Valve query

[Ant]

One of my power amp valves has started to flash blue when I'm playing, what's that all about then?

[Bloodaxe]

[quote name='Ant' post='690448' date='Dec 21 2009, 10:29 AM']One of my power amp valves has started to flash blue when I'm playing, what's that all about then?[/quote]

Badness. Could just be a bias adjustment issue, but sounds like something's on the way out.

Does it flash (!) in time with your playing? Especially when you're digging in?

Pete.

[Ant]

[quote name='Bloodaxe' post='690458' date='Dec 21 2009, 10:49 AM']Badness. Could just be a bias adjustment issue, but sounds like something's on the way out.

Does it flash (!) in time with your playing? Especially when you're digging in?

Pete.[/quote]


Yeah it does, especially with distortion on

[Bloodaxe]

[quote name='Ant' post='690619' date='Dec 21 2009, 01:40 PM']Yeah it does, especially with distortion on[/quote]

The blue glow is electricity in motion - could be the bias (or a component thereof) or the valve's on its way out. One pair or all four? Any sign of "Mirror-ing" (like you usually get at the top) around the [u]middle[/u] of the glass envelope?

[Ant]

I think it was just one valve out of the six

[SS73]

Sounds like the valve is tired and is not coping with the demand, if the bias though is to high it would glow red hot in the very centre of the valve with no bass plugged in. As a quick test see if it reacts the same in another valve position.

[umph]

[quote name='Ant' post='690795' date='Dec 21 2009, 05:01 PM']I think it was just one valve out of the six[/quote]
not a problem thats how 6550's / kt88s work! sounds like your driving them really hard though.

[umcoo]

Thought I'd chime in as my Fender Bassman 135's valves get a blue glow when I take it off standby. Not sure what kind of valves are in it, as long as it rocks hard, I don't mind.

[SS73]

Thinking about it when our Guitarist uses my Burman, it does the same thing especially with a tube screamer, although all 4 EL34's go blue in unison.

[Bloodaxe]

[quote name='SS73' post='691272' date='Dec 22 2009, 09:19 AM']Thinking about it when our Guitarist uses my Burman, it does the same thing especially with a tube screamer, although all 4 EL34's go blue in unison.[/quote]

In unison I can understand - just means they're working very hard & might shorten their lifespan.

It's the idea of just one doing it that makes me think something might be up.

Pete.

[SS73]

[quote name='Bloodaxe' post='691588' date='Dec 22 2009, 03:31 PM']In unison I can understand - just means they're working very hard & might shorten their lifespan.

It's the idea of just one doing it that makes me think something might be up.

Pete.[/quote]

Yes, Its got to be one of the Valves is just not man enough for the job anymore and its showing in his actions.