FWIW, nobody really NEEDS a matched quad ;--) Push-pull amps (the most common) work in matched pairs. However, if your amp takes four of something, or eight of something, then there are certain economic and operational advantages to buying FIVE matched tubes (for each group of four):
1.) You don't have to keep the matched pairs separated. You can plug any tube into any of the four sockets and still be running two matched pairs.
2.) If you buy FIVE matched tubes, then should one fail, the fifth (spare) can replace any one of the four that fails. If you're particularly O/C, you can even rotate the five (like tires) so thay all have the same 'wear'. (This may sound silly, but tubes, especially power tubes, DO change their test readings over time, even though they are still performing just as when new.)
To the question of breaking tubes in 24/7: I don't recommend it. It won't harm the tubes, and back when there were ONLY tubes, a lot of gear was left on 24/7, sometimes for years, for various reasons, with no ill effect. But with NEW tubes, it's best if you are present, with your hand near the on/off switch if fireworks should start -- which they most often will in the beginning -- usually right after turn-on, or as the tubes are warming up. With a few exceptions, most power tubes are substantially 'broken-in' (and can be pronounced 'reliable') after 25 -- 50 hours. That's only a dozen listening sessions at most. And with a lot of power tubes, you won't actually want to 'listen' for the first 25 hours anyway ;--)
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1.) You don't have to keep the matched pairs separated. You can plug any tube into any of the four sockets and still be running two matched pairs.
2.) If you buy FIVE matched tubes, then should one fail, the fifth (spare) can replace any one of the four that fails. If you're particularly O/C, you can even rotate the five (like tires) so thay all have the same 'wear'. (This may sound silly, but tubes, especially power tubes, DO change their test readings over time, even though they are still performing just as when new.)
To the question of breaking tubes in 24/7: I don't recommend it. It won't harm the tubes, and back when there were ONLY tubes, a lot of gear was left on 24/7, sometimes for years, for various reasons, with no ill effect. But with NEW tubes, it's best if you are present, with your hand near the on/off switch if fireworks should start -- which they most often will in the beginning -- usually right after turn-on, or as the tubes are warming up. With a few exceptions, most power tubes are substantially 'broken-in' (and can be pronounced 'reliable') after 25 -- 50 hours. That's only a dozen listening sessions at most. And with a lot of power tubes, you won't actually want to 'listen' for the first 25 hours anyway ;--)
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