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tube talk-12ax7-7025

Discussion in 'Amp Input - Normal or Bright' started by mad axe man, Apr 4, 2019.

  1. mad axe man

    mad axe man Senior Stratmaster

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    question for the pros here...looking for a good/great pre amp tube for a rivera superchamp...alot of selection out there just wondering what your faves are and what they do to your tone...thanks
     
  2. Stevem

    Stevem Senior Stratmaster

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    The character tone wise and gain level and current output level of the first preamp tube in any amp will set the up the basic tonal structure that the whole amp has.

    Circuit wise tons of amps have the tone stack ( tone controls) right after the amps first gain stage which is just one section of the two sections that make up any 9 pin type preamp tube.

    A tubes current output depends on how strong it test , and a high current output tube ( one that comes closer to design specs) will make for having a tone stack that has greater range of control.

    Also I high gain tube will drive the other tubes down stream from it into clipping sooner.

    I would suggest to you to go to the guitar amp blueprinting site and pay to print off the 2 section tube primer he has there and read thru it a few times as I don't think anyone with tons of knowledge about tubes here is willing to fully type out what they know on the subject you ask about as it would be a long, long task!

    One thing has not changed much these days even with all the new preamp tubes we have available to get our hands on, and that is that a good testing NOS tube even like a cheap to find 12AaX7 Sylvania brand or GE will blow out of the water any currently manufactured tube but for the JJ brand at times , and yes sometimes China made tubes even though they do not last terribly long!
     
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  3. Swampash

    Swampash Senior Stratmaster

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    **** nos just go Groove Tubes
     
  4. henderman

    henderman Most Honored Senior Member Strat-Talk Supporter

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    i know nothing about the technical side of tubes but i learned that buying used tubes from audiophile tube freak sellers with good testing equiptment will get you as good a tube as you can buy for the smallest amount of money.

    to me a tube is like a lightbulb, it may last 100 years or break before you get it shipped to you. no real guarantees for anything else.

    however a good tester can verify the tube is doing what it should even if it is older than dirt. new, old or who made it matters not if it is out of spec so get it checked, why gamble.

    don't get me wrong, i have bought new jj tubes and tung-sols and i paid the 2 bux to have it verified that it was in spec from reputable sellers. tube depot and the tube store were great to deal with and i'm 100% satisfied with what i bought.

    but now i buy used and verified golden oldies from reputable sellers on ebay for the same price as a new jj tube.
     
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  5. Stormy Monday

    Stormy Monday Most Honored Senior Member Strat-Talk Supporter

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    I am a beginner with amps and have no experience with a Rivera Superchamp . But....

    On one amp I put a 5751 in V1 to quiet the noise and give a little more headroom. Worked like advertised. One another amp, I was experimenting with tubes, the only one that made a difference to me was a new Mullard 12ax7. The unbranded Chinese tubes were noisier than the branded ones that went in after.
     
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  6. Supernut

    Supernut Strat-Talker

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    I have had really bad luck with Groove Tubes and have bought JJ and EHX since then. That's just been my personal experience. Will certain brands work better with certain amps, or is it just the output of the tube?
     
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  7. rolandson

    rolandson Still Breathing Strat-Talk Supporter

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    Do your homework.

    A good general primer about the function of the preamp tubes in fender circuits:
    http://fenderguru.com/ampsdeluxe-reveinforb

    Read through it and you'll gain some understanding about the various tubes.

    Personally, I stay away from rebranded tubes...Chinese and russian made tubes that have various reputable names printed on them. In fact, any source that rebrands tubes is a red flag...in my opinion.

    I stick with either - old tubes from the 60's and 70's ... GE, RCA, Sylvania...and the JAN line (Joint Army Navy)...they don't have to be new or NOS to be good - Or, JJ's...a brand of tube manufactured by a company in the Slovak Republic...
    https://www.jj-electronic.com/en/

    A word about some old world names like Mullard and Tung-Sol:
    The old ones bearing those names, from the 60's and 70's are very good. Unfortunately a company called New Sensor (parent of EHX, Electro Hamonix) bought the right to use the names ... and bangs out tubes in russia that are in my opinion absolute garbage.

    And I stay as far away from anything with Groove Tube stamped on it...another rebranding enterprise.
     
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  8. joe_cpwe

    joe_cpwe Senior Stratmaster

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    +1 on this.

    I think the old tubes sound better and can be had for about the same as new.
    I currently have RCA and Sylvania.
    I did have one RCA go microphonic on me early in my ownership of it at a rehearsal so I swapped it with the phase inverter position and all was well for the day...so maybe that tube I didn't get my value out of. The tone improvement is worth have a few spares around IMO.
    No 7025 or 5751's for me...tried them. 12AX7 only.
    Also tried new JJ , it was almost as harsh as the no name Chinese stuff. Although I do like JJ power tubes.
    Last year I got a used amp with EHX and Tung Sol preamp tubes. They seemed fine, but are out performed by the old ones in output and tone. IMO
     
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  9. Believer7713

    Believer7713 Most Honored Senior Member Silver Member

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    When I re-tubed my Marshall DSL 401 I decided to try a set of NOS Russian Reflektor 6N2P-EV tubesto go with the 6P14P-EV drive tubes that I put into it When I blew a tube. I got a pretty good deal on them on line several years ago and liked them so much that I bought a second set of each just to keep on hand. They break up a little differently than a regular 12AX7...It's hard to put my finger on it but they sound a little darker in a way but still clean up really nicely for how I play.
     
  10. Stratoskater

    Stratoskater Most Honored Senior Member

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    Yeah I much prefer NOS (GE, Sylvania, RCA) in preamp, power and rectifier positions. JJ's are pretty good but tend to sound a little dark and bassy to my ears. Also as has been said if you want more clean headroom put a 5751 in V1 position.
     
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  11. Stratoskater

    Stratoskater Most Honored Senior Member

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    You do realize that Groove Tubes is not a manufacturer and simply buys other tubes from the manufacturer and labels them right? So you could just buy EHX, JJ, Sovtek, Mullard, etc. and get the same thing.

    https://www.thetubestore.com/tube-brands/groove-tubes
     
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  12. tstone2

    tstone2 Strat-Talker

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    SPAX7 in V1 position = A little quieter. Perhaps in all positions and use the old good ones for spares if it's in your budget.
     
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  13. EC Strat-boy

    EC Strat-boy Strat-O-Master Strat-Talk Supporter

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    +1 on going with a NOS tube for preamp. A significant difference in tone.

    Personally I like the RCA NOS 12AX7. But any of them will be great.
     
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  14. 1300Valencia

    1300Valencia Senior Stratmaster

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    There's many places to buy. "Amplified Parts" has a $70 sampler kit of five 12AX7s. One of each of the following:

    12AX7-S JJ Electronic
    12AX7A-C5 Ruby Tubes
    12AX7WA Sovtek
    12AX7 Electro-Harmonix
    12AX7 Tung-Sol
     
  15. Stratomike

    Stratomike Strat-Talk Member

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    OP, I'd buy 1-2 NOS/ANOS tubes and do some critically listening if you notice a difference. If not, you can save lots of money. If yes, you have probably endless options to tinker around :)

    Personally, I only hear veeery subtle differences, if any. I have some old glass like Telefunken, RCA, RFT, Tungsram etc., but I came to the conclusion that it is not worth it to me. My hearing changes varies more from day to day than the differences I can hear anyway. If I had to describe it, maybe a little more top end or sparkle here and there, subtle effect on bass etc.

    I'm talking V1 here, can't hear any diff. at all in other spots (in my amps, that is).

    YMMV of course, but I'd be careful to expect / hope for a significant difference.
     
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  16. TimTheViking

    TimTheViking Strat-Talker

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    All tubes have a limited life that is dependent upon, among other things, the electrons that are "boiled" off the cathode and race to the anode (plate) through the various designs of grids. Once they're all gone, the tube is done.
     
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  17. Camitampa

    Camitampa Strat-Talk Member

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    The electrons “boiled off the cathode” are instantly replace to complete the circuit. One electron out, one in, which we call cathode current. The electrons never run out. The eventual failure of the tube is from cathode metal fatigue from the heat and other things.
    I may not be a musician ( I’m practicing a lot though) but I’m an electronics tech and have been repairing electronics since the 70’s. I still do it for a living.
     
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  18. Loleary

    Loleary Strat-Talker

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    I recently installed new Marshall Ecc83s(12ax7) and slightly used but strong tested soviet era reflektor EL84s into my vox night train. Sounds much better now. I don't know that much about tubes but the Marshall ECC83s seem alright for the price.
     
  19. Vic Interceptor

    Vic Interceptor Strat-Talker

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    being as you have a Flying V I'm gonna say save your money and just buy Shuguang (chinese) tubes. A dirty amp doesn't express the nuances of a high end vintage tube like a clean amp will. I much prefer the chinese to the russians for clean amps, but you will probably prefer the russian stuff.

    There are no "NOS" tubes left. There are only picked through leftovers that someone else has cast off long before you see it. You're buying someone else's 2nds or 10ths, and the chances of you getting a microphonic or weak tube are likely. Caveat Emptor times 10 here.
     
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  20. JB74

    JB74 Senior Stratmaster

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    There is no pretense that says an original NOS RCA blackplate 6L6 is the holy grail. Just like any 12au/at/ay/ax7 brand is consistently 'better'.

    The only way to guarantee to get what you want is to have the tubes graded and matched.

    matching power tubes is more beneficial from a biasing perspective. for preamp tubes, not important.

    how much gain you want ultimately will determine what tube to put into the amp.

    The original JAN tubes have been proven to be consistently reliable and long lasting, but these days a premium for an unknown is a guarantee you are wasting money.

    I have a set of Genalex B759 12ax7's which have spiral wound filaments - and this is the key to getting a robust tube. You can find cheaper tubes, But I've not had to replace them or any of my previously purchased spiral wound filament 12ax7's.

    Not a fan of GT's or JJ's in the preamp section myself. I don't mind them in the power section of my vox (EL84).

    Don't get sucked into the belief that a $250 tube is somehow sonically better than a $40 one.

    Personal preference and budget will dictate what you choose. You can make an educated decision by learning about the tube specification, and there is no better place than the early RCA tube data manuals.
     
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