plasma tweeter

[Tekko]

Anyone heard of the "plasma" tweeter that is supposed to be the best kind of tweeter you can have ?

If so, what is your opinions ?

Myself i must say it is really good, i actually tossed one together out of scrap i had laying around, and the sound is really good.

Heres some pics and videos of my test unit:
Click here

Maybe i should mention that my digicam has real poor audio pickup, 8khz sampling.

[Tenson]

wow... what sort of frequency range are you getting from it? Also do you have any designs for such a tweeter?

[Tekko]

I dunno but around a few 100Hz up to over 20KHz, the thing runs on around 10-30MHz.

I just searched google pictures for "plasma tweeter"

[Tenson]

Yeah I found this - http://www.hardcoreaudio.de/

It has nice details but I can't read German! It looks like he may sell the PCB and parts?

[Rodeodave]

Hi,

I don't think that he sells PCBs or parts, and there's nothing about it in the text either.
But you don't need a PCB, it's not too many parts. Just avoid any sharp edges (dealing with HF) and wire p2p. I once wanted to build one of them plasmatweeters, but it became one of my unfinished projects...maybe this summer I'll find the time to finish it...
The parts are all off the shelf (hopefully the right expression), the only special thing is the body of the inductor, it should be made of some kind of electrically isolating material that can take some heat...I built one out of clay (!) that I wrapped around a film can (you know, back in the days people used 35mm film instead of CCDs) with a clay-thicknes of ca. 4mm. Clay's cheap and can be "processed" in a stove

The other (smaller) inductor is said to be a tricky choice, but I don't have any experiences yet.
And the tube will get really hot.

Check out http://www.plasmatweeter.de/ He's got a nice design too and that foreign-language thing. And links.

[Tekko]

I wound my coild on used up solder spools, and yet they seem to cope with the heat, i only managed to melt it near the plasma electrode as it was quite near .

Its the plasmatweeter.de unit i have built.

[Marik]

As a coil form for my plasmas I was using straight shaped glass candle holders, drilling a couple little holes with diamond bits. No overheating problems, whatsoever.

[lndm]

I have built a plasma tweeter and have to say it is very revealing, led me to realise that more deficiencies in my treble reproduction were due to electronics than I realised.

The plasma didn't have an 'edge' or a resonance, it was flat and immediate but not artificial in the slightest.

Biggest problem was the power. I tried horns but they interfered with the plasma, grounding the oscillation. I understand that some have done it. I had to start mine with a screwdriver and couldnt reach the electrode with a fine horn on it.

I used a 30W plate dissipation device and a 600V B+. I tried 6 poles of upper midrange rolloff but could only achieve moderate SPL's.

I believe some have used mosfets as the oscillator with massive power dissipation.

PS the trick to efficiency is to give enough space between the windings (adjust the interwinding capacitance) so that the coil is high Q (maybe a dozen coils with a 1/4" between worked for me).

[georgehifi]

One of the best sounds I have ever heard was a Pair of double stacked Quads 57's, a pair of 36ins Hartleys crossed over at 100hz mounted in the brick wall behind the Quads using the next room as the box box, and a pair of Ionic Plasma Tweeters by Magnat (German) crossed over to the Quads at 10khz, the front end was a Stax Electrostatic cartridge that need to be tuned in with a cro that took about 1/2hr and it stayed in tune for about 15mins, then had to be tuned again. Now that's a system. All this was back in 1976. and i have not heard anything that even comes close in the last 30years.

Cheers George

[bear]

Please beware that in most countries there are rules governing emission of Radio Frequency interference and power levels!

Plasma tweeters emit RF.

In the USA all commercial plasma tweeters are set on a frequency set aside for unlicensed low power operation (in the 27mHz band, iirc).

You need to put a GROUNDED CAGE around your plasma itself, and also put the driving circuit inside a grounded box. Otherwise you stand to interfere with other broadcast and communications services.

his becomes increasingly important as you start to build with higher power/larger tubes.

Fwiw, some are also concerned about the production of Ozone by the plasma, and by shortwave UV light from the plasma.

_-_-bear