Home » Audio » Thermionic Emissions » Anyone know how bad this is?
Anyone know how bad this is? [message #9387] Thu, 01 December 2005 15:24 Go to next message
Russellc is currently offline  Russellc
Messages: 397
Registered: May 2009
Illuminati (1st Degree)
Crap, while half asleep I was powering down my P-P 6550 amp which has seperate switches for filaments and the B+. I screwed up and turned off the filaments, but left on the B+ ALL NIGHT while I was asleep.
In the quiet of morning, I could hear a very slight transformer hum.
Inspecting the amp, I noticed the hum was the power transformer, as well as heat coming off the un lit tubes. after powering down, and then later turning it back on, everything seems OK....is this hard on the output transformers or output tubes?


thanks,
Russellc

Re: Anyone know how bad this is? [message #9388 is a reply to message #9387] Thu, 01 December 2005 17:09 Go to previous message
2wo is currently offline  2wo
Messages: 44
Registered: May 2009
Baron
Well there you go,
I don’t believe that not preheating the filaments, before turning on the B+ causes undue harm at moderate voltages.

If the point is avoid "cathode stripping". One mistake like yours and you have subjected your tubes to more stripping voltage then they would see in many lifetimes of instant on use.

That said, I would check the bias and keep a close eye on them for a wile to make sure that say, the heater cathode insulation or something was not damaged.

Has there service life been reduced? Time will tell…John


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