@calieng. Funny I had the exact opposite experience with some 6sn7’s purchased from Viva. It’s been a while so I don’t remember how the test results were noted, but suffice it to say the tubes did not match. Viva also took the tubes back without question. Moral to this story, test the tubes yourself no matter who you buy from, which really doesn’t speak too well to this part of our industry.
Vacuum Tube Snake Oil Salesmen
Just a mini rant to complain about vacuum tube suppliers (not all but most) and their false advertising.
I ordered a set of 4 matched 2A3 Acme tubes direct from PSVane for my Woo Audio WA33 as an upgrade. They cost close to $1k all together.
When I got them I checked on my MaxiMatcher2. The boxes said 65mA but with correct operating voltage and bias set on the tester I could only get 2 of them up to 43mA. One other read 39mA. And the last one was an internal fault short which could have damaged my amp had I not checked them.
I asked to return one "Matched" set for replacement. The PSVane customer service would only offer to send me one tube and not a matched pair. They would not pay return shipping to return one set. Instead they demanded I smash the bad tube and send them a picture. Has anyone ever smashed a large vacuum tube with a hammer and seen where all the pieces of glass fly to? I said no way. I will throw it out or return it but I am not going to risk cutting my hand doing that. So they refused to send a replacement.
While I had the Maximatcher out I decided to go thru some other tubes I had in my spares box to check them (purchased before I had the tube tester). I could not believe the results. Some tubes matched by well known vendors were off by as much as 30% from each other.
It is really a good investment to get a tube tester if you will be a regular user of tube amps.
If you must buy PSVane then get them from Amazon and not direct so you have some safety to return them.
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Well gain is different than transconductance. Remember that the vast majority of these testers only test a tube at one operating point and these point vary from tester to tester. Apples to apples only if the seller uses the same tester as the consumer. The thing to ask yourself is if you would pay much more for tubes which were matched using numerous operating points from a vendor willing to spend the time and money to do it correctly. Most, I think, would not. |
clarifying my earlier post, |
That’s sort of true in the absolute sense; but relatively speaking, matching tubes should match when measured against one another.
Interesting. So, you already paid much more for tubes which were supposed to be matched but were not, now the question is would you pay much more than that for tubes which were actually matched?
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For sure, matching transistors can be critical. For instance, some amps don't let you adjust DC offset, they rely on a matching differential pair instead. The advantage with transistors is that new ones from the same batch are most likely very close to each other already, and a majority of transistors are cheap enough that you can buy a dozen and hand-match them to get the best-matched pair possible.
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