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Building a Bass Cabinet

Saint Nick

Saint Nick

Lifer
I got a free speaker pulled from a bass cabinet from Russo's. I want to build a small bass cab that I can take with me... instead of taking my 4 x 10" everywhere :roll: any tips on making it sound the best? Maybe yoYOyo can chime in? I know that I'm going to have to use particle board... but what should I do about porting? Should I port it at all?

Obligitory pictures of said speaker:

01
02
03
 
Do you know anything about the subwoofer aside from the fact that it's 10"? It'll be hard to properly size a port if you don't know the T-S parameters of the driver.
 
Without the published driver Thiele-Small parameters it's difficult to recommend enclosure design including length and surface area of bass reflex ports, etc.

You can find the approximations yourself by following this guide but it may be too much of a PIA for a simple project.
 
updated OP with some pics of speaker...

i figured it wouldn't be so hard making a cab. isn't it just a box with a hole and a pipe in it?
 
Originally posted by: jndietz
updated OP with some pics of speaker...

i figured it wouldn't be so hard making a cab. isn't it just a box with a hole and a pipe in it?
Click to expand...

Well a simple reflex cab may appear that way but there is a relationship between inside cabinet volume, the size of the pipe and its length. Not all drivers are designed for ported enclosures. Throwing the driver in a box with a four inch pipe ten inches long may sound cool, but if it turns out the tuning frequency is 48 Hz and you push it HARD with 22 Hz and the driver suspension is not tight enough it may damage the driver. How big is the driver?

EDIT: Looks like a 10" by pics unless it has a really monster voice coil which those type of drivers typically don't. 2" typical.

Give it 1.5 cu ft internal volume with a single four inch port seven inches long and start there. Borrow, beg, or steal a signal generator and see where the port tune frequency is - give it enough juice at 20 Hz just to see decent excursion and sweep up until the excursion seems to stop and then it will increase again. The point on the signal generator where the woofer appears still is the port tuning frequency. For a 10" driver the best is probably going to be around 45 Hz so this is not a super duper low frequency box. You can tune it lower but you will lose output in the bass region above 50 Hz - of course you will have extended lower frequency response down to the port tune frequency. A single 10 should never really be tuned lower than 35 Hz though. If you really need more output in these frequencies you should look into larger drivers, more drivers and alternative loading technique such as push-pull (isobarik), etc.

It's all fun until you blow something up but you said it was a FREEBIE so have fun! 🙂
 
Originally posted by: jndietz
updated OP with some pics of speaker...

i figured it wouldn't be so hard making a cab. isn't it just a box with a hole and a pipe in it?
Click to expand...

Dude, theres WAY more to it then that.
The port determines tuning frequency and port air speed. Thelength of the port varies depending on the tuning frequency you want and the diameter of the port. Too high of tuning frequency and you have a very boomy sound and can easily damage the sub by going below the tuning point. Going below the tuning point unloads the sub from the box and power handling drops like a rock. Thelarger the diameter of the port, the longer the port needs to be for the same tuning frequency as a smaller diamater shorter port. But if airspeed is too high through the port you end up with port noise, so its a tradeoff of getting a port wide enough your airspeed is low and long enough you hit your desired tuning point for you application.

Making a port is almost an artform, it is NOT just "a hole with a pipe in it"

Without the T/S parameters of the speaker it will literally be impossible to tell you what the dimensions of the port should be. It cannot be done accurately. You might be able to find the manufacturers recommended box sizes.

As a generic box I would do 2.5ft^3 sealed. Most subs will respond well in a box that size,provided there a car audio sub (Or derivitive thereof).
Home audio subs may not perform as well (Although most would) in 2.5ft^3 due to the fact space in a home is usually not at the same premium it is in your car.

Regardless, 2-3ft^3 (Sealed) should be at least a usable box size for just about any sub on the planet.

*EDIT*
Some subs will respond well in a box (sealed) so small you couldnt put the sub inside of it. If your lucky enough to have such a beast you can make a very small box (say, .5 or .75ft^3) and inverse mount the sub.
Its doubtful, but worth a shot nonetheless.

*EDIT 2*
Also forgot to add, if you try pushing the tuning point too low you'll end up with a real wonky response over your sub frequency range.
 
Originally posted by: jndietz
updated OP with some pics of speaker...

i figured it wouldn't be so hard making a cab. isn't it just a box with a hole and a pipe in it?
Click to expand...

As already posted you need to figure out what you want first, and then build the enclosure to suit those needs that are dependant on your driver.
 
Originally posted by: Specop 007

Some subs will respond well in a box (sealed) so small you couldnt put the sub inside of it. If your lucky enough to have such a beast you can make a very small box (say, .5 or .75ft^3) and inverse mount the sub.
Its doubtful, but worth a shot nonetheless.
Click to expand...

Yes this is popular with many designs and what they do is take advantage of the acoustic suspension's key advantage: gentle rolloff at very low frequencies while keeping the driver in control. (loaded)

Of course this requires lots of equalization which means lots of amplifier power. At this point the voice coil temperature must be considered.

 
Originally posted by: spidey07
Originally posted by: jndietz
updated OP with some pics of speaker...

i figured it wouldn't be so hard making a cab. isn't it just a box with a hole and a pipe in it?
Click to expand...

As already posted you need to figure out what you want first, and then build the enclosure to suit those needs that are dependant on your driver.
Click to expand...

Which will be completely impossible without his T/S parameters. He doesnt need all of them, but he at least needs SOMETHING. Even recommended box sizes from the manufacturer would help.
 
Just look up the specs based on the model number and go to diyaudio and have them help you design a box for it. I'm sure some people on here can give you some decent info, but when a better resource is available, why not use it?

Mark
 
Originally posted by: Specop 007
Originally posted by: spidey07
Originally posted by: jndietz
updated OP with some pics of speaker...

i figured it wouldn't be so hard making a cab. isn't it just a box with a hole and a pipe in it?
Click to expand...

As already posted you need to figure out what you want first, and then build the enclosure to suit those needs that are dependant on your driver.
Click to expand...

Which will be completely impossible without his T/S parameters. He doesnt need all of them, but he at least needs SOMETHING. Even recommended box sizes from the manufacturer would help.
Click to expand...

oh, I agree. recommended from the manufacturer would be a great place to start for a first build.

building the boxes isn't hard...it's how they sound. I mean let's face it...you are in a way making an instrument.
 
well this isn't really a subwoofer. its for a bass guitar. what i thought about doing is finding the dimensions of a similar setup (something by crate, behringer, marshall, etc.) and then finding the measurements of their boxes. and see where they put the port. maybe try to look up more tech specs about their products and build mine according to theirs.
 
Originally posted by: jndietz
well this isn't really a subwoofer. its for a bass guitar. what i thought about doing is finding the dimensions of a similar setup (something by crate, behringer, marshall, etc.) and then finding the measurements of their boxes. and see where they put the port. maybe try to look up more tech specs about their products and build mine according to theirs.
Click to expand...

These are some of the best bass cabs out there. Dimensions should be on there.
 
Originally posted by: Minjin
Just look up the specs based on the model number and go to diyaudio and have them help you design a box for it. I'm sure some people on here can give you some decent info, but when a better resource is available, why not use it?

Mark
Click to expand...
I post on diyaudio.
 
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