PureBasic Forums - English

I just got a new Sony Amplifyer, some nice surround speakers, and a Sony DVD too. [all brand new.]. The loudspeakers is 2 back, 1 center and 2 big front [not just the small thingy's that needs a sub].
I have a subwoofer, a cheap one. [im planning to get a brand new one.].
The system actually doesnt need it but i would like to be able to play with some real baSS.

Ok but before i buy a new one i want to play with my old one.
Its a large 15" woofer, that is in a tube. I want to make it in a real MDF box with air-tubes [not a compressor thats closed..]--

My qestion: Is there any specific size that box should have to make best sound? The sound needs to be deep. u know when watching some movies that have deEp sounds.. I have the air-tubes for some air-out.
The woofer is 15", 600Watts. Yes my amplifyer can take it.. So how big should the box be?

notice: my so called air-tube is a BasReflexTube.

so it was stupid of me to ask here
i guess no one knows it..

thefool wrote: My qestion: Is there any specific size that box should have to make best sound? The sound needs to be deep. u know when watching some movies that have deEp sounds.. I have the air-tubes for some air-out.
The woofer is 15", 600Watts. Yes my amplifyer can take it.. So how big should the box be?

notice: my so called air-tube is a BasReflexTube.

Loudspeaker-Design isn't an easy task. Beside obligatory things like
the utilized speaker-type, dimensions etc. also things like the frequency
response of the room, possible resonances etc. have to be considered.

There's some software (some released as freeware) that could help you
in calculating the proper dimensions and such.

Well, I'm sure, you already know this.

Regarding subwoofers, IMHO the crossover-frequency is quite important,
most consumer crossovers already cut at 100 or even 200Hz which is still
'too high' for a decent *boom*

Of course I'm no engineer...

now sound is definitely an expert field of mine. my old ford escort hit a 144.3 decible mark with 2 Orion 15's in a SEALED box that i made. GENERALLY, you want 1.25-1.5 cubic feet of SEALED airspace for each 15.

for a PORTED box, the airspace needs to be 8-12% MORE in order to allow for the volume of the cylindrical port. the port "tunes" the box to a resonant frequency range that really makes it slam (but only within that 30Hz-40 Hz range)

i.e. a 15 woofer in a 1.75 cubic foot volume with a 6 inch diameter port 8 inches long will rock at 32-62 Hz.

for a BANDPASS box, umm, well unless you have a math or physics degree, forget it. if you REALLY want to design it right, theres some caluculus that goes into it for resonance and correct angular placement.

BANDPASS give you the most BOOM for your watt, that is if you have a low watt system, BANDPASS will juice it up.

if you got 600 watts, go with a SEALED box about 1.4 cubic feet/woofer and make sure you SEAL THE HECK OUT OF THE BOX. remember, YOU ARE USING THE RECOIL OF THE COMPRESSED AIR.

Thanks to both.

@ localmotion: Since i dont have a math degree ill make a sealed box.
1.4 cubic feet. Sorry to ask but whats that in cubic metres (m3)? i dont calculate with feets..

Ok to seal the heck out of my box, should i use double sided?
or is it enough with 1 side and then glue them together [our use screws. Or both] and then use some sort of silicone to seal it?

btw: Since there is going to be somewhere to put the wire from my amplifyer i need to have a panel in the back. Should i INSIDE the sub make a box for that? of should i make the box, then make an addon like a small box with the panel on, and then drill a hole in the big box for the wires from the woofer?

Thanks again

thefool wrote:Thanks to both.

@ localmotion: Since i dont have a math degree ill make a sealed box.
1.4 cubic feet. Sorry to ask but whats that in cubic metres (m3)? i dont calculate with feets..

Here is a little fun with google:
http://www.google.ca/search?hl=en&q=1.4 ... arch&meta=

They have a search feature that will convert from one thing to another. I searched for '1.4 cubic feet in cubic meters' and it popped up the answer '0.0396435852 cubic meters'

I use that feature all the time to convert from imperial to metric. Really handy.

to seal the box, you assemble the box with JUST screws at first. make sure EVERYTHING fits and is aligned. use 2.3-3 inch DECKING screws. then break the box down, and as you assemble each panel, use caulk or silicone on one or both sides, then tighten the screws.

for the wires, you SHOULD use a terminal, use the link below.

http://www.radioshack.com/category.asp? ... 012&Page=1

cut a hole in the box for the terminal, connect the wires, seal it with caulk, and screw the terminal in.

ok thanks.
i have a terminal here.
Are you sure the box shouldnt be biggeR?
1.4 cubic foot is about 39 litres (thx aaron).
i just wonder isnt that about 40 cm for each side of the box?
the unit is about 32 centimeters wide. I just wonder if thats really is enough?
[not that i dont trust you, but i just wondered. But ok its going to get a very big box if i should make it bigger.]

And some of my final questions

1) the unit has 8 holes for screwing in the box. Should i put silicone around the unit from outside too?

2) Is it the transperrent silicone i should use?
3) Is it best that the unit is in the side of the box turning face so one can see it, or should it be at the bottom so it plays against the floor [staning on some feets.]?

4)Should it stand on a flat side of its own or could i make some nice feets?

Finally:
5) What colour should i paint the box Black or White?
[actually i was thinking of a white box, so it didnt look like most of them]


Thank you very much for your help! I really appreciate it.

ok

1. 1.4 cubic feet is PLENTY of space. make the box too big and you are going to REGRET it. you will get a dull thud instead of heart pounding bass. the woofer wont have any recoil in too big a space.

2. DO NOT put silicone on the woofer, as there should be an o ring on the back to seal it just fine.

3. as for placement, unless you want to calculate the PRECISE airspace needed to have the box sit on feet and face the floor (because the airspace underneath act like a BANDPASS) just have it face outward.

yeah i also thought that it would need some other calculations, but i was not sure if the sound would get better or not.

Thanks for your help

White or black??

hmm after thinking: A 15" unit cannot be in an 1.4 cubic foot box..!

15" = 38cm in diameter
1.4 cubic foot= plates of 33*33 cm!