[Triode Pete]

I've been stating this for the past 10 years or so...

For the past 2 weeks or so, my beloved Goldenote Stibbert IV CD player has been acting erratically, "dropping-out", sort of in a "jitter frenzy"... I thought the laser was on its way out so today I pulled the unit and disassembled it. It has two 6DJ8 / 6922 tubes in it. I pulled the West German-made Siemens from the Stibbert and tested them on my calibrated B&K tester. Both were extremely weak; in other words, "Bad"... I thought the tester might be acting up so I put 2 known good pairs of Amperex gold pin PQ 6922's & they tested superb...

The Stibbert has an ON/OFF switch but keeps the filaments on when in "standby" mode. I called my good friend & tube maestro, John Wiesner. John, with over 50 years experience designing, building & maintaining tube gear, said that keeping the filaments continuously lit is the same as keeping your incandescent light bulbs on 24/7... they will wear out... John also stated that if the filament voltage is not precise for that tube, the tube will prematurely wear out as well... I'll be switching OFF (completely) my tube CD player when not in use...

... so the moral of the story is "turn off your tube gear" when not in use, and in my case, "Practice what you preach!"

Cheers,
Pete

[JLM]

Good point.  We know to turn off pre and power amps, but those sneaky tubes found in DAC's, etc. can be easily forgotten.

[dBe]

I found out a long time ago that digital gear sounds best when left on continuously.  That is: all SS gear, not gear with tubes.  Keep the heaters lit is like you say... A waste of tubeage. 

I had Cary 572SEMkII amps that left the heaters powered up in standby.  It ate output tubes, but then 572s are not very robust.  I wondered about switching out diodes to reduce voltage by 50% during standby.  Just another mind game that never happened.

I does seem like there are tubes that can be left on all of the time and those that can't.  Also, in the guitar amps that I build I run regulated heaters at 6-6.1VDC and B+ voltages conservatively and they still sound great.  I think it is all about finding the "sweet spot" (thanks, Nelson) for every active device in the signal path

Great circle, Pete!

Dave