I know the older folks remember the old (YOU-TESTOME-TUBE-TESTERS) of the 50's and 60's. In those days, for a couple bucks you could test and or replace all the tubes in your Radio/amp or TV. Many of those tubes were interchangeable, and many were not. I can remember bending a pin or sniping one off, attempting to get it to fit. Once in a while it would work and sometimes you would get the surprise of your life when one Exploded or got so hot that things began to smoke and catch fire. Don't you take the same risk today trying to swap out one for the other incorrect tube? I know tubes are expensive. But so is rewiring an OPPS/AMP.
----Danny,

"Many of those tubes were interchangeable, and many were not. I can remember bending a pin or sniping one off, attempting to get it to fit. Once in a while it would work and sometimes you would get the surprise of your life when one Exploded or got so hot that things began to smoke and catch fire. Don't you take the same risk today trying to swap out one for the other incorrect tube? I know tubes are expensive. But so is rewiring an OPPS/AMP."

bending a pin or sniping one off, attempting to get it to fit. Once in a while it would work and sometimes you would get the surprise of your life when one Exploded or got so hot that things began to smoke and catch fire

I grew up in the days of Heathkit and Lafayette, back when it was pretty common hobby for kids to build tube radios and tinker with electronics. Tested lots of tubes at the drug store. When I substituted tubes back then, I knew the pin-out and operating parameters of the tubes I was swapping. I never guessed what would happen -- I knew what would happen.

In guitar amps, there are lots of preamp tube swaps that are universally safe. Some power tubes and some rectifier tubes are interchangeable in some amps. Ideally before you start experimenting you should know what you're doing and why you're doing it, but there are a lot of well known swaps you can do simply because you know other prople have done that particular swap in that model of amp without problems.

Of course you shouldn't just try to cram any random ol' tube into your amp. If you don't understand how your amp works and the amp gurus haven't said it's safe to to swap "this" for "that" in your amp, use the stock type of tubes. But there are lots of common and safe tube swaps known.

My point exactly If you don't know what your doing. Do Not Attempt Swapping out tubes.
----Danny,

I've been tube swapping and changing for a long time....it never hurts to have an RCA tube manual handy at times.
BTW what is an OPPS?

I guess an (OPPS) is an (OOPS) in its self.
----Danny,

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These things used to be in just about every grocery store, hardware store, and drug store when I was a kid.

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“All music is folk music, I ain't never heard no horse sing a song.” Louis Armstrong

It would be cool to have stuff like that around... other than amplifiers, are there still other products that people prefer to have tubes with? I bet there some people who collect tube radios as a hobby....

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Kid: "Hey Smokey! Where did you get your name?"
Smokey the Bear: "Well..."
(former user jimbo612)

Yeah antique radios are cool and people collect them,also ham radios,and I'm sure there's some people who collect and repair old tube TVs....then there's the audiophiles who have their tube stereos and buy the best tubes they can find.
I have a friend who converts tube PA's into guitar amps.
I'm just really glad that tubes are still available...and I remember the old tube testers in the stores....those were the days,especially when you bought brand new American made tubes!