subwoofer enclousre help

[Cmac16]

well. im great at making enlosures for cars and having them pound hard, and am currently using a 2.75 cubed, ported box with a 12.

now my question is. what is the best design for sub boxes in home audio?
space isnt a problem. i can make it into a coffee table if need be.

i have a great range up mid bass so im basically looking for the lower frequncies.

and help would be great

thanks,

Cam

[Joachim Gerhard]

i prefer closed boxes with a powerfull amplifier that does the equalising. For example SEAS has a new subwoofer driver and Hypex makes nice plate amps with equalizers up to 400W. One way to reduce distortion (second harmanic) is to use two drivers, one with the magnet in and one with the magnet out. Wire the one with magnet out in oposite phase.
this reduces second harmonic by a factor of three. The next step is a feedback sytem with acelerometer. Bill Waslo had an easy understandable report in AudioXpress.

[Cmac16]

i am not interested in buying anything. except a sheet of wood and some glue.

i am keeping it to a single driver design.

and would rather go with a ported box of some sort.

i have plenty of power to work with if i need it. i have a 12v 100amp power supply. and a pile of amplifyers.

[Joachim Gerhard]

Do you have the parameters of your woofer than i could help ?

[Cmac16]

its not so much parameters that i need help with, its the basic design and shape..

like port shape.. horn boxes.. the general design.

once i have a design im good, and can figure out the details from there

[auplater]

Think Sonotube, and do a search at any of a number of sites *this one included* You'll be amazed at what can be done for a few hundred bucks, and not a lot of watts.

Stay away from all the high end ripoffs, use several cheap subs and drive the room properly; that's what you'll be listening to anyway.

Largest Sonosub yet!!

[davygrvy]

Sealed using a Linkwitz transform is pretty popular and have great phase and impulse response, but push the driver pretty far and your limit to how loud depends on excursion of the driver. They also tend to have the most distortion because of the extra cone motion required.. in a general sense. They need lots of power due to their low efficiency. Quite good, though.

Ported (bass reflex) cabinets are larger cabinets than sealed due to the tuning. Much higher efficiency than sealed, but have the drawback that they need a high-pass filter to prevent excursion damage from signals below their cutoff.

Then there are band-pass boxes that push efficiency higher than ported, but generally speaking have a one note sound to them.

There are higher efficiency types like a front loaded horn. Those tend to be huge but get the most from your driver. See Tuba HT

And there's something called a tapped horn. Very interesting. It's like an organ pipe tuned in a way to balance the mechanical Q of the driver. These have the highest efficiency of all, but is quite a balancing act as most LF drivers don't simulate well in this type. They also have the most excursion within the passband, compared to the FLH which has the most just below cutoff.

[Joachim Gerhard]

Horns that go low, say to 20Hz are huge. Look at the Dick Burween site to see a horn that goes down to 20Hz. We talk about 10 qms horn moth and several meters length at least so a coffee table does not do it.
A ported design that goes down to 20Hz needs to be around 100 liters when you want good sensitivity. make the cabinet as stable as you can eather by bracing or-and stiff materials like birch ply. The tube has to have a diameter of around 8 to 10cm to avoid chuffing noise. It can get quite long when you tune it to 20Hz then so it may need some bending. another option is a slot like in the Onken design.

[Cmac16]

ok. now we have some things to work with

first. the sono tube. i actually put an 8inch sub in a 8inch sono tube, and threw it behind the bench seat of my truck. it sounded like a 10inch.

if you could give me some input about your experiance with it and how it works in a home enviroment. and is it open at the end, or did you put a smaller port in it?

the subs i have are high excursion and can handle ALOT of power.

what about dual tuned ported boxes? has anyone heard about doing that in ahome enviroment?

and for port material, i usually used 4inch abs tubing, and make my own flared ports.

what is a good frequency to tune a box to ?

[Joachim Gerhard]

A tube open on one side has a major resonance that can make it quite boomy. One way to lessen that problem is to put the woofer at one third of the length and put some damping material into it. For 20Hz it should be 5m long theoretical.The damping material makes it posible to lower the length by aproximately 30%. If you can live with 40Hz and some room gain (like in your car) the tube ends up to be around 1.8m long. That is managable.