02-25-2016, 10:45 AM
(This post was last modified: 02-25-2016, 10:57 AM by GoldenVulture.)
Quote:OinkusThe silver was not on the tubes when I put them in the amp or when I swapped out a couple preamp tubes a year or more ago. It was making popping sputtering sounds with no headroom on the clean channel distorting. Opening it up and looking at it there is nothing that is apparently blown up but it now has very low volume and none of the other sounds.
Seems a bit like they're getting too much HT [ Plate voltage ] Do they get very hot , hotter than usual ?
Spots appearing after use is common too. It's something to do with a gas they put in them to absorb anything leftover from the vacuum process. it solidifies on the glass. If it's just black and seems rather a lot it's probably fucking out.
The lack of volume is indicative of dying valves as is the frypan popping [ if that's what it sounded like? ]
Excessive blackening suggests components other than the valve is causing it to fuck out.
There's a relationship between the bias voltage and the HT. either going astray can cause redplating.