I have a 12" combo i love an use as my bedroom amp. I was told it was from the 50's but it looks early 60's to me, it's a fugly mess cosmetically. Ocassionally i take it out to gigs and rehersals but it really isnt loud enough for that. I purchased/found a compliment of replacement NOS tubes for it because i want the amp to last. I installed them maybe 4 months ago.... sounded instantly louder with more headroom and better high end. I was happy. But now im noticing that it makes a sort of static like fart when hitting it hard with chords or od pedals. Not badly enough to notice all the time it just seems to pop out of nowhere and sounds like crackle/distortion, but very "seperate" from the tone of the amp itself. I think the amp may be biased cold for the tube(s) i have in it now. does this make sense?