Should I be more proactive maintaining 3 to 4 year old Cronus Magmum?

[Old Guy8]

This is my second tube amp. First one is a Rogue Sphinx hybrid with two 12au7s, I've had 3 years. New to tube world.
I have a 3 to 4 year old Rogue Cronus Magnum 1 integrated amplifier. I have owned it about ten months. I don't know the hours on the tubes. I believe it has original tubes less one 12au7 pre-amp tube. I run it about 20 hours a week.
I manually check the bias of the four KT120 tubes according to manual. Bias seems to be holding steady since I bought it, 10 months ago.
I use a manual reset ground fault adapter to protect from power flickers.
Should I be more proactive with amp/tube maintenance? Is it relatively safe to wait for signs of tube issues? Bias changes or tube noise.
Amp sounds fine and has been trouble free.

 

[airtime]

If it's holding a bias and sound OK then just sit back and enjoy.

I always have is a backup set of tubes. Sometimes for accidents (usually by my hand) or if I need to find out if a particular tube is starting to sound dull and nearing the end.

 

[Old Guy8]

If it's holding a bias and sound OK then just sit back and enjoy.

I always have is a backup set of tubes. Sometimes for accidents (usually by my hand) or if I need to find out if a particular tube is starting to sound dull and nearing the end.

Thanks airtime.
I'll consider a backup set of KT120s, for when. They may not be in any cheaper in the future also.

 

[GordonW]

The cool thing about a Cronus Magnum, is that they're reasonably well protected against tube failures.

Usually, if one goes out badly (short), it just blows the tube fuse. Worst case, I've seen one take out a screen-stability resistor- but even that's easy to fix.

It's fine to just run the tubes in these, until they wear out, then replace them, IME.

Regards,
Gordon.

 

[sKiZo]

If ya got em, smoke em, I always say ... ;-}

Long as the bias holds steady after a few tests of a new amp, you should be good until a tube starts to fail. In my own experience, that's more of a gradual reduction in output or sound quality instead of a catastrophic failure. I did add meters to my custom amp so I can do spot checks every time I fire it up, and the KT120's are always dead on the mark once they warm up.

Only thing I'd add to your list of things to do is to remove the tubes every now and then, just to break up any oxidation on the contacts. Also good to re-tension the socket fingers long as you're in there.

PS - can you run KT88's as backup? You'd definitely have to do a complete re-bias if switching to those.

 

[Old Guy8]

Thanks for replies, Gordon and Skizo. I'll just Relax and listen.

 

[Brice]

So far my KT120 have been rock solid.
No bias drift, nothing. I do check the bias manually ... when I feel so every 6 months or so.

I would relax as advised, and carry on doing routine check every 6 months and wait for signs of change.

You may have to wait years with the KT120

 

[trinhsman]

I owned an Audio Research amp years ago. Great amp. The only thing that I ended up not liking was how slowly the sound changed over the years. You really didn’t notice it. So one day I decide to get it serviced and have the tubes replaced. Holy Crap! A new and amazing amplifier. I hadn’t noticed how bad the sound had gotten, since it had changed so slowly.

 

[trainbuftony]

In my industry (Auto repair) we have a saying. If it ain't broke, fix it til it is.
Far too often i see posts on this forum of folks who had a perfectly working amp, they thought needed fixing so they monkey around with it and end up witb an amp which doesnt work at all, or which now sounds great to them, but fails in other departments. I too must resist the temptation to constantly work on stuff. Its ok to just enjoy it. Check bias every 6 months like brice said, and dont be surprised if your power tubes are still good in a decade.

 

[airtime]

In my industry (Auto repair) we have a saying. If it ain't broke, fix it til it is.
Far too often i see posts on this forum of folks who had a perfectly working amp, they thought needed fixing so they monkey around with it and end up witb an amp which doesnt work at all, or which now sounds great to them, but fails in other departments. I too must resist the temptation to constantly work on stuff. Its ok to just enjoy it. Check bias every 6 months like brice said, and dont be surprised if your power tubes are still good in a decade.

WOW did you hit that one on the head. I was doing that for years and ending up trashing a few really good stereos. The good news is I learned my lesson and REFUSE to even touch my Marantz 250m (professionally restored and upgraded) and VTA ST-70. I still have several "trashed" stereos in the garage that sits as proof to what you just said.