Wood Cylinders

[sdclc126]

Hello All,

I have been reading a lot about subwoofers and some regular speakers being made out of Sonotube and similar materials that come in a cylinder/tube shape (see the "Sono-sub" etc.). The advantage to this is the sonic benefit due to the inherent non-resonance of the cylinder shape.

The disadvantage most people mention is aesthetics - they just don't look good, at least not compared to nicely finished traditional wood cabinets. Painting helps, and so does veneering, but I don't think I'd ever try to apply veneer to curved surfaces - doing it on flat ones is hard enough. PVC pipe is another popular material, especially for small TL, surround (Linkwitz) and such speakers, but again we're talking rather ugly here.

So one day I decided to put the term "wood cylinders" into my search engine, and found www.tapeease.com (enter the site, then look for, you guessed it, "wood cylinders" in the menu on the left. They make plywood cylinders in a variety of heights and diameters, and will even veneer them for you! I haven't built any speakers with these, nor ordered any of their products, but I can't imagine a stronger, less resonant speaker enclosure (other than a sphere, but DIYers and few others rarely go there) than a plywood cylinder, and this would seem to strike a nice balance between aesthetics and performance.

I haven't seen this discussed in any "sonutube" or other circles - is anybody else out there aware of this site? Has anybody built any speakers with this type of material? If you have please post your photos - I'll bet a lot of us would like to see them and get some ideas.

Another quick thought - one could always hide a cylinder inside a traditional box, thus really getting the resonance and appearance issues resolved with little compromise. How about housing drivers at the end of a cylinder, then loading them horizontally into a box enclosure, facing forward, to form a more or less traditional looking floor standing design?

- Curtis

[Stocker]

This is one degree removed from putting a square peg into a round hole

Veneering a flat is not hard. Veneering a cylinder shouldn't be that hard. The only obstacle I can see would be getting a sheet big enough and even that isn't insurmountable.

as for the cylinder within a square, why bother? the amount of material used could easily be put to better use in a STOUT, braced traditional shape.

[sdclc126]

It's actually fitting a round peg into a square hole, and the idea of using a cylinder inside a box is so that one doesn't NEED all that complex bracing in the box - the cylinder IS the bracing!

[Stocker]

... note about the "one degree" comment... referring to the "six degrees of separation" idea. It was supposed to be funny, but oh well...

As far as complexity... if you need complex bracing in a less-than-huge box, you need thicker walls. You would have maybe (guessing) 1.5x the amount of total enclosure material with a cylinder in a cube, as you would with just a cube. That 1.5x amount of material could take you from 0.75" MDF to 1.125" of 1"MDF and 1/8" veneer. If you need more bracing even after having 1 1/8" thick walls, it would probably not need to be very complex.

Aside from that, you lose even MORE material and volume with the cylinder in a box idea... all the volume around the cylinder, in the corners of the box are wasted airspace that could have been used to have lower frequency extension or alternatively a smaller box overall.

Now what I am NOT saying at all is that this is an intrinsically bad idea, just that for most purposes (and for those not really REALLY concerned about resonances and unwilling to brace the box) it is perhaps unneccessary.

/edit: actually, it seems like kind of a neat idea...perhaps the physics for resonance control are quite good even... A thing that you could take secret pride in having pulled off well, but nobody would ever know about until you told them... sort of like anything else DIY!

/edit2: I forgot: the "wasted" corner airspace could be a handy place for a port, if you could calculate the airspaces properly. Coupling to it may be a problem, as well as delay, perhaps.

also, you might be able to get away with far less material/ weight if you -could- use thinner material in the cylinder for resonance control, and a thinner outside shell, just for the aesthetics of the thing... but not too thin! Beware of fragility and induced resonances in the enclosing box!

[sdclc126]

Your humor wasn't missed - my reply was intended as same, but didn't come across well.

The cylinder-in-a-box was just a sidebar anyway - sonosubs are very functional but huge and ugly, so the thought was what to do about that. A wood cylinder/column, especially a nicely finished one, is a very aesthetically pleasing form, whatever it's used for. And I thought it just might open up a lot of imaginative ideas for speakers - we DIYers like to experiemnt by our very nature, mixing form and function.

I saw a hilarious bumper sticker once - it said:

Jeseus loves you; everyone else thinks you suck!

[Joules]

Although I haven't done the tests my self (maybe someday) I'm not so sure a tube is with out internal reflection resonencees. For instance when the half wave lenght becomes less than any internal dimention you start to get standing waves. A square or rectangular enclosure has many different lengths, from side to side, from corner to corner and every demention inbetween, there by spreading any standing waves of a range of freq's an at a smaller amplitude. A tube on the other hand has but one dimention from side to side and from top to bottom and all around. This should greatly faver one Freq. and be very strong at that. I've allways wanted to use a tube my self but afraid of these problems. I sure wish some one would give me a convincing argument to the contrary.

[sdclc126]

You're right about this, but damping/stuffing the cylinders works just as it does in boxes. I think there are FEWER resonance issues with cylinders, but certainly not zero. No perfect solutions out there I guess.

This page might give you more insight: http://www.linkwitzlab.com/surround_speaker.htm

[Greg B]

A cylinder is one of the worst possible shapes from the point of view of internal (air) resonances. You are much better off with a golden ratio rectangular box IMO. However, a cylinder is inherently extremely strong and stiff, so there will be few cabinet resonances. Moreover, it is nearly ideal AFA diffraction. If this is to be a sealed enclosure, the internal resonances can probably be sufficiently damped the internal stuffing.

GB

[Stocker]

guys, don't forget that the back of the driver itself is a pretty big cone with funky irregular shapes, probably pretty good for breaking up any harmonics.

And it would have to be long indeed to resonate at sub-bass frequencies.

One member here has indeed made a (very) nice-looking tube-sub.

[454Casull]

Originally posted by Greg B
However, a cylinder is inherently extremely strong and stiff, so there will be few cabinet resonances. Moreover, it is nearly ideal AFA diffraction.

GB

Depends on where you place the drivers.