Burn-in time for a Shuguang 845B tube?

In my experience, new 845 tubes take around 50-75hrs to open up. In the early burn in stage, you will find the dynamics restricted. Unlike some other power tubes, 845 tubes should not be left on unattended, therefore, the break in stage will generally take longer. Patience will be rewarded.

Thanks Brf! I guess I still have to be take easy. Thanks for the advice about no letting the amp unattended.

Hello Brf
I was wondering about your advice about the 845 tubes should not be left unattended...does this also apply to the 211 power tube? Normally, I don't leave my amps unattended by leaving my home but sometimes I am in another room. Does this apply about being in another room? Are these tubes generally more volatile? I have two in each mono amp. Thanks!!!!!

I'm working on a new pair right now to replace a pair of Pavane 845-Ts and it started showing signs of life around the 50 hour mark. I committed the no-no though and left them unattended over night for the first 48 hours and at night they were playing the Isotek burn in disc. Whether it accelerates the burn in or not can be debated, but I doubt it slows things down any.

Chuckie, some will argue that no tube amplifier should be left unattended to avoid the risk of fire in the event of a catastrophic tube failure. 845, 805 and 211 based amplifiers have over 1000v applied to the tube’s grid, therefore, by the nature of their design, present a greater risk of fire in the event of a catastrophic tube failure.

Leaving an 845, 211 amplifiers on and unattended will not hurt the tubes and will accelerate the burn in process, but as a general rule, it is not a safe practice.