Very Expensive Tubes

A couple of my friends who sell on Evilbay and who have custom built audio systems, have offered to let the "Audiophools" do a blind listening test to see if they could tell any actual difference between brands of tubes, black/grey plates, top/bottom/side getter, matching, etc.

NOT ONE PERSON was willing to do it.

That says to me it's in the mind, not physical reality.

 Then we get into the nebulous world of so called "power ratings" of amplifiers.
 I experienced this first hand when a kid would bring in a "brick" out of his car that was 2" x 3" and supposedly put out 1000 watts. (Yeah, sure. Maybe if it was hit with a bolt of lightening, just before it disintegrated.) 
 I would ask them just how it was rated; peak, peak to peak, IHF, RIAA, RMS or what. They never knew. (Maybe it drew 1KW out of the car battery  through that 18 ga zip cord feeding it?) 
 And what was the distortion level at full volume "output"?  None knew that either. "Oh, it has the best, clean sound at full volume."
  Looking up the specs on the output IC's, I would find they were, at best 25W with up to 25% THD at 60% volume. Again, more idiots with the Bullwinkle Syndrome. (No brain, No effect.)
 Sigh.. Glad I am not servicing consumer electronics as a living anymore.

It's interesting to watch the tubes being manufactured and to then speculate on how many of the variables are routinely controlled in manufacture as opposed to gradation of the finished products.

19&41 wrote:

I think if a person has sensitive enough hearing to discern the difference in tubes' responses,  the differences must be in the physical, mechanical characteristics in the tubes construction, the resonance of the internal components and their vibration in the tube in response to the sound pressure.  I think it is the acoustic feedback and the tubes' response to it that accounts for any difference in the tubes' tone characteristics.  I have had a number of microphonic tubes with more pronounced effects that have led me to this belief.

Here are some clips of what the audio guys are claiming;

Aside from black plates, they're described as "long plate" tubes. Notice in the data sheets that the 7025 and 12AX7A sometimes mention lowered microphonics. That's because they shortened and stiffened the plate structure, with some variants adding extra mica spacers. No manufacture ever really went back to a longer plate, higher microphonic tube.

Same for reduced hum. Some changes were made regarding heater coatings, and a number of manufacturers wound the heater in a spiral to relieve tension causing breaks in heater insulation and leading to higher heater to cathode leakage (and therefore hum). The spiral wind might also reduce current-induced hum inside the tube.

The A in 12AX7A stands for "a higher grade" of preformance
In fact there should be les noise comming from the tube like
microphonics,etc.

Often there is a extra shield between the two side of the tube, and the
claim is that there should be let crosstalk between the two sides.


Also the "vacuum" is claimed to be better



RCA 12AX7 '50s black-plate exhibits more clarity and earlier breakup, compared to the RCA short-plate '60s 12AX7A, to name a few obvious sonic characteristics.


All I want is 12AX7's which will be used to in circuits like the Knight Kit broadcast band transmitter of the 1960's. This is a tube that should be in the $5 price range of every other common tube out there.  I think these audio guys are all a bit crazy!

Frank!
To go along with Matched tubes, I'm sure the Audio Manufacturers of sound equipment had elaborate Tests standards that were matched for the circuitry they made. They were in competition with each other for sales, and quality made the difference.

Off Topic--------------
But not just tubes, but Transistors. I recently purchased a Zenith Transistor Radio 500H, that has a matched audio Pair.
I think I will pull them from their sockets and measure the gain just for a reference. It may help to know when others need to replace because of damage.

I have to replace caps and find an intermittent on the board somewhere, I may have to get an inspection microscope to find, as my jewelers' loupe is lousy.
--------------------------
I would also like to have the TV2 Military tube tester as it allows display of the voltages on each of the elements in tubes for Matching. But Sigh the price is inexcusable because of greed on the internet.
I still haven't got my TV7 reading correctly, so right now it collects dust Magnificently. 

I think if a person has sensitive enough hearing to discern the difference in tubes' responses,  the differences must be in the physical, mechanical characteristics in the tubes construction, the resonance of the internal components and their vibration in the tube in response to the sound pressure.  I think it is the acoustic feedback and the tubes' response to it that accounts for any difference in the tubes' tone characteristics.  I have had a number of microphonic tubes with more pronounced effects that have led me to this belief.

Cryogenic tubes, power cords, wall outlets, etc?
What  BUNCH OF HOOEY!
  I even saw one person selling "Cryogenically treated hookup wire".!!!!

Another way to sucker the "Audiofools" out of money.
 (Actually, if they are that stupid and ignorant, maybe they deserve to be taken?) 

These are the people that buy old, leaky bumblebee caps "Because they make their guitar or audio amp sound better"

"There is one born every minute".

I love the EvilBay sellers selling tubes, especially the so called "Matched" ones.
 Many use that term to mean they are the same brand, or the same date code,  color  of base, envelope, mfgr. ad. infintium.
Unless they are run on a full curve tracer, and come with the printout, they are not "matched" in my estimation. 
 Now I do have some Tektronics tubes on boxes of 2 that state: "Matched" for the Tek scopes. I have no doubt they are/were legitimately matched.

wildcat445 wrote:

I have enough tubes to last me several lifetimes.  Perhaps I'm sitting on a few that would be worth something.  They will all go to the landfill after I don't need them anymore.  It is too much hassle trying to sell in the current environment.  I want nothing to do with the audiophile crowd for any amount of money.  I have even had to hear comments when I tried to give them away.  The landfill is not picky.

I put a Telefunken 12AX7 in the tuner of my Concert Grand.  That one tube may be worth more than the Concert Grand!  It is just a tube to me.  It works.

MEZ, if you need some 12AX7's let me know.  I have more than I'll ever use.

Thanks WC, I may have to take you up on that.

chas,  I agree with much of your explanation and as a business owner, I understand market forces for a modest increase but $1698.88 for 2 used 12AX7's is just nuts!

Something that i noticed is cryogenic tubes. What a bunch of baloney!! If that were actually scientifically proven to improve tubes, the military would have had a Federal class rating indicating there worthiness in milspecs.

Just because a seller has the latest in test equipment, it is a red herring unless they can provide traceability to Metrology standards, and provide signed authentication certification.

I have enough tubes to last me several lifetimes.  Perhaps I'm sitting on a few that would be worth something.  They will all go to the landfill after I don't need them anymore.  It is too much hassle trying to sell in the current environment.  I want nothing to do with the audiophile crowd for any amount of money.  I have even had to hear comments when I tried to give them away.  The landfill is not picky.

I put a Telefunken 12AX7 in the tuner of my Concert Grand.  That one tube may be worth more than the Concert Grand!  It is just a tube to me.  It works.

MEZ, if you need some 12AX7's let me know.  I have more than I'll ever use.

I'm not surprised at all...

Some consideration has to be given to the market the seller is catering to...

Buyers looking for a tube that works as intended when plugged into their device. Bragging rights to their friends. "See what I can afford",  with that comes a delivery and performance guarantee.

Consider too. The ever dwindling supply of all U.S. manufactured tube types both new and used.

Same buyers are naive to most of electronic technology and are easily misled by claims of performance, thickly lathered in metaphor.

Granted, there are some qualities that do help, however, terms such as "matching" are entirely bogus unless it is by a family of curves of the individual tube.

Consider too, how many tubes would fail a matching process, leaving just a scant few that "PASS".

Such matching is not without expense of a bench technician. Consider too the advertising costs, storage, all the other expenses that go with running a business.

Then there are the losses, "shrinkage" of the inventory, breakage, failures of the tubes. Incoming inventory is not going to be perfect, culling out the "duds" or devaluing them as a lesser grade is all a part of doing the tube biz...

I thought a lot about it myself, becoming a tube seller. But after doing my life's work and retiring, I find not having the responsibility to track the money, file the reports, pay the appropriate fees, is a blessing.

I still like finding the tubes, in the "rough", though opportunities are getting few and far between. Occasionally, a carton or two will come out of an attic, garage or cellar...

Chas

Look at the price of some of these tubes; 


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Note the price of the matched, used 12AX7's!!!!!!