New Tubes

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guitarnate69

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How often do you have to replace the tubes in a tube amplifier?

How much does it cost?
 
It depends on the amp and how many tubes there are, what kind they are, and how often you keep the amp on. Also, keeping your amp properly biased will extend tube life. On my main guitar head (Rivera K100), I swap out the tubes for new ones about once per year. I've had my Marshall EL34 100/100 power amp for a couple of years now, and haven't had to swap out the tubes yet.
 
Back in the old days, people actually tested tubes before they repalced them, too. Now people replace tubes as a matter of preventive maintenance because they are not as long-lived as the tubes made in the West thirty years ago before tube production stopped in non-Communist countries.
 
Wait... so no Western country manufactures vacuum tubes anymore? When did this happen? I'm confused. And hungry.
 
I was wondering because I haven't replaced my tubes in my marshall yet, and I've had it for a year and a half. Will the amp ever stop working? Or will the sound just not be of as high of a quality?
 
Mentat said:
Wait... so no Western country manufactures vacuum tubes anymore? When did this happen?
Click to expand...
The early '70s. GT is trying to start making viable power tubes on the old tooling in the US but that's still iffy - and very expensive.

Tubes were considered obsolete in the west by the '70s and environmental controls on the manufacturing processes (particularly those involving mercury) finally killed them off as unprofitable businesses around tirty years ago.

All the tubes sold today are from the former Warsaw Pact countries and China, where they were producing fairly crude tubes on Soviet machinery, which were still very much part of the backwards electronics of the communist world.

The so-called 5881 tube that's seen in Fender amps is actually a Soviet-era military avionics relay tube being used as an audio power tube!

The top-grade, old stock US and western European tubes that people pay big bucks for now are far better than what is being produced today. A 12AX7* tube, for example, had a useable life of around 3000 hours. The typical 12AX7 import made today usually is only good for about a third of that.

The Chinese tubes being made today are getting better, however, and some are considered quite good.
 
What about the tubes that are in the Marshall amps?
 
I doubt Marshall is using NOS EL34's. They are probably using Yugoslavia (former) made tubes from names like Svetlana, JJ, Ei, or russian.

NOS tubes should last a very very long time in typical operation. I have a 66 Gibson Skylark with all original RCA tubes, and it still sounds the better than with new tubes. I play it a lot. (To be fair though, Im not sure how much use it got until I bought it a few years ago). I have lots of old used tubes that sound great when compared to new tubes.

Power tubes wear out most readily...compare the volume you have with a new set of power tubes (after rebiasing). Loss of volume is what you'll mostly likely notice with worn out tubes.

Preamp tubes last a very long time, but a phase inverter tube normally works hardest and is more likely to expire early. Preamp tube failure comes in many disguises...

As far as tubes go, just use what sounds good...and keep the power tubes biased safely.

Ahhh...the warm glow of tubes on a cold winters day...
 
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