Slot port measuring ?

PaRaN0iD

Member
2015-08-26 10:21 am
Good evening

So i made a Sealed subwoofer with JL Audio 12w3v3-4 driver and a Hypex DS4.0 plate amp. It sounds good, better than my BK XXLS400. But still i think a ported subwoofer is more of my liking. Kind of a bass heavy listener.

The one i made is the left one, on the right is the BK XXSL400

[IMGDEAD]http://i67.tinypic.com/21sqwg.jpg[/IMGDEAD]

So There are some Specs on the JL audio site for a enclosure with a slot port. But like the one i got now, i would like it to be more evenly on all sides. Square instead of rectangle on the JL specs. 737x356x321 But if i want to make it more close to lets say 450x450x450 what dimensions should that slot port get ? And i need to make an air tight compartment for the plate amp. And it needs to be a downfire subwoofer.

Any good pointers for me to get going with ? Thanks in advance.
 

PaRaN0iD

Member
2015-08-26 10:21 am
Hello, What do you mean with loaded like this ? There are specs available from JL audio and there are T/S parameters so should be sufficient to make a good box ?

btw , they make home theather subwoofers also ;-)

Btw2 , i calculated with some parameters, and it was 2.68% so it should be fine.
 
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Ron E

Member
2002-06-27 10:41 pm
USA, MN
Say you make a box, then say you put that box face down an inch or three from the floor. The port tuning frequency and even the driver parameters are going to change a bit as they will be mass-loaded by the space under the box.. The amount of change cannot be simply predicted as it depends on the speaker and vent locations and the dimensions of the space under it. Cut and try. Make your port length easily adjustable...
 

infinia

Member
2005-05-15 9:51 am
SoCal
Any good pointers for me to get going with ? Thanks in advance.

JL woofers are usually designed for sealed boxes, you could probably quickly measure F and Q and work backwards to get your actual T/S specs but they are probably are not ideal for ported and if they were, the box will be about twice as large. slot tuning comes later. EQing should help, unless you running out of amp watts / Sd * Xmax displacement.

PS sadly your image doesn't show any of the money shots. (the woofer or the amp.)
 
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Say you make a box, then say you put that box face down an inch or three from the floor. The port tuning frequency and even the driver parameters are going to change a bit as they will be mass-loaded by the space under the box.. The amount of change cannot be simply predicted as it depends on the speaker and vent locations and the dimensions of the space under it. Cut and try. Make your port length easily adjustable...

True, though you can simulate the effect in Hornresp if you get creative with TH segments and chambers. I'll dig something out.

Chris
 

PaRaN0iD

Member
2015-08-26 10:21 am
Thank you guys for the reply thusfar. I do know on the site of JL they specify dimensions and such for a Ported and a sealed box. Surely it would be ok for both of them ?

Here are some money shots of the components :

[IMGDEAD]http://i65.tinypic.com/96m9nq.jpg[/IMGDEAD]

[IMGDEAD]http://i63.tinypic.com/348n2tg.jpg[/IMGDEAD]

[IMGDEAD]http://i66.tinypic.com/xgfdb4.jpg[/IMGDEAD]
 

PaRaN0iD

Member
2015-08-26 10:21 am
Btw, here are some parameters

Free Air Resonance (Fs) 26.72 Hz Electrical “Q” (Qes) 0.472 Mechanical “Q” (Qms) 7.572 Total Speaker “Q” (Qts) 0.444 Equivalent Compliance (Vas) 2.844 cu ft / 80.54 L One-Way Linear Excursion (Xmax)* 0.510 in / 13.0 mm Reference Efficiency (no) 0.31% Efficiency (1 W / 1 m)** 87.15 dB SPL Effective Piston Area (Sd) 80.600 sq in / 0.0520 sq m DC Resistance (Re) 3.563 Ω

Physical :

Nominal Diameter 12.0 in / 300 mm Overall Diameter (A) 12.5 in / 318 mm Mounting Hole Diameter (B) 11.0625 in / 281 mm Bolt Hole Circle Diameter (C) 11.7 in / 297 mm Motor Outer Diameter (D) 5.5 in / 140 mm Mounting Depth (E) 6.65 in / 169 mm Driver Displacement 0.071 cu ft / 2.01 L Net Weight 14.50 lb / 6.58 kg
12W3v3-4 - Car Audio - Subwoofer Drivers - W3v3 - JL Audio
 

PaRaN0iD

Member
2015-08-26 10:21 am
Not sure how you re-read but basicly i asked if there is some way to re calculate the slot port with the different dimensions. Thought this was a forum for questions? We got to start somewhere right ? Maybe some want to help and maybe some not. Thanks i guess ;-)

Because there are specs available for this driver...
 

infinia

Member
2005-05-15 9:51 am
SoCal
Not sure how you re-read but basicly i asked if there is some way to re calculate the slot port with the different dimensions. Thought this was a forum for questions? We got to start somewhere right ? Maybe some want to help and maybe some not. Thanks i guess ;-)

Because there are specs available for this driver...
yes we can help YOU diy but we are not a volunteer drop-in service station.

JL will offer some suggestions if call them, but basically you need to calculate the inside volume Vb (cuft) of YOUR box and vent tuning (Hz) from area dia and length lv THEN you can convert the tubular vent to a slot with some corrections. look for them or come back and search the forum.
try JL Audios suggestions or Rons above or ? by using a freeware box program like 'unibox or 'winsd.
 

Ron E

Member
2002-06-27 10:41 pm
USA, MN
Not sure how you re-read but basicly i asked if there is some way to re calculate the slot port with the different dimensions. Thought this was a forum for questions? We got to start somewhere right ? Maybe some want to help and maybe some not. Thanks i guess ;-)

Because there are specs available for this driver...

I am trying to drop hints... You seem to want someone to figure it all out.
Try this, ask questions: Car Audio - PORT Size Calculations and Formulas for WOOFER and Subwoofer BOXES
 

PaRaN0iD

Member
2015-08-26 10:21 am
Feeling at home already, but i found a awesome pointer from infinia in the right direction that was basicly under my nose, re calculate the slot length and diameter into my slot port design.

So i can basicly alter that port in length with my max internal height of 414ishmm with the bent included. Is the bent always needed ?
 
don t believe does numbers

Those numbers are a rough estimate of your speaker, to do it good, remeasure and why not using a line output , a bit more difficult to maken, but those ports are seldom well sounding is my experenience, but a line-output can you tune the sound much more then fit a simple tube.
But building a speaker from scratch takes a lot of time and those programs give an advice,
and a lot is done by ear. and offcourse know you equations, so you know what to change and you can have a a speaker, made of material which just ain't your taste.
 

PaRaN0iD

Member
2015-08-26 10:21 am
Ok So i need to adjust the port width to adjust for the same volume is it that 'simple' ? So i can adjust the length and height to fit in my box and play with the width to get the same volume ?

On JL specs the slot port is for instance 35x681x318= 7579,53
When i make this for other dimensions i.e. 62x350x350= 7595

If i would make the enclosure 420x420x420 = 59 litre (sealed) when that port is in it, it would make 51 litre so thats near the JL spec of 49.6litre. Or doesnt it work like this ?

Sorry Richie14 i dont understand what u mean with using a line output ?
 

Ron E

Member
2002-06-27 10:41 pm
USA, MN
Port "volume" is not the right way to go about it. Use the calculator!
Port area interacts with the volume of the box and requires a certain length to tune properly.
You enter your box volume into the calculator
you then enter your slot dimensions
It then tells you how long the port has to be to tune the box to the specified frequency.

As I said before, your port tuning frequency and driver parameters will be somewhat affected by the downfiring arrangement.
 

infinia

Member
2005-05-15 9:51 am
SoCal
Thank you guys for the reply thusfar. I do know on the site of JL they specify dimensions and such for a Ported and a sealed box. Surely it would be ok for both of them ?

Here are some money shots of the components :

thank you,
so what are you really saying is that you ( or your decorator LOL) desires a small square sided cube changed to incorporate a tuned port using a slot with one of the inside dimensions & none of the money stuff showing. correct>?
1) as Ron said > woofers facing down sag after a while and throw off the sound and can ruin the driver eventually ~ 2-3 years. solve or live with this then pass to go
2) changing to ported will increase the box volume by double or more from sealed ( important to remember the box volume Vb excludes the area occupied by 'stuff' > amps, speakers , ports ) ok with a cube estimate of ~ 3cuft ? then pass go
3) are you going to cover up the amp ( ideally the amp has open good cooling and is sealed from the woofer ) changing this can degrade the amp to early fail and increase volume too! add more volume to increase 3 cu ft., what now have now isn't really ideal from the amps POV and degrading it further is unwise.

are you ready?
 
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PaRaN0iD

Member
2015-08-26 10:21 am
I dont really want a huge box thats true, and while checking the JL specs it can be as little as 50 litres its tuned for 30Hz then so maybe when i tune it to 25 like someone said it would get much much bigger. Twice that number maybe.

Thats why my initital question was about that slot port. Because it takes up less space than a round tube so the box can be smaller.

1) I calculated the possibilty for horizontal usage and its well below the 5% that is the max for horizontal hanging ? its 2.68 % not afraid anything will mess the driver up.

2) Not sure what u mean with this ? But yes it wil get bigger. But not that extreme bigger because of what JL specced.

3) No concerns on the Hypex DS4.0 , not sure if u know these units but they are rock solid and there is no heat coming of it whatsoever. And yes like with the box i have now it needs its own compartment.

Ok am i ready ? No idea where you are going with this. Totally blank here.

@Ron :

Bummer it doesnt work like that. When i enter my figures it requires a porth length of 129cm :D when tuned to 30 Hz and almost 192 for 25 Hz

I wonder how JL comes up with this box of 49.6Litres with a slot lenght of 68cm.
 

infinia

Member
2005-05-15 9:51 am
SoCal
Ok am i ready ? No idea where you are going with this. Totally blank here.

ready to design a box given warnings I listed & knowing its gonna get big..
Most box recommendations from the drivers makers like JL are NOT giving tuning that sound good in peoples rooms they tune for optimum bass /size.

P.S. yes I know about class D amps and slotted ports are rarely EVER smaller than a tube port with the same air velocity.
mostly because the owners have some fixed dimension making the slot opening a poor aspect ratio\
 
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