Power Amp


My power amp keeps burning up the power tubes.  I get maybe 4 months out of them  . I have use three different type of tubes that are recommended for the amp. Can anyone help, why this is happening, are all of the power tubes bad?
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I had solid state amps and sold them off. Wanted to get a tube amp a chance ,keeps blowing the power tubes . It does not sound like a tube problem but a amp problem. Thanks for all the responses.  
Whoever designed this amp the boss is running to high,
what brand  , integrated or power amp, and manual bias or auto bias ?