Yes special hi dfi air for the listening room. It has to be an air tight room, and needs to be replenished every so often. Why is it better than normal air? Ah well, it has precicely the right humidity and negative ions to make speakers mor complient in most temperatures. brian
"most temperatures"?
Amateur! Don't you _CARE_ about your listening experience?
Bugger me, I see some tripe in this newsgroup. Worrying about temperature?! Did you forget about Boyles law? There's pressure too for god's sake!
I took it for granted that the listening room was pressure-controlled. Doesn't everybody do that?
No point in having a pressure controlled room unless it tracks the listener's blood pressure and maintains it relative to that.
The room needs to be completely isolated acoustically, too.
Visiting someone who said his listening experience was ruined by RDS interference, he turned his volume up so that we could hear a very slight background noise. His wife then flung open the door and yelled "Turn that bloody row down!"
In message , charles writes
RDS? Really Dreadful Spouse? A common source of interference; easily rectified though.
Surely such trials are better conducted in vacuum, to ensure no distortion from passing air molecules?
Theo ;-)
Oxygen-free air?
Well, nitrogen filling is suggested for car tyres - that might work better than normal air with it's unpredictable mix of molecules.
Well I like it cool. Mind you at least I'm not running Lowther speakers that need to be turned every few months and fall to bits every five years and need reconing. Brian
The oxygen-free listening room was done some time ago:
Automated ear syringing as well?
Was that a typo, or a Freudian slip?
Unpredictable? The mix is pretty predictable (20.946% Oxygen, 78.084% Nitrogen, 0.9340% Argon, 0.035% Carbon Dioxide[1] and 0.002691% of trace rare gases) other than a variable quantity of water vapour.
However, it is true that the composition of that mix after inflation to circa 2 bar for six months or more will be less predictable due to different rates of diffusion through the walls of the rubber tyre and the materials used for the wheel rim (I've no doubt the tyre manufacturers may well have some empirical data to reduce the uncertainty level in the exact composition of an air filled tyre after charted time periods under different operational/storage conditions - if anyone knows, it'll be the tyre manufacturers even if no one else does).
Pure *dried* Nitrogen is used by aircraft and F1 race cars. Aircraft operate at altitudes where the temperature can drop below -40 deg C causing moisture to accumulate and freeze in one spot which, in turn, causes imbalance and severe vibration on landing. The benefit of Nitrogen for F1 race cars is that the lack of moisture helps to reduce tyre temperature under extreme race conditions.
In both cases, the key aspect of using compressed Nitrogen is that it is supplied completely free of any water vapour content. Dried air can provide almost the same benefit.
However, the molecules of Nitrogen diffuse more slowly through the tyre than the smaller Oxygen molecules so will maintain tyre pressure for a longer period than a filling of compressed air which is of greater significance in the case of tyre pressures higher than 14 bar (in excess of 200 Lbs/sq inch) typically used by commercial aircraft.
In the case of commercial aircraft, pure nitrogen reduces the risk of fire from overheating. Dried air in F1 race cars would give the benefit of a 'Nitrogen Fill' (moderate to low pressures) but the oxygen content at 200 Lbs/sq inch simply represents too great a fire hazard for commercial aircraft use.
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It sounds like you aren't aware that various tyre chains will offer to sell you nitrogen filling.
Or that CO2 is used by F1 teams, as was revealed inadvertantly in one of those "Oops, we f***ed up the redaction" F1 industrial espionage reports a few years ago. CO2 inflation, via soda-stream type cartridges, is also widely available for bike tyres.
They use nitrogen bubbles in guinness too.
I *think* this quote is more accurate: "Mixed gas comes in an all-in-one air tank that contains 75% nitrogen and 25% CO2."
That's a surprise. I thought they'd care about the extra weight.
I'm sure I heard a rumour about helium a few years ago!
Andy
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