Output tube radiation exposure - thoughts?

K-e-i-t-h Richards. Duh!

I before "e" except after..

A friend of ours was a runner since grade school, lean & trim, vegan, didn't smoke or consume alcohol. Died in 2002 from lung cancer even though he had no known family history of cancer back to his grandparents. Go figure.

Kieth Richards is still living well. Go figure.

over 10,000 volts and there is risk of Xrays.
I use a number a different type Mercury Rectifiers in my audio system. Some of the inserts that come in some of the tube boxes will warn you about the use if over 10,000 volts.

You can find some data on some tube data sites, look for 872a or 575a tubes and some of the data pages will say the same thing.

I use them well under their rated voltage.

I hope Oliver Stone is reading this.

Were there a danger, these tubes would have been outlawed in Western Europe and Canada a long time ago.

Not so much in China, Russia, USA, where anything goes.

Certainly there MUST be a way to measure this with some sort of hand held style meter and put some real hair on this subject. I mean they already have specialized portable devices for measuring hazardous materials of all types in this day and age.

Very interesting thread! I do not own any tube amps myself, but I have asked and been advised over time by 2 separate tube-amp manufacturers on this exact subject.

In both cases I was advised, that indeed some x-ray radiation is produced by the higher voltage tube-amps (but not from low-voltage tube linestages e.g. preamps and dacs etc). They do NOT prefer to talk about this aspect! Most (including the end-users) will, for understandable reasons, accordingly try to laugh it off / dismiss it as a paranoid non-issue. I was told the concern is roughly equivalent to the exposure from the older CRT-style TV sets - which also can produce x-ray radiation as they age and gradually get out of proper specification. The absolute energy level from tube-amps is not likely very high (especially from over 20 feet away), but long-term user (and/or family) exposure to even low-level x-ray radiation is in fact, now showing to be a likely health risk - especially as the damage builds in the body over time, and adds to other more common radiation exposures received throughout our lives.

Also, some of the older NOS tubes (especially the Russian variety) actually also contain radioactive material which improves the ionization process, and thus have radiation warnings & symbols on their packaging. If such a tube breaks in one's home, I was advised this can be a genuine risk as well.

I am not personally an expert on the subject, but only repeating the info that I've personally received - as I was extremely surprised to find this particular topic discussed here.

Thanks for all the informative responses, especially the electronic history, and good listening to you all...

Honest1 & Viridian

The Rotel is just a temporary measure. I used to have a great audiophile amplifier but I had to give it up do to certain reasons.

I also had a set of QUAD mkII amps in the past - they were awesome.

Viridian, the chassis is going to be a bit complex and thus needed to be cut with a CNC plasma cutter. I want an ultra-professional look (a la EAR... Jadis etc).

OK, good enough, case settled.
Going from a Rotel to a hand built 6C33C tube amp on a stainless chassis - that's awesome. Why screw around with all the baby steps to climb the audiophile ladder when you can just get it all done right at once the first time? I hope it comes out great.

Case settled then? Good... now I need to get myself a tube amp again... I have a nice 6C33C project that is progressing to slowly for my taste- need to have a stainless steel chassis CNC'ed.

I like tubes!!

Lonestarsouth -- I think that the comments provided by your EE friend are good, and are likely to be completely correct.

I too, btw, am an experienced electronics engineer.

In regard to my comments about OLDER televisions, though, I would like to offer the following quote from United States Patent number 3562518, which was applied for in 1967 by National Video Corporation, and granted in 1971. National Video Corp., btw, had in 1963 developed the world's first truly rectangular color tv picture tube, in conjunction with Motorola.

Ordinarily, the electron beams which scan the viewing area in a color television kinescope are energized by an accelerating potential of 25,000 volts. At this limit of accelerating potential, there is little or no danger of generating harmful X-rays. Further, since the faceplate panel of conventional color kinescopes are usually quite thicker than the rest of the tube and comprise a lead type of glass, whatever X-rays are generated within the tube are absorbed in the faceplate panel. However, if the accelerating voltages exceed by as little as 2,000 volts the 25,000 volt specified accelerating potential, the safety limit for X-ray generation may be exceeded with resulting hazardous generation and escape of X-rays. At this level, the X-ray penetration at the back of the tube becomes considerable, and additional protection must be provided ....

The present invention provides for coating the shadow mask mounted within the peripheral flange of the faceplate panel of a conventional color kinescope with a thin layer of bismuth thereby substantially reducing the penetration of X-rays generated by high energy electron beams impinging on the phosphor screen escaping through the rear of the tube. In addition, the constricted neck portion of the tube is encompassed with a paper pulp sleeve impregnated with bismuth trioxide; and the external surface of the funnel from the paper pulp sleeve to the flange of the faceplate panel is coated with a nonconducting mixture of bismuth trioxide and sodium silicate. It has been found with this particular arrangement of means for protecting against X-ray penetration, there is provided sufficient safety for personnel even if the accelerating potential rises to the 30,000 volt level.

Note too that this was more than 20 years after tv was first introduced on a widespread basis, and I believe that the earliest crt's used glass that was either unleaded, or at least not as heavily leaded, as in the later ones.

And re your comment that

"It is useless to stress about such things. Sit back and enjoy the music!!"

I agree, and even more so because we are all agreed that the answer to the op's question about radiation from audio tubes is that there is no problem whatsoever.

Regards,
-- Al

My statement about the satellites was based on the fact you stated. It is useless to stress about such things.

Sit back and enjoy the music!!

My comment was based on military radar transmitter tubes that operate in the 45KV or higher range. As I said, much higher than any audio equipment uses. I meant it as a possible explanation of the source of concern of the original poster, and to help him not be concerned.
Truly ridiculous is the assertion that we get any significant radiation from the satellites orbiting the earth. They are very low power, since most of them rely on only the power they can collect with their solar panels. Some of this gets wasted as heat, then whatever is broadcast back to earth spreads over a very wide area.

Global warming and bank failures can be directly attributed to the use vacuum tube components.

However, the dangers to radiation exposure are ridiculous.

Some folks will believe anything.

This is a reply from an electronics engineer:

"Potentially hazardous radiation (e.g. X-rays): There are weak X-rays requiring about 1kV to 20kV to be generated, then medium X-rays needing about 20kV to 60kV, then hard X-rays needing 100kV to 1MV. The first group can theoretically come from tvs and oscilloscopes - they 'penetrate' about 0,1mm through glass to about 0,001 mm through metal - different depths for different metals. The other groups are irrelevant for this discussion.

So no fear - unless you go to sleep with a giant oscilloscope close to your ..... in which case you are so
queer anyway that radiation is the least of your worries.

Folks live close to 30kV - 100kV lines. Radiation cannot be caused unless there is a heated cathode, and an anode, contained in a special vacuum tube. But ozone can be smelled then.

Ozone to higher than one in a million concentration is considered potentially hazardous, but it is smelled long before that (hazardous as in affecting the respiratory system primarily; it can also cause a headache in some people). Such concentrations are very rare; it must be generated to get there. It is a powerful oxidant which in low quantities can be beneficial and is used as a purifier more potent than chlorine. Notably, a small quantity can be generated in air conditioners to purify the air. "

I would rather not begin to argue with him. He is a true scientist that knows his electrons.

Well A1marg... what amplifies operate at 30 kVa? Not even the huge WAVAC amps run near that.

Both Honest1 and I said very clearly and explicitly that the concern about X-rays would only arise in the case of tubes that operate at far higher voltages than are used in audio applications.

If the above were true then we all would have been dead a long time! Tubes are around quite a while - long enough to have wiped out the entire earths population.

I'm not totally certain as to what you are referring to by "if the above were true," but I assume it is my reference to early tv sets having an issue with X-ray emissions.

For starters, please read the last section in the Wikipedia writeup I linked to in my previous post, which is entitled "Hazards of x-ray production from vacuum tubes." Then please do some Googling on the subject and you will find additional commentary to the same effect.

I am an antique radio collector, and as such I have had occasion to accumulate significant knowledge about early tv sets as well (ca. 1946 to the 1960's). The issue was not that they would "wipe out the earth's population." The problem was that those sets, when viewed from close distances (such as children are often known to do), for considerable amounts of accumulated time, would pose unacceptable long-term health risks. As I said, those risks have presumably been eliminated in more modern sets.

Regards,
-- Al

My advice: Don't eat yer tubes, and you'll be OK. This is good advice if you live in an old house with lead paint, as well.

Well A1marg... what amplifies operate at 30 kVa? Not even the huge WAVAC amps run near that.

If the above were true then we all would have been dead a long time! Tubes are around quite a while - long enough to have wiped out the entire earths population.

We get more radio radiation from the thousands of satellites orbiting the earth - not to mention cell phones!

Enjoy your tube equipment gentlemen and ladies!

Honest1: I thnk it has more to do with the voltage the tubes operate at, rather than the frequencies they are amplifying. I don't think there is a problem until you start getting into much higher voltages than any audio amplifier uses, But at those voltages, tubes can emit Xrays. May be an issue with CRTs, not sure.

Lonestarsouth: This is utter nonsense!! Ionizing radiation only can occur when sub-atomic particles are excited by a high energy, high frequency power source. If your statement was true then electrostatic loudspeakers would have been ultra-deadly.

Actually, I believe that Honest1's statement about x-rays potentially being generated by high voltage tubes (much higher than any audio tube would use) is correct. As I understand it, an x-ray tube functions by bombarding the material in its plate with electrons that are emitted by a heated cathode, and then accelerated to high energy levels by means of a very high dc voltage applied to the plate. The voltage is typically in the range of 30,000 volts or more.

The analogy to electrostatic speakers is not applicable. While several thousand volts may be present between the elements of an esl, there is no electron emitter, no vacuum, and no plate being bombarded.

X-ray emission was definitely an issue with early tv sets, both from their crt's and from the tubes in their high voltage power supplies. Modern tv's and crt monitors use solid state power supplies, and presumably/supposedly limit x-ray emission from crt's via lead shielding which is impregnated into the glass.

See this wikipedia article for further information:

http://en.wikipedia.org/wiki/X-ray_tube

Regards,
-- Al

Google CRT radiation. Do you trust the people that poison their own for greed in the factories that made the CRT monitors.If they don't block the radiation properly on those CRT's,who is getting it?Do you trust their cheap junk? NOT ME.They are supposed to be meeting FDA guidelines,but do they?Even the plastic case may contain lead.Also google radio waves,and radiation.Its not made in the USA anymore.

"Honest1
I thnk it has more to od with the voltage the tubes operate at, rather than the frequencies they are amplifying. I don't think there is a problem unitl you start getting into much higher voltages than any audio amplifier uses, But at those voltages, tubes can emit Xrays. May be an issue with CRTs, not sure."

This is utter nonsense!! Ionizing radiation only can occur when sub-atomic particles are excited by a high energy, high frequency power source.
If your statement was true then electrostatic loudspeakers would have been ultra-deadly.
Read here: http://en.wikipedia.org/wiki/Ionizing_radiation

"Hifitime
Those audio frequencies are probably a lot less worrisome than the computer you answered on, especially if it has a CRT.There is more stray radiation on the power lines in the wall above your head,or that lamp cord when you sleep."

True in a sense. CRT units are capable of emitting X-rays due to the frequency they operate at. Power lines frequency corresponds to that of the wall socket you get in your house - either 50 or 60 Hz - not dangerous.
The wee bit of OZONE discharge could be harmful but a gentle breeze around the power lines quickly dissipates it.

Humans get more daily radiation exposure from cosmic rays and RADON than anything else.

Those audio frequencies are probably a lot less worrisome than the computer you answered on, especially if it has a CRT.There is more stray radiation on the power lines in the wall above your head,or that lamp cord when you sleep.

I thnk it has more to od with the voltage the tubes operate at, rather than the frequencies they are amplifying. I don't think there is a problem unitl you start getting into much higher voltages than any audio amplifier uses, But at those voltages, tubes can emit Xrays. May be an issue with CRTs, not sure.

When I listen to my tube amps I usually go into the next room to avoid those issues.

09-20-09: Viridian
I use tube gear and am unable to have children, so yes, I would say that there is a definite correlation.

Viridian, LMAO! Wait a minute.....that may explain why my children each have 12 fingers.......

Yup, A1marg is correct.

Audio equipment does not operate at UHF (Ultra High Frequencies) or related energies. No sweat man - only if you listen to "COSMIC OPERA" with a freq range of 2250 kHz to 10 gHz on a 100, 000 watt system with your head up against the transmitter dish - yikes!!

Doesn't seem like a concern at all, to me, in the context of an audio system.

The key distinction with respect to the situations you mention about shipboard equipment being that in the audio application the frequencies involved don't radiate through the air (at least to any degree that is remotely significant, considering the power levels that are involved), while of course radio frequencies do.

Regards,
-- Al