AscendantMax

iTrader: (7)

If ported, the Brahma is recommended to be in a 2.2 ft^3 box tuned to 30 Hz. How will a smaller box...say around 2.0 ft^3 tune to the same frequency sound like compared to the one in a larger box?

joebangaa

iTrader: (3)

is this a 12? how much power?

AscendantMax

iTrader: (7)

yes, brahma 12", about 480 watts going to it.

HitManSE

iTrader: (1)

0.2ft^3...you wont really notice the difference. However, the box size will be about the same, so whats the point The smaller the box, the longer the port has to be. So if you go smaller, the ports gonna have to take up a bit more room so...ehh whatever, back on topic You shouldnt notice too much diff.

Maxima Dan

Check out this post:

http://www.caraudioforum.com/vbb3/sh...d.php?t=195460

The answer is from the man himself.

AscendantMax

iTrader: (7)

Thanks for that link, good info

Yeah I didn't think that small of a difference would matter, but better to ask than to guess

joebangaa

iTrader: (3)

480? what amp? why not...double that power

HitManSE

iTrader: (1)

He doesnt need to use a lot of power. Its ported, making it A LOT more efficient. It will be plenty loud with 480w. I had less then that going to my Brahma (425w) and it was still monstrous. He could still give it 3x the power if need be so still plenty of head room.

AscendantMax

iTrader: (7)

it's a RF Power 451s amp. And like HitManSE said, 480w can get loud as is in my big sealed box (temperary box). I should see even more SPL when I build my ported box.

HitManSE

iTrader: (1)

Correction.

HitManSE

iTrader: (1)

There are a few "little" tricks you can do to increase output as well. Each one itself wont do much, but if your trying to get as much output as possible, you can do these to help increase it a bit.

Larger port area.
No edges inside the box, the corners, fill it with a small triangle piece of MDF to round it off, and use fiberglass resin to coat the interior of the box. The smooth surfact helps too
The inside end of the port, sand down the edges as bit so the air flows freely, decreases tubulance of the moving air. It wont mess with the port tuning much & if your really worried about it, make the port 1/4" longer

Btw-I didnt know any of these things ^ when I got mine done. So whenever I decide to re-do my box ill be doing those as well. Not the biggest increase in the world, but if you those small things increase output...why not.

joebangaa

iTrader: (3)

well i'd only use more power for the sake of the amp. with only four hundred something seems like you'd be running that amp pretty hard.

AscendantMax

iTrader: (7)

well, that thought did come to mind a few times, but i'm not attempting to set off car alarms...yet But the brahma gets plenty loud as is. the amp is running a bit warm though. it's stable to 4 ohms bridged, but it's actually seeing ~ 3.4 ohms when i measured with the voltmeter.

and thanks for those tips HitMan

Maxima Dan

Yeah that's your Re...actual impedence will vary depending on frequency, but will never go below 3.4 Ohms. If your amp is 4 Ohm stable it will be fine.

When you do decide to build a ported box follow Dan Wiggins advice and make it 1.25 NET tuned to 26Hz. I built my box for 2 B12s to 2.5 ft^3 tuned to 26 Hz and it sounds amazing. Much tighter bass than the box I built for my single 12 (2 ft^3 tuned to 28Hz).

HitManSE

iTrader: (1)

I know what you mean, id rather have the head room as well


Fosgate Fan: I dont "think" you'll be setting off many car alarms. The strangest thing ive realised with the insane setups are you cant hear them too well outside (unless its a SUV or something) I still dont know why this is, the only time I turn heads due to my system is for 1 of two reasons. The retarded rattled, or if I open my front door(s). Then it shoots the bass all over the damn place, but with the doors closed, even the windows down you cant hear much bass outside. Its the strangest thing & makes 0 sense

The smaller setups could be heard though

AscendantMax

iTrader: (7)

So generally people tune high for SPL and low for SQ right? Main goal for me is for tight bass, but can get mad loud when I crank it up.

I'm still amazed by the B12's reponse to my music's fast bass beats. I really should think up of a new user name

HitManSE

iTrader: (1)

How should I say this... Oh yes...told ya

Tune it low for SQ, it has better response & can play lower. Dont go too low though, or your gonna lose some impact. When I say too low, I mean dont go down to 22hz tuning freq. 27hz is low enough, just make sure your amp has a SSF (sub sonic filter for those that dont know) and set it around 30-35hz.

Most likley you wont need it, but its nice to just have that saftey net there

As for your user name PM Sprint, it can be done.

AscendantMax

iTrader: (7)

I'll get excessive cone movement if the sub is playing below the tuning frequency right? Never really messed with ported boxes until now...

HitManSE

iTrader: (1)

You'll get less and less cone movment all the way down to your port tuning freq. At that point your sub will move the least, once you go below that though, the port is no longer a cusion of air, now its just letting the sub go. This is where that high xmax comes in. Depending on the sub, ect... you usually cant go too far below your tuning freq (3-4hz) be4 you start damaging the sub & possibly even unloading (... Not good)

If you get bored, you can always toss in a cheap sub and play a 20hz test tone (with the SSF off) and see low long it lasts Funky Pups roxor!!

Maxima Dan

We should all go in on a box 'O Pups and see who can shoot the funniest, most distructive video. I have a USA2000X on hand that will put a serious hurt into a pair of those!

machinehead

Ported boxes are fun. just be sure to use a sub sonic filter or dan is gonna be mad at you for busting his beautiful sub You'll definitely be happy with this setup though.

smooth hard surfaces in a box reflect waves back at the cone resulting in some cancellation.

AscendantMax

iTrader: (7)

his sub?

any evidence of this? this is the first time i heard of this...and besides, even if there were cancellation, the brahma gets loud enough that i don't notice

Maxima Dan

I'm guessing he meant Dan Wiggins and not me.

For cancellations to occur you would need to have the distance between the cone and the enclosure wall equal to wavelength. Most speaker manufactures use dampening material on the walls of their enclosures to help minimize cabinet resonances. Not really an issue if it is in your trunk. In other words...don't worry about it.

AscendantMax

iTrader: (7)

Oh, I thought he meant the inside of the sub enclosure

machinehead

I did. Subs push air in 2 directions. 1) Out into the cabin of the car and 2) into the sub box. The waves inside the box can bounce off the wall and hit the sub, screwing with the sound. The most common way to battle this, is to avoid having the rear wall parallel to the baffle. To take it a step furth, put a deflex pad against the rear wall, or stuff pollyfill in there. If you throw some polyfill in there, you'll be fine