My really dumb tube mistake(s)


8 years ago, I bought a sweet sounding Line Magnetic amp for my office system which a few years ago died and had to go to the repair shop. $500 later it was back working, but then recently I noticed the sound was getting thin, I couldn’t bias the tubes and thought something else was wrong with it, arghh.

Then I noticed one newer tube was able to be biased and decided to replace all 4 KT-88 power tubes.
Presto, the amp sounded great again!

Like the boiled frog, the sound degradation had been so gradual my brain had gradually adjusted. But the new tubes brought it back to life.

So, then I thought, wow, maybe I should try the same thing in my primary system with my Primaluna monoblocks, switch out the Primaluna tubes for some new Gold Lions. Again - wow! What a difference. Like I bought new amps, much richer and fuller sounding.

Tubes wear out, even if they don’t blow out.
Yes, duh, it’s a good idea to replace them every 4 years or so and not wait eight.
cdc2
My system started sounding thin and lifeless last year. I got my tube tester out and went through my gear one at a time. Found a tube in my pre amp that tested very low. Changed it out and now back to amazing music. Not sure how I would have proceeded without my tube tester short of replacing one tube at a time until I found the bad one. Or, at a very high cost, replace all the tubes at one time.

When music turns lifeless, lacking, punch, drive, dynamics, air, bass, then is time to check which tube has gone bad, no need to blow if its an output tube. Or even if they cannot bias properly (output ones). For me it should be best to change all output tubes at the same time. A tube tester will not show when a tube is going to go bad but can give a good indication of its life. So if close to end of life readings, replace. Always have a spare set, you never know.

G
SET amps run at 100% duty cycle all the time. I wonder how fast that wears out tubes compared to a push/pull amp?
__________\\\\\\markpao: Can you please provide the name of the tube tester you have. Do you know if it will test 805, 300B, 6SN7 and 6SL7?
__________\\\\\\tvad: for 300b replacement tubes, please look at the Psvane Acme. They made a nice improvement in my Line Magnetic (along with the other rolled tubes on it)
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@ veerossi
TV-7D/U tester.
 It will not test the 805 
Yes on the 300b, 6SN7, 6SL7