Whens the RIGHT tubes replecement time

Discussion in 'The Squawk Box' started by picoman, Feb 8, 2015.

  1. picoman

    picoman Senior Member

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    Well the title says it all.
    I have a friend hows changing tubes every year no matter what. I dont Know if this is ok or not but for me this seems maybe egzaturated given that he plays only 1-2 hours 3-4 times a week....I dont Know...

    I currnetly have my Peavy Classic wich has 4 x JJEL84 power tubes and 3 x 12AX7 preamp tubes. I migh missmatched the power and pre names.
    Anyways, how to Know when you need to change your tubes and WICH ONES to be more specific?
    DO they worn out all the same or power tubes get waisted sooner?
    What are consequnces of not replacing the tubes at the right time?
    Thank you.
     
  2. bilbarstow

    bilbarstow Premium Member

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    If you watch the threads around here, you'll notice a lot of "my amp started sounding funny this way, what could be wrong ?" - and the answer (without hearing or being able to check the amp directly) is almost always :

    Change out your tubes (often one at a time to identify which is going bad).

    Your ears will tell you most of the time when it is needed. Just keep spares around so if they go out at an inopportune time (like when you need to play !), you can get on the issue right away.

    Pre-amp tubes usually last longer than power tubes, but not always. Often you may only need to replace a single pre-amp tube. If your power tubes are in pairs, keep a matched pair set. If in quads, sometimes just a pair is sufficient for your active spares, or keep a matched quad.

    Tubes are a little like light bulbs. They work and then they don't.
     
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  3. picoman

    picoman Senior Member

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    Any chance of turning the lights off in the room and observing wich ones shining the weakest?...sounds sily....
     
  4. bilbarstow

    bilbarstow Premium Member

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    Nah, that won't do much for you unless it helps you spot a tube that is completely gone. The "glow" is really just the filaments or "heaters" of the tube, must be there to create the conditions necessary for current flow, but not indicative of the functionality of the tube. If you have a standby on your amp, you will notice that in standby, the tubes are already glowing, but not amplifying any sound.

    Play 'em as long as they sound good. Replace them if you think that you should be getting more out of your amp. If they are still working when you pull them, keep those for your emergency spares.
     
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  5. johan.b

    johan.b Senior Member

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    When i worked as an amp tech mid nineties, Sovtek came on the scene, and they provided data sheets with their tubes. The power tube according to the sheets, had life expectancy of 5000 hours and end of life when dissipation was down 50%.
    I don't think there is more than very few people who runs their amps 5000 hours in a year. Most people struggle to get 500 hours in a year.
    today's players run through nos tubes like they are in a hurry to use them all up. Preamp tubes basicly lasts until filament Burns out, I know of tubes that has been in service for decades
    j
     
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  6. ScottMarlowe

    ScottMarlowe Senior Member

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    More important is to have a tested, known good set of spares handy. A couple of 12AX7s and at least one power tube for each type etc.

    If a tube dies or you think it might have, having a known good, working spare ahead of time is a godsend for troubleshooting.
     
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  7. picoman

    picoman Senior Member

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    Interesting.
    So what is working life of an avarage JJ EL84 tubes?
    Is there any data on tubes working life.

    One thing I noticed browsing ebay for new tubes is that there are some offers of PLATINUM MATCHED QUAD SET oppostive to MATCHED QUAD SET.
    Whats the difference except PLATINUM being more expensive...

    WHat happens if one of your tube dies while playing? AMP damage?
     
  8. johan.b

    johan.b Senior Member

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    Blown fuse and silence. Replace tube and fuse, check bias and play
    j
     
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  9. ScottMarlowe

    ScottMarlowe Senior Member

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    A set of EL84s should be able to run for several thousand hours. However, if they're biased hot and running over spec (Peavey Classic 50s run them 390 to 420V, 100V over spec) they won't last as long especially if you're playing them hard. Even then most will last 6 months to a year. Under more normal use, i.e. 300V and less not at full volume all the time etc, you can expect a set of EL84s to last a few years.

    But they're electromechanical devices, and they can fail at random times due to shock or manufacturing defects.

    I keep a spare or two handy. They really don't need to be matched. If you were using an audiophile amp with perfect Class AB crossover etc, maybe, but in a guitar amp matching is not really needed. If money's an issue order a batch of 8 or 12 or whatever EL84s from russia, used tested as new. You can get them, shipped, for ~$2 or $3 a tube. Then you'll have spares for years to come.
     
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  10. Paragon

    Paragon Senior Member

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    What Scott said. Some amps are kind to tubes and run lower voltages. Others (like old Fenders and apparently your Peavey) run them beyond the spec to get a certain tone.
    Changing tubes just because a year has gone by is silly and a waste of money. I'd be getting your friends old tubes and keep them as spares if he just tosses them.
     
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  11. six pack

    six pack Senior Member

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    I do about every 2 years unless one blows.
     
  12. MooCheng

    MooCheng Senior Member

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    tubes can last for years if not worked too hard, but like all electrical things you might get one crap out for no apparent reason

    its always a good idea to let the amp cool before moving it, and the thermal shock thing you get loading up outside
     
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  13. ScottMarlowe

    ScottMarlowe Senior Member

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    I've done a lot of swapping around since I now have about 5 or 6 spare quads of EL84s. Honestly if I was just looking for a good solid reliable setup I'd just have 4 JJs in it and 4 in a box ready as spares. They're solid, sound good and seem to last a long time.
     
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  14. picoman

    picoman Senior Member

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    Thank for the advices.
    SO what thy hype with these PREMIUM MATCHED SET of tubes?
    Just commercial trick or....
    Found ones here:
    JJ EL84 (6BQ5) Valves Tubes *Platinum Matched* Quad *NEW* | eBay


    forgot to ask....what does even "matched" mean?
     
  15. THDNUT

    THDNUT Senior Member

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    I have a 17 year old Carvin Vintage 33 with the original Sovtek EL 84s and 12AX7s. It still works great.
     
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  16. northernguitarguy

    northernguitarguy SWeAT hOg

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    I'm getting 8-10 months out of my power tubes in my Night Train and I'm on my third pair. I had been using it as my main amp for weekly rehearsal, monthly gig and daily home practice. I'm now switching between my NT and a Tiny Terror. I hope to get a couple of years out of the power tubes for both with this setup.

    OP, replace them when they crackle. Even then, try removing and reseating the tubes before chucking them. Replace one at a time as mentioned. Spray the sockets with cleaner once a year.
     
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  17. Paragon

    Paragon Senior Member

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    I'll try a stab at it.. In a nutshell: Matched tubes have the same operating levels (current draw at a certain level of voltage on the plate and cathode.. etc.)
    It is impossible for companies to always produce tubes that have the same exact output level. Within batches they will usually be in certain ranges but between batches it will usually vary. Matched sets allow for optimal performance with a push pull amp, especially on paper (for a guitar amp, we usually don't mind adverse affects to the tone). Required? Not from what I have read. Some people get them so they don't have to worry about re-biasing amps (if their previous set was a certain number, they get a new set the same).
    Some people feel a mismatched pair will have a different sound that is better depending on the amount of mismatch.
     
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  18. TheX

    TheX Voice of Reason

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    I love to roll tubes, but I keep the old ones.
     
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  19. THDNUT

    THDNUT Senior Member

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    A matched set will become unmatched after they've been used a while.
     
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  20. Jupa

    Jupa Senior Member

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    7:32PM, no earlier, no later. (EST)
     
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