diy sub

[thumperxes]

so i decided to make a ht sub. i didnt want a large foot print so i made i made the cabinate 16x20 inches with a base of 17.75x22.25 and so what it stands just under a mear 53 inches. i was lookin for loud deep bass with impact and i achived it well my concrete slab in my living room vibrates confirmation from a few friends i still cant belive it. i ended up using jl audio subs 12w3v2 dual 2 ohm to get one tower to 2 ohms and when i get 2 more speakers ill have two towers i have them both built just not the speakers for the other one. even musicaly these speakers bleend nicely but rarely use them for music mostly movies. each tower is like 6 cu ft and tuned to 28hz and i can change this if i need to i made it so i can change it if i so desire. i have no idea on the actual output other than it can play down to 1 hz with the amp im using an evq66 capable of bridged 4 ohm 1700 watts or 2 ohm per channel at 850 continous the speakers are 300 rms each

[Colin]

how did you measure 1 Hz?

[Zealot125]

That is hardly the optimal cabinet size or tuning frequency for that

driver. You would have been WAY better off with a tuning

frequency of 20 hz and a cabinet volume of about 8.2 ft^3. Then

you would have ended up with 0 dB at 20 hz and -3 dB at 17.5 hz rather

than 0 dB at 25 hz and -3 dB at 23 hz. Another problem is that

with your design there is a large peak in FR between 26 and 55

hz. It is actually +4 dB at 34 hz. This may result in a

somewhat boomy subwoofer.

EDIT: There is no way you will have output at 1 hz no matter what

the design. Maybe you mean 10, but that is still impossible,

especially considering your cabinet volume and tuning frequency.

[thumperxes]

i measured 1 hz using a cd that has a swee[p from 80 to 1 and it played all of it i could see it with my eyes at the last sec of the track. the 1 hz may not have output as far as spl but it is there

as far as box size im use to car audio sub boxes and i went with my gut feeling on what i thought for home theater and it roocks with thunderous bass for movies i still need an eq for music but by ear its not to bad the box size was for a small reason i need it to fit in my back seat and get it home from work lol

thanks for the box size and tuning for my next one in time

[DrWho]

Here's a few plots for ya using that driver (in the 2 ohm configuration):

Orange = Sealed cabinet

Blue = My Ideal

Green = Your current design

Purple = Optimized for your cabinet volume

Btw, don't get confused by the scaling (notice 1Hz -200Hz and 0dB -135dB are the extremes; every line is 1octave or 5dB)

[thumperxes]

dr who my box is 6.92 before driver displacement and port displacement does your blue chart take this into effect is the 7.0 a empty box or a loaded box im pretty surt its loaded just want to make sure

[DrWho]

The "Volume:" entered into the program is the volume of free air behind

the driver. So the actual cabinet itself will need to be larger to

compensate for driver and port volume.

WinISD pro Alpha is actually a free program if you wanted to mess around with it yourself:

http://www.linearteam.dk/default.aspx?pageid=winisdpro

(The JL driver you're using is already included with the speaker

library that it comes with, which is why I bothered modelling it) []

[Zealot125]

Thumper, as far as enclosure proportions and sizes (for transpotation

purposes) think outside of the box. Cylindrical enclosures

are very space efficient. I remember a forum member, maybe Mr.

Hurd that used a good stiff material for a diy cylindrical sub and had

good results. As far as whether that driver will work for a

down-firing application or not, you will have to ask others more

knowledgeable than I. I dont know which T/S parameter accounts

for the stiffness of the suspension, but I would assume that

down-firing sub drivers must be stiffer.

[DrWho]

Funny I just posted this link earlier today on another forum:

http://www.partsexpress.com/resources/downfire.html

In regards to cylindrical enclosures...they're just easy to build, but

really aren't space savers. Say you have a 1 foot diameter tube. It

will have the same effective footprint as a 1x1 cube, but the cylinder

will need to be taller for the same overall volume (You can stuff a

square shape all the way into a corner, but a cylinder wastes some

space...most furniture is also square in nature). Nevertheless it

certainly is much easier to make a tube look good (to pass the WAF) and

the height difference usually isn't an issue.

[Zealot125]

Thats a great point, I guess I never thought about cylinders from a

practical applications standpoint. Only goes to show you that

mathematics only gets you so far...[]

[intotubes]

I built mine out of 24" dia. sonotube. It looks like a tall end table. If you went with a larger diameter it might look more like a table for improved WAF. Mine doesn't mind. It sits in the corner. Even with 1/4" wall thickness you won't feel any vibration on the walls. A cylinder is VERY strong. I used 1" thick plywood for the top and bottom and they do vibrate.