[Boatanchors] tubes

[Albert LaFrance]

Sure, there are measurable differences in electrical characteristics among
tubes, but my question would be: can it be demonstrated that there's an
always an *audible* difference?  Obviously, some defects like microphonics
can be heard and are undoubted lower in better-quality tubes, but can it be
shown in a valid double-blind test that a listener can detect all of the
differences used to justify the higher prices for certain specimens.

In other words, just because a particular tube is scores on the high end in
a particular measure doesn't mean that it sounds better, and thus merits a
higher price from someone who's buying the tube for listening purposes (as
opposed to visual aesthetics or scarcity).

Albert

----- Original Message -----
From: "Kim Herron" <kherron@voyager.net>
To: "Horace W. Hall" <hwhall@compuserve.com>; "BOATANCHORS List"
<boatanchors@mailman.qth.net>
Sent: Monday, April 19, 2004 9:07 AM
Subject: Re: [Boatanchors] tubes


>       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