partial pressures of each gas chemical species/component are what drive diffusion, what eventually equalizes - although the earth's atmosphere is kinda dilute in SF6
long ago HeNe lasers had He diffusion life limit - but you could put the fading tube in a bag filled with He and it would top off the laser He to a workable fraction by diffusing from the 1 atm He in 10s of hours
long ago HeNe lasers had He diffusion life limit - but you could put the fading tube in a bag filled with He and it would top off the laser He to a workable fraction by diffusing from the 1 atm He in 10s of hours
As a sealed subwoofer is a simple compression spring design, I would assume that whatever gas you placed INSIDE the speaker box, Boyle's Law would dictate the speaker would feel the same back pressure vs displacement whether you used Sulphur Hexafluoride, Helium or ordinary air!
In a quarter wave pipe design, the resonance would change based on the speed of sound in the gas but of course, the gas would escape in any 'open air' design.
If you wanted to pump the entire room with Sulphur Hexaflouride, then the increased acoustic impedance could give you more output. A bass reflex design would have its tuning lowered by increasing the mass of air in the port.
The only way I know of to increase the compliance of a sealed box is to, Loosen the driver slightly, lug it up mount Everest, Re-tighten the driver, plug into your 12 Volt inverter and listen. The lower atmospheric pressure on both sides of the driver would give you more compliance. You would lose some SPL from the thinner air. Or you could simply build a bigger box!
In a quarter wave pipe design, the resonance would change based on the speed of sound in the gas but of course, the gas would escape in any 'open air' design.
If you wanted to pump the entire room with Sulphur Hexaflouride, then the increased acoustic impedance could give you more output. A bass reflex design would have its tuning lowered by increasing the mass of air in the port.
The only way I know of to increase the compliance of a sealed box is to, Loosen the driver slightly, lug it up mount Everest, Re-tighten the driver, plug into your 12 Volt inverter and listen. The lower atmospheric pressure on both sides of the driver would give you more compliance. You would lose some SPL from the thinner air. Or you could simply build a bigger box!
PROJECT 8: THE OXYGEN-FREE LISTENING ROOM.
If oxygen-free copper is a good thing, then clearly oxygen is a bad thing for audio. The largest quantity of oxygen the sound is likely to encounter is in its passage through the air from loudspeakers to listeners. The only way to address this is: The Oxygen-Free Listening Room, which is filled with SF-6.
On the left , breathless with excitement, a couple of brave "volunteers" prepare for a listening session. The "listening room" is on the extreme left.
There have been criticisms of the acoustics of a steel cylinder, but this is the kind of petty-minded carping that greets every major breakthrough.
gasses in bass enclosure
During the late 70's, early 80's
Cerwin Vega had a speaker enclosure with a rubberized bag filled
with Helium and Argon, worked great.
During the late 70's, early 80's
Cerwin Vega had a speaker enclosure with a rubberized bag filled
with Helium and Argon, worked great.
From the CV patent (4,101,736):
The gas 30 or fluid 34 which may be used may be a flurocarbon such as Freon 11, Freon 113 and Freon 114 or any gas or fluid which has a gaseous state with a gamma less than 1.4, such as carbon-dioxide (CO.sub.2), and a compliance factor which is larger than the compliance factor for air [1/(.rho.)c.sup.2 ]. In TABLE I, which is set out below, several appropriate compounds are listed with their physical properties that make them useful in the present invention.
(see post #9 for the patent abstract)
The gas 30 or fluid 34 which may be used may be a flurocarbon such as Freon 11, Freon 113 and Freon 114 or any gas or fluid which has a gaseous state with a gamma less than 1.4, such as carbon-dioxide (CO.sub.2), and a compliance factor which is larger than the compliance factor for air [1/(.rho.)c.sup.2 ]. In TABLE I, which is set out below, several appropriate compounds are listed with their physical properties that make them useful in the present invention.
(see post #9 for the patent abstract)
at that time, I was Western Sales rep. Canada for Cerwin Vega, Marantz,
and little known...Superscope. BC, Alta., and Sask.
That was roughly 40 + yrs. ago.....still alive and kicking, fairly good memory(s)
of those times.
I may be wrong about the gas in the bags in spkr. cavity.....but was long ago.
If you know better then OK. I do remember technical arguments between
employees:
and little known...Superscope. BC, Alta., and Sask.
That was roughly 40 + yrs. ago.....still alive and kicking, fairly good memory(s)
of those times.
I may be wrong about the gas in the bags in spkr. cavity.....but was long ago.
If you know better then OK. I do remember technical arguments between
employees:
Datapoint:
I had the Dayton-Wright SF6 ESLs for about 35 years. Before selling them recently, I tested with the bias knob full - maybe 12kV, not sure exactly. No noises or sparks in the dark. So I'd conclude the gas was still sitting inside.
(While the SF6 treatment has several benefits, inevitably playing in a mylar-fronted box has drawbacks when we are talking about the sparking-clean sound of ESLs. Today, I am using panels comprised of Dayton-Wright cells in fresh air and rather prefer it, even if I can't get the amazing low frequencies the SF6 ESL boxes provide.)
Not sure I'm able to understand all the physics issues, but I do know the great challenge in HiFi is setting light air in motion using relatively heavy "motors". The issue is more than just eyeballing a sim and thinking you need a bit more power. Having a proper impedance match results in a degree of degenerative feedback that is sorely lacking with cone drivers (unless you use motional feedback, of course).
Ben
I had the Dayton-Wright SF6 ESLs for about 35 years. Before selling them recently, I tested with the bias knob full - maybe 12kV, not sure exactly. No noises or sparks in the dark. So I'd conclude the gas was still sitting inside.
(While the SF6 treatment has several benefits, inevitably playing in a mylar-fronted box has drawbacks when we are talking about the sparking-clean sound of ESLs. Today, I am using panels comprised of Dayton-Wright cells in fresh air and rather prefer it, even if I can't get the amazing low frequencies the SF6 ESL boxes provide.)
Not sure I'm able to understand all the physics issues, but I do know the great challenge in HiFi is setting light air in motion using relatively heavy "motors". The issue is more than just eyeballing a sim and thinking you need a bit more power. Having a proper impedance match results in a degree of degenerative feedback that is sorely lacking with cone drivers (unless you use motional feedback, of course).
Ben
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CV's S1 was a lot of fun back in the day with my DH200 - not sure if the underdamped 2nd order highpass eq box was as quiet as it could have been.
Also, the mylar boundary films moved in an out a bit with the weather in my music room, and otherwise felt firm like a big beachball. Further indicating DWs were gaseously intact after 35 years.
The speakers have Schrader valves for gas management... same as on your car tires. Simple.
I wish I could contribute more about the acoustics. The DW speakers, as best as I can recall, have a resonance (with gas) around 55 Hz and it is mild. You'd be surprised (if all you know is what you learn by reading) that the sound on almost all acoustic-instrument music is just wonderful with that bass. Except of course, music which esp. features lower bass.
Now here I am just guessing, but I think those cells vibrate in free air around 100 Hz.
Again, it isn't just the resonance lowering that is needed but the damping by virtue of improved impedance matching (AKA degenerative feedback), at least for film diaphragms. The situation may be hopeless for shaking-cardboard drivers.
B.
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Busy lamenting past......Was only fellow in Canada, able to sell Marantz "8"'s
during early 80's, that and tuner was $ 700 + new with extra tubes in fancy
lined box.
Took entire stock as had one great audiofile, on West 41st, Van who could sell same. We slowly sold them all, I think was 18 sets. DIDN'T take one for myself
......long mental kick of my own ***.....!
Dealer was happy with transactions.....so much so, offered me beautiful teak
Paragon, all JBL's best, 2500 bucks, no crossovers, was fed from 3 stereo Sony amps....with rare Sansui control unit.
Was moving into smaller, exclusive digs, not enough room, and was 850 lbs.
Didn't grab, still have bad dreams about that one.
Guy bought it added Ess tweeters along side bullets.....best sound ever.
TOO SOON OLD........Too late Smart !!
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