First off, I would like to say that I am not new to installing, tuning, and selecting car audio. I have put a few "complete systems" in some of my previous vehicles. I have been through a ton of amps, subs, boxes, components, coaxials and everything in between.

However, funds are not exactly what they used to be and I have limited space to work with in the camaro. So I have decided to build my own box. Many people on here have done just this, but I have a few general box building "newb" questions.

The sub I bought the other day is the Treo RSX 10.22. It's a dual 2 ohm woofer wired in series. This raises the impedance to 4 ohms.
Here are the complete specs of the sub in PDF form.

In a nutshell, this is a 350 watt RMS sub.Building a ported box is the only way for me. It's not going to be setting off car alarms, or knocking off rear view mirrors, but it will be a great learning experience.

Here is where it gets tricky for me.
The manufacturer specs call for:
A) Small Ported
Net Internal Volume = 1.0ft with 7" Port Area 10.75" Long

B) Large Ported
Net Internal Volume = 1.2ft with 9" Port Area 11.5" Long



Let's see what the guru's have to say. Is there a program (that you have personally used, preferably free) that can help.

I have a clue, but don't really know where to start. Which of these two would you recomend and why?

 

I used winISD to build my home theater sub. Worked great for figuring out frequency response, cone excursion, SPL, etc. Are you looking for that info? Or are you looking for 3-D modeling software.

 

winISD definitely the way to go for the DIY'er.

the size of the box and port will play into your tuning freq. if you throw the sub specs into the program, it should be able to model the expected freq response (go for the flatest possible).

**also remember (rookie mistate) - you need to add the size of the port to the box size. you cannot count the inside of the port as part of the enclosure. miss this one, and you're gonna have a sub that'll peak in weird place

 

Not really 3D modeling software. Something that I can type my specs into and it will pretty much create a box I should build. That may be asking for a whole lot, haha. I will check out winISD.

By the way 1ADan, do you work for 1A Auto Parts? I see you on here all the time and have always wondered. I love that place!

 

do it by hand, thats how ive always done it, measure the size of the bottom well and treat it as its own box, then measure where you would put the rest (from the shelves up), take out the mdf in between of course when calculating total volume, keep in mind that your front to back (width) and your left to right (length) are going to be the same no matter what, so to adjust for the volume just change the height, and build from there, no real program needed

to be honest you dont need to match it PERFECTLY to the optimal specs and just as a side note you dont neccesarily need it ported, im running a 12" type R and its in a sealed box, hits hard as hell too, plus being in a hatch you will hear a lot of port noise especially with it firing upwards

id just do it by hand, follow the specs listed in the sticky and calculate the volume and adjust from there

 

Hand calculations are fine and recommended for figuring out box volume and dimensions but not for optimal box size, port size, port cross section, tuning frequency, excusion plots, frequency response, etc

Also, a properly designed port will not chuff. I have a 15" ported sub in my family room tuned to 21HZ for home theater. No port chuffing. Its a 2.5"x10"x42" port though

WinISD is the right tool for the job.

 

What do you mean "fine"? You take the optimal volume needed and then plug in your hard numbers and adjust the variables until your internal volume matches the optimal number, its not hard and I'm pretty sure thats how I've built every single box, if you want to use a program to save yourself from doing math more power to you but I trust my math better than I do a program IMHO

 

I was agreeing with you, lol. Did you read what I said? "Hand calculations are fine and recommended for figuring out box volume and dimensions".

The other parameters are challenging to do by hand. How have you calculated frequency response by hand? How about minimum port cross section? or port length?

 

Here is some example data you can get out of WinISD with a little bit of work. This is from my home sub.

Frequency Response


Cone Excursion with 1200w input


Port Velocity with 1200w input

 

my bad its been a long day, for ports I use the port calculator supplied by the12volt.com you can calculate either round or vent ports

 

I ran the numbers for that sub. The small recommended box has a tuning frequency of 38hz. It has a 4db peak at 50hz and a -3db frequency of 32hz. Not bad at all for such a small box. Most music only goes down into the 30's anyway, if that. However the port velocity is really high with 350w input. Its already 90ft/sec at 50hz. Generally you want to keep it under 40 or so.

The large box also has a tuning frequency of 38hz with a 4db peak at 45hz and a -3db frequency of -32hz. However it has the advantage of having a lower port velocity which is really good. Its still high though. I'd seriously consider a bigger and longer port if you really want to fire 350w at it.

 

and thanks!