Newb with a Mesa tube question

Hi guys great forum you have here. Excuse me if this has been asked before.

I have an old .50 caliber+ (late 80's early 90's I think) that hasn't seen a ton of use in it's lifetime. I've recently fired it up and the sound from it is definitely not what I remember. It sounds very flubby on the low strings no matter how low I turn the bass down. The highs seem really ice picky unless I turn the treble down quite low. I just can't seem to get a good sound from it although it seems like there is lots of volume and jam.

When I pull or push the gain knob to switch to lead mode and back there is a slight popping sound that kind of fades out kind of like a short laser beam sound from an old 80's space flick.

I keep reading that the 12AX7 tubes only need to be changed if there is a problem and that they last for decades, etc. After this much time should they be changed regardless.

I did change the 6L6 tubes years ago and don't think they have much time on them. The 12AX7s I believe are original.

Thoughts???

Thanks

Sam

It is simple to change the preamp tubes. You could get a couple and roll them, replacing one at a time with new and seeing if that helps. They do eventually degrade if used for many hours. If you have another speaker, give that a try regarding tone. Depending on storage conditions, the speaker could have degraded. Could also try with the 6L6's, in case something other than playing time was the problem.

Another possibility is the electrolytic capacitors in the power section and those used for filtering. Yours are at least 20 years old, they will dry out and go bad. Would affect tone and maybe the pop.

Try what is easiest or readily available first.

I would change the filters in an amp that hasnt seen a lot of use,as you said.That will cure the flabby bass issue and overall tighten things up.I wouldnt be too concerned about the pop when you switch to lead mode,just a cap discharging.After changing the filter caps you can address the "ice pick" tone with tubes and possibly re-biasing the power tubes.

Before you start "fixing" the amp, I hope you play it through an EXTENSION cab (other speakers) to see how it sounds.
Guitar, amp, speakers... all parts of the sound chain and all have to be evaluated separately.

Depending on storage conditions, the speakers can degrade as stated in the first response. If you have another cab or speaker on hand that would be easy to check quickly and for free.

Try power tubes next if you have a spare set available (free, if you have them). Same with preamp tubes (not as likely to go bad).

The electrolytic caps could be going south with that many years on them. If you feel comfortable taking out the chassis and discharging the caps, they might appear swollen on the ends with some debris there. Definitely need replacing. Still could be bad and look OK. At this point, find a good tech Who can diagnose, repair, check bias, etc. Shouldn't take too much to get it like new.