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Tesla coil based stereo plasma sound system

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Mates

Tue Mar 02 2010, 08:55PM

Registered Member #1025 Joined: Sun Sept 23 2007, 07:53PM
Location: Czech Rep.
Posts: 566

Hi guys,
I started a new project. My aim is to prove that the real super hi-fi quality based on simple resonant transformers is possible. The design employs two ungrounded (bi-polar) Tesla coils working at 4Mhz (ClassE) and amplitude modulation. The scheme is based on Reachingâ€™s great and simple idea

with certain modifications. To avoid any plasma hiss I decided to design the speakers as arc instead of streamers based. This also significantly improves the loudness while reducing the power consumption.
My general feeling from the stereo sound is really good. It still needs some optimization; probably I will need some filter to remove lower sound frequencies, those can be played by normal bass speakers anyway. On the other hand the trebles are reproduced in incredible sound quality (it must be heard to understand).
So the project is still in the beginning, now I plan to box everything up and make some nice complex sound system which could impress few of my friends with sense for a good sound reproduction and maybe even my father who is a classical music freak

Video:

Btw: The sound quality is messed a bit by youtube movie converterâ€¦

Any questions ideas and comments are welcomed!

Cheers Mates

ragnar

Tue Mar 02 2010, 09:27PM

Registered Member #63 Joined: Thu Feb 09 2006, 06:18AM
Location:
Posts: 1425

Mates, looks and sounds very crisp indeed! I hope this one is certainly destined for a dedicated power supply and enclosure.

Did the right-hand discharge become *louder* after interaction from the screwdriver?

raff

Wed Mar 03 2010, 03:52AM

Registered Member #2315 Joined: Tue Aug 25 2009, 02:35AM
Location: Leyte, PH
Posts: 161

I have a question:

ever tried connecting the outputs to a camera FLASH bulb? (xenon?) wonder if the sound is smaller compared to open air arcs..

sportcoupe

Wed Mar 03 2010, 10:08AM

Registered Member #2664 Joined: Sat Jan 30 2010, 03:27PM
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Posts: 12

That is one of the coolest things I have ever seen! Thanks for sharing.

Mates

Wed Mar 03 2010, 12:37PM

Registered Member #1025 Joined: Sun Sept 23 2007, 07:53PM
Location: Czech Rep.
Posts: 566

Blackplasma wrote ...

Did the right-hand discharge become *louder* after interaction from the screwdriver?

Yes, the sound was bit louder. This effect is caused by the fact that by touching the elctrode I increased the distance between. Longer distance between electrodes means higher energy loss in the arc and thus louder sound.

raff wrote ...

I have a question:

ever tried connecting the outputs to a camera FLASH bulb? (xenon?) wonder if the sound is smaller compared to open air arcs..

No, never, but logic and experience tells me that any sound source hermetically encapsulated inside a glass chamber will be much more quite than open air. Btw: Did you ever shorten fully charged flash capacitor by a screw driver? If not I can ensure you get much louder effect than the same discharge performed inside the xenon tube

HV Enthusiast

Wed Mar 03 2010, 03:55PM

Registered Member #15 Joined: Thu Feb 02 2006, 01:11PM
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Posts: 3068

Just keep in mind that you lose a lot of volume and lower end frequency response by having an arc/electrode arrangement. You need lots of surface area for low frequency and volume, and the electrode arc defeats this.

However, its a trade-off between notible hiss and volume.

If the frequency is high enough however, you won't have the hiss with the arcing to air.

Mates

Wed Mar 03 2010, 05:22PM

Registered Member #1025 Joined: Sun Sept 23 2007, 07:53PM
Location: Czech Rep.
Posts: 566

EastVoltResearch wrote ...

Just keep in mind that you lose a lot of volume and lower end frequency response by having an arc/electrode arrangement. You need lots of surface area for low frequency and volume, and the electrode arc defeats this.

However, its a trade-off between notible hiss and volume.

If the frequency is high enough however, you won't have the hiss with the arcing to air.

Actually my experience tells me the right opposite. My first attempts were of course air streamers based arrangements. I played a lot with different types of breakout points like single breakout, multiple breakouts using different wires including ultra thin tungsten wires, but I've never reached satisfactory volume. However, once I tried the arc based design the volume increased in orders while power consumption decreased significantly (actually you can try it by yourself). The absence of plasma hiss is only another extra positive about such approach. Moreover, the hiss in very high frequencies (above 10MHz) is probably not an issue, but there are other practical problems of such coils, so it is out of discussion. The only negative aspect in the â€œplaying arcâ€ design compared to playing streamers is that it looks a bit less attractive (to my eyes at least).

Cheers Mates

radiotech

Wed Mar 03 2010, 06:09PM

Registered Member #2463 Joined: Wed Nov 11 2009, 03:49AM
Location:
Posts: 1546

Mates wrote
"Btw: Did you ever shorten fully charged flash capacitor by a screw driver? If not I can ensure you get much louder effect than the same discharge performed inside the xenon tube "

The sound of a HV capacitor spark affects people in unpredictable ways.Unless they are part of a group accustomed to this activity,
it might cause problems. One person in a group, who was used to ship sonars, simply was struck dumb for a while. After that and other obversations, all public demos of cap sparks was dropped for good.

The demos were to show the dangers of charged caps.

HV Enthusiast

Thu Mar 04 2010, 01:35AM

Registered Member #15 Joined: Thu Feb 02 2006, 01:11PM
Location:
Posts: 3068

The bipolar coils are great btw for this providing you have enough power to get some good arc out of them. We will be offering a full class-e based kit using a a vertically mounted bipolar coil inside a custom machined plexiglas enclosure. Looks very avante-gardish and a perfect display piece. Complete with blue LED VU meter its really sweet!

We're having our machining done by monkeys down in the jungle of some third world country (trying to cut costs) so once we get delivery we'll post some pics. Of course its nice that we only need pay in bananas! :)

Mates

Mon Mar 08 2010, 08:42PM

Registered Member #1025 Joined: Sun Sept 23 2007, 07:53PM
Location: Czech Rep.
Posts: 566

Hi guys,
I spent some time with my new â€œhi-fiâ€ toy. First of all I moved the coils away from the main driver board and I was surprised how long cables I can employ while the coils are still working. So, it looks like there will be no problem to make real satellites without the need to make separate driver with cooler for each of them. Thatâ€™s the good part.
The not so good part is the sound quality. I must say, that the sound is great for the trebles and it really provides extraordinary sound experience, but unfortunately I know quite well what the real high-fidelity means. For example classical music is not reproduced so nicely. Call me a freak but I invested quite a lot of money into my home sound system (NAD amplifier and Celestion speakers) and I know why. As a problem of the plasma sound system I see very primitive way of driving the FET which is responsible for the amplitude modulation. The driver employs only one NPN transitor and I know for sure that modern hi-fi FET amplifiers working in classA use much more sophisticated way of driving the power FETs. I know it is against the rules, but maybe somebody of you know about nice scheme for a FET driver (ideally based on some low noise opamp) which could be used. What I need is a perfect control about the audio signal position related to 0V (to allow the transistor to be partially open) and control about the max voltage of the audiosignal (gain) to keep it in the linear response of the FET. Thanks

New video:

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