"SACD and DVD-A proven no better the CD in a year of listening tests"

Yes, but with the .1 channel fed to the HVAC system in a sealed room, you'd have some potential to change the barometric pressure.

Yes, but with the .1 channel fed to the HVAC system in a sealed room, you'd have some potential to change the barometric pressure.

Well, since the 'V' in HVAC stands for 'Ventilation', I think that you might have a bit of a problem with this...   

Now Steve, don't throw cold air on his warm ideas! 

If you search the inner recesses of your brain (or maybe someone elses brain through subliminal techniques),
you might recall that there IS a subwoofer available that DOES go down to DC, assuming it is mounted at
the room interface and the room is well sealed.  If I can find the link I will post it, but I think it was discussed
here before and works like a fan with blades that can change their tilt dynamically (or statically for that matter).

Now if you fill the room with bats who had to take the day off from work due to FOEN you could make full
use of the dramatic range of Bert's brilliant but somewhat atmospheric conception.

 

If you search the inner recesses of your brain (or maybe someone elses brain through subliminal techniques), you might recall that there IS a subwoofer available that DOES go down to DC, assuming it is mounted at the room interface and the room is well sealed.  If I can find the link I will post it, but I think it was discussed here before and works like a fan with blades that can change their tilt dynamically (or statically for that matter).

Doesn't really work though - all reasonable loudspeakers respond to DC - if you apply +ve DC to the positive-marked speaker terminal, the speaker moves forward and stays there until you remove it. Also, if you compare the volume of air moved forward by even a large speaker cone, and its effect on the elastic medium it's compressing (which averages out over the room), you'll find that it's well less than the volume of air you are breathing in and out. And so, your mere presence within the space invalidates any DC air compression effects by the loudspeaker completely!

Doesn't really work though - all reasonable loudspeakers respond to DC

.

Depends upon what the definition of reasonable is.

And unlesss I am entirely mistaken, I do not that Bert was suggesting anything reasonable!

Here is the subwoofer if which I spoke, which if mounted at the room interface (read through
the optional installation instructions), can raise the atmospheric pressure in a fairly well sealed
(perfect seal not needed) room.  Since "sound" is a pressure variation this would represent
response to DC.

It is not a sub-woofer I would choose to use, but I do have a problem with FOEN or cats or
bats either!

Doesn't really work though - all reasonable loudspeakers respond to DC

.

Depends upon what the definition of reasonable is.

That they follow the Rice/Kellogg design... in other words, that they have a moving cone with a surround, at a bare minimum. And the voice coil has to be sealed from the rear of the cone as well - which not a lot of loudspeakers achieve particularly well.

Here is the subwoofer if which I spoke, which if mounted at the room interface (read through
the optional installation instructions), can raise the atmospheric pressure in a fairly well sealed
(perfect seal not needed) room.  Since "sound" is a pressure variation this would represent
response to DC.

A perfect seal is needed. If the air can return to its previous pressure state, then you have an AC response, albeit a very low frequency one. And at VLF, and even more so at DC, it's the pressure of the entire vessel that you have to consider, because we are not talking about a wave propagation effect at all.

I feel deeply depressed about what my post has caused. I intended it for being taken as a joke, but obviously my language skills in English are bad enough that my words had not been taken ironically. Assume a heavy cone loudspeaker with an effective diameter of 38 cm perfectly sealed experiencing an excursion of 1 cm. This will move approx. 1 litre  (0.001 m3) of air. A common small living room of 5 x 5 x 2.5 m has a volume of 62.5 m3 or 62500 litres. Thus for a change of 1 mbar in a medium barometric pressure of 1000 mbar there is need for 62.5 such speakers.  I hope that someone living in the imperial world can translate this into imperial units. Although the speakers might be placed on one wall only (it is the same number even in imperial units),  it must be noticed that the changes caused by FOEN usually are several mbars. Furthermore - based on 8 Ohm units connected in series, they would present a load of 500 Ohms which is rather uncommon for most power amplifiers. BTW: Fortunately I personally do not suffer by FOEN.

You could connect them in series/parallel configuration. That way you could get the impedance nearer to 8 ohms.

Thus for a change of 1 mbar in a medium barometric pressure of 1000 mbar there is need for 62.5 such speakers. 

I am deeply depressed by the fact that after I go to all the trouble of re-sealing and re-caulking my room, then find enough amplifier power to run them all, the formidable challenge remains of where to find a half speaker that still works.

Thus for a change of 1 mbar in a medium barometric pressure of 1000 mbar there is need for 62.5 such speakers. 

I am deeply depressed by the fact that after I go to all the trouble of re-sealing and re-caulking my room, then find enough amplifier power to run them all, the formidable challenge remains of where to find a half speaker that still works.

No, it's not quite that bad... If you use a series/parallel arrangement, you can present a much more sensible impedance to the amp - but you are still going to need a lot of power.

Think 2 x 8ohm speakers in series (16 ohms). Then get another two, also wired in series, in parallel with the first pair. You then have 8 ohm speakers still presenting 8 ohms to the load. The snag so far is that for the same displacement, you'll need more volts and more current - you don't get owt for nowt. But by extending the principle, you should be able to achieve a drivable load, I think - if you have a DC coupled amp that's up for it, of course... but like I said, you are going to need a lot of power.

I've just seen this result attributed to "bias"!  Someone has no concept of what testing means, I think.

[A new type of Loudspeaker]

the formidable challenge remains of where to find a half speaker that still works.

Why artificially limit the universe of consideration?! 

A new type of Loudspeaker

A motor controller and electric motor rotate a set of blades at a constant speed. The TRW-17 Rotary Woofer pitch mechanism uses a conventional voice coil and magnet assembly. This is connected to your amplifier to pitch blades in proportion to the applied audio signal. As the blades pitch while rotating a pressure wave is generated, the degree of pitch controls the amplitude of the pressure wave. Air is allowed to transition through the blades. Thus oscillating the pitch of the blades creates sound while they are rotating .

One advantage of the Thigpen Rotary Woofer (patent pending) occurs in understanding the impedance match with the air in this approach to sound reproduction versus the impedance mismatch with the air in a cone woofer.

The air density is much too low and the velocity of sound in air is too high to be a good impedance match with a cone loudspeaker at low frequencies. Take your hand and try and grab some air or flatten your hand and try and push some air as fast as you can. This illustrates the futility of trying to move air to create a small amount of pressure at low frequencies with a cone speaker. You can barely feel the resistance of the air to the motion of your hand, the air molecules simply slip around.

Now take your hand while driving down the road and stick it outside the window of a car. The faster you go the thicker the air feels. Also a simple twisting of your hand enables you to deflect a large number of air molecules. This illustrates the way the rotary woofer works and how effectively it couples moving blade surfaces to the air to create sound pressure. Because of aerodynamic affects and swept area versus frequency, the displacement of the rotary woofer pitch mechanism barely has to increase at all as the frequency goes down.

A speaker cones displacement must increase four times for each halving of frequency to maintain the same output. This is why conventional cone woofer companies are trying to develop “long throw” woofers adding more and more amplifier power. These types of subwoofers are extremely inefficient.

A second advantage with the rotary woofer is understanding that the electric motor provides the energy to make the sound, not the audio amplifier. The audio amplifier provides the energy to pitch the blades which represents a small amount of the total energy input.

The rotary woofer represents a new and much more efficient way to move air at low frequencies.

Several of these and you can very substantially increase the DC pressure in a room!

(even with leaks in the room) 

There might be a small problem with a whirring noise on quiet passages (the MFG, of course, does not comment on this).

Here is the Freq response measurement:



You will need another Woofer to take over above 40Hz, (i.e - a regular muli-element speaker system) and then some pretty good tweeters to handle the above 40Khz (for your 192Khz sample rate), otherwise you are set to go.

The rotary woofer represents a new and much more efficient way to move air at low frequencies.

Several of these and you can very substantially increase the DC pressure in a room!

(even with leaks in the room) 

What you have effectively done is to cause a local DC offset in the air, and modulated it. What you can't do with this system is create a relative offset in the other direction without stopping the fan and rotating it the other way. The transmission linearity of this system is going to be simply appalling! At the heart of it, what you've created is a system where the air velocity is controlled, not the pressure.  In fact, if you ran this system in a relatively small enclosed space, you couldn't possibly cause any pressure shift across the entire space at all - think about it!

So you have whirring, and wind noise, and to top it all, the enormously bad smell of a right load of BS...... 

What you have effectively done is to cause a local DC offset in the air, and modulated it. What you can't do with this system is create a relative offset in the other direction without stopping the fan and rotating it the other way.

Wrong.

The blades when aligned to neutral generate no pressure,  when tilted "full clockwise" generate positive air pressure, when tilted "full counterclockwise" generate negative pressure.  (the fan does not need to reverse because the blades will tilt BOTH ways). And it IS pressure we are talking about here since the fan (Just like many rotary impeller devices including most water pumps) is acting as a pump.  The transfer function can be made to be fairly linear too.  This thing has been demonstrated at a number of Audio Conventions and t really works down to DC as advertised. If you baffle it sufficiently, it can even be made to be "fairly" quiet, but not quiet enough for me  , besides, I am not particularly interested in any sound under say 20Hz or so.

But then, ultimate practicality is NOT what is called for here because we are fighting the SCOURGE of FOEN!!

(but then some people do not seem to have any sense of humor whatsoever)

The blades when aligned to neutral generate no pressure,  when tilted "full clockwise" generate positive air pressure, when tilted "full counterclockwise" generate negative pressure.  (the fan does not need to reverse because the blades will tilt BOTH ways). And it IS pressure we are talking about here since the fan (Just like any rotary impeller is acting as a pump. 

It's true that you could make it flow both ways, but you are wrong about this being a pressure change.There is NO WAY that this is a pressure change - because that fan is suspended freely in an elastic medium that is not contained. It is a velocity change - it has to be. It's the same as with weather changes - what appears to be an increase in pressure in one place has to be caused by a flow in another - usually a long way away. But it's not a static effect - it's only the rate of change passing though zero at the centre. And because air is an elastic medium, that change will not be constant, and will be represented throughout the atmosphere as a gradient - just as it is on any weather map. Any locally generated effect that isn't contained can only be achieved by molecular movement of the air, not compression of it.

Just because they told you it was a pressure change, it doesn't mean that they know what they are talking about - because if they said this, then they don't. I had a look at the website, and the only accurate statement about it was the last one in the explanation, which says

The rotary woofer represents a new and much more efficient way to move air at low frequencies.

That's move it, not compress it. Whoever wrote their advertising copy should learn the difference. In fact, even a trivial analysis of this device reveals that it is effectively behaving as a very long-throw unsealed cone - which it would have to be to partially overcome the impedance mismatch at low frequencies. The impedance is the force divided by the velocity - there's not a lot they can do about the velocity in free air (it's pretty much fixed at about 330m/s), but by increasing the force they can reduce the effect of the mismatch, but not the mismatch itself. The idea that they can force more air over the blades by rotating them  simply compensates for the fact that it is not sealed. In all other respects it behaves as a cone driver would - albeit with more force. And if you really want to analyse how it works, you have to look at mass-spring systems, because that's exactly what this is.

Pumps inherently cause flow, not pressure. And this thing is a reversing pump, so it wouldn't cause a constant pressure anyway. To cause a build-up of pressure, you have to have containment. Any changes in pressure will only happen as compressions and subsequent rarefactions of the wavefront - they won't occur as the equivalent of DC at all.