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?
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?
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:
http://www.diyaudio.com/forums/showthread.php?s=&threadid=78041&highlight=
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!
Look here:
http://www.diyaudio.com/forums/showthread.php?s=&threadid=78041&highlight=
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!
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
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
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.
http://www.belljar.net/xray.htm
http://www.eskimo.com/~billb/amateur/blljar3.txt
Google "X-ray 6BK4" for more info.
http://www.eskimo.com/~billb/amateur/blljar3.txt
Google "X-ray 6BK4" for more info.
ionomolo said:
I've done this for fun on one of my headphone amps. I hooked up a large mercury vapour rectifier tube to a dummy load just so that I could see a pretty glow. The tube isn't in the circuit since I couldn't find the parts to make it work properly, so I just hooked it up to a transformer & dummy load to see the pretty colours.
Measurable? Maybe. Linear enough to be useful? I don't know.
I decided that whatever it would take to make these tubes work was not worth the effort, so they are gone. I have more ideas, tubes, and projects than I can possibly complete in two lifetimes and I am paying far too much in warehouse rent just to keep them all.
We have recently had two close relatives pass on and we had to find homes for their lifetime's worth of unfinished projects. Sadly, most went in the trash. This was an eye opening experience. Sherri and I both decided to attempt to reduce our collections of "stuff" by at least half. Tubes that I don't see a valid use for are gone, or going. Tubes and other items that may have a use in audio, but that I don't think I will ever get to will be sorted out over the next few months. I plan to list the good stuff on Ebay. I have been saving a pair of Western Electric 367A's for about 10 years. They would make a good amp, but I haven't got to it yet, so they will go on Ebay.
tubelab.com said:
OT:
Hi George,
Battling many of the same issues here after the death of one of our relatives. I've been selectively paring down the tube collection to types I actively use. Trade or sell gear as I find better/more functional items to replace them, etc. Space is always a problem.. Once I had warehouse space and got awfully tired of paying for it. Figured out what I had to have and what I could do without. Painful, also illuminating as I looked at all the things I once had to have and wondering why...
At one time I had over 10 stereo amplifiers, (or pairs) sold a bunch of them, lately I've been wondering if I shouldn't get rid of the rest with the exception of the 300B SE amplifier I use daily. They take up space and tie up resources that could be re-applied to that big 845 based SE I keep thinking about... Such is life.
Sale value is not that high since I have sunk back into relative obscurity, one day the up & coming darling of the local audiophile community, the next a relative unknown, come to think of it.... 
I think I would even include in the dispensable category the original amplifiers I designed for that long ago VTV PP300B amplifier article.. (Did that 10yrs ago..
)
That is where I am at now. The warehouse rent is now $5K per year for only 400 square feet. I had most of it all organized, then I was given 100,000 tubes all stored in about 30 2' X 2' X 2' boxes. I put them all into the warehouse creating a wall of tubes, blocking access to a lot of stuff. That was 6 years ago. Little by little the wall has been coming down. I am finding stuff that I had forgotten long ago. I have tossed several car loads, sold 3 station wagon loads full of tubes, and sorted another car load for eventual Ebay listing. I want to cut the warehouse space in half by the end of the year.
I can count 11 tube amps and 3 sand state amps in this room, not counting the incomplete ones. There is at least a dozen more in the warehouse. I guess it is time to let some go, but which ones?
I built that big 845SE amp that was in my head about 5 years ago. It sits on the shelf, but hasn't been plugged in for at least a year. I had an 833A amp on my mind for a long time, but I finally came to my senses, this IS south Florida, and I can't keep this room cool as it is now. I still have about 20 833A tubes and some really big power transformers.
Drag it out and hook it up. listen to it for a while, then ask yourself if you really want to sell it. In my case, my 300Beast P-P began as a seriously modified (cost reduced) version of the amp from your article. It was hastilly built using the cheapest of parts but it sounds good, too good. I can't even bring myself to rebuild it. I will probably design and build a new one, then sell (or dismantle) the one that I like the least.
Yes, I think that ditching the 6BK4's, the thyratrons (some were really big), the HV rectifiers, and other similar tubes was a step in the right direction. With all of the "stuff" that I have, would I EVER possibly build anything with them? I doubt it.... goodbye. Could I part with my 845SE, or some of the amps that I built for myself? Not yet anyway. The old Heathkits, Magnavoxes, and Zeniths, yeah, they are next to go.
tubelab.com said:
Hi George,
I spent some time with them a few days ago which is why I am now somewhat reluctantly considering their sale. The SE amplifier is just a better match overall to the system as it currently stands. The PP is very good, but in every way except output power the SE just ever so slightly betters it. The PP amplifier was intended as an everyman's project whereas my SE was an evolution (and less fancy looking version) of my statement product - they weren't meant to play in the same space.
Warehouse space is expensive, given what you have to pay I can well imagine that you would want to get stuff out of there. I was more fortunate in that I was able to get about 1/2 the space for about 1/5th your annual cost - I gave it up 4 yrs ago.. Given the clutter here it would be nice to have something comparable. We have a garage with a loft which gives us enough space for our Christmas, and Halloween decorations. There are a few chassis and other odds and ends lurking up there as well..
All I've got left are 2 SE amplifiers (45, and 300B), a pair of 300B PP monoblocks, a heavily modded integrated, a partially restored Realistic Stereodyne 40, and two tube based headphone amplifiers. I'm thinking some scrapping/selling needs to happen soon..
- Status
- This old topic is closed. If you want to reopen this topic, contact a moderator using the "Report Post" button.