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So how long 12ax7 tubes last?

serviviente7

Member
Messages
1,328
Lately my Mesa 50 caliber + amp has been giving me fits. I hear a "distorted" sound, (kind of when a speaker is broken) coming from it no matter at what volume. I replaced the power tubes but the problem continues. I have had this amp for 16 years and NEVER have I replaced the preamp tubes. I giged with it pretty strong for about 5 years and after that it has been my practice amp so it has been played regularly but at lower volumes. Do you guys think that the preamp tubes could be the problem? I was under the impression that the preamp tubes hardly ever need to be replaced. Any help will be appreciated. Thanks.
 

Jagsound

Member
Messages
1,235
16 years! That might be some sort of record!

Preamp tubes do last a long time, but most techs seem to think that after 5 years of regular use you should have some spares handy. Sounds like you've had a great run!
 

serviviente7

Member
Messages
1,328
Ok I officially feel like an idiot!!!!LOL So the answer is YES preamp tubes would be a good start! I apologize for posting in the wrong forum. Mods please feel free to correct me.
 

mad dog

Silver Supporting Member
Messages
11,040
The old ones can last a real long time, depending on how much the amp is played and how it's treated. Both my Magnatones came to me with original pre-amp tubes, 40 plus years later. And they were just fine.
MD
 

franksguitar

Member
Messages
3,683
In Boogies usually the culprit in #1 position 12AX7 when it craps out . 16 years for original tubes, wow !
 

ant_riv

Silver Supporting Member
Messages
5,960
Good for you that the preamp tubes have lasted so long.

As has been mentioned, amps from the '60s can still have the original preamp tubes. (I have two.)

When they go, they go, but preamp tubes do not suffer the same wear that output tubes do.
 

BPSUL

Member
Messages
1,664
I recently acquired a VTM60 ('86 I believe) with all original tubes. Along the way someone mounted a HUGE fan inside the amp, which I assume helped the tubes survive all these years. The tubes sound totally fine to me. I know the power tubes (Sylvania) are still in great shape - Im going to swap out some of the preamp tubes just to see if I can get them to sound better but they're still functioning without any issues after 24 years - and this is a somewhat high gain amp... I don't know who made the preamp tubes, they are actually branded Peavey tubes - I assume they are chinese or some cheap import...
 

tnvol

Ufologist
Silver Supporting Member
Messages
6,929
The tubes in my JCM 900 lasted for about 15 years. It was played almost daily for like 12 of those years.
 

Pietro

2-Voice Guitar Junkie and All-Around Awesome Guy
Messages
16,448
I've gotten 10 years out of preamp tubes. Twice.
 

Tone_Terrific

Silver Supporting Member
Messages
35,066
If you are cheap (like me) swap the tubes around and check.
But, really, a spare tube or 2 is should be at hand at all times.
 

Julia343

Member
Messages
7,610
Some guy I know has a Soldano... 15 yrs old. Never any tube change. Plays it hard. It's even been dropped. Original Sovtek 5881s. Finally a tube has gone microphonic.
 

jamison162

Member
Messages
7,750
How long do they last vs. how long do they sound good?? is the question. You guys can use the same valves for 15, 16 yrs. but I change mine every couple esp. new prod. :)
 

Dica3

Member
Messages
1,336
I pulled an RCA 12ax7 out of a malfunctioning 1958 Hammond m3,popped in my Victoria and it works and sounds great
 

5150user

Member
Messages
1,503
Take one "known good" spare preamp tube and swap it out in each position, one at a time. It will most likely be just one bad preamp tube.

Or, maybe a speaker has blown?
 

rockon1

Platinum Supporting Member
Messages
13,509
Ive got 60 year old tubes (for sale-shameless plug) that test and work like new! Bob
 

5150user

Member
Messages
1,503
Ive got 60 year old tubes (for sale-shameless plug) that test and work like new!
That weren't running in an amplifier all that time.

BTW: Send me a message about those 60 year old tubes that you have for sale.:idea
 

serviviente7

Member
Messages
1,328
Well after the persistent "speaker blown" bad sound i decided to do a bit of research before taking it to the amp tech. From the mesa manual i learned that if the power tubes (brand new) are installed and they lean too much or are a bit loose out of their ceramic socket they could do that sound. Today i tooked them out and lined them perfectly and voala! Clean sound immediately.
 




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