[jrun]

Hello all,

I am a long time lurker, not so frequent poster.  My Audio Space ref.3.1 Kt88 amp was turned on and stupidly left unattended for about two hours.  When coming back into the room a very noticiable "hot" smell was detected.  It was one of the Gold Lion Kt88 reissue tubes glowing very red hot.  I shut the amp down and let every thing cool off.  I replaced the hot tube with a spare and turned the amp back on.  After about 10 minutes, the replaced tube was definitely glowing brighter than the other three tubes.  I was able to bias the tube and the amp did play, but I shut it down and called my dealer who recommended that I send it in for a look see.  This is my first tube amp and I was wondering if this is just part of the pleasures of tube amplification For the time being I have put my bel canto integrated in the big rig to have something to listen to.  Thanks for any replies.

                               JR

[kingdeezie]

Yes.

I just bought a used pair of Manley Neo Classics 250s, that when I turned it on, a power tube blew a d took out the fuse and a resistor. The amp was bricked until I could order a new resistor and replace it.

However, if both tubes are glowing hot orange, i would have to assume that maybe something else is wrong with the amp and that one particular tube section is misfiring.

A red-hot tube means that the tube is getting too much voltage; if you can bias tube I don't think it should be glowing red; unless somethif is wrong with the pot and it's not working.

[JoshK]

The smell is likely a resistor.  That is also consistent with a glowing tube.  I am surprised you were able to bias it correctly though if the resistor went bad.  Did the tube still glow red after re-biasing, and if so did the bias stay the same (or did it drift lower)?

It could also be something like a failed coupling cap, but I somehow doubt it. 

[jrun]

Thanks for the input guys, I really appreciate it.  I wasn't clear in my original post.  The replacement tube is the one I could bias, and the amp would play, but it was soon obvious that the replacement tube was glowing much brighter than the other three power tubes.  Sounds like I did the right thing.  Already have a new set of Gold Lions waiting.

                        JR

[kingdeezie]

Let us know how it turns out.

The only thing that clued me in on my problem was the fact that the one tube would not properly bias at all, and was getting severe overvoltage with the amp in standby mode; something like 9volts.