 is flat
1.2 will sound peaky
If you aren't going to fix your box by going by my or anothers suggestion, complaining that it's already in your car (big deal) than you have come to the wrong place because that's just viewed as lazy. You're going to break your brand new sub.
03-10-2011, 07:56 PM
#10
You won't blow it up if you block the port/seal it. You really did just put a ... um... I don't want to say Ferrari because it really isn't, but it's like putting a built Ferrari engine into a Yaris Chassis, things are going to break because of a myriad of reasons, and you went to the racing afficiandos to ask which steering wheel will give you a better lap time.
You want loud? Get someone here to design you a custom box (that a shop can make for you for $200-$300 or make it yourself for $50) and you'll be wondering what the hell you were listening to before.
You want loud? Get someone here to design you a custom box (that a shop can make for you for $200-$300 or make it yourself for $50) and you'll be wondering what the hell you were listening to before.
Last edited by Lord Huggington; 03-10-2011 at 08:12 PM.
