.5cu ft too small?

skydeaner

ok, I know it will hurt some of the low bass extension of the speaker, but will a .5 cu ft enclosure hurt one of the new db124's. I am making enclosures out of fg in the side of the rear of my trunk. It looks really nice, I will try to get some pictures up here, i only have one side 75% completed, but I might have to get some of the 10's if .5 is too small for the 12. I haven't actually measured the volume of it, i am just kinda eyeballing it and saying .5 I will fill it up with water tonight and get a real measurement, but what do you guys think?

skydeaner

anyone?

MacLeod

.5 wont hurt your sub but it will hurt your SQ.

Ive never like subs in too small of boxes, they sound really choked off.

If all you have room for is .5 then you should look into a db 10, but even thats a little smallish.

skydeaner

It recommends a .88 cu ft box, is that even a little on the small side? I ran it through WinISD and it recommends 1.2cu ft or something like that

neomagus00

winisd may be reccommending that size without taking into account the transfer function of the car... if you set the volume and let it tell you the tuning, you'll see what polk reccommends, and can choose to use that or not... but 0.5 is pretty tiny in any case, try stuffing with about 1 pound of polyfill...

skydeaner

Ok, i will be filling it with water when I get home to see how much volume it really is. And is it true that a .88cuft enclosure that polk recommends takes into account the displacement of the basket?

neomagus00

yes, .88 accounts... but be cautious with the water, line the box with a garbage bag or something first, MDF HATES water...

Eric W

.5 is quite small for a 12". It would be OK for our 8" though.

Oh yeah, heres a less hazardous method of finding the volume- use packing peanuts. Get a 12x12x12" box to determine 1 cubic feet. Skip the water, which has the potential to make a huge mess. Although water within a fiberglass enclosure is great for finding leaks.

MacLeod

.5 works well with the MM2104 too.

I was only able to squeeze out .53 for my box with the room I had. I stuffed about a half pound of pollyfill in there and it sounds pretty sweet to me.

We'll find out Nov 12th. My first USACi SQ competition! Woohoo!

neomagus00

sweet! good luck!

Jstas

.50 cu. ft. is small for a 10 inch. I don't even think the magnet structure of a typical 12 inch sub would be able to fit in a box that was .50 cubic feet and still have enough surface area on the mounting baffle to screw in a 12" sub.

I put the 12" dB sub I got from ebay into a box that is .8517 cubic feet and that worked out perfectly. I think you should be looking at a box that is at least that big. The probalem with going too big is that the sub gets boomy and muddy. A box that is over 1.00 cubic feet is, IMO, too big for either the new DB subs or the old dB/DX subs. They won't perform well at all.

beardog03

stuffing the box makes it hit harder..?

(get yer mind outta the gutter"..!!)

honest question..

MacLeod

Putting pollyfill in the box slows down the waves and makes the box act like a bigger one. The general rule is 1 pound per cubic foot. It doesnt increase it by much, most of the figures Ive heard over the years average about 15% more volume so my .53 box behaves like a .58 box.

But if you build your box to recommended spec, you wont need any pollyfill.

beardog03

The ones in question are Q-logics..

not to derail...sorry..

MacLeod

If its interior volume matches up with the subs specs you wont need any. If its smaller than recommended you may want to consider some.

skydeaner

Yeah the enclosure ended up being too small I think. It doesn't sound all that good like I thought it would. I am trying to decide weather it is the enclosure or the amp... probably the enclosure, here is a link to a picture, tell me what you guys think about the size of the enclosure... click here to take a looksy


you may have to hit refresh a couple of times for the page to come up, I dont know what the hell is going on with my breifcase, I will try to move them somewhere else... but in the meantime just refresh it a few times and it should come up.

MacLeod

Never could get that link to work.

Either way, if it sounds messed up, chances are its the enclosure. The amp wouldnt have much effect on how it sounds other than loudness.

neomagus00

hum... based on a rough approximation of that enclosure as a 12" diameter, 6" tall cylinder, you're only at 0.39 ft^3... that's a teensy bit small...

cam5860

Im not a big fan of pollyfill you might as well do it right and build a box the right size for what your planning. But if space is tight and you cannot build it quite big enough pollyfill will help. Just be carful and leave enough space behind the magnet so the pole piece can get some cool air in there on those voice coils.

skydeaner

ah, neomagus, that's a good way of looking at it and yeah thats really small. I am ditching the box. I'll come up with some other idea that looks cool and for right now I will just make a normal mdf one. Even at low levels it sounds like it's distorting. Anyone wanna give me some dimentions for a .86 cu ft per chamber box made out of 3/4" mdf... If you wanna be real nice to me, could you give me the dimentions for all 7 pieces of wood? (including divider to seperate two chambers)

neomagus00

yes, i can do that... give me boundary conditions (i.e. how tall, wide, and deep i could possibly make it), and you'll have a box... and it is just one db124 going in, right? and do you want provisions for carpeting?

skydeaner

well I'd like the front baffle to be 36x18 external dimentions, depth is adjustable and I am going to want to carpet it, do i do that before I put it all together, or afterwards?

MacLeod

cam5860 wrote:

Im not a big fan of pollyfill you might as well do it right and build a box the right size for what your planning. But if space is tight and you cannot build it quite big enough pollyfill will help.

Bingo!!

neomagus00

um... 36x18 is really really big for a single sub: the depth comes out to 2.75"...

skydeaner

oh sorry, I meant 2 polk db124's

neomagus00

i kinda thought so... i'll be back in a few minutes with some dimensions for ya...

edit 001: that still comes out to just over 5.5 inches, still too small... i'll make it a bit smaller in the front, see how it does...

edit 002: otay, with internal measurements of 14.5 x 14.5 x 7.25 for each box, you get total externals of 32 x 16 x 16.

cut measurements: both sides and the center are 7.25 x 14.5; they are sandwiched bewteen the top and bottom, which are both 32 x 7.25; these are in turn sandwiched between the 32 x 16 front and rear panels... i'm a little tired, so please please check these numbers before you cut...

skydeaner

hey, that'll work out great, thanks for all your help man