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.
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 tubes 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 dont forget to check the bias during the tubes burn in process.
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!
Besides the Shuguang 845 T tubes do you any experience with some others 845 tubes burn in time?
Yeah, the original 845's that came with my amp. But that's not really relevant because the whole amp was burning in at the time.
My experience has been that the graphite plate 845 take less time to burn in than metal plate 845.
Sorry to hear that! In my case the originals tubes are Sino 845 and the replacements are Shuguang 845B (I guess Shuguang makes them for Sino). So far the difference is notable in all regards: soundstage, bass, definition, etc. I hope that as time goes by the tubes will improve a little more.
Hello, anyone experience with the Shaguang HI-FI model?