New idea with sub. 60 feet long?

[bobcat190]

Hello

Yes i searched.

I have been looking for a fun sub project for some time now, and i think i found it but i cound use some of your help.
i'll give a link to the page that gave me the idea.
here it is http://www.cornu.de/en/tml.html

also are these PVC type subwoofer bass tubes any good? i like the idea A LOT!

Ok now I am not a speaker wiz (mostly here for the projectors)
i know this tube sub is at like 1/4 or 1/8 wave length. i want a 1/1 wave length (if possible) the tube can be around 60 feet long so this is where i need your help. With the math stuff.
my idea is to have the main part with the speaker under the floor
and pop up in my room.

Thanks for any help. I'd like to try this.

[sreten]

A 1/4 wavelength has the properties you need
to increase bass ouput and power handling.

The higher harmonics, 1/3, 1/2, 1/1 are unwanted.

60 feet is simply too long, ~ 5Hz, unless your into subsonics.

15 feet gives you 18.5Hz without taking into account any stuffing.

checkout www.quarter-wave.com

sreten.

[bobcat190]

Ok around 15 feet would work just fine.
But is this still a good way to diy a subwoofer? or is wood and nails better?

[Cees]

For the math stuff go to:
http://www.aj-systems.de/indexe.htm
AJHORN is able to simulate tml-like designs.

[kevyjo]

It depends on if you want to build a subwoofer or a "wave cannon". I know almost nothing about wave cannons, but I believe they are designed to produce very strong frequency response over a very narrow bandwidth, not really of any use as far as i know for a conventional hifi/HT system. "Tubes" are still ideal for subwoofers, but I would suggest a sonotube. It would be very difficult and expensive to get a PVC pipe big enough to give you enough volume for a sub, but sonotubes are cheap and redily available from concrete supply companies, and come in sizes ranging from about 6" to three feet in diameter. Sonosubs are less suseptable to resonance problems that box subs can be.

[kevyjo]

here are just a couple of examples of DIY sonotube subs, though there are zillions more out there:

http://www.hometheaterhifi.com/volum...tember-99.html

http://terryctheater.tripod.com/shivaphotoalbum/

[Da5id4Vz]

and then there is "El Pipo" which is a very nice read:

http://www.passdiy.com/projects/el-pipe-o-1.htm

[Timn8ter]

Originally posted by sreten
A 1/4 wavelength has the properties you need
to increase bass ouput and power handling.

The higher harmonics, 1/3, 1/2, 1/1 are unwanted.

60 feet is simply too long, ~ 5Hz, unless your into subsonics.

15 feet gives you 18.5Hz without taking into account any stuffing.

checkout www.quarter-wave.com

sreten.

Exactly. I've done this twice now with very good results. The easiest good sub to build. Use a length of Sonotube equal to 1/4 of the Fs, diameter equal to the driver (or close) and stuff to taste. Works every time.

Shiva tube
AV8 tube

[bobcat190]

Thanks all

You've given me some handy info.

the AJhorn demo look like it would help (if i knew how to use it)
does anyone else have a good program i could use?

well i guess i'll aim for around 15 feet then?? any idea on the dimater? i have a bunch of 3" pvc i was going to try.

so do these long bass tube work good for that theater sound i'm going for? cause that is what i'm mostly going to use it for movies.

Thanks Bob

[sreten]

The implication orf your replies is you should use a length
related to the Fs and possibly the Qt of the driver.
You cannot assume 15ft is a good choice.

sreten.