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I thought that I had seen everything

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I still have about 50,000 loose unboxed, unsorted tubes stashed in a warehouse that I have collected over the last 40 or so years. Many of them are broken due to mishandling before I got them. When I find a broken tube of a type that I am unfamiliar with, I often take it apart.This allows me to see how it was made. Over the years I have seen all sorts of unusual things, including some poor workmanship and mistakes.

Every weekend since I returned from up north, I have been sorting tubes in an effort to organize my collection and eliminate some tubes that are not useful to me. I would guess that I have had about 10,000 dirty tubes through my hands in the last 4 weeks.

Today I found something different. It is a GE 6AG5 that came with "spare parts" inside. I removed the lettering so that I could take the picture. At first I thought that the heater had somehow worked its way out of the cathode, but no, it is still in there. In fact this tube STILL WORKS in a tube tester. Some poor assembly line worker dropped an extra heater inside this tube. I am not quite sure how since the heater should have been inside the cathode before the cathode went into the assembly and was fastened to a base.
 

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Better than the surgeon who left his "tools" behind.

I still (today) work in the electronics plant that I started my engineering career in 36 years ago. Back then there were assembly lines where "board stuffers" put leaded components into PC boards. There were random audits where the auditor would count your components at the beginning of a shift, then again at the end of a shift. The number of components used should equal the number of boards built. Maybe the assembler had too many heaters!
 
Did ya here the one Vice-Grips (TM) ad from the ninties? featuring this tool that had been left behind inside the sheetmetal of an early sixties Chevy right off the assembly line. The tool was still in place some thirty-five years later where it had been locked, holding together two pieces of sheetmetal.
________________________________Rick...........
 
Where do these come from. I got some tubes, OK a lot of tubes. I started with 54 boxes that looked like this. And about 15 more that contained big tubes wrapped in newspaper. They are all loose, unsorted tubes. This one weighs 41 pounds. These tubes average 73 tubes per pound. The larger miniatures, about 60 per pound, and octals between 25 and 40 per pound. Some boxes weigh about 30 pounds, some over 75 pounds. Rough guess, 100,000 tubes.

I have been paying rent to keep these for several years. In todays economy, I can not continue to do this. So I have finally been forced to dig through the boxes and really see what is in them. Last year I went through all of the boxes full of big tubes (easy) and sold off all of the thyratrons and other usless (to me) stuff. I also sold off many of the boxed tubes, and others that I realized that I would never have time to use.

I have spent all of my free time since Christmas sorting the boxes full of small tubes. I have found some useful tubes, but a lot of garbage. The box in the picture contains about 2900 6AK5's, I have two more boxes of them and another box full of 6AL5's Obviously these have to go.
 

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Did ya here the one Vice-Grips (TM) ad from the ninties?

I got an old motorcycle from a friend back in the 70's because the splined shaft that the shift lever goes on had the splines stripped off. I drove it for over a year with a pair of vice grips for a shifter.

I set up 3 racks like this one. I have been sorting tubes into these bins. Yep, more 6AK5's and 6AL5's. I have at least 1000 12AU7"s and about 500 5993's. I plan to do some serious testing to find out if 12AU7's really do suck, or if there is a valid use for them in HiFi audio. I will find out if they can be made to glow. I have now got a lifetime supply of 12AT7's too.
 

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I have been asked "why don't you just toss all of the tubes in the trash. You could just buy what you need with the rent money you will save." At first, I laughed. Now those words make too much sense, the rent keeps going up, but I just can't toss any tubes in the trash......yet.

I have been sorting tubes and finding junk, so I begin to wonder why I don't toss some of them. I can't figure out why the eccentric old collector who was the previous owner of all this junk seemed to have a thing for 6AK5's. Some of the boxes that I have sorted were mostly 6AK5's with a few 6AL5's and 6AS6's mixed in. Just when I get the urge to dump the whole box, I find one or two of these. I guess the sorting will continue. Found some funny looking Bendix pentodes too 6094's I believe.
 

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I have a much smaller, though frankly still sizable, collection of tubes that came from a university basement. Probably a couple of thousand in total. Oddly, there is an enormous number of 6AK5's and 12AU7's in mine, too. Must have been useful to someone for something.

Triode strapped, the 6AK5 is not too useless. It works well as the second gain stage in a phono stage with a 6GK5 in the first spot. It also makes a decent line level cathode follower, or cathodyne perhaps. Probably good for guitar duty, too.

http://www.mif.pg.gda.pl/homepages/frank/sheets/138/5/5654.pdf
 
I have experimented with the 6AK5 in audio service, and found that it is definitely not worthless. I just don't need 5,000+ of them! I will probably keep a few hundred. I don't see myself keeping more than 10 6AL5's, but I have at least 500 of them. I may keep all of the 12AU7 types until I have the time to explore the "all 12AU7's suck" myth. Even if they do suck, they still fit a zillion guitar amps out there. Some will wind up on Ebay after testing.

make nice little RF amps in the VHF range.

I got a bunch of 2C51 / 5670's. They make good RF amps too, and good audio amps. I also work with RF, but my RF work has all been with sand based life forms. I may use tubes for a big RF power amp though.
 
dsavitsk said:
I have a much smaller, though frankly still sizable, collection of tubes that came from a university basement. Probably a couple of thousand in total. Oddly, there is an enormous number of 6AK5's and 12AU7's in mine, too. Must have been useful to someone for something.

Triode strapped, the 6AK5 is not too useless. It works well as the second gain stage in a phono stage with a 6GK5 in the first spot. It also makes a decent line level cathode follower, or cathodyne perhaps. Probably good for guitar duty, too.

http://www.mif.pg.gda.pl/homepages/frank/sheets/138/5/5654.pdf

6AK5s have definite audio uses. They also used to use lots of these to make distributed voltage amps as vertical deflection amps for o'scopes. 12AU7s found lots of use in digital and semi-digital applications.
 
Actually, if biased properly, the 12AU7 is an excellent tube... the 5814A is even a bit nicer. The 5963 was a premium variant intended for switch functions. My 45/2A3 SET uses a 5814A as the input/driver. These are very low-distortion amps with zero feedback and are within 1dB out to 45KHz (at full power). In short, they don't suck... unless you crack them... and then only briefly.

Regards, KM
 
Do you really have 500 5993's (or did you miss-type 5963's?)

Oops, the brain to finger connection isn't what it used to be. Makes for some rather frustrating guitar playing. I meant to type 5963, but I do have a good collection of 5993 too, but not 500.

Actually, if biased properly, the 12AU7 is an excellent tube... the 5814A is even a bit nicer. The 5963 was a premium variant

I have seen plenty of arguments on both sides of that statement. Morgan Jones, SY and other well respected tube heads call them non linear. I have done no testing myself, yet. I have plenty of 12AU7, 6189, 5963, and 5814. I will have to hook a few up and see for myself. It has been my observation that a suitable operating point can be found for most tubes. In some cases the tube to tube variation is bigger than the sweet spot, making a plug and play situation impossible.

What is the proper bias and load that will get rid of these tubes' notoriously high and high order distortion?

I am 100% sure that I can find a bias point that can eliminate the distortion. It might however eliminate the tube! :hot:

Well, these + a few friends + a bunch of boxes of .22 LR and a day of fun!

My aim isn't what it used to be either, hands shake too much. Need to find bigger targets like CRT's.
 

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SY said:


What is the proper bias and load that will get rid of these tubes' notoriously high and high order distortion?


Well, I guess one needs to define "notoriously high and high order distortion" in more quantifiable terms. The 45-SET I designed using one as the input/driver measures under 0.5% at 1-watt and under 1.0% at 2-watts, even less at 20KHz and up. Extensive listening sessions which include myself and some old friends/colleagues who have been involved in audio for 35 years have not noticed anything unusual in listening or measurements, quite the opposite, the amps are very neutral and strain free to listen to. They have a frequency response within 1dB from 25Hz to 45KHz at 1-watt.

This tube is not foreign to audio gear and has been used in many designs over the many decades. Granted, I did not use any hybrid stuff like LED biasing or CCS plate feeds, just the published plate curves and calculated loads which were fine-tuned thru bench measurements and listening tests. I've actually swapped more than 50 tubes (12AU7, 6189, 5814A, 5963 and ECC82) and the results are very consistent for in-circuit performance.

I guess I would be inclined to ask how you biased it to get such high levels of distortion... and what measurements were done to confirm them.

Regards, KM

PS - agreed on the CRTs... a more exiting target. My uncle was a Zenith dealer for over 40 years.... we used to bust the old ones from up on the hill tossing large rocks down... of course that was 40 years ago.... great sound that would echo thru the woods (Beacon NY).
 
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