Latest 12AX7R3 tests (Electro Harmonix / Tung Sol

Discussion in 'Amps and Cabs' started by myles111, Jun 15, 2006.


  1. myles111

    myles111 Member

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    This is the most recent batch and a mid point average of 100 tubes.

    Specs such as current and TC are nice but gain is a bit lower on this current factory run.

    This tube is the Electro Harmonix 12AX7EH as well as the Sovtek 12AX7 Tung Sol Reissue.

    [​IMG]

    [​IMG]
     
  2. bryan k

    bryan k Member

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    yeaaahhhhhh myles! good job! Im constantly checking your GAB site to see if you have any new news and specs on current production tubes!

    do some more! i love it!

    the current is only down .1 compared to spec. That seems pretty good to me! seeing as much current tubes to get that close now a days!
     
  3. Timbre Wolf

    Timbre Wolf GoldMember Supporter Gold Supporting Member

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    :confused:

    Myles -

    As familiar as I am with the experiential differences in NOS preamp tubes (especially 12AX7), I'm not hip to the EE aspects. You've clearly done a lot of work in generously providing these tables and graphs, but I confess that I have no idea as to how to interpret them.

    As a self-confessed NOS tube snob, I recognize how exceptional the new Reflektor "Tung-Sol" 12AX7 is. I believe New Sensor is on to something with this tube - I've been pleasantly surprised by its fat character, low-noise clarity, and dynamics.

    Do you have some pointers for electrical-engineering tyros, such as myself, on how to interpret your tables and graphs? How does one go from the numbers to predicting or explaining the experiential results when these tubes are fired up in an amp?

    Thanks a bunch!! :eek:

    - T
     
  4. myles111

    myles111 Member

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    This was a good batch but the gain is a bit low and from batch to batch there is a lot of variance.

    I will be collecting my test results and when I get the time start uploading them to my website in what might be a new area or I may expand the area where I have data sheets on tubes now and some schematics on amps.
     
  5. bryan k

    bryan k Member

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    YES! cool!

    im hoping to see some test results on the JJ803,.................

    i cant wait! so excited!
     
  6. myles111

    myles111 Member

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    T -

    The best way to get a handle on these things is hit a place like Antique Electric Supply .... www.tubesandmore.com ... and get their RCA Receiving Tube Manual that is a new reproduction of the original book. It has a lot of data on most tubes (all used in guitar amps are there), and good explanations that will let one go very deep into things if they want to.

    One reason I will be doing this, is that all current tube makers show the specs for their tubes by just copying the specs of the past that are the standards. Unfortunately ... everybody falls way short of the standards and the range of specs in any given run is +/- 50% typically, and typically on the minus side. There is very little consistency today.

    I am in the process of building datasheets for all the GT proprietary tubes and I am working with Aspen to get him to allow me to publish ACTUAL data and curves, not just replicate spec. I want to do this on EVERYBODIES current production tubes and publish this. Doing things this way will there be a bit better chance of keeping the tube makers honest and have them improve or utilize better QA processes. I spent almost ten years at United Technologies doing QA so it is a bit hard to let go of some of those methods. That is one reason the GT-12AX7M has gone through at least ten design and tooling changes, and many material changes. I get samples, I find problems, I shut down production if I can.

    If the GT 12AX7M has specs that are not as good as they should be, they will be published just like everybody elses as an example. Hopefully some day we can once again have tubes that are the same in their specs and the only decision for the player will be to pick what tonal characteristics they prefer. Right now most people cannot even compare two tubes tonally as they generally differ way too much to make it an accurate comparison.
     
  7. Timbre Wolf

    Timbre Wolf GoldMember Supporter Gold Supporting Member

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    Do you believe the RCA Receiving Tube Manual helps explain tube qualities and characteristics, in layman's terms, that would relate to modern guitarists needs? I've been under the impression that the intent of tube circuits, at the time that manual was published, was to accurately amplify electrical signals, and minimize pesky distortion.

    As an electric guitarist, I try to do things that'd make those engineers cringe - increasing harmonic distortion, and controlling the transition from "cleans" to overdriven signals. Do you think there's wisdom in that manual that directly relates to us distortion cretins?

    I've heard this stated before, but it is not my experience. I've auditioned hundreds of NOS tubes, in several amps, and I've found that I can rely on characteristics (tone, dynamics, clarity, etc.) within the same tube type/manufacturer/era - they're repeatable and identifiable, as long as the tubes are in good condition.

    What I was getting at, with my original question, was - what general statements can you make about how the measured values you're posting relate to sonic characteristics of a tube? Lets take a specific example: what would a 12AX7 with lower plate resistance do differently from another with higher plate resistance (all other parameters being identical)?

    I'm just trying to figure out how to make the most of your diligent postings. I can tell you're dedicated to quality manufacturing, and I also appreciate your dedication to accurate data (which is much needed on the internet). I just can't quite translate it to my world of plugging in a tube, playing, and using my ears to determine what I like - but I'm trying! :D

    - Thom
     
  8. bryan k

    bryan k Member

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    the data i mostly look for is gain and current. this is probly what you would want to look for if you play electric guitar, and want to know if one tube will be more "agressive" and push harder than another.

    another is 'rise time", which will determine when and how soon the tube will compress/distort. which may be measured in conductance maybe? im not sure about that................................
     
  9. myles111

    myles111 Member

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    Your statement of:

    I've found that I can rely on characteristics (tone, dynamics, clarity, etc.) within the same tube type/manufacturer/era - they're repeatable and identifiable, as long as the tubes are in good condition. ....

    is the secret. One needs to KNOW the actual condition of the tube and not just suspect it. Even NOS tubes varied widely and many "new" tubes today are pulls or from date codes where things had regressed.

    I cannot make a blanket and simple characteristic statement as there are too many variables and too many circuit aspects. I do make statements on my website about why I prefer long plate tubes for phase inverters as an example and most of my thoughts are on my website.
     
  10. myles111

    myles111 Member

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    Bryan,

    Current and gain are two very different things and one can have one and not the other. The last run of Ei 7025's had current 1/2 of what spec is yet they were the most gainy tubes (many at actually 100 and more) of any current production tube. It is almost like gain = horsepower and current = torque ... and the old adage of "there is no subsitute for cubic inches" fits here ... current can be very critical. In an amp with a complex front end ... Bogner, Mesa Recto, JCM 2000 ... having 0.8mA vs a spec'd 1.2 result is very noticible to me. The amp is just flat and dead when you are down 30% on current. BUT ... in a clean front end such as a Fender Tweed amp or plexi Marshall this is less noticible.

    Rise time is not when the tube will distort, it is a matter of how fast the tube reaches a target rated output. Fast is great for speed metal players and jazz folks ... folks that want articulation. Low rise time is loved by blues players and harp players. This is generally not published as one needs some pretty sophisticated and pricy stuff to measure this. This is what the SAG at GT does.
     
  11. Timbre Wolf

    Timbre Wolf GoldMember Supporter Gold Supporting Member

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    Well, Myles, I'm still scratching my head... :confused: but I'm still listening, too!

    But I'm intrigued about your reply to Bryan, above, with several points to ponder. The concept of rise time is something I can certainly relate to, as different amounts of sag from a rectifier change. I'm not confident I've been able to notice rise time changes from preamp tubes, though.

    Is rise time displayed in your graph? If not, what measurement expresses rise time, from the SAG?

    - T
     
  12. bryan k

    bryan k Member

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    thanks for the clarification................i knew i wasnt right, but i think thats what the other guy was trying to get at, and i knew you would chime in and correct it.

    so i think you answerd what he was really trying to get at.:cool:
     
  13. Timbre Wolf

    Timbre Wolf GoldMember Supporter Gold Supporting Member

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    I think this must be why I prefer a 12BZ7 as the main output tube of my Mesa Triaxis preamp: twice the heater current. Its just so much more dynamically alive!

    - T
     
  14. myles111

    myles111 Member

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    T -

    rise time is not shown .... but think of it in a way as compression in nature. Rise time is measured in microseconds and this is pretty complex and is better demonstrated in your own amp while I change tubes and you play.

    This is a factor that is not a standard industry factor and all I am trying to do here is publish actual data in these posts.

    There is a lot of info in the second half of my 200+ page tube primer that goes into many details I don't really have the time to cover here as they have been covered before.
     
  15. myles111

    myles111 Member

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    Heater current and output current have nothing in common.

    As a side note, your BZ7 has the same 0.3 amps of heater current as an AX7.

    It is not the heater current that is making the difference.
     
  16. Timbre Wolf

    Timbre Wolf GoldMember Supporter Gold Supporting Member

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    Sorry, I mis-spoke. I meant twice the plate current (2.5mA). Weren't you referring to plate current?

    But, since you've mentioned it, I thought the 12BZ7's heater current was also twice that of a 12AX7, at 0.6 amp. That's what it says at the NJ7P database - is that source incorrect?

    I'm feeling a bit perplexed and taken aback at this reply. I've got some genuine, and humble questions, and I hoped you'd be open to explaining your original post - doesn't have to be a 200-page tome. Isn't that the reason we have this forum - to share our experiences, expertise, discoveries, etc. and support each other in the process of authentic inquiry?

    Maybe I missed the point of the original post? I'm disappointed to find that you don't want to take a moment and share some of your knowledge, but I'd still be willing to partake of it, if you're willing to (briefly) oblige.

    By the way, I've avidly read your postings, on this and other boards, for a couple of years, and I've not ever heard you explain these questions I have, so the search function doesn't help, in this case. This is why I finally spoke up and asked.

    Thanks.

    - Thom
     
  17. myles111

    myles111 Member

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    Thom,

    Yes .... plate current.


    On the other issue ... I am happy to talk to you on this directly but these things are complex, my time is short, and it would be easier on a telephone. Feel free to email me for my contacts. I would be more than happy to discuss this. I already moderate the Guitar Player forum, Dr. Z Forum, and Carl Verheyen forum. I really am on the minus side of the scale time wise. My intension here was to post the basic test results.
     
  18. Timbre Wolf

    Timbre Wolf GoldMember Supporter Gold Supporting Member

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    Will do, Myles - thanks. I'll re-visit your site, first, so as not to waste your time with questions already answered there. I understand about the value of time, and appreciate your offer.

    - Thom
     
  19. myles111

    myles111 Member

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    I have some later Tung Sol tests from yesterday over on the Z Forum
     
  20. Timbre Wolf

    Timbre Wolf GoldMember Supporter Gold Supporting Member

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    I'm slowly stewing in your information, and will get back to you, sometime (after a period of cogitation), with a few choice questions.

    Meanwhile, I still like these "Tung-Sol" best of any new-production, even though your two test samples reveal poignant inconsistencies. Myles - you said "low current may not be liked in complex front end amps with a complex circuit" I think my Triaxis preamp may fall into this category, if I'm not mistaken, but I found my samples to sound fine there, as input and second gain-stage tubes.

    Good as they are, they're not as nice as at least a dozen '50s-production types that I prefer, always. I guess the question I'd most like answered is "why are those old tubes so incredibly good?" And "how can current manufacturers learn from the old tubes, and make new ones that compare?"

    My latest infatuation is with a long-plate Siemens 12AX7. Truly, nobody makes 'em like they used to. But I still appreciate current manufacturer's efforts.

    Thanks Myles!

    - T
     

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