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Old 12th December 2005, 03:34 AM   #1
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Default I need help with my 30" subwoofer design

hi everyone

Its my first time of DIY my subwoofer box. I need some help of designing a box for my 30" subwoofer (Electro-Voice EV-30W) (thinking of it sealed). I am thinking of using maple plywood (from Home Depot) with a dimention of 48" (H) x 36" (W) x 36"(L), and maybe 2 bracing inside the cabinet. However, I have been reading a lot from the threads that the cabinet has to be very stiff, I am wondering if this is enough? any comment or idea? I don't want to put too much money ( under $300 cdn is my budget)and concrete in it, because its too heavy. Also that I don't have much information about this driver.

One other question is that, do I need a very very high power amplifier for this sub? (such as 1000W)?

I really need help, since I don't want to make something that turn out to be bad

thank you
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Old 12th December 2005, 03:57 AM   #2
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where did you come across this 30" beast?

A BIG ported box will probably be just the thing. Judging by the size of a cone that baby has sensitivity should be rather high and a smaller amplifier will be able to crank out some SPL, but if the sub can handle the power... might as well have an amp that can push it
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Old 12th December 2005, 04:32 AM   #3
simon5 is offline simon5  Canada
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I found out the T/S parameters, you get only 3.8 mm Xmax.
You don't need much power, 60W RMS.
BTW, Vas is huge (5947 liters), you'll need a monstrous box.

MANUF EV
ID 30W
RE 4 ohms
FS 16 Hz
VAS 5.9472 m^3
QES .3
QMS 2.61
SD .3626 m^3
PE 60 W
XMAX .0038 m
LE 1.28 mH
DIAM 30 inches
MMS .30624
BL 20.261
SENS 101.09
QTS .2691
ACCEL 66.2 (???)
FRAME CAST
CONE POLYSTYR
SURR FOAM
RECNO 507 (???)
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Old 12th December 2005, 10:50 AM   #4
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thanx for the quick response guys

i heard this 30" sub from my dad's friend before, so then I start to search for people who is selling it, unfortunately, i think that woofer has been hard pressed by other object, so i think its some what damaged, I am still trying to make it good.

Now, this driver is just in a open box and I am using a very old guitar amplifier (came with purchase of this 30") for this driver, however, it start to give me those cracking sound. Which does not happened when I connected this 30" to subwoofer out from a small sound system (i connect my sub out from my receiver to that sound system's in and then connect the 30" to its output).
any suggestion what might have happened???

So i guess my with 36" x 36" x 48" (around 1000Liters) is not enough eh? or I would need to make a lot of bracings???

sorry that I am asking so many questions, because I don't have much knowledge of speakers and subwoofer
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Old 12th December 2005, 04:03 PM   #5
simon5 is offline simon5  Canada
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1000 liters internal net volume will be ok, you'll be at Q = 0.707 (1035 liters), keep the box sealed.

Then buy a nice ~60W amplifier, anything between 50-100W will be ok.

Because the box is so big, yes you'll need alot of bracing. The box will be very heavy!

This woofer would be perfect for infinite baffle setup if you can cut holes in your house hehe!
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Old 12th December 2005, 05:49 PM   #6
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Quote:
Originally posted by simon5
1000 liters internal net volume will be ok, you'll be at Q = 0.707 (1035 liters), keep the box sealed.

Then buy a nice ~60W amplifier, anything between 50-100W will be ok.

Because the box is so big, yes you'll need alot of bracing. The box will be very heavy!

This woofer would be perfect for infinite baffle setup if you can cut holes in your house hehe!

thank you simon5
what do u recommand for 60W amplifier (or 50-100W)? I was thinking getting a buttkicker (1000W) (~$300cdn) or another amplifier for 200W ($150 cdn).

As for the box, do you think I need the external structure? I am thinking of just one layer and then seal the internal edges with hot glue or the bathroom glue.

As for infinite baffle setup, I wouldn't dare to drill holes in my house, I will get kicked *** by my parents..hahahaha. However, i will be placing it in the middle of a room so I will have 4 meters between wall and the subwoofer
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Old 12th December 2005, 07:37 PM   #7
simon5 is offline simon5  Canada
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http://www.partsexpress.com/pe/showd...number=300-784

That thing would be enough. You'll need to ask first to see if there's a bass boost. You want an amplifier WITHOUT bass boost. Alot of PartsExpress amplifiers got stupid bass boost like 6 dB at 35 Hz and that's destroying what we are trying to do.

There's also this one at 109$ USD...
http://www.rythmikaudio.com/nonservo...t.htm#250basic

It's overkill, without bass boost, but quite cheap, so you could use it if you can control yourself. That means don't set the volume knob too high hehe!

What do you mean by external structure? How do you plan to build this?
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Old 12th December 2005, 08:25 PM   #8
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This woofer moves the same amount of air as a 15" driver with 18 mm xmax, like a TC Sounds TC2+ for a few hundred $.
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Old 12th December 2005, 08:43 PM   #9
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I have confirmed with the part express technician about this 70W subwoofer amplifier, he said that it does not have a bass booster in it, so I will put this amplifier into consideration, since its within my budget.

What I mean about the external structure is that I have been noticing a lot of subwoofer cabinet design, they build an internal cabinet structure with MDF (around 1/2" to 3/4") and then attach it to an external cabinet structure with plywood. I am just curious if I can just use one layer (internal structure) rather than putting another external one

http://home.earthlink.net/~bdanser/

in that webpage, this guy glue the plywood (external structure) to the MDF (internal structure), I am wondering if doing that is necessary in my case? or one layer is enough and making a lot of bracing inside??
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Old 12th December 2005, 10:54 PM   #10
simon5 is offline simon5  Canada
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I almost forgot...

You can make that box smaller by using stuffing.

I would build it with 850 liters internal net, then stuff with about 25 lbs of stuffing, I'd use dacron-polyester fiberfill.

http://web.archive.org/web/200208082...ces/fiberfill/

For the box, use a single layer of 3/4" hardwood plywood (baltic birch if you can) then brace alot and it will be more than enough. I hope you have alot of strong friends.

To seal the edges, start by cutting/sanding the wood correctly so everything fits perfectly, then glue your enclosure correctly with plenty of wood glue, then yeah hot glue would probably be ok just to be sure. You want absolutely 0 air leaks. That's essential.

Add some silicon under the driver frame to seal it when you'll screw it to the enclosure too. You could use some weatherstripping stuff also instead.
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