Please Enlighten Me On The 5751...

Discussion in 'Amps/Cabs Tech Corner: Amplifier, Cab & Speakers' started by Electric I, Jul 26, 2006.


  1. Electric I

    Electric I Member

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    I've read where the 5751 can possibly 'tame' a given amp's gain.

    What does that mean, exactly? More headroom? Lower overall amp volume?

    Also, it's said that a 5751 has less highs & can warm up a bright/harsh amp.

    Agree/Disagree?
     
  2. Blue Strat

    Blue Strat Member

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    All of the above to varying degrees. Knowing the amp and pickups would help a lot.
     
  3. Guinness Lad

    Guinness Lad Silver Supporting Member

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    A 5751 is a military 12ax7. It's a lower gain tube, this will help to increase the head room in an amp. American tubes which use numbers are military variations of tubes.

    I have 6 NOS 5751's and to be honest all they do is sit in a box and collect dust, I really don't like how they sound. To my ears they make everything a little hollow (suck the mids out) and harsh...I'm sure the next guy will say they are the best thing ever.

    It really all depends on your amp and what you want to hear. For $20 you could buy one and find out if they are for you.
     
  4. Reeek

    Reeek Member

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    Tube Gain

    12AX7 = 100

    5751 = 70

    12AT7 = 60

    12AZ7 = 60

    6072/12AY7 = 44

    5965/12AV7 = 27

    12AU7/6189/5814 = 20
     
  5. Electric I

    Electric I Member

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    The amp is just a cheapass johnson loredo. 2 12ax7s & 2 el84s. The amp is kinda bright & since the dirt isn't all that great, I have it set up clean & run pedals in front. Good enough for practice, anyway.

    Pups are stock in a parker pm20 (lp-style guitar)
     
  6. Electric I

    Electric I Member

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    Got a jan/phillips 5751 in the basement ready to go. Thanks for the input.
     
  7. Electric I

    Electric I Member

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    Cool. Thank you for that.
     
  8. Blue Strat

    Blue Strat Member

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    Definitely try it. 100 opinions are worth nothing compared to your personal experience.
     
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  9. VaughnC

    VaughnC Supporting Member

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    FYI, if I remember correctly, the 5751 also has balanced triodes....but that means very little in guitar amps.

    However, its been said that SRV preferred a 5751 phase inverter in his Fenders.

    When it comes to tone, there's no right or wrong though....whatever sounds best to you is the most important thing.
     
  10. Broken

    Broken Member

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    Are you sure about the balanced triodes? i've got 4 new JAN 5751's here and need a new phase inverter for my 45
     
  11. Chuckracer

    Chuckracer Supporting Member

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    I used to use a 5751 in the v2 slot of my SLO to tame the gain ever so slightly. I liked it, as did other SLO owners I knew who tried it. It was a subtle difference, but nice.
     
  12. Guinness Lad

    Guinness Lad Silver Supporting Member

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    I use a 12at7 (Mullard) in V1 of my Guytron to tame the lead channel a bit, any lower gain tube will have a similar affect on the tone it just depends on the particular tube (brand) you are using. It's good to a have a bunch of different tubes to choose from because one type of tube throughout the amp hasn't worked for me so far. I think tubes are like speakers, there is no perfect one.
     
  13. jpervin

    jpervin Supporting Member

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    I just bought 2 GE 5751s off of Ebay for this very purpose for my homemade 5E3 tweed Deluxe.
     
  14. Blue Strat

    Blue Strat Member

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    I've read this too. However, after having tested about 5,000 5751s I can tell you that more than half (a lot more) are not balanced. It doesn't really matter though.
     
  15. Swarty

    Swarty Member

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    I think they make a great input tube, especially in med-high gain amps. They just seem very musical with a smooth top, tight round bottom and just enough mids. If you have an amp that has more gain than you use try one out. It will typically tighten things up very nicely.
     
  16. Electric I

    Electric I Member

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    Wow... some great info here. It's no wonder I love this place.

    Thanks a ton, everyone.
     
  17. rockon1

    rockon1 Member

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    Some say unbalanced PI tubes are just fine to use,perhaps even better.
     
  18. michael.e

    michael.e Supporting Member

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    I am using a NOS 5751 in the PI pos. in my Reinhardt JTM45. I find that I am getting more of the high volume response without the higher volume, but, just a bit. I also find it to be very musical and keeps my lead tones tighter and the higher register notes from sounding too unfocused under gainier situations. I use boxes btw. Great tubes imo. M.E.
     
  19. hw2nw

    hw2nw Member

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    5751's are great, smooth tubes to bring down the gain a bit. Sounded great in the V1 spot on my Bogner Shiva (EL-34), but took some of the magic from my Bad Cat Hot Cat 30R, made it sound a bit too thin. Moral of the story, totally depends on the amp! I always like to keep one handy, ever now and then it finds an amp it loves and it sings :D
     
  20. Blue Strat

    Blue Strat Member

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    They certainly worked fine for the first 40 years when people didn't realize that balanced tubes existed:crazy
     

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