[chrislittle]

Hi,

If I mount some 10" speakers on the ends of a couple of 2 foot lengths of sonotube, will the behave like dipoles?

thanks,

Chris

[opnly bafld]

Woofers? Fullrange?

"...will they behave like dipoles?"    Yes and No ~ see u frame and dipole models in links below

http://www.quarter-wave.com/

http://www.linkwitzlab.com/index.html

http://www.musicanddesign.com/NaO-II-U-frame.html

see THE PERILS OF HAVING WINGS at bottom of page
http://www.hi-fiworld.co.uk/loudspeakers/68-technology/144-designing-loudspeakers-open-baffles-and-bass-part-15.html

Lin

[JohnR]

U-frames are harder than they look....

OP: part of the answer depends on what frequency you are planning to run them up to.

[guest42212]

2 drivers each tube (driver on each end) ?

[chrislittle]

one driver in each tube.

I want to set them up like collumns so they radiate omnidirectionally, with the woofers in the top and the tubes set off the ground by a couple of inches with feet.

I know OB is not supposed to have good off-axis response, but I hope firing them at the floor will change that.

Apparently there will be a resonance in the tube I should be concerned with too.

[JohnR]

I want to set them up like collumns so they radiate omnidirectionally, with the woofers in the top and the tubes set off the ground by a couple of inches with feet.

Um, this doesn't sound much like OB at all. Probably more like a transmission line or maybe bass reflex (depending on driver parameters and dimensions.)

[JLM]

Set up vertically they will load the space omni-directionally not in a dipole pattern.  The sonotube would provide an inexpensive/rigid enclosure and two 10 inch drivers could make for mighty amounts of bass (wired in-phase of course).

SVS still offers a similar subwoofer (but with only 1 driver at the bottom and a port at the top).  I've not modeled them, but as mentioned they certainly behave as a transmission line.  Using a relatively short tube, your project would simply act as a sealed cabinet with the additional advantage of canceling cabinet vibrations.

[guest42212]

> Apparently there will be a resonance in the tube I should be concerned with too.

Big Time. It's a transmission line.

[chrislittle]

 Using a relatively short tube, your project would simply act as a sealed cabinet with the additional advantage of canceling cabinet vibrations.
[/quote]

Can you explain to me a little bit further how the cabinet vibrations would cancel?

Chris

[chrislittle]

Big Time. It's a transmission line.
[/quote]

 So if it's a transmission line, and my pipe is only 2-4 feet long, I'm still pretty far away from being 1/4 wavelength. Can I tune into a 1/8 of a wavelength, or 1/16 of a wavelength for a similar benefit. Can I model this on the Martin King software. It's been a while since I have used that software. Do you think I can develop the idea with listning tests, like changing the tube length or the distance from the open end to the floor?

[opnly bafld]

Using a relatively short tube, your project would simply act as a sealed cabinet with the additional advantage of canceling cabinet vibrations.

Can you explain to me a little bit further how the cabinet vibrations would cancel?

It won't act like a sealed cabinet, unless you make it sealed.
Round tubes are inherently stronger and don't flex like a box (I wouldn't call it canceling).

[BoJonJovi]

I used an 18" sonatube as aberration of Martin's H frames with Eminence Alpha 15-a. I made the length approximately the same and I figured the volume was very close. I am thrilled with them and it made it a pretty easy build. I used construction adhesive and drywall schools to mount the round plywood doughnut baffle in the tube, then attached my Alpha. these were part of an OB build using the Alpha's and 12" Betas.

I thought I could perhaps get some vinyl flooring and stick it to the sona tubes to get a nice wood look. The problem is that the tubes have a waxy coating so they release from the concrete. Glue does not stick and preglued vinyl wood flooring just falls right off.

I ended up using Elmers glue to reinforce the edges and found Latex paint sticks well so I ended up painting mine. Do they look great; well no. Do they sound great, well yes. So "sona" form followed function.

Hope this helps. They were certainly cheap as I remember 30 bucks bought enough tube to make 4 speakers. Another guy used 18 PVC pipe. The best I could find were short sections that costed well over 100 bucks. Nothing cheap about big PVC pipe but I would sure love to get some. The guy that did the PVC said he contacted Martin and Martin said the round forms should work fine. However, that is a second hand statement by me so I cannot vouch for it's accuracy. I do like the sound of mine and intend to do a similar build using a larger sona tube and Martin's larger build. I guess I liked it enough to keep doing it.

[BoJonJovi]

Sona Tube build modeled roughly after poultrygeist build.