[mort]

Can any one explain the basic workings of the Acapella Audio Arts, Spharon Excalibur's horn loaded ion tweeters? these things are amazing, 50KHz and 100 db of sensitivity! How do they sound?

[Double Ugly]

Can any one explain the basic workings of the Acapella Audio Arts, Spharon Excalibur's horn loaded ion tweeters? these things are amazing, 50KHz and 100 db of sensitivity! How do they sound?

I don't have the foggiest about how they work, but I don't recall having heard or read anything but rave reviews.

I heard the Acapella (Triolon Excalibur?) in Denver last October, and I was mightily impressed with the tweeter.  Smooth, extended and detailed, without a hint of stridency or sibilance. 

[JimJ]

http://www.plasmatweeter.de/

So frickin' cool. The DIY page explains the idea, and how to build one...

[TheChairGuy]

At first I thought the plasma tweeter was one of these....a local fella' sells these and I've always been curious about them

http://www.warrengregoire.com/hifi-stereo-ikonoklast-tweeters.htm

Seems it's different, tho.

So many driver implementations, no?  Very confusing 

John

[jon_010101]

I've been tempted to build one.  Basic principle is you generate a plasma "flame" with a strong RF source, and then modulate it at audio frequencies.  The temperature of the plasma varies and forces acoustic waves.  It's a real point source, with negligible mass, and -- if you can avoid interference problems -- it's quite nearly ideal.  I'd be concerned about RF interference issues, ozone generation, and UV light emissions -- i.e., don't look directly at, or sniff, the plasma.  Or touch it 

[JimJ]

Definitely is not FCC Part 15 approved

[Alan]

Anyone remember Nelson Pass' Ion cloud speaker? IIRC he had to go to the hospital for ozone poisoning.

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

[Imperial]

The Acapella tweeter does not create ozon as a bi-product... It's one of the very few not doing this.

Acapella write this on their web page about their ION TW1S:
High voltage within the unit produces a constant arc. This arc is modulated with the musical signal (flame oscillates with the time of the music). This is the reason why the number of electrons within the arc varies. A larger or smaller amount of electrons requires similar space. Due to this variable need of space the surrounding air molecules have to dodge the more or less quickly. This evasive action or bumping of the air molecules generates over-, resp. underpressure and, therefore, sound. In this way, the Acapella ion tweeter is able to reproduce sound without membrane and without mass
Regarding transient capabilities and phase stiffness, the obtained sound quality cannot be realised by using conventional tweeters. Comparing the ion tweeter with other tweeter systems, its unobstrusive sound image will attract you. This kind of reproduction is to be attributed to the lack of harmonic and transient distortions.

Imperial