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Tube amp question

Discussion in 'Glowing Bottle Tube Amp Forum' started by HotRodSteve, Jan 24, 2014.

  1. HotRodSteve

    HotRodSteve Poster Extraordinaire

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    How long do tubes generally last in a tube amp? Was just wondering because next week I'll be buying my first tube amp.
     
  2. XKnight

    XKnight Tele-Afflicted

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    It depends and many different factors, including luck. Some amps from the 60s still have the original tubes.
     
  3. Bartholomew3

    Bartholomew3 Friend of Leo's

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    I have a 68 silverface twin, bought it that year and am still using the original 7025 tubes - they test good and sound good.
     
  4. coloradojeff

    coloradojeff Tele-Holic

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    All four of my amps are tube amps (Marshall, Fender Vibro king and ProSonic and a Blackstar). The VibroKing hasn't required a single fix since '95. The ProSonic was my main gig amp and I've had the tubes replaced in it once since 1995. The Marshall is the 30th Anniversary model with a zillion tubes in it. It just went in for a major fix but still the big power tubes were fine. Only required two of the preamp tubes. The BlackStar…don't care…don't like it anyway.
     
  5. telex76

    telex76 Doctor of Teleocity Ad Free Member

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    Depends on the amp and the tubes.

    Vintage Fender amps running NOS tubes, the preamps might last longer than you and the power tubes should last hundreds of hours of playing time.

    New production tubes won't last that long. Some of the new amps won't last that long even with good tubes.

    If you can find tubes your amp likes you can still get long life with new production tubes.

    Always have a spare set. Experiment with different brands until you find some that sound good a have long life.
     
  6. HotRodSteve

    HotRodSteve Poster Extraordinaire

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    Thanks for the info guys, I wasn't sure if tubes burnt out like cheap lightbulbs and I'd be replacing them every few months.

    The amp I'm buying is a Carvin BelAir 212, haven't actually played one yet because it's mailorder but the Youtube videos all sounded good. Hopefully Carvin uses good tubes, their amps sound like they're built like brick ****houses. UPS says it'll be arriving next Wednesday! Might have to call in sick that day.
     
  7. Shiro

    Shiro Tele-Meister

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    Congrats on the new amp. Pretty exciting stuff. I've been very lucky in that after all the years of playing tube amps, I've never had a tube fail at a gig. I do change them every 1-1 1/2 years of use. I've noticed that with every tube change the amp has a more chimey, jangly sound to it (which I like). Seems to me that older tubes still sound good but in a smoother,darker way. YMMV
     
  8. suave eddie

    suave eddie Friend of Leo's

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  9. waparker4

    waparker4 Doctor of Teleocity Ad Free Member

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    In my experience they do (VT50 head) it sounds good and there is minimal hiss or other noise.
     
  10. 73Fender

    73Fender Friend of Leo's

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    Time to do some reading on NOS vs new production etc. Lots of good info right here.
     
  11. HotRodSteve

    HotRodSteve Poster Extraordinaire

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    Sounds like the tubes should last me quite awhile since I'm not in a band. Thanks again for the info, this is gonna be fun, can't wait until Wednesday. Life is good!
     
  12. DaveKS

    DaveKS Friend of Leo's

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    If your not moving and banging them around a lot they will last a long time on preamp tubes, many months to years on power amp tubes. If your buying a new production amp that uses cheap Chinese tubes, around couple yrs is about most you can expect out of power tubes if you baby them.

    Now as previously has been stated many of the NOS stuff is still going strong after 30yrs+. Don't expect to get that type of life out of most new production power tubes.

    In the end it's just luck of the draw with tubes, any tube, new or old production can fail at anytime. Just the banging around in shipping can damage a tube before you even open the box. Always check that tubes are seated well and tight in socket before you even turn it on for 1st time. If your getting a floor model that's probably not needed, as that would already be taken care of but it never hurts to check once you get it home. Use a per towel when touching tubes.

    I always let tubes warm up for 2-3 minutes. 1 min. minimum.

    And be aware that combos are torture chambers for tubes, the speaker vibration wears on the tubes, so shorter life can usually be expected in a combo. Tube life in most heads can usually be twice the life compared to a combo.
     
  13. sacizob

    sacizob Friend of Leo's

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    I always bring spares to a gig.
     
  14. Hiker

    Hiker Poster Extraordinaire

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    We get that question quite often on the forums...Drive 'em hard and use them several hours a day, and you'll might be shopping for replacements before the year is out. Play them clean, and a handful of times per month, and they may last 10-25 years! You asked a loaded question when you didn't qualify how you plan to drive them, or how often.
     
  15. HotRodSteve

    HotRodSteve Poster Extraordinaire

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    To be honest they won't be driven too hard very often. I'll probably play the amp at a quiet level (volume at 1 or 2) a few hours per week and a few times per month when the house is empty I'll let it rip and shake the windows for an hour or so. Even at a quiet level I usually play with some dirty gain.

    When the amp arrives I'll make sure the tubes are seated all the way even though I hear Carvin uses clips to lock them in. Since the temperature up here is freaking cold right now the box may be sitting outside after UPS drops it off, unless I catch them, so I better let the box and amp get to room temperature before I debox it and try it out.
     
  16. String Tree

    String Tree Doctor of Teleocity Ad Free Member

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    Treat your Tube amp nice and they will last for many, many, years.
    Don't treat it like a piece of wood. They break.

    Electronic components that are left in the shed, or car, or whatever, overnight, when it's cold, rainy, hot, dusty, die faster than ones kept inside.

    Dust build-up leads to Corrosion, which leads to heat build-up, which shortens it's life.
     
  17. Hiker

    Hiker Poster Extraordinaire

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    Consider making sure the tubes are seated without touching the glass with your fingers. Clean fingers can still transfer sweat/oil or fingerprint them. Use a cotton or other cloth that's not thick when you check 'em.

    A full set of spare replacement tubes is not the norm-from what I've gathered from others on TDPRI, although I went all out and put them on the shelf, anyway. To date, I've only replaced one tube on two amps in the last several years. It came in the door needing replacement on an older amp. Tubes I've got.
     
  18. CoolBlueGlow

    CoolBlueGlow Tele-Afflicted

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    Key Factors Affecting Preamplifier Valve Life

    1. The number of on/off cycles
    2. The use/abuse of standby
    3. The roughness of handling when hot
    4. The presence of a SS rectifier design
    5. The phenomenon of cold storage out-gassing

    These are the largest influences wich the USER can control in determining the useful life of typical guitar amplifier preamplifier tubes' lives. (Design abuses such as poor cooling and long periods of operation at maximum plate dissipation, and plate overload are the fault of the designer, not the user)

    On/off cycles = filament death (exacerbated by rough handling when hot) through Larson-Miller effect, which is grain reorientation and stretching of the tungsten as it passes through the 8-900c temperature range, (leading to filament surface cracks which make the filament somewhat prone to failure...like an excessively switched incandescent bulb.)

    Use and abuse of standby - see here http://www.peavey.com/monitor/pvpapers/Chapter6.pdf

    Long standby periods led to cathode poisoning, resulting in reduced emission and poor tube performance. The older the amp the more statistically likely that it has experienced long standby periods. (see RCA Transmitting Tube Manuals for explanation of cathode poisoning)

    Solid state rectifier designs, which provide instantaneous plate voltage, are much harder on preamp tubes than tube rectified designs. In SS rectified amplifiers which have been subject to many on/off cycles, cathode stripping may have occurred which will reduce emission, leading to poor gain and eventual tube unusability. (see RCA Rceiving Tub Manual Vol 3 pp16)

    Tubes which have been started up after long cold (temp) storage in particular are subject to out-gassing and subsequent cathode emission reduction. (Think "yard sale find in Iowa" amps). This is due to the relative chemical inactivity of the getter, experienced during the storage of the tube at low temperatures. Therefore, always wise to warm these tubes in an oven to about 150 degrees Fahrenheit for about a half hour to re-activate the getter BEFORE applying filament current. (Source: Morgan Jones, Valve Amplifiers, Vol 4. Morgan Jones is a highly respected BBC engineer, and the science behind getter inactivity and cathode poisoning by cold cycle out-gassing is thoroughly and convincingly explained in his writings.)
     
  19. chumpchange

    chumpchange TDPRI Member

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    may want to read up on tube amp bias and tube power rating.

    if the amp isn't biased correctly to the output of the tubes, then they run either too hot or too cold, don't last as long and don't give optimal performance.
     
  20. CoolBlueGlow

    CoolBlueGlow Tele-Afflicted

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    I refer in particular to preamplifier tubes in my post, btw.

    As chumpchange points out, output tube life is strongly affected by the work load, which is heavily influenced by the amount of current they are allowed to consume, which is regulated by the bias point.

    Output tubes are also subject to all the issues in my preamplifier tube list.
     
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