Pass plasma speaker history?

[roddyama]

Re: The Ionic Man

Who is that man and what is that he is standing by?

H.H.

Let's see,... A Best Buy salesman showing off the cooling coils from the new GE refrigerator.

 

[Michael Rothacher]

You mean they airbrushed out your Ked's? Is nothing sacred?

 

[Prune]

Is RF modulated signal driving a tesla coil necessary for a plasma tweeter? Why not just amplify the AF to a few kV and send to the electrodes? Power amp into 1:1000 audio-band custom transformer, anyone?

 

[Lisandro_P]

Well, getting zapped by a few mW at 10kV is *no* fun... multiply that 10000-x fold. I won't be arround that speaker, thank you very much

 

[Prune]

Thanks, but no one asked for your patronizing.

 

[Jennice]

Regarding the "Ionicman" picture that H.H. attached...

Has anyone (certainly not the designer!) considered the Wife Acceptance Factor of those things!?!?!?

 

[phase_accurate]

Regarding the "Ionic Man":

This is definitely not N.P. because he prefers to wear sneakers together with a business suit !!!!

Regards

Charles

 

[Nelson Pass]

Actually, the photographer lent me his boots for
the photo, as they didn't want the sneakers.

 

[splodman]

Nelson,

When did you work on your "Ion Cloud Loudspeaker", and was it very loud?

Adam

 

[MIKET]

History Lesson

Go to
www.ionovac.com

and get a history lesson on an early plasma tweeter that was in production for a few years.

The basic problems with plasma are either OZONE or RF.
If memory serves me right the Ionovac was shut down by the FCC, because it was a great radio station.

 

[Prune]

RF is just one of the problems from these tesla coil-driven, modulated corona discharge tweeters. Hill's Plasmatronic tweeters used neither RF nor corona discharge, but a glow discharge into helium. The disadvantage there is obviously the need for a helium supply. Recent research into getting a stable glow discharge into air (by the use of microhollow cathode discharges) should allow a Hill-type plasma speaker without the need for a tank of gas.
More in this thread: http://www.diyaudio.com/forums/showthread.php?s=&threadid=29600&pagenumber=2

 

[jackinnj]

This is the first time I've seen a set for sale: http://cgi.ebay.com/Rare-DuKane-Ion...s_R2?hash=item1e57e635b6&_trksid=p3286.c0.m14

 

[vdi_nenna]

And then there's the Stereophile interview...

http://www.stereophile.com/interviews/1191pass/

 

[Nagrapex]

Plasma Tweeter electrode material

Hi,

I build a pair of plasma tweeters, and there is no smell even after hours, likely because it is hot inside the housing.

Ozon falls to pieces fast, when it is hot.

This is not my explanation, just read it somewhere else.

Bernhard

Hello Bernhard,

it has been a long time since you wrote this post, but I hope you might be able to help my DIY efforts. I have built plasma tweeters, and they work very well. The problem is the electrode. I have tried Kanthal, Tungsten, Platinum-plated Kanthal and Stainless Steel (various alloys). So far, I have not found anything that lasts very long without oxidizing too much to start up. The stainless steel seems the best from an oxidation point of view, but it disintigrates faster than Kanthal does. Tungsten oxidizes very quickly.

Could you tell me what material you used for your electrodes, and how you obtained it? It would be a huge help!

Thanks,
Jonathan

 

[Nelson Pass]

I recall that Gold will not tend to oxidize, nor Platinum.

I used tungsten wire, the kind found in copy machines.

 

[Antoinel]

I recall that Gold will not tend to oxidize, nor Platinum.

I used tungsten wire, the kind found in copy machines.

Carbon nanowire [or the filament of Edison's incandescent light] maybe oxidized in situ by O3 to preferably CO2 and not CO. It is preferable to pursue cheap metal wires which oxidize [sacrificial]; Magnesium to MgO, Aluminum to Al2O3, Copper to CuO, Iron to Fe2O3, etc..I remember the spoof about Cold Fusion. Platinum and Palladium do absorb and split Dihydrogen [to a field of Hydrogen atoms] by as much as 30% their weight, and retain electrical conductivity. Toxic O3 plus Hydrogen atoms will no doubt make water vapor.

 

[Nagrapex]

Electrode material for plasma tweeter

I recall that Gold will not tend to oxidize, nor Platinum.

I used tungsten wire, the kind found in copy machines.

Hi Nelson. I remember seeing your speaker on the Stereophile cover back in the day. What fun. I wonder if that Tungsten wire wasn't some kind of an alloy (thorium, etc.) to help prevent oxidation. Maybe the next step is some TIG welding electrode material.

I didn't think of gold. The melting point is a bit low, but it might work if I didn't care about the cost. The 30um platinum plating only lasted a few hours before it was eaten away, exposing the Kanthal base material. Solid platinum would work very well, I am sure.

Jonathan

 

[Antoinel]

It also had several flaws, one of which did result in a
trip to the local emergency room with breathing problems
similar to those sometimes experienced by arc welders and
caused by extended exposure to ozone.

The Wall Street Journal printed my comment:

"It was the perfect high end audio product: Exotic, inefficient,
expensive, unavailable, and toxic."

EPA calculates an acceptable exposure [for adults] equal to 80 parts per billion of Ozone in air during 8 hours. Given:

• The volume of the living space with active closed-loop air circulation.
• A living space with furnishings which are organic in nature, and thus are attacked [oxidized] by the circulating ozone; thus depleting it.
• Then, one can calculate a maximum weight/second of generated ozone by the Pass speaker to satisfy the EPA number.
• Calculate the weight of air = volume of the living space [milliLiters] multiplied by the density of air in milligrams per milliLiter.
• Convert milligrams to nanograms.
• Multiply the weight of air by 80 X10E-9 [nano scale; EPA requirement]
• The answer is the weight of ozone in nano grams generated from the Pass speaker.
• Add the time element to it [per second] with the cautious assumption that in that second, the generated Ozone disperses fully in the whole living space, and is completely consumed by organics therein.

I'll do a sample calculation and report the result.

 

[Antoinel]

Here is a sample calculation per the previous post.

• Density of dry air at 20 Celsius is 1.2041 Kilograms per cubic Meter.
• A living space of net volume [plus furnishings] = 16,000 cubic feet. It is 2000 square feet floor space muliplied by 8 foot ceilings.
• 16,000 cubic feet is 453 cubic meters
• Weight of air in living space is 545 Kilograms.
• Weight of Ozone in the livng space = 545 Kilograms of air multiplied by 80 x 10E-9. The answer is 4.4 x 10E-5 Kilograms.
• The answer is also 44 milligrams.
• Two unknowns exist. First; what is the average output per hour [rate of generation] of Ozone from the Pass loudspeaker? Is its value in micrograms or milligrams; must know this specification?. Second; what is the average rate of Ozone depletion per hour via oxidation pathways in the living space; assuming an effective circulation of its air laiden with Ozone?
• The above calculation is clearly a guide, and a fun exercise. It is best to have a certified laboratory determine Ozone quantitavely. Called monitoring. Or one buys a certified direct reading Ozone detector; if such a device exists.

Best regards
N.B. Google shows the availabilty of devices which directly read Ozone levels,

 

[Antoinel]

Checked Google for Ozone generators. A Sylvan Ozone Generator puts out 3,400 milligrams per hour to be injected in a space of 160,000 cubic feet so as to kill odors. This amount of ozone calculates to be 600 parts per billion ~10 times the EPA number; clearly banking on this peak number [at time zero] to be depleted quickly with adequate air circulation to or below the acceptable 80 ppb as it neutralizes odors.