Sub placement, does it matter?

[MellowHype 10+ year member]

EDI:: Change of plan, ive now got two Type R's and am in the process of designing a box

Im going to have a go at building a new box, as my current running a type R @700 watts isnt very loud and i think its got a lot to do with the box.

the current box is 2.0cbf 32hz before displacement.

the new will be 2.52 @ 30 hz before displacement.

My current sub is in its box like number one in this pic, is that a bad place to mount it? with the port wall just behind it?

i was thinking of going with it like this (number 2)

does that make a difference at all?

and could anyone tell me what the displacement would be?

my specs

Mounting Depth: 162mm (6-3/8'')

Mounting Diameter: 275mm (10-13/16'')

Displacement: 0.100ft^3

Added Volume: 0.090ft^3

Really appreciate any help

Click to read more...

 

[bbeljefe]

Yes, placement matters. Both where the sub is mounted in the box and were/how the box is placed in the vehicle.

Location one is better because the sub isn't loading directly into the mouth of the port.

 

[MellowHype 10+ year member]

Yes, placement matters. Both where the sub is mounted in the box and were/how the box is placed in the vehicle.
Location one is better because the sub isn't loading directly into the mouth of the port.

ahh ok, thanks alot.

Ill go with that then.

Also a couple more things, is fibreglassing the inside worth it? i can only find a tin for £25 and i suppose im not going to need all of it.

and are 45 degree cuts a must for the corners?

im asking as i dont want to build another for it to still not sound very good.

 

[T3mpest 10+ year member]

ahh ok, thanks alot.
Ill go with that then.

Also a couple more things, is fibreglassing the inside worth it? i can only find a tin for £25 and i suppose im not going to need all of it.

and are 45 degree cuts a must for the corners?

im asking as i dont want to build another for it to still not sound very good.

No they aren't. They are nice things that usually helps, and can show off woodworking skills, but they rarely even make audible difference.. Just make sure you have a good amount of port area and that fixes 90% of the problems associated with ports.

 

[macsdad 10+ year member]

Yes, placement matters. Both where the sub is mounted in the box and were/how the box is placed in the vehicle.
Location one is better because the sub isn't loading directly into the mouth of the port.

If he did a labyrinth type port, would that eliminate the unloading in the port? Giving him more options?

 

[MellowHype 10+ year member]

No they aren't. They are nice things that usually helps, and can show off woodworking skills, but they rarely even make audible difference.. Just make sure you have a good amount of port area and that fixes 90% of the problems associated with ports.

Ok thanks.

how does the design in the OP look? i want to keep it very simple

 

[bbeljefe]

ahh ok, thanks alot.
Ill go with that then.

Also a couple more things, is fibreglassing the inside worth it? i can only find a tin for £25 and i suppose im not going to need all of it.

and are 45 degree cuts a must for the corners?

im asking as i dont want to build another for it to still not sound very good.

Wave guides (the 45° corner braces) make very little difference so if you don't have a table saw, don't worry about them. Fiberglass is not necessary unless you're running a lot more power than you are and, as Tempest said, correct port area is very important.

The box and the port area you have in the drawing above look to be good for that sub.

 

[bbeljefe]

If he did a labyrinth type port, would that eliminate the unloading in the port? Giving him more options?

No. If the port provides that much acoustical suspension, it's too small. Doesn't matter what it's shaped like.

 

[T3mpest 10+ year member]

If he did a labyrinth type port, would that eliminate the unloading in the port? Giving him more options?

You really don't want to bend a port more times than necessary anyway.. Airflow in a port needs to be as smooth as possible, especially since turbulence in the middle of a port wont' be flushed out the ends and will cause compression easier, even if you don't hear chuffing.

 

[MellowHype 10+ year member]

Wave guides (the 45° corner braces) make very little difference so if you don't have a table saw, don't worry about them. Fiberglass is not necessary unless you're running a lot more power than you are and, as Tempest said, correct port area is very important.
The box and the port area you have in the drawing above look to be good for that sub.

Thanks alot for your help, gonna start gathering materials and give it a go

Edit: oh yeah, and what would my specs be after displacement with that box in the OP??

Displacement: 0.100ft^3

Added Volume: 0.090ft^3

2.42cbf? what hz am i looking at roughly?

 

[Loudmp5 10+ year member]

I suggest you download Torres box calc it's way more accurate than the re calc

 

[bbeljefe]

Thanks alot for your help, gonna start gathering materials and give it a go

Edit: oh yeah, and what would my specs be after displacement with that box in the OP??

Displacement: 0.100ft^3

Added Volume: 0.090ft^3

2.42cbf? what hz am i looking at roughly?

After sub and port displacement what you have is 2.24ftⁿ and tuning is ~30.5 Hz.

 

[MellowHype 10+ year member]

After sub and port displacement what you have is 2.24ftⁿ and tuning is ~30.5 Hz.

the 2.24ft^3 is fine (most recommend 2.25-2.5 for single 12 type R), and i cant get much bigger than that in my boot, so if i mess around with port diameter i can aim for 31.5hz on RE Calculator and 32hz is what ill get?

sorry to bother you with these questions i just dont know how to work it out, quite new to this kinda stuff

 

[hispls 5,000+ posts]

Yes, placement matters. Both where the sub is mounted in the box and were/how the box is placed in the vehicle.
Location one is better because the sub isn't loading directly into the mouth of the port.

Of course the front wave from the cone may cause some issues with the mouth of the port on the outside if it's in #1 .

OP, couldn't you go right in the middle? That way the sub isn't too close to either opening of the port.

I find that position of the box and port in the vehicle has a much more dramatic effect on output and response than just moving the sub from one side to another of the baffle.... moving position of the sub (to the top, back, or side) of the box may also make a noticeable difference. Nothing for it but to build a dozen boxes for that car, buy a meter, and test..... OR if you can find someone who has built a lot of boxes for the same car they can probably tell you what works best.

 

[bbeljefe]

the 2.24ft^3 is fine (most recommend 2.25-2.5 for single 12 type R), and i cant get much bigger than that in my boot, so if i mess around with port diameter i can aim for 31.5hz on RE Calculator and 32hz is what ill get?
sorry to bother you with these questions i just dont know how to work it out, quite new to this kinda stuff

I have no idea what kind of results you can expect from that calculator because I don't use it. I've heard a lot of people say it's not accurate but the times that I've double checked it, it has been pretty close.

And no worries, I'm happy to help any time I can.