18 watt Rectifier tube question?

[pigman]

Hey guys, I was swapping some tubes in my GDS 18watter the other day and I noticed my rectifier tube was looking somewhat dark and the plates look kinda blueish. Is this normal? It's been in there ever since I built the amp(2 years). Is there a life expectancy on these , and how often should they be changed? Or is it more like they work or they don,t? Sure appreciate your comments! Pigman

[str82hvn]

Hey guys, I was swapping some tubes in my GDS 18watter the other day and I noticed my rectifier tube was looking somewhat dark and the plates look kinda blueish. Is this normal? It's been in there ever since I built the amp(2 years). Is there a life expectancy on these , and how often should they be changed? Or is it more like they work or they don,t? Sure appreciate your comments! Pigman

They pretty much work forever until they don't. If the amp stops working replace the rectifier. You can always check your B+ voltage if you are worried.

str82hvn

[dotfret]

I hate to contradict anyone, but sometimes it is wise to replace a rectifier tube before it fails. A friend of mine, who is an AC30 freak, once looked in his amp just in time to stop using it! The dying rectifier was causing the PT to overheat, and he could see molten wax bulging out of the PT. Since he told me of this experience I replace my rectifiers regularly - it is cheaper than replacing the iron. You could try monitoring the temperature of your PT to form a decision, using one of those cheap indoor/outdoor temp monitors. My friend tell me that if the PT gets to 50-55 deg C, it is time to change the rectifier.