MP-02 style plasmatweeter
If someone have any idear how to make the balls out of stainless steel mesh please left me a note. Here I am using mesh balls from original Magnat development which I had the chance to buy many years ago but the outer ball is missing.
some pictures from ongoing development...
Wenn jemand einen Hersteller kennt der diese schönen Kugeln aus V2A Drahtgeflecht herstellt oder diese Kugeln sogar selber machen kann würde ich mich über eine mail freuen !!!
Ich habe noch ein paar alte aus dem Magnat Versuchslabor - wie man hier sieht - aber dort fehlt die Außenkugel. Zwei ineinander geschachtelte Kugeln sind notwendig sonst stink der Hochtöner nach Ozon. Das wird auf Dauer unangenehm und man muß ständig lüften.
History - My old dream...
It was 1993 when I the first time decided to build a Magnat MP-02 like tweeter. I don't want to spend over 2000.- DM (EUR came years later) for a pair of original Magnat. I thougt it could not be that difficult. The RF Transistor was expensive too but I had a big collection of tubes. I decided to use a beam power tube EL519 for the self oscillating device. My first plasma tweeter was born and I had a lot of fun matching it with different type of speakes.
I shared it with the DIY community on my old site "www.plasmatweeter.de" in the hope that there are other enthuisiasts out there to improve the circuit. After 25 years now I can say this did not really happened, maybe but I don't know about. My old circuit plan is circulating all over the world mostly unchanged.
A while later I make a new circuit for the modulation with a transistor. This version was often copied and some guy's improved it with more modern FET devices.
Time to make a new one ! Now with transistors. Today they are not expensive and easy to get. One thing I want to mention. Most of the cheap chinese transistors are bad quality. Especially RF transistors. I struggle with this often in my old job. I have a bunch of 2SC1306 and PT 9783, which were used in the MP-02, out of chinese production thrown in the trash because they dont work properly in the circuit. Therefore I always try to use NOS (new old stock) examples.
To start we are using the original Magnat schematic. The circuit is easy to explain. T1 is the oscillation circuit with a crystal locked to 27.125Mhz. T2 is driver and T3 is the RF power amplifier. A simple amplitude modulated transmitter in the CB band with approximately 50W of output power. In the upper section wie have the active crossover with IC1a and IC1b (TL072 or TL082) and IC2 power amplifier STK086. Thats it !