Re: Cylindrical vs. box shaped subwoofers

[Arny Krueger]

"Barkingspyder" > wrote in message
...

> Are there any advantages other than a smaller foot print for
> cylindrical subwoofers?

Potentially low cost and easier assembly, particularly if the cylinder is
based on Sonotube.

> Do they require damping material in the
> same way a box would?

Yes.

> I'm considering a DIY project and would be curious as to the science
> on this topic. Are there the same problems with vibrations inside
> the enclosure, or does the cylinder reduce or make them a non-issue?

Two types of vibrations

(1) Vibrations of the air
(2) Vibrations of the enclosure

(1) Is based on enclosure volume, driver characteristics, stuffing, and are
the same given the same volume, driver, etc.
(2) Is based on the stiffness of the enclosure.

> I see a lot of the sonotube desgins have the driver at one end and he
> port at the other. Does it make any difference if they are are at
> the same end of the tube assuming a large enough diameter?

Not unless the enclosure is itself a signficiant portion of a 1/4 wavelength
at the port tuning frequency.

> I am considering a 143 L EBS alignment with both the port and the
> driver at the bottom. The tube would be 20" in diameter and a 4"
> port. I am not married to these dimensions but I thought there
> would be a higher WAF if the thing looked less like a water heater.

What driver?

I've never heard of a 143 L EBS alignement and can find no online references
to it.

[Arny Krueger]

"Barkingspyder" > wrote in message
...


> Based on what I have read here if I'm going to use Sonotube, it would be
> very wise to find some way to brace it internally.

Not exactly rocket science. Get a bunch of 2x2 clear pine, some 3 1/2" dry
wall screws, a 1/8" drill, and some construction adhesive.

Your knuckles and ears are probably your best tools.

> Possibly, there is some other brand of tubing that would be thicker and
> possibly more rigid.

Unlikely. This stuff is built for a different purpose (concrete forms), and
it is entirely adequate if not overbuilt for that purpose.

[Audio Empire]

On Wed, 18 Jul 2012 05:45:18 -0700, Arny Krueger wrote
(in article >):

> "Barkingspyder" > wrote in message
> ...
>
>
>> Based on what I have read here if I'm going to use Sonotube, it would be
>> very wise to find some way to brace it internally.
>
> Not exactly rocket science. Get a bunch of 2x2 clear pine, some 3 1/2" dry
> wall screws, a 1/8" drill, and some construction adhesive.
>
> Your knuckles and ears are probably your best tools.
>
>> Possibly, there is some other brand of tubing that would be thicker and
>> possibly more rigid.
>
> Unlikely. This stuff is built for a different purpose (concrete forms), and
> it is entirely adequate if not overbuilt for that purpose.
>

What's wrong with ceramic (or concrete) pipe or chimney flue liners? They're
cheap, unbelievably stiff and easy to find.

[Dick Pierce[_2_]]

Audio Empire wrote:
> On Wed, 18 Jul 2012 05:45:18 -0700, Arny Krueger wrote
> (in article >):
>
>>"Barkingspyder" > wrote in message
...
>>
>>>Based on what I have read here if I'm going to use Sonotube, it would be
>>>very wise to find some way to brace it internally.
>>
>>Not exactly rocket science. Get a bunch of 2x2 clear pine, some 3 1/2" dry
>>wall screws, a 1/8" drill, and some construction adhesive.
>>
>>Your knuckles and ears are probably your best tools.
>>
>>
>>>Possibly, there is some other brand of tubing that would be thicker and
>>>possibly more rigid.
>>
>>Unlikely. This stuff is built for a different purpose (concrete forms), and
>>it is entirely adequate if not overbuilt for that purpose.
>
> What's wrong with ceramic (or concrete) pipe or chimney flue liners? They're
> cheap, unbelievably stiff and easy to find.

From the viewpoint of stiffness and mass and availability,
they're probably okay. One problem is that their internal
losses are low, which means any mechanical resonances that
might get started are goign to hang around for a while.

They're also not the easiest material to work with.

--
+--------------------------------+
+ Dick Pierce |
+ Professional Audio Development |
+--------------------------------+

[Dick Pierce[_2_]]

Arny Krueger wrote:
> "Barkingspyder" > wrote in message
> ...
>>Based on what I have read here if I'm going to use Sonotube, it would be
>>very wise to find some way to brace it internally.
>
> Not exactly rocket science. Get a bunch of 2x2 clear pine, some 3 1/2" dry
> wall screws, a 1/8" drill, and some construction adhesive.

Onw of the real big problems with these concrete forms
is that they are wax-coated (first to prevent water
from soaking in to them when they're filled with
concrete, secondly to make it easy to strip them off
once they're done.

The wax coating makes the use of any adhesive-based
solution a real challenge.

>> Possibly, there is some other brand of tubing that would be thicker and
>> possibly more rigid.

If you're so committed to marrying these things, what's
wrong with the idea of taking two forms of somewhat different
diameter and filling the space between them with sand?

--
+--------------------------------+
+ Dick Pierce |
+ Professional Audio Development |
+--------------------------------+

[Audio Empire]

On Thu, 19 Jul 2012 04:04:21 -0700, Dick Pierce wrote
(in article >):

> Audio Empire wrote:
>> On Wed, 18 Jul 2012 05:45:18 -0700, Arny Krueger wrote
>> (in article >):
>>
>>> "Barkingspyder" > wrote in message
>>> ...
>>>
>>>> Based on what I have read here if I'm going to use Sonotube, it would be
>>>> very wise to find some way to brace it internally.
>>>
>>> Not exactly rocket science. Get a bunch of 2x2 clear pine, some 3 1/2"
>>> dry
>>> wall screws, a 1/8" drill, and some construction adhesive.
>>>
>>> Your knuckles and ears are probably your best tools.
>>>
>>>
>>>> Possibly, there is some other brand of tubing that would be thicker and
>>>> possibly more rigid.
>>>
>>> Unlikely. This stuff is built for a different purpose (concrete forms),
>>> and
>>> it is entirely adequate if not overbuilt for that purpose.
>>
>> What's wrong with ceramic (or concrete) pipe or chimney flue liners?
>> They're
>> cheap, unbelievably stiff and easy to find.
>
> From the viewpoint of stiffness and mass and availability,
> they're probably okay. One problem is that their internal
> losses are low, which means any mechanical resonances that
> might get started are goign to hang around for a while.
>
> They're also not the easiest material to work with.
>
>

I found just the opposite to be true. You need to make a couple of endcaps
out of 3/4" plywood and affix them to the pipe using threaded rods (makes a
sandwich. Wooden end-caps (one with woofer, one with port) and the pipe
essentially squeezed between them by the threaded rods). Paint the pipe (or
leave it natural clay color) and you have it made.

[Dick Pierce[_2_]]

On 7/19/2012 7:05 AM, Barkingspyder wrote:
> On Wednesday, July 18, 2012 5:45:18 AM UTC-7, Arny Krueger wrote:
>> Not exactly rocket science.
> You never know, get a nose cone and some fins................ :-)

I once sat down and went through the exercise of designing and
simulating a rocket on a 36" diameter, 40 foot long sonotube
loaded with about 3/4 ton ammonium perchlorate/polyurethane
solid fuel. With an optimized thrust profile, optimum cone,
glass-smooth finish, etc., I figured I had about a 20% chance
of putting the carcass into on unstable earth orbit.

Now, the issue of the illegality of launching such a contrivance
from one's back yard came up, but I figured that when the town
police showed up in my driveway to investigate, the fact that
I was sitting at the bottom of a pretty substantial column of
smoke 30 miles high might raise the though that, indeed, I
was a force to be reckoned with. The first question they should
probably entertain is: did I have another one at hand.

Ironically, I did this work about a month before the Oklahoma
Federal Building bombing: right after that, getting a half a
tone of ammonium perchlorate on the open market got a bit more
difficult :-)

[Dick Pierce[_2_]]

On 7/19/2012 3:03 PM, Barkingspyder wrote:
> On Thursday, July 19, 2012 4:04:43 AM UTC-7, Dick Pierce wrote:
>> One of the real big problems with these concrete forms
>> is that they are wax-coated (first to prevent water
>> from soaking in to them when they're filled with
>> concrete, secondly to make it easy to strip them off
>> once they're done.
>>
>> The wax coating makes the use of any adhesive-based
>> solution a real challenge.
>>
>> Possibly, there is some other brand of tubing that would be thicker and
>> possibly more rigid.
>>
>> If you're so committed to marrying these things, what's
>> wrong with the idea of taking two forms of somewhat different
>> diameter and filling the space between them with sand?
>
> Nothing I suppose. I was hoping to keep the whole thing as small
> as possible and as light as possible, but since this is likely
> to be the last sub I ever construct it's entirely doable.

swell, unfortunately, the mechanical properties that best suit
the design and construction of subwoofers don't include "as
light as possible" as viable choices. "Light as possible"
means flexible (claims about the superior rigidity of cylinders
notwithstanding), acoustically transparent, and a bunch of
other things: all are poor choices for a subwoofer enclosure.

Consider a piano: the soundboard is deliberately made "as
light as possible." Is that what you REALLY want?

[Gary Eickmeier]

"Dick Pierce" > wrote in message
...


> If you're so committed to marrying these things, what's
> wrong with the idea of taking two forms of somewhat different
> diameter and filling the space between them with sand?

Is that what you would do?

The reason such silliness is not necessary is that Sonotubes are audibly
plenty stiff enough. Refer to Hsu and SVS's use for their commercial subs.
If somebody is paranoid about what a Sonotube will do when trying to get
down to really low frequencies, they should just build a clone of the Hsu
TN1220 or one of the bigger SVS models. That way, they will be taking
advantage of research done by people who know what they are doing.

Gary Eickmeier

[Arny Krueger]

"Dick Pierce" > wrote in message
...
> Arny Krueger wrote:
>> "Barkingspyder" > wrote in message
>> ...
>>>Based on what I have read here if I'm going to use Sonotube, it would be
>>>very wise to find some way to brace it internally.
>>
>> Not exactly rocket science. Get a bunch of 2x2 clear pine, some 3 1/2"
>> dry wall screws, a 1/8" drill, and some construction adhesive.

> Onw of the real big problems with these concrete forms
> is that they are wax-coated (first to prevent water
> from soaking in to them when they're filled with
> concrete, secondly to make it easy to strip them off
> once they're done.

> The wax coating makes the use of any adhesive-based
> solution a real challenge.

Friends who have done projects with them tell me that scrubbing with
petroleum distillates solves that problem when it exists.

>>> Possibly, there is some other brand of tubing that would be thicker and
>>> possibly more rigid.
>
> If you're so committed to marrying these things, what's
> wrong with the idea of taking two forms of somewhat different
> diameter and filling the space between them with sand?

Now that would be a robust and very acoustically dead solution, not to
mention very heavy.