speaker phasing

[Phil Allison]

"William Sommerwanker"

Here's the answer to your question about Boyle's Law (which you will
ignore, of course)...

PV = k assumes a constant temperature.

** PV= k shows that it does not matter what the gas is - the same
volume
changes produce the same pressure changes.

Uh... No it doesn't.

** Yes it does.


> k is temperature-dependent.

** Irrelevant when there are simply no temperature changes going on.

So the stiffness of an enclosed volume of gas is the same for all gasses.
The resonance frequency of a woofer will be unaffected by it.

That's not what we're talking about,

** Yes it is.

You bullshitting, tenth wit asshole.




..... Phil

 

[William Sommerwerck]

"Phil Allison" wrote in message news:bgkj0mFas01U1@mid.individual.net...

> k is temperature-dependent.

** Irrelevant when there are simply no temperature changes going on.

They can occur when you compress (or rarefy) the gas. What do you think the
terms "adiabatic" and "isothermal" refer to?

 

[Phil Allison]

"William Sommerwanker"

Here's the answer to your question about Boyle's Law (which you will
ignore, of course)...

PV = k assumes a constant temperature.

** PV= k shows that it does not matter what the gas is - the same
volume
changes produce the same pressure changes.

Uh... No it doesn't.

** Yes it does.


> k is temperature-dependent.

** Irrelevant when there are simply no temperature changes going on.

So the stiffness of an enclosed volume of gas is the same for all gasses.
The resonance frequency of a woofer will be unaffected by it.

That's not what we're talking about,

** Yes it is.

You bullshitting, tenth wit asshole.

You simply have no case - so fuck off.



..... Phil

 

[William Sommerwerck]

Consider the following statements:

"For a fixed amount of an ideal gas kept at a fixed temperature, pressure and
volume are inversely proportional."

Right? Now this one...

"Boyle's law is used to predict the result of introducing a change, in volume
and pressure only, to the initial state of a fixed quantity of gas. The before
and after volumes and pressures of the fixed amount of gas, where the before
and after temperatures are the same (heating or cooling will be required to
meet this condition), are related by the equation P1V1 = P2V2."

See the disclaimer? Compressing/expanding a non-ideal gas heats/cools it.
Assuming that both air and SF6 are non-ideal, this produces a non-linear
restoring force. SF6 is supposedly closer to ideal, so it should provide lower
distortion in a "true" acoustic-suspension system, where the gas provides a
big percentage of the restoring force.

You'd better give up, because I'm going to keep posting this until you do.

 

[Phil Allison]

"William Sommerwanker"

Here's the answer to your question about Boyle's Law (which you will
ignore, of course)...

PV = k assumes a constant temperature.

** PV= k shows that it does not matter what the gas is - the same
volume changes produce the same pressure changes.

Uh... No it doesn't.

** Yes it does.


> k is temperature-dependent.

** Irrelevant when there are simply no temperature changes going on.

So the stiffness of an enclosed volume of gas is the same for all gasses.
The resonance frequency of a woofer will be unaffected by it.

That's not what we're talking about,

** Yes it is.

You bullshitting, tenth wit asshole.

You simply have no case - so fuck off.



..... Phil

 

[Phil Hobbs]

On 12/09/2013 06:02 PM, Phil Allison wrote:

"William Sommerwanker"

Here's the answer to your question about Boyle's Law (which you will
ignore, of course)...

PV = k assumes a constant temperature.

** PV= k shows that it does not matter what the gas is - the same
volume changes produce the same pressure changes.

Uh... No it doesn't.

** Yes it does.


k is temperature-dependent.

** Irrelevant when there are simply no temperature changes going on.


So the stiffness of an enclosed volume of gas is the same for all gasses.
The resonance frequency of a woofer will be unaffected by it.

You're quite right that the compressibility of the gas *at constant
temperature* is very nearly independent of the composition, by the ideal
gas law. However, acoustic waves aren't isothermal, they're nearly
adiabatic (i.e. heat doesn't have time enough to diffuse very far in one
acoustic cycle). In an adiabatic process, the compressibility depends
fairly strongly on the number of degrees of freedom of the gas molecule.

There's a quite reasonable discussion at
<http://en.wikipedia.org/wiki/Adiabatic_process#Ideal_gas_.28reversible_process.29>

SF6 has lots and lots of degrees of freedom.

Cheers

Phil Hobbs

--
Dr Philip C D Hobbs
Principal Consultant
ElectroOptical Innovations LLC
Optics, Electro-optics, Photonics, Analog Electronics

160 North State Road #203
Briarcliff Manor NY 10510

hobbs at electrooptical dot net
http://electrooptical.net