[Vinyljh]

The original Western Electric 300B -until 1988- is known to last 40,000 hours under ideal conditions, one of the most reliable tubes in history. The F2a is also extremely reliable and can compete with WE 300B's in longevity. To say the 300B is known for premature failures is a new piece of info to me. I would say very strongly that this is not the case. Sadly, original WE 300B tubes are very expensive and no longer available in any quantities.


As for the new production Gold lion tubes, I have no idea. 500-600 hours on this current set is certainly premature for one to fail. I would hope for 2-3000 hours from a modern 300B at a minimum before any failures.


Several things can affect tube longevity in an amplifier- high a/c line voltage and/or surges, poor ventilation, vibration, tube operating points, transformer/speaker load, tube manufacturing quality and mechanical contacts within the socket. In my mind, the only way an amp itself, without human error, can cause premature tube failure would be high operating points or poor contacts. This is certainly not the case with the D'Yquem. The tubes are running quite comfortably in both plate voltage, current as well as filament voltage. Shindo Laboratory has been producing commercial 300B amps since 1981.


Human error is generally the faults we see- Using low impedance or low efficiency speakers, improper ventilation, tube rolling without biasing, flipping the power on and off without allowing the amp to cool down, strong vibrations due to poor racks or floor placement, not using Switchcraft terminated light weight interconnect cables etc


In your set up with the tube cages off, being on a heavy piece of wooden furniture and connected to a mild speaker load, it seems it can only be the Gold Lion tubes. Whether its a production run issue or just the way these tubes are, I do not know. Many new production tubes have good runs and bad. I have asked Shindo for their thoughts.


It would also be interesting to know the line voltage. If this rises significantly, even for short periods, the tube plate voltage and current rise with it. A power tube failure could be the result. Preamp and driver tubes wouldn't be affected by this. Years ago, pre Tone/Shindo, we had a client that had an amp that failed repeatedly. We measured his line voltage and found he had 133V! A power transformer multiplies the incoming voltage. 1V in can result in 2-3V out to the power supply of the amplifier. 13V over could have been 40 V of overage in the circuit. Thats an extreme case and would not expect your line to be over 120V. However, only way to know is to measure. My line has gone from 119V pre Hurricane Sandy to 112V post Hurricane Sandy and most recently with new lines run in my neighborhood, to exactly 120V.


That being said- tubes fail. They will always fail. Sometimes prematurely and sometimes not. Its totally unpredictable. A tube swap, bias adjustment and you are back in business. Its frustrating to be without music but all is easily resolved with a multimeter, screwdriver and a spare tube.


While certainly more than 10 pairs have been made so far, this is a Shindo amp. Production numbers are always low. These are hand made, one at a time.

Jonathan