How often do you change your output tubes?

[supersonic]

Just wondering how long you change your output valves? How long before you can hear degeneration in tones?
I'm talking about an amp that gets used regularly at gig volume.

 

[guitarnie]

When my meter says "Fail". Seriously a tube meter is nice to have . You are pissing in the wind without an accurate reading.

 

[supersonic]

When my meter says "Fail". Seriously a tube meter is nice to have . You are pissing in the wind without an accurate reading.

A tube meter heh. Sounds like a good idea. Are they expensive?
Sometimes my ears play tricks on me and I'm thinking "Are those tubes bad"?
General rule is 12 months but no use changing them if there's life left.

 

[petejt]

Maybe once a year if that.

 

[2tallmusic]

A tube meter heh. Sounds like a good idea. Are they expensive?

Depends on what you want. I once picked up a mercury 990 for around 85$ (testing emission and shorts). Those are very likely cheaper to get if you are not depending on abroad shipping.

The full monty boxes like Neuberger, B&K, Hickok, Eico, etc. are mostly a couple of hundred bucks or a restoration project.

 

[Deleted member 8761]

When my meter says "Fail". Seriously a tube meter is nice to have . You are pissing in the wind without an accurate reading.

What is a tube meter and exactly what are you measuring?

Normally I follow the amp manufacturer recommendations in the manual. From what I understand is that most manufacturers use a cold bias so that the tubes dont run as hot. In general I would say power tubes will last 2-4 years depending on usage. The wearing is a gradual process though.

 

[Ventura]

I go with my ears. Ya ya, they're typically deaf in the grand scheme of things - but if my amps start to sound like they're lacking in sizzle, or bottom end, or the frequencies that made me love 'em to start with; and I find myself squeezing more and more out of the EQ/preamp to get the amp to a certain place - it's glass time. And it all depends on usage. Sometime the bottle will blow in which case it's a new quad, sometime it's my ears telling me something's lacking, in which case it's a new quad. Generally though, no more than 1x per year, and I've stretched a good 2.5 years out of a quad before too.

 

[glpg80]

Bottom end will go first - tubes absolutely hate chugging. tubes also dislike harmonic feedback - that plays hell on plate coatings.

Next is visual notification - tubes that go gassy.

When i was gigging heavily with my 5150 and 5150 II, each amplifier was going through power tube quartet's around every 3 months. This is with regular playing plus practice at home and at the band area. Under normal circumstances i can make a quartet last around a year or more today - assuming nothing is defective to begin with.

I also bias mine colder when i know i am in heavy rotation - easier on the tubes, better low end definition, and the small loss on saturation is worth a few extra months on the pocket.

 

[racerevlon]

My rehearsal amp is about every 6-9 months rehearsing 3x / week.

 

[MississippiMetal]

Bottom end will go first - tubes absolutely hate chugging. tubes also dislike harmonic feedback - that plays hell on plate coatings.

Hmm... I find the opposite to be true. The top end becomes dull and clarity becomes an issue. Loss of lowend I suppose could suggest diminished plate current at the given bias point, which obviously happens when the valve begins to wear out. I typically attribute loss of low end response to worn filter caps, which is obviously not as frequent as valve wear.

 

[glpg80]

Bottom end will go first - tubes absolutely hate chugging. tubes also dislike harmonic feedback - that plays hell on plate coatings.

Hmm... I find the opposite to be true. The top end becomes dull and clarity becomes an issue. Loss of lowend I suppose could suggest diminished plate current at the given bias point, which obviously happens when the valve begins to wear out. I typically attribute loss of low end response to worn filter caps, which is obviously not as frequent as valve wear.

Technically plate current will run-away by increasing, not decreasing regardless of other parameters like filter cap age or B+. Tubes are rated in siemens or mohs, which is a rating of conductivity. As time progresses this decreases due to age which is where you hear the highs come into play simply due to old age. But another negative is bias drift due to the inverse relationship of bias voltage to bias current. The cathodes can no longer operate from negative bias reference to B+ as efficiently as before. This produces more heat if the tube bias is not checked as the tube is biased off and turned on by oscillating grid signals. But as hardware degrades bias voltage will decrease (closer to 0) and bias current will increase. This is the downside of tubes - they dont just drift with age, they wear out. Eventually it becomes a short circuit - unable to hold a negative reference bias, a short circuit to plates due to the inability to be negatively referenced off, and thus it runs-away and blows - taking out screen resistors and amp fuses at the worst case instance.

Normally what you see is a tube becoming gassy - its inability to hold a vaccum at temperature and overheat - causing bias runaway, arcing, blue-nova type glowing at all times and not just during playing, and plate current run-away. Hence the low end going first - that is why i bias cold when i am out playing gigs - i can tell a difference immediately in the response of my amplifier at volume. Highs do go as well - and you get visual notices as tubes degrade as gassy tubes are not stable.

 

[supersonic]

For me I notice the bottom end going first. I kind of assimilate tubes to strings, a fresh set of tubes always sounds bright and full like fresh strings. I guess I'm up for a new set, they've been in 18 months, I'm playing pretty loud, rehersing once a week and gigging once a month.

 

[MississippiMetal]

Bottom end will go first - tubes absolutely hate chugging. tubes also dislike harmonic feedback - that plays hell on plate coatings.

Hmm... I find the opposite to be true. The top end becomes dull and clarity becomes an issue. Loss of lowend I suppose could suggest diminished plate current at the given bias point, which obviously happens when the valve begins to wear out. I typically attribute loss of low end response to worn filter caps, which is obviously not as frequent as valve wear.

Technically plate current will run-away by increasing, not decreasing regardless of other parameters like filter cap age or B+. Tubes are rated in siemens or mohs, which is a rating of conductivity. As time progresses this decreases due to age which is where you hear the highs come into play simply due to old age. But another negative is bias drift due to the inverse relationship of bias voltage to bias current. The cathodes can no longer operate from negative bias reference to B+ as efficiently as before. This produces more heat if the tube bias is not checked as the tube is biased off and turned on by oscillating grid signals. But as hardware degrades bias voltage will decrease (closer to 0) and bias current will increase. This is the downside of tubes - they dont just drift with age, they wear out. Eventually it becomes a short circuit - unable to hold a negative reference bias, a short circuit to plates due to the inability to be negatively referenced off, and thus it runs-away and blows - taking out screen resistors and amp fuses at the worst case instance.

Normally what you see is a tube becoming gassy - its inability to hold a vaccum at temperature and overheat - causing bias runaway, arcing, blue-nova type glowing at all times and not just during playing, and plate current run-away. Hence the low end going first - that is why i bias cold when i am out playing gigs - i can tell a difference immediately in the response of my amplifier at volume. Highs do go as well - and you get visual notices as tubes degrade as gassy tubes are not stable.

lolwut?

Siemens are a brand and Mohs is a mineral hardness rating. Conductivity is rated as transconductance. Transconductance decreases with age, requiring a decrease in negative voltage at the control grid to maintain the established quiescent plate current. I caution people obsessed with their bias against bumping the bias point back up as the tubes begin to wear. Your tubes will wear out. It's the natural process, and no amount of bias compensating is going to do anything but usher them toward death that much more quickly.

 

[glip22]

Bottom end will go first - tubes absolutely hate chugging. tubes also dislike harmonic feedback - that plays hell on plate coatings.

Hmm... I find the opposite to be true. The top end becomes dull and clarity becomes an issue. Loss of lowend I suppose could suggest diminished plate current at the given bias point, which obviously happens when the valve begins to wear out. I typically attribute loss of low end response to worn filter caps, which is obviously not as frequent as valve wear.

Technically plate current will run-away by increasing, not decreasing regardless of other parameters like filter cap age or B+. Tubes are rated in siemens or mohs, which is a rating of conductivity. As time progresses this decreases due to age which is where you hear the highs come into play simply due to old age. But another negative is bias drift due to the inverse relationship of bias voltage to bias current. The cathodes can no longer operate from negative bias reference to B+ as efficiently as before. This produces more heat if the tube bias is not checked as the tube is biased off and turned on by oscillating grid signals. But as hardware degrades bias voltage will decrease (closer to 0) and bias current will increase. This is the downside of tubes - they dont just drift with age, they wear out. Eventually it becomes a short circuit - unable to hold a negative reference bias, a short circuit to plates due to the inability to be negatively referenced off, and thus it runs-away and blows - taking out screen resistors and amp fuses at the worst case instance.

Normally what you see is a tube becoming gassy - its inability to hold a vaccum at temperature and overheat - causing bias runaway, arcing, blue-nova type glowing at all times and not just during playing, and plate current run-away. Hence the low end going first - that is why i bias cold when i am out playing gigs - i can tell a difference immediately in the response of my amplifier at volume. Highs do go as well - and you get visual notices as tubes degrade as gassy tubes are not stable.

lolwut?

Siemens are a brand and Mohs is a mineral hardness rating. Conductivity is rated as transconductance. Transconductance decreases with age, requiring a decrease in negative voltage at the control grid to maintain the established quiescent plate current. I caution people obsessed with their bias against bumping the bias point back up as the tubes begin to wear. Your tubes will wear out. It's the natural process, and no amount of bias compensating is going to do anything but usher them toward death that much more quickly.

You are both correct. Tubes are in fact rated in milisiemens or mohs. Transconductance obviously will decrease but bias drift plays a big part in tube life as well. Its best to check bias and rematch your tubes, if a quad, in to pairs for each leg of the Ot to see. Bias drift will cause failure whereas conductivity decrease will not do damage. glpg knows much more than I as he is an electrical engineering major and knows well how this field works with tube amps.

 

[Capulin Overdrive]

When i was smart enough to have only one amp and actually played that amp. I went through power tubes every 6 months for chinese, and would get a year out of SED's.

 

[MississippiMetal]

Bottom end will go first - tubes absolutely hate chugging. tubes also dislike harmonic feedback - that plays hell on plate coatings.

Hmm... I find the opposite to be true. The top end becomes dull and clarity becomes an issue. Loss of lowend I suppose could suggest diminished plate current at the given bias point, which obviously happens when the valve begins to wear out. I typically attribute loss of low end response to worn filter caps, which is obviously not as frequent as valve wear.

Technically plate current will run-away by increasing, not decreasing regardless of other parameters like filter cap age or B+. Tubes are rated in siemens or mohs, which is a rating of conductivity. As time progresses this decreases due to age which is where you hear the highs come into play simply due to old age. But another negative is bias drift due to the inverse relationship of bias voltage to bias current. The cathodes can no longer operate from negative bias reference to B+ as efficiently as before. This produces more heat if the tube bias is not checked as the tube is biased off and turned on by oscillating grid signals. But as hardware degrades bias voltage will decrease (closer to 0) and bias current will increase. This is the downside of tubes - they dont just drift with age, they wear out. Eventually it becomes a short circuit - unable to hold a negative reference bias, a short circuit to plates due to the inability to be negatively referenced off, and thus it runs-away and blows - taking out screen resistors and amp fuses at the worst case instance.

Normally what you see is a tube becoming gassy - its inability to hold a vaccum at temperature and overheat - causing bias runaway, arcing, blue-nova type glowing at all times and not just during playing, and plate current run-away. Hence the low end going first - that is why i bias cold when i am out playing gigs - i can tell a difference immediately in the response of my amplifier at volume. Highs do go as well - and you get visual notices as tubes degrade as gassy tubes are not stable.

lolwut?

Siemens are a brand and Mohs is a mineral hardness rating. Conductivity is rated as transconductance. Transconductance decreases with age, requiring a decrease in negative voltage at the control grid to maintain the established quiescent plate current. I caution people obsessed with their bias against bumping the bias point back up as the tubes begin to wear. Your tubes will wear out. It's the natural process, and no amount of bias compensating is going to do anything but usher them toward death that much more quickly.

You are both correct. Tubes are in fact rated in milisiemens or mohs. Transconductance obviously will decrease but bias drift plays a big part in tube life as well. Its best to check bias and rematch your tubes, if a quad, in to pairs for each leg of the Ot to see. Bias drift will cause failure whereas conductivity decrease will not do damage. glpg knows much more than I as he is an electrical engineering major and knows well how this field works with tube amps.

I know, I was trying to make a joke, and failed.

 

[AndyK]

I know tubes wear when you push them (loud), but if I play low in my basement, will tubes still wear, just from being on?

 

[glip22]

Bottom end will go first - tubes absolutely hate chugging. tubes also dislike harmonic feedback - that plays hell on plate coatings.

Hmm... I find the opposite to be true. The top end becomes dull and clarity becomes an issue. Loss of lowend I suppose could suggest diminished plate current at the given bias point, which obviously happens when the valve begins to wear out. I typically attribute loss of low end response to worn filter caps, which is obviously not as frequent as valve wear.

Technically plate current will run-away by increasing, not decreasing regardless of other parameters like filter cap age or B+. Tubes are rated in siemens or mohs, which is a rating of conductivity. As time progresses this decreases due to age which is where you hear the highs come into play simply due to old age. But another negative is bias drift due to the inverse relationship of bias voltage to bias current. The cathodes can no longer operate from negative bias reference to B+ as efficiently as before. This produces more heat if the tube bias is not checked as the tube is biased off and turned on by oscillating grid signals. But as hardware degrades bias voltage will decrease (closer to 0) and bias current will increase. This is the downside of tubes - they dont just drift with age, they wear out. Eventually it becomes a short circuit - unable to hold a negative reference bias, a short circuit to plates due to the inability to be negatively referenced off, and thus it runs-away and blows - taking out screen resistors and amp fuses at the worst case instance.

Normally what you see is a tube becoming gassy - its inability to hold a vaccum at temperature and overheat - causing bias runaway, arcing, blue-nova type glowing at all times and not just during playing, and plate current run-away. Hence the low end going first - that is why i bias cold when i am out playing gigs - i can tell a difference immediately in the response of my amplifier at volume. Highs do go as well - and you get visual notices as tubes degrade as gassy tubes are not stable.

lolwut?

Siemens are a brand and Mohs is a mineral hardness rating. Conductivity is rated as transconductance. Transconductance decreases with age, requiring a decrease in negative voltage at the control grid to maintain the established quiescent plate current. I caution people obsessed with their bias against bumping the bias point back up as the tubes begin to wear. Your tubes will wear out. It's the natural process, and no amount of bias compensating is going to do anything but usher them toward death that much more quickly.

You are both correct. Tubes are in fact rated in milisiemens or mohs. Transconductance obviously will decrease but bias drift plays a big part in tube life as well. Its best to check bias and rematch your tubes, if a quad, in to pairs for each leg of the Ot to see. Bias drift will cause failure whereas conductivity decrease will not do damage. glpg knows much more than I as he is an electrical engineering major and knows well how this field works with tube amps.

I know, I was trying to make a joke, and failed.

Way to many variables with tubes. The correct answer is to replace them when needed for whatever that is worth. NOS tubes last so much longer. One quad of the same tube can last half as long as a quad of the same brand. I check mine for bias drift. If they go too far out, I replace them. The OT sees a quad as two pairs, not single tubes. For example, if my four tubes measure at the same bias setting:
1) 34ma
2) 30ma
3) 36ma
4) 29m
Some will say this quad is matched within 7ma which is not good. If you take tube 4 and pair it with tube 3 you will have a total current draw of 65 ma. Tube 1 and tube 2 as a pair will give you 64ma. This quad is now matched within 1ma. The only downside of this is sometimes the furthest tube out(tube 4) may work harder and therefore lose its transconducatance quicker than the others which is why I test them for current draw in the actual amp and transconductance. I see allot of sellers calling tubes matched because they are close in transconductance which is not matched. Sometimes I can reaarange the tubes to get the matching closer as they drift for bias and get more life from them.

 

[racerevlon]

Bottom end will go first - tubes absolutely hate chugging. tubes also dislike harmonic feedback - that plays hell on plate coatings.

Hmm... I find the opposite to be true. The top end becomes dull and clarity becomes an issue. Loss of lowend I suppose could suggest diminished plate current at the given bias point, which obviously happens when the valve begins to wear out. I typically attribute loss of low end response to worn filter caps, which is obviously not as frequent as valve wear.

Technically plate current will run-away by increasing, not decreasing regardless of other parameters like filter cap age or B+. Tubes are rated in siemens or mohs, which is a rating of conductivity. As time progresses this decreases due to age which is where you hear the highs come into play simply due to old age. But another negative is bias drift due to the inverse relationship of bias voltage to bias current. The cathodes can no longer operate from negative bias reference to B+ as efficiently as before. This produces more heat if the tube bias is not checked as the tube is biased off and turned on by oscillating grid signals. But as hardware degrades bias voltage will decrease (closer to 0) and bias current will increase. This is the downside of tubes - they dont just drift with age, they wear out. Eventually it becomes a short circuit - unable to hold a negative reference bias, a short circuit to plates due to the inability to be negatively referenced off, and thus it runs-away and blows - taking out screen resistors and amp fuses at the worst case instance.

Normally what you see is a tube becoming gassy - its inability to hold a vaccum at temperature and overheat - causing bias runaway, arcing, blue-nova type glowing at all times and not just during playing, and plate current run-away. Hence the low end going first - that is why i bias cold when i am out playing gigs - i can tell a difference immediately in the response of my amplifier at volume. Highs do go as well - and you get visual notices as tubes degrade as gassy tubes are not stable.

Couldn't have said it any better myself. Tubes are "consumables" or wear and tear items. They get used up, just like. The brake pads on your car. There's ways to maximize tube life but let your ears be the barometer -- when you no longer like the way your amp is sounding, replace the valves or get another amp. After all these years I finally learned to not rehearse with my "good/live" amp cuz it'll wear on the tubes. Now I rehearse with my 6L6 Jet City Amps and keep the Splawns for recording and live shows.

 

[MississippiMetal]

And thus completes this thread with the obligatory amps-cars analogy.