Hey you lot.

Looking at a new box for the 2512a, at the moment it's in a large ugly rectangular slot ported box built to DD's specs. (2.5cuft / 42sqin port 16in deep)

It sounds nice but I'm looking at getting maybe a fibreglass box built to fit nicely against the drivers side of my VP boot.

This is where you guys come in, do any of you have a good set of specs for a better all-rounder box than what DD provide on their site? (I listen to everything, which makes life difficult for deciding which tuning freq to go for)

Also I have absolutely no idea how to take the specs for a slot port, and calculate multiple round port dimensions, does anyone know of a converter or a formula to work this out?

Finally, your thoughts on fibreglass subwoofer enclosures, who to buy from, strength, and the practicality of having so much port area within the usually confined space inside one of these boxes?

Thanks in advance to anyone who takes the time to share some knowledge.

1. Slot to round, work out the surface area of the opening and that should be equal to that of your number of ports eg. your slot is 20cm x 5cm giving a surface area of 100cm/sq so say you want 2 round ports each round port should have 50cm/sq surface area, at the same length of the slot. Do you know how to work out area of a circle?


2. ported boxes are very touchie with volume and port tunning as you may or may not know. So building a fibreglass enclosure in the side will have to be done by someone who knows what they are doing. Iregular shapes while there is no problem with them can be difficult to measure volume which is more important than a sealed box. This is why most show cars with funky boxes are kept sealed. Not saying it cant be done but just be aware of this.

3. Have not used DD's myself but the ported boxes i have had have been tuned @ around the 40hz mark i like the snappier sound of a little higher tuning. Tunned @ 30hz or so will help you get some of the lower freq's a lil better. It helps and is a good idea with ported boxes to have a subsonic filter in your system if you dont have one or is turned off

Thanks I do now how to work out the area of a circle, but I'm not sure how to get a diameter from the surface area... It's been too long since school. I wasn't sure if all ports stayed the same length or if something went on there too, good to know.

work backwards, divide surface area you have by pie(3.1415) then square root this will give you radius then x2 to get diameter. While since school for me to but i do this every day

Apparently a 42sqin slot port turns into a 7.31in round port, does that sound right? I think I've worked this out right but it just seems too small... maybe. Your thoughts bsyde?

you worked it out right for 42sq/in as long as that is right 7.31 is correct. 7in port is quite a big whole, should not get any turbulance through that

How about twin 3.6505" ports? I'm imagining between two, the chance of turbulence would be reduced a fair bit... I have no idea where I would find 7.3" pipe is all.

Who is building the box? If you're getting a pro to build it just get them to do all the calculations.

If you want to build it yourself there are a few tuts on here about fibreglass work on speaker pods and sub boxes. I'd also recommend downloading Win ISD and having a play with box sizes etc.

Thanks KGB, I think I'll be getting it built, I don't have the patience to fibreglass, I've tried before but I end up rushing. I have winISD, but DD don't supply the params of their woofers so basically all I have to work with, is their recommended enclosure, and what others with the same sub recommend to me...

I'm sure DD Phil will be able to give you some advice. Send him an email in case he doesn't see this thread.

Anywhere from 1-8-2.5 cubic feet is fine.

Our woofers are designed to work in higher tuned boxes than most other woofers, and they will still play down to below the tuning frequency.

In Commodores, you get a lot of low end gain from the boot, so I like to tune around 37Hz or 40-42 if you're after maximum output. The lower tuned box will have slightly more mechanical power handling also.

Build your box then shoot me the dimensions, I'd be happy to design the port(s) to suit.

Phil

PS Sorry for late reply I was in SA until Sunday night.

Oh remember that twin 3.6505" wide ports has less surface area than one 7.301" port, so make sure you keep that in mind.
And if you can find a port size you need, just get as close as you can and adjust the length to tune it to the desired frequency, just sing out man if ya need a hand working out lengths and diameters etc

Thank you Mr. Hissey Adjusting to the warm climate well? It's still f***ing freezing here.

I was exchanging emails with DDPhil, and the idea of a 'mini-wall' is seriously appealing to me.

mini-wall????? now thats what i like to hear
Ive adjusted to the weather, loving it now, wet season probably wont be fun

Yeah, ah well at least it isn't hot+dry season.

Has anyone fitted a 'mini-wall' style ported box to any sedan with a ski-hatch? If so could you please share your experiences/photos with me? Thanks!

From my experiance its not worth tuning below about 35hz as DDs seem to loose output.

If you want low lows with dd leave the tuning at about 35hz and make the box bigger

They can then destroy the lows, while buzzzing your eyes out on the highs

Sounds good! At the moment I'm theoretically tuned to 42Hz, which isn't so bad, but yeah lower would definately be nice. I'd still love some mini-wall pics/more comments.

The sliver box with two 10s is from my last BMW, the other from a VX SS, along with a pic of how the ports work.

Phil

Ah niiice, thanks for that Phil! I'm doodling up some sketches of what I have in mind for my car, the mini-wall style for sure, but I'll probably do the ports with pvc pipe/dressy end pieces to make fabrication a little easier... maybe. I can't imagine your standard pvc plumbing would be too smooth inside when it comes to elbow pieces and so on, which is my only problem there.