blown 12au7?

Inside the valve, the chrome bit has gone, replaced by a milky coating on the glass. I pulled the valve out and noticed there was a couple of cracks around the pins.

Any one know what happened ?

It is plugged in to my WAD KEL34 which I switched on for the 1st time last night. Guess something went wrong ;-)

Cheers

 

The glass of your valve has been cracked, perhaps when the amp was being moved or when the valve was pushed into the socket. The silver material (called getter) has been oxidised which turned white in colour. It can happen to any valve. If you want more detail how a valve work, read http://www.vacuumtubes.net/How_Vacuum_Tubes_Work.htm

Get yourself a new valve and hopefully your amp will sing again. Good luck.

Hon

 

It's passed on to the great valve heap in the sky.

 

thanks for that - the thing was only on about 5 minutes. As it was the first time I'd switched it on, I'm wondering if I had wired the thing up wrongly to cause this ?

 

Ah now I see where your coming from........

were the valves new or old ?

do you have replacements ?

is the amp new or old ?

 

hi zanash
new ecc82 /12au7 made by EI, the amp needs a pair, one has blown up, so I'm on the look out for some replacements, something not too special/expensive, as I don't know if the amp works or not ! Its my 1st poweramp, I've made a couple of preamps already, they worked more or less straight away ... this one is giving me problems.

Cheers

 

causes ......could be the valve was damaged in transit ?

triple check your schematics with your build .......you can never be too careful.

try" hot rocks uk".............Ive had some superb sounding valves at good prices from these people.