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View Full Version : two 15" alpine type r's some ported box questions



4bannger
10-13-2013, 04:37 PM
Vehicle : 2004 toyota sequoia
Location in the vehicle: behind third row
Space available (Length x Width x Height): 40x20x18
Subwoofer make and model: Apline type r dual 2 ohm
Subwoofer Size: 15"
Number of Subwoofers: 2
Type of Port (Kerfed, Slot, Aero, etc.): slot or kerfed
What type of music do you like?: rap ; music with good base
Is your goal SPL or Everyday Music?: SPL
Tuning Freq (Hz): 32 hz
Volume : 6 cubes

Questions 1: What is the difference besides look between a kerfed or sloted port

Questions 2: Is having the port on the same side as the subs the best

Questions 3: So when i use my port length calculator and figure im using a 15" high X 8" wide port. going for 32 hertz tuning frequency with 6 cubes. Its giving my a port length of 43.59" which is is too big. how do i account for this?

4bannger
10-13-2013, 04:57 PM
any ideas would really help me here

NASTY08IMPALA
10-13-2013, 05:00 PM
a 8" wide port seems far too wide ..play with the width to get the desired tuning and port area

Audio4ever
10-13-2013, 05:30 PM
Sell em to me lls

4bannger
10-13-2013, 05:38 PM
a 8" wide port seems far too wide ..play with the width to get the desired tuning and port area
I was just using that as an example. But I really wanna know if that is where "L" and "U" ports come into play


Sell em to me lls
lmao. I bought them both used for $100 at a local shop. Pretty good deal if you ask me

NASTY08IMPALA
10-13-2013, 05:40 PM
I was just using that as an example. But I really wanna know if that is where "L" and "U" ports come into play


lmao. I bought them both used for $100 at a local shop. Pretty good deal if you ask me

Yea thats where secondary port lengths come into play

4bannger
10-13-2013, 05:47 PM
Yea thats where secondary port lengths come into play

i will upload my idea in a few and maybe you or someone else can tell me if im right

NASTY08IMPALA
10-13-2013, 05:51 PM
Ok..say u have a port thats 5"wide and needds to be 30" long but ur interior depth is only 30" u would go 25" toward the back the L sideways 5" so u maintain the 5" port width

4bannger
10-13-2013, 05:56 PM
would a "L" port sound better then a straight port. Spl or sql wise?

NASTY08IMPALA
10-13-2013, 06:00 PM
would a "L" port sound better then a straight port. Spl or sql wise?

The shape of a port isnt used for more or less sq or spl its merely a way to achieve proper tuning and port area...some designs need more than one port length some do nit..u wont here a audible difference if u do the math correct

4bannger
10-13-2013, 06:45 PM
The shape of a port isnt used for more or less sq or spl its merely a way to achieve proper tuning and port area...some designs need more than one port length some do nit..u wont here a audible difference if u do the math correct

So If I wanted to do a wider port for a better look( the look a perfer) lets say 8" wide x 32.51" long I would then need a "L" port. Would making the port that wide mess with sound quality as long as i was keeping it tuned right.

also. whould it change me tune hertz if i made the port kerfed?

NASTY08IMPALA
10-13-2013, 10:04 PM
So If I wanted to do a wider port for a better look( the look a perfer) lets say 8" wide x 32.51" long I would then need a "L" port. Would making the port that wide mess with sound quality as long as i was keeping it tuned right.

also. whould it change me tune hertz if i made the port kerfed?

Kerf wont change tuning that much...andyea thats way too wide u want around 12-16" of port per cube

Full Tilt
10-13-2013, 10:11 PM
OP, my port for my dual XFL 12 box is only 4 5/8" wide, and I ended up with 15.8in^2 of port area. An 8" port is way big.

4bannger
10-14-2013, 05:52 AM
OP, my port for my dual XFL 12 box is only 4 5/8" wide, and I ended up with 15.8in^2 of port area. An 8" port is way big.

Okay so I guess ill go with a smaller kerfed port

bbeljefe
10-15-2013, 09:43 AM
In short, larger ports equal less possibility for port noise but too large a port lowers power handling and makes the sub(s) more prone to damage when played below Fb. With respect to box tuning, more port area causes you to need a longer port. i.e., a 3" port tuned to 30 Hz will be shorter than a 4" port tuned to 30 Hz, all other things being equal. Larger box volumes will allow for shorter port lengths to achieve the same tuning frequency.

Bent ports won't change increase SPL but they can decrease it if not constructed properly. When you do a bent port, you need to maintain port dimensions as closely as possible throughout the turns, which can be sufficiently achieved using 45° wave guides in the corners.

Lastly, if we assume about 3 cubes per sub for the subs you mentioned, you need ~100inē of port, which isn't too far off from the 120inē of port area you mentioned. And in the end, I'd rather see a little more port area than needed than a little less, as turbulence in a small port can ruin the sound quality of the box.

4bannger
10-16-2013, 06:06 AM
In short, larger ports equal less possibility for port noise but too large a port lowers power handling and makes the sub(s) more prone to damage when played below Fb. With respect to box tuning, more port area causes you to need a longer port. i.e., a 3" port tuned to 30 Hz will be shorter than a 4" port tuned to 30 Hz, all other things being equal. Larger box volumes will allow for shorter port lengths to achieve the same tuning frequency.

Bent ports won't change increase SPL but they can decrease it if not constructed properly. When you do a bent port, you need to maintain port dimensions as closely as possible throughout the turns, which can be sufficiently achieved using 45° wave guides in the corners.

Lastly, if we assume about 3 cubes per sub for the subs you mentioned, you need ~100inē of port, which isn't too far off from the 120inē of port area you mentioned. And in the end, I'd rather see a little more port area than needed than a little less, as turbulence in a small port can ruin the sound quality of the box.

That's answered a lot of the questions that I had. One more that I forgot to post the other day and should
Be my last question.

**** I get material for free at work. So I plan on making the box walls 1 1/2" thick by doubling up the 3/4" mdf. I wanna make the box really stiff so there isn't flex. But is there such thing as too dense. Do I want a little flex or
None at
All.

ThatChevyGuy
10-16-2013, 08:00 AM
That's answered a lot of the questions that I had. One more that I forgot to post the other day and should
Be my last question.

**** I get material for free at work. So I plan on making the box walls 1 1/2" thick by doubling up the 3/4" mdf. I wanna make the box really stiff so there isn't flex. But is there such thing as too dense. Do I want a little flex or
None at
All.

None.

4bannger
10-17-2013, 05:58 AM
None.

So today I talked to this guy who said he "knows what he's talking about". Long story short he basically went against all the information I've obtained online. So either you can't believe everything you read
Online or you can trust everything a stranger in a parking lot tells you.


Okay so here's my new questions.

What is the best tuning frequency range for subs?

Will different sub sizes play different frequencies better and if so would it be better to have multiple sizes in the same set up

bmk6795
10-17-2013, 07:15 AM
So today I talked to this guy who said he "knows what he's talking about". Long story short he basically went against all the information I've obtained online. So either you can't believe everything you read
Online or you can trust everything a stranger in a parking lot tells you.


Okay so here's my new questions.

What is the best tuning frequency range for subs?

Will different sub sizes play different frequencies better and if so would it be better to have multiple sizes in the same set up

for music i tune from 35 and down, for pure spl it's usually 45+.

don't mix sub sizes or brands.

and i think id trust a car audio forum over some stranger, lol.

bbeljefe
10-17-2013, 09:58 AM
The best tuning range for subwoofers is dependent upon your goals, your box and the sub you're using. Sub bass is in the <80 Hz region and most enclosures will do well from 50-80 Hz and even higher, although you don't want your subs pulling midbass duty, which is why we cross them over at ~80 Hz.

As far as different sized subs playing different frequencies better, yes and no. A 6" (true) subwoofer will play a 25 Hz note and an 18" sub will play an 80 Hz note. But sound waves are peculiar, in that lower frequency notes are less audible to human ears and thus, must be played at higher sound pressure levels in order for us to hear them. And actually, once you get into the low 20Hz range, you really feel the note more than you hear it. Also, low notes are more difficult to produce in a vehicle because they are very long and a vehicle cabin isn't.

So... a 6" sub can produce 20 Hz notes but in order for those notes to be heard and felt, it needs to be in the right cabinet and it needs a lot of power. Even still, there isn't much cone area so while it is indeed playing the low note, it isn't moving a lot of air and thus, doesn't seem to be playing the low note. Contrast that with an 18" sub and you're moving much more air on the same power, so obviously, it would appear that the 18 is doing better. But technically, it isn't playing anything the small sub isn't... it's just playing the same notes louder.

As for mixing sub sizes, you can do that if you need upper sub bass reinforcement because of a narrow bandwidth box like a 4th or 6th order but on balance, it isn't necessary or very effectual for the space and expense.

And lastly, don't fall for the myth that big subs aren't musical. I'm running two monster 15" subs in a transmission line in my truck and the upper sub bass is tight, fast and accurate. And, I have no smaller subs in the system. Sound quality has to do with the box, not the amount of piston area each driver displaces.

4bannger
10-17-2013, 10:34 PM
The best tuning range for subwoofers is dependent upon your goals, your box and the sub you're using. Sub bass is in the <80 Hz region and most enclosures will do well from 50-80 Hz and even higher, although you don't want your subs pulling midbass duty, which is why we cross them over at ~80 Hz.

As far as different sized subs playing different frequencies better, yes and no. A 6" (true) subwoofer will play a 25 Hz note and an 18" sub will play an 80 Hz note. But sound waves are peculiar, in that lower frequency notes are less audible to human ears and thus, must be played at higher sound pressure levels in order for us to hear them. And actually, once you get into the low 20Hz range, you really feel the note more than you hear it. Also, low notes are more difficult to produce in a vehicle because they are very long and a vehicle cabin isn't.

So... a 6" sub can produce 20 Hz notes but in order for those notes to be heard and felt, it needs to be in the right cabinet and it needs a lot of power. Even still, there isn't much cone area so while it is indeed playing the low note, it isn't moving a lot of air and thus, doesn't seem to be playing the low note. Contrast that with an 18" sub and you're moving much more air on the same power, so obviously, it would appear that the 18 is doing better. But technically, it isn't playing anything the small sub isn't... it's just playing the same notes louder.

As for mixing sub sizes, you can do that if you need upper sub bass reinforcement because of a narrow bandwidth box like a 4th or 6th order but on balance, it isn't necessary or very effectual for the space and expense.

And lastly, don't fall for the myth that big subs aren't musical. I'm running two monster 15" subs in a transmission line in my truck and the upper sub bass is tight, fast and accurate. And, I have no smaller subs in the system. Sound quality has to do with the box, not the amount of piston area each driver displaces.

Okay so just for clarification.

1. Mixing subs is okay only when needed but can
Be almost pointless in okay cases

2. All sub can hit the same frequency as long as they are powered right and in the right enclosure.

3. 35hz and down for music and 45+ for spl

bbeljefe
10-18-2013, 12:06 AM
Okay so just for clarification.

1. Mixing subs is okay only when needed but can
Be almost pointless in okay cases

2. All sub can hit the same frequency as long as they are powered right and in the right enclosure.

3. 35hz and down for music and 45+ for spl


It isn't that easy. One and two are but three isn't. There are a lot of guys doing stupid sound pressure on 35 Hz tuning and lower. Again, there are a lot of factors.

4bannger
10-18-2013, 05:40 AM
Well I'll have to keep working on it with trial and error

basicbasshead
12-16-2013, 03:26 PM
Check out my pictures. 60 inch port for2 15inch Type R and a 7cube box!