D94R

I have an Fi SSD 10" I've used for a couple years in a custom enclosure designed by Pete from Teamtoxicbass for my Ranger. The Ranger is gone and I want to use the sub in my F150, but that enclosure simply won't work now so I'm hoping someone here can confirm some questions and design elements (getting a hold of Pete again to design another box is impossible it seems).

Anyhow, here's two screen shots of the calculator at two different Port Frequencies that I intend to build. One at 32Hz and one at the speakers Fs of 27.6Hz.






Now my question is do I build the box port to the speakers Fs so I don't fall below the resonant free air frequency of the sub, or build it to a specific frequency based on what type of music I intend to listen to (IE 32Hz for rap/hip hop etc)? I understand the enclosure will increase the resonant frequency of the sub a bit, so is that why boxes are usually tuned to ~32-33Hz???


Here's my old setup that I can no longer use. It was a HUGE box for one 10" sub, but man did it thump. It was a Tline bass reflex hybrid.






I really don't expect this new setup to be as loud as the one in the Ranger since the box is smaller, but maybe I'll be wrong.

loganberry

you don't have to build to the fs of the sub... I like 35hz as a good medium, you still get lows but it plays everything across the spectrum very well

D94R

I'm thinking I'm going to change plans a little and build a Tline again, I much prefer the sound and output to a simple ported box. However, I'm gonna be sacrificing the rear middle seat's leg room for this.

Logan, I understand the box doesn't need to tuned to the Fs, but I vaguely understand that if it's tuned higher than the speakers resonant frequency there is a possibility of over excursion of the speaker right? This seems like it would be more of a problem for a Tline since it's basically a free air setup. Though I believe my box from the Ranger was tuned to around 32Hz. However, right before I sold the Ranger I was having a problem with my amps going into protection (two of them) when playing the sub hard. I didn't change any of the setup, but one day it just started going into protection. If I kept the volume down it was OK though. Speaker ohmed out OK so I couldn't establish if it was a over heating coil that wasn't totally failing, or bad ground for the amp(s) or what the deal was.

Anyhow, reading up on Tline theory and design I wonder if I wasn't having an over excursion problem with the sub since it was tuned higher than the Fs of the sub. But again, the sub sounded fine, it would just go into protection after 10 seconds or so of hard loud bass.


In short, I guess what I'm wondering is if I should tune a Tline to the Fs, or around 32/33Hz again like my previous box?

loganberry

The sub over excurting will not send the amp into protect so your either had bad ground or low voltage, tlines are great for all around sound..but so are sealed boxes, if I was you I would do a regular slot port at 35hz and have the gains set with a o-scope to fix all clipping, when a subs coil slaps the back plate its very loud and you will hear that sound as there is no other like it...if your good with numbers and building the boxes try a fourth order bandpass, it would work great in your case

D94R

Im running calcs for a Tline based on a few different tuning frequencies right now to see if I have the space. I'll give 4th order band pass a shot too and see what I can come up with.

D94R

Well, for a Tline I've come up with this so far:

Outside: 20.5H x 13.5W x 32L
Port: 5H x 12W = 60in^2
Port Length: 101.5"
Tuned to: 33.39Hz

Or

Subtract an inch from the box length (and subsequently 2" from the port length) and be tuned to 34Hz.


This is with a rear facing sub and port. My only concern is the baffle directly behind the cone won't be 100% covering the cone. Not sure if this will effect the wave or not? The port takes a 90* turn after that baffle.




I can do a sub up, port back box that would be infinitely more simple to make, but this puts the sub at the front of the box. I kinda wanted to keep the speaker on the back to keep it kinda hidden instead of in plain view. Of course I can reverse that and put it sub up in rear of box with the port firing forward.

loganberry

When I'm not at school and off my phone ill try to find a picture of a tline I built for a customer, the design would be great for you so ill post it up tonight

D94R

Look forward to seeing it.

I've been running math for 4th order bandpass, but not totally sure what the lower frequency cut off is supposed to be represented by. Is that just the frequency I want to tune to?

loganberry

for the most part yea, its a super efficient design with a small sealed portion firing into a large ported portion, the design is fairly hard to get down and takes up lots of space but is well worth it

D94R

Hrm, I need to examine my excel formula's then, because I'm calculating just the opposite with formula's from diysubwoofers.com. Getting larger sealed areas than vented. And actually, the numbers seem rather small (in the .28ft^3 size). The formulas don't seem to account for woofer size, unless the speakers Vas is accounting for that?