n0catchyname

So I asked about building a dual sub box (Shared vs. seperate chamber for dual 12's). Finding out the for everyday use, shared is optimum.

I got my hands on a cheap 4-channel, 250Wrms @ 4 ohms/bridged channel (Power Acoustik so yea, probably overrated but no worse than the Dual monoblock I'm using now), & found out my trunk is actually much bigger than I thought, so I built this...




4.75 cu.ft., ~4.1cu.ft. after sub and port displacement, tuned 32hz

For those who don't know/remember, subs are Cerwin Vega 124's. Will try it out tomorrow (if I have time) after everything has had a day to set in, see how it compares to my current setup, single 12", ~2.2cu.ft net, 200Wrms, tuned ~26hz, main difference I'll be looking for is the tuning difference to the ear (obviously it should be much louder considering everthing else is pretty much doubling).

n0catchyname

"First clip is the single 12 running on 200Wrms @ 4 ohm in a ~2.2cu.ft. (after displacement) tuned about 26hz, box building and comparison, then 1.5 hrs of fighting, kicking and cursing, 2nd box...which is 1" too wide to fit between the strut towers - ****, is finally in. Dual 12's running on 300Wrms @ 2ohm for now. I ran out of time so I didn't have time to swap the other amp in, might have time next week/weekend."

Just made a quick vid today, would've spent more time on it, but had other things to do, and now have to go to more other things. The tuning difference (after only a couple tracks listening) doesn't seem to have much effect, probably because it was tuned so low before, but I'll have to see how it works out in the longer run.

Garvok

such low power.....try sealing up one of thos ports.......too much port for low power.......i dont think ur loadingg very well....cap one off.....and try again.....than when u get some real power open it up again

n0catchyname

Considering I didn't change any settings on the amp, just plugged them back in the way it was set before and ran with it, it's performing pretty decently. I had to turn my sub settings on the deck down from 0 to -3db, and have to watch my volume on certain songs. Haven't had time to screw around with settings much.

I don't think the 2nd sub I put in is worked in as well as the sub I've been using, they didn't look like they were pushing evenly, but couldn't really tell just looking back quickly while driving. I forgot to check them before I hooked them up to see if there was a noticeable stiffness difference (they were equal when I bought them). I used the same lengths and gauge of wire to hook both subs up, so I know they are equal that way. I'll check them later (I can do that at home, just can't set screw around with the volume up here, the neighbours will get pissy)

Tuning freq. is noticeable in some songs, but only those that have extreme lows (certain dubstep tracks), but I gained on the top end, a decent compromise.

Sealing off one port would drop my tuning freq. to ~23hz. I'm going to put the other amp in sometime this week or next weekend (depending on my ambition level), so it's not worth trying to seal it off for a week or less. The subs are only rated at 400Wrms/each, recommended enclosure for each sub @ 125-400Wrms is 2.0cu.ft tuned to 35, so I'm pretty close to spec in that respect. Port design is bigger than spec, but not much bigger (area wise) than in my previous box (per sub that is), which worked quite well.

But out of curiousity, what are the downfalls of too much port area? And what exactly is meant by the "subs aren't loading well"? I've heard it used many times before and never quite understood what it meant.

madwarrior

iTrader: (3)

The other sub wouldn't be moving as much as the sub you been using because the sub you been using is broken in already. While the other one still has a stiffer suspension in it. Give it time it will break in

n0catchyname

^That's what I thought, I had bought them used, so I figured they'd already been broken in, but apparently not fully. Checked them and the less used one is stiffer.

madwarrior

iTrader: (3)

Well at least you know they weren't used much before you bought them used lol.

Garvok

in your box design, imo, you'd be better off with separate chambers, for a dual chamber, i use dual ports, for a common chamber i use a single port to one side or the other, they will just want to work better that way.....less standing waves, more efficient

side note did you compare imp rise between the 2 boxes, i would alomost bet its higher in the 2nd box!!!

also you should start a log book....it will really help in your testing....unless u already have....in which case NM

n0catchyname

Well, seems I'm learning something new everyday. I'm stuck with a shared chamber until I feel like cutting this box out and building a new one (not happening anytime soon).

Didn't measure imp. rise, just going by averages, 2x 4ohms wired parallel = 2ohms, nor have I started a log book as the only testing I will be doing is by ear. I'm not setting up to compete or anything unless I happen to go to a comp for the hell of it just to see what kind of number it'll do. I just thought I'd try it out because I have the stuff laying around anyway.

n0catchyname

Got the other amp hooked up (last night) and setup (today). Found out my one sub (the one I had been using) got abused in my trunk, which I should've expected since I ran it for 3 months without ever properly setting it up. It's not completely cooked or anything, but definitely not 100% anymore.

Garvok, I think I know what you were talking about now, so I might need to try a seperate chamber box. Not looking forward to cutting up that box to get it out, building a new one and trying to shove it in there again though, so going to stick with what I've got for now.

Ah well, maybe I'll get out sometime this summer to an event to see what kind of numbers it puts out. Seems fairly loud for a throw together trial system though. Definitely cleaner with the new amp.