JJ KT77 vs Genalex KT77 Tube Shootout

Discussion in 'Gear & Equipment' started by Belensky, May 26, 2019.

  1. Belensky

    Belensky SS.org Regular

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    Amp settings, and recording chain exactly the same, both sets set to 65mA per pair.

    I don't know about you guys, but I had already two sets of JJ KT77, that dying in my Diezel Herbert, first set (that eventually I got replaced under warranty) started to make troubles after 6 mouths: one of tubes starters to glow almost like a light bulb, second set started to do the same thing after year.
    I bought more expensive set of Genalex Gold Lion KT77. I hope they will work longer than JJKT77, because it's quite frustrating and expensive to retube Herbert every year.
    have anyone had same problems with JJ KT77, or it's just me or some bad batch of tubes in shop?
     
    Last edited: May 26, 2019
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  2. Edika

    Edika SS.org Regular

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    The Genalex sound more alive for sure but I'm not sure if it's new tubes Vs old tubes that produces this effect. If they JJ's are relatively new then the Genalex slay them. Of course if I heard the Herbert only with the JJ's I still think it sounds great.

    I have no experience with KT77 JJ's so I can't tell. The 6L6 JJ's and 12AX7 I have bought haven't given me any issues. It might have been a bad batch or their KT77 are maybe not as robust.
     
  3. MetalHex

    MetalHex SS.org Regular

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    Nice tone! Genalex
     
  4. Krucifixtion

    Krucifixtion Duncan Hills

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    I'm on my second sextet of JJ KT77's in my ENGL Invader 150. Didn't have any issues at all with the first set and I had those in the amp for quite awhile. Kind of procrastinated on changing them, but I just re-tubed again about a month or so ago. I have also run plenty of sets of JJ 6L6 and no problems with those either.

    There is a big volume jump in your vid from the JJ to Genalex. Were the JJ's old?
     
  5. Belensky

    Belensky SS.org Regular

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    There isnt volume Jump between Genalex and JJ. Genalex just sounds bigger.

    JJ is less that one year old.
     
  6. jarledge

    jarledge SS.org Regular

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    65ma seems really high. I am no expert and I am sure someone else will post up but the kt 77 should only produce 22 to 25 watts per tube and depending on your plate voltage it would probably be less than 65ma .

    23 watts / 500v = .046 or 46 ma as max . Eurotubes recommends going 70% of that which would make 32.2 as the ideal bias setting.

    25 watts / 400v = .0625 as max 70% = 43.75

    you running them hot might explain the short lifespan.
     
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  7. Belensky

    Belensky SS.org Regular

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    65 mA per pair of tubes is suggested setting by Diezel himself. So I don’t think it’s high setting
     
  8. efiltsohg

    efiltsohg SS.org Regular

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    that's really hot for kt77 yeah (which is probably the reason you can even tell the difference between the two)

    I'm just surprised it's the JJs not the sovteks that can't handle it, I've found the opposite with most tubes types
     
  9. DudeManBrother

    DudeManBrother Hey...how did everybody get in my room?

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    It’s 65ma for the pair, which is 32.5ma average per tube, which is right at the 70% bias point.
     
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  10. neotronic

    neotronic SS.org Regular

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    Really hard to tell, the Genalex parts of the clip are louder, and that always tricks the ear to perceive it as better sounding.
     
  11. neotronic

    neotronic SS.org Regular

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    I downloaded the video from youtube, extracted audio from that file, opened it in reaper and this is what I got.
     

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  12. oneblackened

    oneblackened Doesn't Actually Play a Seven String

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    Regardless of tone, JJ's KT77 is unreliable as fuck. That tube has been plagued with issues pretty much since introduction. That alone makes me say "go Genalex".
     
  13. budda

    budda Guiterrorizer Contributor

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    Why are you retubing every year?
     
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  14. jarledge

    jarledge SS.org Regular

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    general consensus puts the average octal base power tube at a lifespan of around 1000 hours. That is around 3 hours a day for a year. If you are playing a lot, tubes can start to loose some character and tonal qualities much sooner than 1000 hours. If you are blowing out tubes fairly consistently there may be something else going on. If you are changing because of dullness and playing a lot, a year is a little on the short side but not unreasonable. I have seen a lot of recommendations that power tubes be changed yearly and pre amp tubes be changed every 3-5 years if you are playing on a regular basis.

    I have used JJ tubes in quite a few amps over the years. The last few sets i bought had some issues, mostly with pre-amp tubes. I am not sure i'll be buying JJs again. That said i have had an integrated quad of kt66s and 6l6s running in my peavey xxx for a while and they are really great. I don't know if it is hit or miss, or just the more recent stuff.
     
  15. Belensky

    Belensky SS.org Regular

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    It’s JJ tubes that started to die after year. I hope Genalex will last longer.
    But I really suspect it’s just poor selection from the tube shop. I spoke with couple amp techs they told me not to buy from that place, cause they were doing bad work on matching and burning in their tubes.

    I was told that Tube Amp Doctor(I’m in EU) is really good at selecting and matching tubes so next time I’ll go there.
     
  16. Belensky

    Belensky SS.org Regular

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    Friend of mine has old RFT EL34 tubes that is already 10 years in his amp, and still sounds great. I just wish they cost less
     
  17. Belensky

    Belensky SS.org Regular

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    Double post.
     
  18. Belensky

    Belensky SS.org Regular

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    Well, I haven’t adjusted anything on the amp, same settings, same bias level, record done at the same time.
     
  19. wakjob

    wakjob SS.org Regular

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    No offense, but I just don't understand statements like this.

    A set of NOS RFT el34's won't cost as much in the long run.
    Especially if you are burning up tubes yearly.

    I guess some people don't like up front costs, and rather keep putting $40 wheel bearings in their car every year plus the service charge.
     
  20. MaxOfMetal

    MaxOfMetal Likes trem wankery. Super Moderator

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    For me it's always been the lack of a guarantee that pricier tubes will last. I've had newish tubes fail. It happens.

    When it comes to consumables, I tend to steer mid-range. Good, but not an issue if premature replacement is needed.
     

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