Yeah, now it's finally clicking in my mind, so the 0.1uf capacitors between the filament windings are shorting the RF to ground. Also I'm wondering if it's alright for me to have center tapped my transformers the way I did, I don't have center tapped filament transformers, so instead I have two 100 ohm resistors in between them and have a center tap at that connection is that alright?
If I'm understanding correctly, then I'm supposed to ground the grids and then apply a positive voltage to the center tap of the filament transformer as a bias?
here's a redrawn schematic as well.
http://www.flickr.com/photos/14031769@N06/2325740744/sizes/l/
If I'm understanding correctly, then I'm supposed to ground the grids and then apply a positive voltage to the center tap of the filament transformer as a bias?
here's a redrawn schematic as well.
http://www.flickr.com/photos/14031769@N06/2325740744/sizes/l/
Hill's Plasmatronic speakers used a DC powered glow discharge. No RF, crossover as low as 700 Hz (without horns), and if you search these forums (they have been mentioned numerous times, which indicates to me you haven't done much research even around diyaudio) you'll find the measured frequency response and waterfall, showing that nothing else comes even close. You can also find Hill's patent (now expired 
) for the theory of operation. And no you don't really need helium
) for the theory of operation. And no you don't really need heliumYeah, I've definitely done my research on this forum, I've looked at all the forum threads for plasma tweeters. The ones for plasmatronic type tweeters seemed mostly conceptual and if I recall there was much bickering on those threads and nothing too useful. Initially I thought about doing something like that mentioned in the Hill patent but it seems beyond the scope of my abilities.
abzug said:Hill's Plasmatronic speakers used a DC powered glow discharge. No RF, crossover as low as 700 Hz (without horns), and if you search these forums (they have been mentioned numerous times, which indicates to me you haven't done much research even around diyaudio) you'll find the measured frequency response and waterfall, showing that nothing else comes even close. You can also find Hill's patent (now expired
If you say so...
The Hill is an excellent measuring device, gotta discount the HF noise though... and it sounds fantastic.
I'm sure Dr. Hill would have not have included the expensive and difficult to handle inert gas in his design because it was not needed, right?
And, I have a copy of the patent, fyi... thanks.
_-_-bear
Member
Joined 2003
A few quick suggestions... At least in the new schematic, L4 is shorted by the second (lower) line coming from pin 1 of the right 811...delete that line. Pin 4 of the right 811 should go to the junction of L5 and R5. Delete R6 & R7 unless you want them for layout symmetry. Maybe add small RF bypass caps from the 6.3V secondary, and the junction of R4 & R5, to ground. Double check all component values.
This may be a dumb question, but is there a reason for biasing the heater/cathode rather than the grid? (I've never worked with heater only tubes.)
This may be a dumb question, but is there a reason for biasing the heater/cathode rather than the grid? (I've never worked with heater only tubes.)
What are you talking about? There is no HF. It's a DC-powered plasma--even if the patent mentions other types plasma, the actual product had a DC supply.bear said:
Wrong! He included it because a modern technology that was developed in plasma engineering which make it unnecessary did not exist during his time.
abzug said:
Abzug,
Wonder why you don't mention your location or have contact buttons up? But anyway...
HF noise = High Frequency NOISE.
NOT RF noise. Ok?
...you misunderstood.
Ever listen to a Hill Plasmatronic? No?
It hisses... fwiw.
And yes, you are correct, he used HV DC to create the plasma, but he needed to strap on a tank of Helium to make it work.
Any other commercial products use DC?
Would be interesting to know...
Ok, now we're getting somewhere.
What "modern technology" are we talking here?
Or are you the same guy who posted under another login who was on about "platinum catalysts" a year or more back??
Actual information on this would be of interest.
_-_-bear
What does this have to do with anything?bear said:
You can contact me through forum PM.
I've been with contact with an owner and he said it does not hiss (though his is modified). But not to take his word, in the prototype I built, there is no hiss either--and I'm even using much higher power levels.
Corona discharges are noisy. Arcs are noisy. Glow discharges are not. Maybe the version you heard had a noisy regulator on the helium tank or whatever, but if the discharge is making noise, that means something's wrong with the supply and/or amplifier.
Did you read even one of my posts here? I've pointed out repeatedly that it is not necessary.
How you can confuse "electrodes" with "catalysts" is beyond me. And it's platinum-plated, not platinum.
abzug said:
Dunno - you seem to be somewhat angry and confrontational.
Wondering why?
Can't say what someone else hears...
I've heard them a few times over the years, and they all had hiss from the discharge. Dunno.
You say many things it seems.
If you would back it up with some actual information it would be better than just asserting things...
Confuse? So you are the same fellow who was posting extensively on this subject some time ago? The one with many assertions who did not actually build anything? This is what, your third or fourth login alias? More? Otoh, perhaps that is not you?
Look, I don't care who is "right" only about getting better understanding and helping others... what is your interest?
_-_-bear
What is that supposed to mean?bear said:
What information exactly do you need?
Even back then I had produced a discharge and modulated it with sound, and that was in those posts. What I have not built is a complete speaker, just the driver itself.
Since then I used multiple electrodes to get the same plasma shape as in the Plasmatronics, and it's been quite useful in identifying some problems.
Speakers with distortion as low as is typical of electronics, not speakers.
There are no new photos. I'm pretty sure I posted a photo of one pair of MHCD electrodes before; the only difference in the later version is that I had five pairs of them (though I had only Pt-plated the original pair, since it was just for a test).
No heatsink or anything the way Hill used, just held together by clay.
HV to single anode through ballast resistor. Paralleled HV transistors and hooked up through resistors to bottom electrodes. Bases were biased with resistors to set DC through this makeshift VCCS; added (highpassed) audio through HV caps from my computer speakers amp.
Electrodes weren't heatsinked and got hot very fast. The unplated ones had serious damage (holes burned to about double size) in less than a minute, and that was the end of the test. It wasn't particularly loud, but I had limited the discharge with the ballast. I didn't hear any other problems unless I tried to play low frequencies, which get quieter and with very low ones the discharge is not continuous.
I'm not continuing this project until I can finance further development to build a proper speaker--that's why I'm working on a DAC.
No heatsink or anything the way Hill used, just held together by clay.
HV to single anode through ballast resistor. Paralleled HV transistors and hooked up through resistors to bottom electrodes. Bases were biased with resistors to set DC through this makeshift VCCS; added (highpassed) audio through HV caps from my computer speakers amp.
Electrodes weren't heatsinked and got hot very fast. The unplated ones had serious damage (holes burned to about double size) in less than a minute, and that was the end of the test. It wasn't particularly loud, but I had limited the discharge with the ballast. I didn't hear any other problems unless I tried to play low frequencies, which get quieter and with very low ones the discharge is not continuous.
I'm not continuing this project until I can finance further development to build a proper speaker--that's why I'm working on a DAC.
links to previous threads?
Hi abzug,
Would it be possible for you to give the links to your previous threads about the plasmadrivers that you mention here?
I'm researching the possibility of building a plasma microphone and what you write about corona, arc and glow discharge noise is very interesting to me. Also what you write about the way you have hooked up your plasmadriver electronically. Would it be possible for you to draw a simple diagram of the design?
Also, if you are willing to share more information about what voltages you use, the length of the glow discharge, how you have designed the electrodes and more relevant/interesting information, I'd be pleased to hear about it
Maybe you already know this - in the 70's Fransson & Jansson in Sweden built a plasmamicrophone (the "Ionophone" used as a microphone). They used voltages in the range of 500 ~ 2KV for a glow discharge of a few millimeters. And it seemed to have a modest S/N range....
For a microphone the self-hiss/noise needs to be very, very low - in practice inaudible. Would you say that the noise of your design is this low? Or could the principle you use be modified to have lower noise?
I've briefly investigated the possiblility of using gases around the electrodes to lower the voltages needed for a discharge - it seems possible, though, I just don't consider it very convenient (maybe oxygen derived from a simple electrolytic processing of water could be used?) so if it can be done without I'd be very interested to hear about it....
Happy Easter!
Jesper
Hi abzug,
Would it be possible for you to give the links to your previous threads about the plasmadrivers that you mention here?
I'm researching the possibility of building a plasma microphone and what you write about corona, arc and glow discharge noise is very interesting to me. Also what you write about the way you have hooked up your plasmadriver electronically. Would it be possible for you to draw a simple diagram of the design?
Also, if you are willing to share more information about what voltages you use, the length of the glow discharge, how you have designed the electrodes and more relevant/interesting information, I'd be pleased to hear about it
Maybe you already know this - in the 70's Fransson & Jansson in Sweden built a plasmamicrophone (the "Ionophone" used as a microphone). They used voltages in the range of 500 ~ 2KV for a glow discharge of a few millimeters. And it seemed to have a modest S/N range....
For a microphone the self-hiss/noise needs to be very, very low - in practice inaudible. Would you say that the noise of your design is this low? Or could the principle you use be modified to have lower noise?
I've briefly investigated the possiblility of using gases around the electrodes to lower the voltages needed for a discharge - it seems possible, though, I just don't consider it very convenient (maybe oxygen derived from a simple electrolytic processing of water could be used?) so if it can be done without I'd be very interested to hear about it....
Happy Easter!
Jesper
Has anyone seen this PlasmaSonic device?
http://www.easternvoltageresearch.com/oldwebsite/datasheets/plasmasonic2_manual.pdf
I have no interest in this subject and haven't read any of this thread, but I found this device while researching something else. I searched the forum for "PlasmaSonic" and only found a few references to some headphones with the same name. I figured I would bring it to this threads attention in case anyone is interested.
So ummm, there you go.
http://www.easternvoltageresearch.com/oldwebsite/datasheets/plasmasonic2_manual.pdf
I have no interest in this subject and haven't read any of this thread, but I found this device while researching something else. I searched the forum for "PlasmaSonic" and only found a few references to some headphones with the same name. I figured I would bring it to this threads attention in case anyone is interested.
So ummm, there you go.
To abzug ..
Found some previous threads on the plasmatweeters and will read this first - so no need to answer my questions above - maybe except for the level of hiss. In one of the threads the member "prune" says that the glow discharge is noise-less. Is that a general observation?
Also, you mention platinum for an electrode. What do you use for the other electrode (may have missed this information in the threads, though)?
Regards,
Jesper
Found some previous threads on the plasmatweeters and will read this first - so no need to answer my questions above - maybe except for the level of hiss. In one of the threads the member "prune" says that the glow discharge is noise-less. Is that a general observation?
Also, you mention platinum for an electrode. What do you use for the other electrode (may have missed this information in the threads, though)?
Regards,
Jesper
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