tubes glowing blue after...

[alcoholocaust]

turning the amp on without a speaker cable. one tube blew. it has been replaced along with the paired match for it. they are glowing blue and i cant tell for sure if all the others are glowing blue with them or if its just a reflection from the glass. its been turned on since that happened and it sounded less muddy. maybe that was due to the tubes being replaced. or as i am asking if there is a problem with the amp. please explain for me

thanks in advance.

 

[Rich M]

Blue glow (not to be confused with internal arcing!) is normal and due to ionization of gas residue inside the tube (Argon, IIRC) Common with 6L6's and completely normal. This is a diffuse blue outside of the plates. Arcing between internal components is, however, not normal and indicative of a wayward tube.