Noise & Hum Rating

and to try to charge me $40 each for EH EL 34s that cost $13 from any number of sources.

Like ARC tested tubes,..... there are tested good tubes and then there are very good closely matched tested tubes.

Out of all the tubes Cary buys from the distributor I would bet they probably throw at least half of them away or sell them to another tube vendor because the tubes did not meet their testing standards.

You pay for what you get when buying new production tubes....
Quality control in tube factories ain't what it used to be in the 1950s and 1960s. Even the 1970s and 1980s....

That's nonsense. My amp takes a dozen EL 34s. Cary tried to tell me that the tubes that were in it were bad. When I had them tested locally not only weren't they bad, they were actually very strong, and except for a little degradation in two of them, pretty well matched. Cary said they were all bad and needed to be replaced, and it simply wasn't true. They also said that the tubes were causing the hum, which also wasn't true.

The EH tubes they wanted to sell me are nothing special. Electro-Harmonix EL34s are an inexpensive tube. Tube Depot, Doug's Tubes, Amplified Parts - all of which were highly recommended by A-gon members - and a few others sell that same tube for $13 (or $27 a pair) matched and tested, and graded for early or late distortion - a pretty thorough QC process.

IMHO Cary was less than upfront about the state of my existing tubes, and trying to gouge me for replacements. Even if Cary does go through such a rigorous QC process themselves, that's not an excuse to triple the price of the tube, especially when the same service is available through some other reputable sources.

That's nonsense. My amp takes a dozen EL 34s. Cary tried to tell me that the tubes that were in it were bad. When I had them tested locally not only weren't they bad, they were actually very strong, and except for a little degradation in two of them, pretty well matched.
02-25-12: Grimace

What kind of tube tester was it? Service or laboratory tester?

When was the tester last calibrated?

http://alltubetesters.com/articles/howto_test_tubes.htm

Grimace,

Scroll down the page of the link provided below.
A great video on testing a pair of 6V6 power tubes.

BRENT JESSEE RECORDING & SUPPLY, INC.
.

We actually did to tests. The first was on a B&K tube tester, set at a sensitivity of 53 - which was the spec for the machine for an EL34. All of the tubes tested out between 95 and 110, with two of them a little low at 85. Then we did a sine wave test for noise with an attached meter for output. Using a baseline control we got 21 watts in push-pull per pair of tubes - any combination of any of the dozen, even the two low ones (although I confess, I do not know the plate voltage). The sine wave - control at the bottom of the wave, and tested tube at the top - revealed no noise in any of the tubes.

The guy that did the test has been doing this for forty years - a really cool shop btw - and his opinion was that not only were the tubes still good, but they showed remarkably little wear at all.