Burn-in time for a Shuguang 845B tube?

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.

I forgot to mention that tubes have the greatest chance of failure in their first 25 hours of use. Even if you buy tubes used or have them burned in at the factory, tube internals can shift during shipping, and this is more true the larger the tube like an 845, 805 and 211 etc.

PS – don’t forget to check the bias during the tube’s burn in process.

Brf
Thanks,for the info I am sure it will be helpful to someone besides myself. My amps are self biasing and I will be more diligent when listening.

Well I just past the 50 hr mark and the sound started to open up, the rought edges are (almost) gone, but I think the biggest improvement is in the soundstage area! The music is wide, tall and deep as it suppose to be! I guess a few more hours should bring more detail and smooth the music a little bit. Thank you all for your comments!

I can tell you that my Shuguang 845T's took about 75 hours before they started to open up. By 100 hours they had stopped improving.

I remember when I first dropped them in to the amp. They sounded horrible, and I thought that I had made a serious mistake. They were closed in, sounded muffled, and had poor dynamics and no sparkle. Now they are the opposite - open sounding, dynamic, great sense of scale, and pleasant to listen to.

Keep the faith :) And good luck!