what tubes for my 811?

[airplane1]

I have an 811 amp, it works flawless but I want to get a set of tubes to keep for when they do start going south. I see on the net that operators put 572b tubes in them so they last longer and then there is word that the old tubes are better so should I look for them?

What are your sugestions?

Thanks,
AP

 

[Captain Kilowatt]

Both lines of thought are valid. 572B's should last a lifetime in that amp if the tubes are not abused. The older tubes in general' and not just the 811A's' were better build. Personally I would use the 572B's simply because the 811A's are already being run beyond their ratings even when ran according to Ameritrons specs. There must be something to running 572B's in an AL-811 series amp. Ameritron started selling them with 572B's and called the AL-811HD.