Amp Paranoia!

lol my ritual in gaining new gear has begun...i think what if theres something wrong with it!...i have an engl powerball head just bought and it has a see through front grill as you know....i notice the 4 tubes back light, light up red wen i turn it on..but then wen i go off standy by mode into play mode it seems as though 2 of the 4 tubes hav a purpley tinge to them when i turn off standby mode into play lol is this normal in tube amps? i cant notice any audible defects but that paranoia is takin over! someone reassure! thanks rex

A blue or purple glow is normal.

Not all tubes do this, but the ones that do are OK.

thanks for the reassurance!

Hey Lordathestrings. Quick tube questions. I understand blue/purple glow is normal for El34's (or is it EL84's)? Anyhow, I have an old original RCA 5Y3 in one of my older champs that glows blue on one side. I'm assuming this is due to air/gas leakage due to age. The base of the tube is missing also. I bought a replacement, but it still sounds great (the best of all 3 of my SF Champs), do you see any problems with me keeping the older one in or should I go ahead and replace it?

Thanks
Jack

Air leaking in will rapidly destroy a tube. The 'getter flashing', usually a silver-coloured coating on part of the inside of the glass will disappear, and the metal structure will change colour, often turning white.

The blue or purple glow is apparently the result of small amounts of impurities left in the gas by an incomplete purging process. AFAIK, no harm done.

Thanks for the info. I work on Hi volume laser printing systems for a living. They big ones that print your utility bills and credit card statements. I've seen things similar to this and have learned through much heartache just to "leave well enough alone" when all is working well or i'll end up resetting power supply nul voltages/currents and changing miriads of software switches to get me back to where I was. If it aint truly broke, I usually don't fix it.

Thanks again, you guys rock when it comes to technical stuff

Jack