[Boatanchors] tubes

[Kim Herron]

>Hi gang,
>I must be missing something.  4 brand new 12AU7 tubes by telefunken just
>sold for $220.  $55 per tube!  wonder if there's any differnece in the
>sound out of them compared to my regular 12AU7's?
>I have been mystified by the demand for certain tube brands, plate shapes &
>colors, and even getter shapes. I doubt there is a real difference in
>sound, but there are people in the audio community who believe there is.

      I've been working with a fellow here in my area that is one of the 
HIGH end audio
tube suppliers.  He's routinely getting $70.00 for 6SN7's and 12AU7's.  Now 
that's IF
these tubes make it past all of the testing that he does with them, which 
mean putting
them in a circuit, looking for NOISE that can only be seen with a scope, 
and checking them
for micro phonics in an anechoic chamber with the tube used in the circuit 
that it will go in when
it get to the end user.  These tubes are going in some REALLY, REALLY 
expensive audio
gear and the people that use this stuff are still spinning records, so they 
are VERY concerned about
noise first, availability second and cost last.
      This same fellow has 10 to 15 rejects  for every tube that passes his 
testing and most, if not all,
of them are very good quality, very usable tubes that would do anything we 
wanted.  But since he won't
sell them himself, they will find another outlet, at a lower price.  I 
thought it was all smoke and mirrors
too, till He showed me what he was talking about and what he did with these 
things.  His procedures do
uncover a difference between one tube and the next and he can prove it over 
and over again.  What people
are paying for, with his tubes, is his time to find the tube that will run 
in a particular circuit to do a certain job.
It's the same thing as buying a matched set of Finals for an amp or 
transmitter, the only difference being
is that he actually puts them in the circuit that they will be used in and 
meters the current draw versus voltage
and bias setting and measures the noise with a scope and audio analyzer and 
checks dB gain versus input level
in the actual circuit.  What would you pay for a pair of 3-500Z's set up 
like that?
      Now, there are a bunch of people that are trying to do the same 
thing, without all the test gear and know-how
and they are making money on this too.  So it's still caveat emptor, but at 
least I now know that it's not all
fraud.


Thanks!!

Kim Herron  W8ZV
1-616-677-3706