I've been waiting months for the VT1000 to finally land here in Australia and I finally got my expectant hands on a unit which shipped to me last week. I'm now questioning the results, just like another poster here.
A good friend of mine is a valve collector. In fact, he has 1000s of them but has very little use for guitar-style valves. I've been able to take around 100 of them from him on approval ($5 each, regardless of size / type). The valves are all either new old stock (in boxes) or scavenged from various appliances and garage sales over the years. All of them are from the 50s and 60s and are British, German, Australian or American.
My concern relates to lower gain pre-amp valves. My collection includes Philips, Telefunken and Mullard 12AX7, 12AU7 and 12AT7s.
- I tested 24 12AX7s: 14 good, 5 worn and 2 failed. Ratings varied from 4s to 10s both triodes
I tested 23 12AT7s: 12 good, 8 worn, 1 failed. Ratings varied from 2s to 9s, both triodes
I tested 26 12AU7s: 3 good, 1 worn, 21 failed! Ratings for the failed valves 1s, occasionally 1 and a much higher number, though this changes, oddly, when re-testing.
The unit I received was supposed to be brand new, but had some cosmetic marks on the case I suspect it's taken a knock. To their credit, the supplier has agreed to either refund my purchase or replace the unit with another brand new one, although it'll take a week to get to me.
Anyone else had issues testing known good 12AU7s with this unit? Or have I just hit a rich seam of duff valves purely by chance? Your responses might make me rethink the results I've had for the other valves and the EL34 / KT66 / EL84s I've tested with it...
Thanks in advance for your thoughts.