Plasmatronics listening is a little more complicated than with conventional speakers.
First and foremost, we recommend wearing polarized sunglasses while listening to protect your eyes. However beguiling, try not to stare at the plasma cells while they are operating.
Second, you’ll need to make sure the two internal helium tanks are filled up. If you haven’t filled yours in a few years, each tank runs around $200 each for industrial grade helium (with a tank exchange) here in Southern California in March 2015. I haven’t tried balloon grade helium which is substantially less expensive. Helium prices have risen 5x in the last fifteen years.
You’ll have to adjust the gas flow and current bias meters after startup.
Recently we bypassed the internal passive crossover and decided upon triamplification mode using an electronic crossover, which raises the obvious question:
What are the appropropriate settings for the crossover?
Our initial starting point was with an 800 Hz, Butterworth, -12 dB octave setting for the midbass to plasma driver and a 200 Hz, Butterworth, -12 dB/octave for the bass to midbass driver.
The acoustic polarities all match now, and am trying to figure out how to set the relative delay settings, which is not the easiest of issues.
The speed of sound is based on three variables: the adiabatic constant of gas, the molecular mass of gas, and the temperature.
Using a handheld IR thermometer to measure the temperature, the majority of measurements were around 460 degrees F at the center of the plasma after warming up.
When striking it’s around 250 degrees F and I did get a few edge readings of the plasma at 650 degrees F. Room temperature was 75 degrees F.
In a pure helium environment, this calculates out to 4,316 ft/second. A bit different than the 1,132 ft/second of air. Obviously the gas in the chamber is not pure helium either.
My next step is to make some impulse measurements (ETC) of the system and observe the differences in arrival time between the three drivers.