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Old 28th June 2008, 11:38 PM   #1
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Default How long until someone tries

Besides the large amount of "normal" (triode, tetrode,etc...) tubes there are that can be used for audio that are also "normal" tubes that are simply too dangerous to use.

My friend today showed me a NOS 6BK4A that he bought at a flea market and wanted me to help him make an amp out of. After reading the first few lines of the specs on it I simply laughed and said "**** NO!"

So now that I mentioned this tube online how long do you think it will be until someone tries it?

What other crazy specs tubes have you encountered?
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Old 29th June 2008, 12:06 AM   #2
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Default Re: How long until someone tries

Quote:
Originally posted by lochness
Besides the large amount of "normal" (triode, tetrode,etc...) tubes there are that can be used for audio that are also "normal" tubes that are simply too dangerous to use.

My friend today showed me a NOS 6BK4A that he bought at a flea market and wanted me to help him make an amp out of. After reading the first few lines of the specs on it I simply laughed and said "**** NO!"

So now that I mentioned this tube online how long do you think it will be until someone tries it?

What other crazy specs tubes have you encountered?
Oldeurope asked for a low mu triode. It may fit!
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Old 29th June 2008, 12:13 AM   #3
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A while back I hooked one of those up. I was impressed by the Mu of 2000, but with my power supply maxed out I couldn't get it to draw much current. I posted that here somewhere and someone brought up the idea of using them for direct drive of ESL panels. Maybe?

Look here:

6HV5A Single Ended Amp

If it has a vacuum, and glows, I'll hook it up and see what happens even if the result is fireworks. I melted a couple of thyratrons once out of boredom. I just got a new 1000 volt 200 mA power supply that needs a workout!
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Old 29th June 2008, 12:18 AM   #4
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Yeah, the problem is current (design max = 1.6mA). You can't swing enough to charge and discharge a panel fast enough. Maybe a headphone amp, though...
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Old 29th June 2008, 12:28 AM   #5
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Curves are needed...
I would try it on relatively low voltages. However, plate can dissipate 30W, but how robust is the grid?
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Old 29th June 2008, 01:13 AM   #6
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Its kinda scary that people are seriously considering using it...KFH (Kentucky Fried Human).
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Old 29th June 2008, 01:44 AM   #7
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The blue glow would look very cute on my amps... Cherenkov radiation? Uhm... talking about radiation, wouldn't this thing be a huge source of X-rays and really a bad thing to have in one's dorm room?
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Old 29th June 2008, 01:45 AM   #8
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Quote:
Its kinda scary that people are seriously considering using it
I wound up with a collection of over 100,000 tubes several years ago. I have been going through them to determine which ones are useful for audio use regardless of their original purpose. For many tubes this means actually hooking one or two up and turning some knobs. The ones that don't work get voted off the island (wholesaled). The 6BK4's (about 50 of them) were in the last station wagon load that I sold, just a few weeks ago.

Scary is playing with electricity without knowledge of the dangers. I know what I am doing, and there is usually a 1/4 inch piece of Lexan between me and my experiment, and a large fire extinguisher nearby. What do you do when you discover a bunch of 833A's in the warehouse? Vice grips, hose clamps and 1500 volts = 200 Watts of SE power! I'm keping these.

http://www.tubelab.com/833SE.htm

Quote:
Curves are needed... I would try it on relatively low voltages.
I couldn't get them to draw any measurable current on 550 volts even with the grid at +25 volts. I have too many usable tubes.....NEXT
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Old 29th June 2008, 01:54 AM   #9
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Quote:
wouldn't this thing be a huge source of X-rays and really a bad thing to have in one's dorm room?
There are people who are actually building amateur X-ray machines, and guess what they are using for a source. The 6BK4 and its offspring. Those of us that are old enough to remember the dawn of the color TV era may also remember the X-ray scare that came in the late 60's. It seems that TV sets DO emit X-rays from the 6BK4. Later versions of this tube incorporated lead in the glass and some of the compactron versions had a composite coating over the glass.

The concept of a shunt regulator on the secondary side of the flyback transformer (the 6BK4) was replaced by a shunt regulator on the primary of the flyback (the 6HV5) in the early 70's. The 6HV5 and its offspring are more suitable for audio. I have about 20 of them, but have yet to get any decent sound out of them. The plate resistance is too high.
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Old 29th June 2008, 02:18 AM   #10
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Quote:
Originally posted by tubelab.com


There are people who are actually building amateur X-ray machines, and guess what they are using for a source. The 6BK4 and its offspring.

Wow.... cool project.
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