Valves

[mia]

...how do you know when to change them???

Is it obvious whe they wear out?

[indysmith]

Power Tubes will generally last 1 - 1.5 years.
Preamp Tubes will generally last 2 - 3 years.

Signs of Wear
Power Tubes:
•  Low end response is not as clear and distorts earlier.
•  You turn your amp’s master volume up to hear the level that
   you are used to hearing.
•  Eventually you will hear 'crackling' 'popping' sounds, often accompanied by:
•  'Swelling' volume levels.
•  Buzzing.

Preamp Tubes:
•  Hissing, 'shooshing'.
•  Sputtering, 'grumbling'.
•  Microphonic squealing (feedback type sound).
•  Loss in signal in one or more modes of the amp (channel, reverb, fx-loop).

[Underground_Player]

I agree with the above, but also I've had one pre-amp valve turn bright orange, and another turn bright purple. Needless to say day-glo colours are bad.

[HTH AMPS]

I've had a few ECC83s go bad recently - they all displayed the same symptom whereby there was some loud hum which turned into bassy oscillations.

 :twisted:

[HJM]

I've had a few ECC83s go bad recently - they all displayed the same symptom whereby there was some loud hum which turned into bassy oscillations.

 :twisted:

Were they JJs??

[HTH AMPS]

actually they were all NOS Brimar ECC83s - awesome tone but three of 'em went in close sucession.  It's probably only the second or third time I've EVER had NOS preamp valves go bad though which is more than can be said for anything current production.

I've got a love/hate thing going on with JJ, they seem SO well made but the QC must be shitee - sometimes the EL34s are just bad right out of the box.  For shear consistency I've found that you can't beat Svetlanas (the REAL ones, i.e. Winged-C)

 :twisted:

[Underground_Player]

Were they JJs??

Don't tell me Matamp have been having problems with them.....not now..... :!:

[Crazy Gra]

I've got a love/hate thing going on with JJ, they seem SO well made but the QC must be shitee - sometimes the EL34s are just bad right out of the box.

 :twisted:

On the JJ, admittedly I've only bought 2 x jj 6v6s  but one of them drew 25mA and the other drew 100mA out of the box!!!! This is what they call a matched pair! I nearly had a heart attack going for the switch LOL

I wish winged c would make a 6v6.................

[JamesHealey]

^^ lol i find that ammusing yet i'd be pretty gutted aswell, im thinking of retubing my ENGL before i donate it to my friend adam it's starting to misbehave.

[Bainzy]

I just retubed my Plexi with JJ E34L's, I'm really loving the sound right now. NOS preamp tubes and current production power tubes is the perfect match in my opinion.

[gwEm]

...how do you know when to change them???

Is it obvious whe they wear out?

I asked a similar question a few months ago here:

http://www.bareknucklepickups.co.uk/forum/viewtopic.php?t=2208

When you switch the amp on, if the valve glows very brightly for a few seconds before quickly going very dim, thats also a bad sign

[mikeluke]

Another question on the same lines - do you need to 'bed in' new valves? Just changed my power valves and now the amp makes quite a loud 'pop' when you switch it off (doesn't have standby) - thanks