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View Full Version : 2 18s 4th order help or oppinion



joshy629
11-01-2011, 03:17 PM
ok so i just did my first 4th order. im only doing a 149 at the head rest but that is at 27 hrtz....lol i have 2 dc xl 18s and a soundstream xxx 10000d amp. plenty of batt power. the subs are in a 8.5 cube sealed box firing to the side into a 16 cube ported box. the ports are 2 8inch flared ports. i have 38 inchs of width available. 28 heigh and 50 depth and thats to leave just enough room for all my equipment to fit. look at the pics and tell me what you would do diffrent to get a higher score say maybe a 152 out of it.

basic of the box

http://i1216.photobucket.com/albums/dd380/joshy629/11.jpg

the ports front view

http://i1216.photobucket.com/albums/dd380/joshy629/12.jpg

looking into the ports

http://i1216.photobucket.com/albums/dd380/joshy629/14.jpg


and the back just for looking =]

http://i1216.photobucket.com/albums/dd380/joshy629/13.jpg

813thumper
11-01-2011, 03:28 PM
increase port area
shrink sealed chamber

bgowdy31
11-01-2011, 03:36 PM
id like to do one but i have a blazer no need. one of my friends has a single fi btl in a 4th order with 4 4" aeros and is doing 150+ playing music.
ive never seen or heard of him burp it seeing we compete in a daily driver type comp.

---------- Post added at 03:36 PM ---------- Previous post was at 03:35 PM ----------

but yea i would have probly went with maybe 3 8" or 4 6" aeros tho

Ninesvnsicks
11-01-2011, 03:36 PM
Geez those 2 dc's can take 10k rms?

bgowdy31
11-01-2011, 03:46 PM
ha together on a burp maybe. probly not to many times tho. lol...

but now that i think. i dont see how they can take that honestly...

---------- Post added at 03:46 PM ---------- Previous post was at 03:46 PM ----------

well unless his gain is down a bit

joshy629
11-01-2011, 04:31 PM
The sealed box causes a lot of impediance rise. I've clamped it at 1.4 ohms with 3x impediance rise and it was doing 6k and these 2 are wired to 1. So idk what it is putting out. But the amp gets hott quicker than the subs lol. I love these subs. But would adding another port tune it higher? And what do you think the results of making the sealed box smaller would do? I'm taking oppinoins here. Help me out?

joshy629
11-01-2011, 10:35 PM
anybody? anyhelp at all?

hispls
11-01-2011, 10:46 PM
Geez those 2 dc's can take 10k rms?

Those amps won't do 10KW on 18V system (there's a guy around here who uses 4 on a pair of 18s and breaks glass....mid 165's 67's at kick). That being said LV5 softparts can take 5KW for half a song or so.

813thumper
11-01-2011, 10:46 PM
i bet it slams the low end and that is mainly because you have a huge sealed section. if you shrunk everything up then you would end up getting the response that you want. right now i am running 2 18s in a 4th order. about 4.5 cubes sealed and 14 ported off of about 2000 watts and i can tell you that i am in the very high 40's. the XXX seems to like a larger box so what i would recommend is that you shrink it about 2 cubes and see where that gets you. also increasing the port area is going to change your tuning. what did you tune it at?

hispls
11-01-2011, 10:46 PM
anybody? anyhelp at all?

Have you attempted just a big ported box? Seems to me that would probably get louder.

joshy629
11-01-2011, 10:49 PM
its peaking at 28 hrtz. would adding another port raise the peak?

joshy629
11-01-2011, 10:52 PM
and yes its doing a 149 at 28 hrtz but i want atleast a 52 out of it

813thumper
11-01-2011, 10:53 PM
your truck peaks at 28 hz? thats nasty lol. sometimes it will sometimes it wont. you really have to test it on order to know. what is the 4th order tuned to right now

joshy629
11-01-2011, 10:57 PM
no clue man just threw it together 8.5 cubes sealed 16 cubes ported. 2 8 inch aeros that are 11inchs long each. lol u tell me idk. and yeah 28 hrtz pretty good flex. but i know that it has alot more potentual in it for sure

RAM_Designs
11-01-2011, 11:05 PM
increase port area
shrink sealed chamber

This

joshy629
11-01-2011, 11:09 PM
shirink it a couple cubes? and add another 8inch aero. and you think it will be alot louder?

813thumper
11-01-2011, 11:17 PM
ok wow lol. right now you are tuned at 30 hz. that is really really low for a 4th order. what i would do is shrink your sealed chamber by at least 2 cubes and put a huge 45 in the opposite corner of your box from the subs to eat up some of the ported side. and i would suggest adding 2 more 8" ports about 8" in length.

so:
6 cubes sealed
14-15 cubes ported
4 8" aero ports 8" in length
puts you at about 43-45hz and 200sq" of port.

RAM_Designs
11-01-2011, 11:18 PM
shirink it a couple cubes? and add another 8inch aero. and you think it will be alot louder?

Yeah, shrink it down to 5-6ft^3 at first. Right now with 16ft^3(asusming before port displacement) and two 8" ports 13" long, you're tuned to ~32hz. Add a third 13" long aero and you'll raise the tuning to ~40hz...which is still pretty low for a 4th order bandpass. You can add another aero and raise the tuning to the low to mid 40's if you want. Those two things should give you a good amount of gain. The smaller sealed chamber will also allow the subs to mechanically handle more power.

joshy629
11-01-2011, 11:19 PM
good god. lmao. that is alot of work. haha well tuned to 30 peaking at 28 hahahah sooo crazy but the lows are pretty cool. it was def worth the experiance. but i will make the changes...eventually. lmao im out of money and its insurance time. but i will shirnk the sealed and round corners with some sono tube and fiberglass

joshy629
11-01-2011, 11:25 PM
they dont seam to move as much as they should. would adding more port cause less compression on the subs allowing more movement

galacticmonkey
11-01-2011, 11:34 PM
To get your peak note up and score up, add another port, maybe two. I'd also shrink the sealed chamber way down. Shoot for about. 5 cubes sealed.

joshy629
11-01-2011, 11:40 PM
will do guys. thanks so much. i just dont know when that will happen. lol

galacticmonkey
11-03-2011, 12:52 PM
Just cut a 280in^ hole in the front of the box an make it about 6" deep. Would be real easy to do and you would only need a few small pieces of scrap wood to do it.

joshy629
11-05-2011, 03:47 PM
Doesn't adding more port in a ported box tune it lower so why does more port in a 4th order tune it higher? Just asking

duanebro
11-06-2011, 12:48 AM
adding more port area (not length) will up your tuning. I'd add two more ports just like what you have. But uping your tuning will hurt your low end power handling. shrinking the sealed part of the box will help that out. I'd guess your peak will be about 45 Hz. Anyone have a guess as to where his peak will be? LOL

Duane

snoopdan
11-06-2011, 01:14 AM
uhm, IMO you should be experimenting with large ported enclosures first before attempting a 4th order.


For example, my 24 cube ported enclosure tuned to 32 hz does 149.1 at the headrest with a 1400 watt autotek amp. When I slap on my 5kw Atomic, im in the low 155's... Sometimes, a big *** box just works.

joshy629
11-07-2011, 01:52 AM
ted to do a 4th order. Its what I wanna work with. Flat walls are loud. I jus want something diffrent

galacticmonkey
11-07-2011, 02:21 PM
adding more port area (not length) will up your tuning. I'd add two more ports just like what you have. But uping your tuning will hurt your low end power handling. shrinking the sealed part of the box will help that out. I'd guess your peak will be about 45 Hz. Anyone have a guess as to where his peak will be? LOL

Duane

Its a sealed chamber in the back, so the power handling will be pretty much the same.

Ronny
11-07-2011, 02:59 PM
Not enough port, sealed chamber is a tad large too.

GeekSquad
11-09-2011, 06:39 PM
Move the batteries to the front and put the subs as close as possible to the back of the vehicle and dynamat the hell out of the rear hatch! lolz Good looking system though!

GeekSquad
11-09-2011, 06:48 PM
Oh, and do NOT try to get good numbers out of multiple ports. If anything, try to go with one HUGE port (8.5cf x 18sq in/cube=153 square inches so, let's say 10in.x15.25in) would be much more efficient than multiple ports, I don't care what kind of flare you have on it.

joshy629
11-09-2011, 07:57 PM
Thanks guys. I might try a slot port. But I've never built one. I assume theyy are pretty easy though correct?