Frequency Chaning???

[kfx450r 10+ year member]

Well, had my (1) type R tuned to about 32hz in my big box, hit the lows great. Well I threw in another type R in the box today and it doesnt seem to hit the lows as good anymore but hits the highs a little better. All the port calculators ive seen dont say anything about number of subs so wut gives.

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[squeak9798 5,000+ posts]

When you increase the number of subs, you need to increase the volume of the enclosure accordingly.

 

[kfx450r 10+ year member]

When you increase the number of subs, you need to increase the volume of the enclosure accordingly.

The box is a 7cu ft ported box..I really dont thin i need mre than that for 2x 12" type rs

 

[boomzilla 10+ year member]

7 Cubes for two 12's?

 

[boomzilla 10+ year member]

Anyways, when you add a sub to an enclosure made for 1 woofer, and add another woofer, you're displacing more air in the box, making the tuning higher. When you change airspace, you need to change tuning also, which can really only work with aeropoorts, or if you built a removable slot port.

 

[kfx450r 10+ year member]

7 Cubes for two 12's?

Ya dont ask. I got crazy..the single type r slammed in it..i throw the 2nd in and the tuning just totally changes. I just ordered a third for it also..so itll be a good box.

How do I change the port to tune it lower then.

 

[boomzilla 10+ year member]

You can't. Once you build a standard slot port, it's done. Unless you're really **** good with woodworking, then maybe you can get away with adding/ taking away port length. You'll need to build a new box. A box about 5 cubes would probably be better, tuned to anywhere from 30-34hz would be good IMO.

 

[kfx450r 10+ year member]

You can't. Once you build a standard slot port, it's done. Unless you're really **** good with woodworking, then maybe you can get away with adding/ taking away port length. You'll need to build a new box. A box about 5 cubes would probably be better, tuned to anywhere from 30-34hz would be good IMO.

Its a simple round port..I can change it very easily..

 

[squeak9798 5,000+ posts]

Anyways, when you add a sub to an enclosure made for 1 woofer, and add another woofer, you're displacing more air in the box, making the tuning higher. When you change airspace, you need to change tuning also, which can really only work with aeropoorts, or if you built a removable slot port.

A 1% change in enclosure volume won't affect the response or tuning nearly as much (or audibly at all, really) as reducing the effective volume per sub in half.

 

[squeak9798 5,000+ posts]

The box is a 7cu ft ported box..I really dont thin i need mre than that for 2x 12" type rs

If you want to maintain the same response characteristics you need to.

I'm not saying that you need a 14cuft enclosure for 2 12" Type R's.

But don't toss a 2nd sub in an enclosure and expect the response characteristics to remain unchanged.

 

[kfx450r 10+ year member]

A 1% change in enclosure volume won't affect the response or tuning nearly as much as reducing the effective volume per sub in half.

Hm, I really only like subs for low bass around 30-32...but i like it to get real deep and loud..do u think i shuld make a smaller box?..also..1 type r is a old version the other is a new.and the other one i ordered is a new version..so i may kep this box for when i get the 3rd one ad see how it sounds. Also..longer round port = lower frequency..so I think i will add .1-2" and see how it sounds.

 

[kfx450r 10+ year member]

Alright used RE's box calculator thing for a box for my 3x type Rs and anyone think this would be a good box. in a ext cab midsized truck firing all 3 toward front. It says a 50x22x15, counting in port and all 3 sub volumes, 6.6cu/ft tuned to about high 29/low 30hz. Im going for deep ear rattling bass, but also want it to be nice and clean. Gives each sub about 2.2cuft. Slot Ported

Or I can use every space i have an build a 9.2cu ft ported box ported to the same hz but giving each sub about 3 cu/ft each

Or i can make it a little easier to build and get 8.5 out of it and have 2.7 cu/ft for each sub..

This is all with the possibility of adding a 4th down the road. So if I built one that was 50x27x16..counting sub displacements..i would get 8.5cu/ft which gives 3x subs 2.8cu/ft eac and 4x 2cu/ft each..still more or equal to spec. Goofy lookin box tho, all tuned to about 30hz

 

[terra 5,000+ posts]

how big is the port?

 

[kfx450r 10+ year member]

how big is the port?

I always left it about 4-5" wide..and it filled in the rest which changed with every box..i just modified the length to get high 29-low 30hz

Oh if u mean on my current box..its a roung port i forget was like around 2 inches at 4" diameter..tuned to either 32 or 34 i forget.

 

[sikcavy 10+ year member]

u have only 1 4" port for two 12's? good luck with that lol