Vali 2+ Tube Rolling (Measurements)

Discussion in 'Headphone Amplifiers and Combo (DAC/Amp) Units' started by purr1n, Sep 14, 2021.

  1. purr1n

    purr1n Super Friend

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    This is a continuation of my earlier efforts starting here where I rolled different tubes (WE396a on adapter, stock 6BZ7, Telefunken 6D78), on the Vali 2 before I did Texas or bust. The same methodology was used as back then to keep things consistent. Volume knob was maxed and output level set to about 0.550Vrms. Gain set to low. Load is 300-ohms. This voltage level is enough to drive HD650s to near 100db SPL.

    https://www.superbestaudiofriends.o...-2-review-and-measurements.10139/#post-325301

    5F4A0034.JPG

    WARNING: Oh, if your religion is dogmatic and based on AmirNADS, then get a JDS Atom, Geshelli, or Schiit IEMagni and go away. (We do not recommend the L30 because of some issues with it exploding headphones and fixes which we do not feel will fix the problem, especially with the ESD prone OPA1612). DO NOT SPEND MORE MONEY THAN $149 and certainly stop here and do not read further.

    Electroharmonix 6922EH standard (new production, barely used) #1
    upload_2021-9-14_19-28-21.png


    Telefunken 7DJ8 #1 (vintage)
    upload_2021-9-14_19-30-25.png
    Really good results here, although I would not have minded even if we saw successively lower harmonics at 4kHz, 5kHz, etc. Subjectively, this is often what I mean when I say richer sound. This tube is delicate and clean sounding. This tube is highly sought after and more or less unobtainium. This is the 7V version.


    Electroharmonix 6922EH Gold Pin (new production, barely used)
    upload_2021-9-14_19-32-6.png

    I always wondered if the Gold Pins were really better than the standard. Good indication from here that they really are!


    Electroharmonix 6922EH standard (new production, barely used) #2
    upload_2021-9-14_19-33-10.png

    But then we see a standard EH6922 that looks to be on the same playing field as the Gold Pins? Perhaps the standard is more like a box of chocolates and that the Gold Pins are binned. I don't have any extra Gold Pins to get more data.
     
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    Last edited: Sep 14, 2021
  2. purr1n

    purr1n Super Friend

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    Telefunken 6DJ8 #1 (vintage)
    upload_2021-9-14_19-34-28.png

    Little bit higher noise floor on this one in the L triode.


    Reflektor 6N23N #1
    upload_2021-9-14_19-35-33.png

    Known to be more robust sounding than all other 6DJ8s. This is the Russian beast. Unfortunately, a single measurement has limits and won't be enough to tell us much. Unobtanium.


    Sovtek (semi-vintage) #1
    upload_2021-9-14_19-36-27.png

    This one is a bit more microphonic (the 7kHz and 8kHz - they go up and down). Not known for being great with respect to reliability. These are upper mid-forward sounding compared to most others.


    Telefunken 7DJ8 #2
    upload_2021-9-14_19-40-13.png

    This is the 7V version of the 6DJ8 which is 6.8V. Many like to substitute this part. Some say it's not as good. This sample ain't too hot.


    Telefunken 6DJ8 #2 (vintage)
    upload_2021-9-14_19-41-42.png


    Sovtek 6922 (semi-vintage) #2
    upload_2021-9-14_19-42-38.png
     
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  3. purr1n

    purr1n Super Friend

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    Summary: everything kind of looks the same with respect to this specific measurement. This is typical with small signal tubes with medium gain. Some tubes have higher noise floor than others. Some have more hum. Some have more microphonics. Some have a little bit more 4th harmonic than others. But otherwise it would appear that the 6DJ8 family has similarities with each other, namely a second harmonic at at about -75db and a third harmonic at -110db. Finally, this measurement seems too limited in scope to fully realize the differences among the tubes which are very easily perceived by even novices with minimal ear training.

    This distortion is astonishingly low for a tube amp (the Vali 2 is actually a hybrid amp). See below chart from http://www.sengpielaudio.com/TableOfSoundPressureLevels.htm
    upload_2021-9-14_19-59-57.png

    So basically -75db would be like being able to hear the "silence" (there are always background noises) in a studio while being 10M away from a dumpster truck. Or being able to hear the background noises in a quiet library while you had a chainsaw in your hands fighting zombies who invaded that library.
     
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    Last edited: Sep 14, 2021
  4. Woland

    Woland Friend

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    Thanks @purr1n , it's a delight to see harder analysis come to tubes. A few questions..

    What measurements might pick up the tube differences better?

    What's with the 60Hz and harmonics? In some of the graphs its just on one of the triodes/ channels which suggests it might be tube specific.

    For the 6H23 aka 6n23, I buy these and the related 6n3p's, and their higher grade military variants (-e, etc) for a couple of dollars a piece. What's unobtainium about the one you tested?

    Why set gain to low, which in Schiit amps usually means adding global feedback?
     
    Last edited: Sep 14, 2021
  5. atomicbob

    atomicbob dScope Yoda

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    Very nice comparison, thank-you @purr1n .
    Question.
    You show a Telefunken 7DJ8 #1 (vintage) in post 1 with one set of measurement results.
    In post 2 you again show Telefunken 7DJ8 #1 with a different set of results.
    Are these different tubes with the distinction being vintage vs current production?
     
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  6. purr1n

    purr1n Super Friend

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    Corrected. The 7DJ8 in the second post is #2. All are vintage except the EH tubes which are current production.

    Could try different frequencies, different levels, different gains (high gain). Some tubes hum more than others - just happens. Sometimes on triode hums more than the other. It's a particular 6H23P-EB with specifics that was available a few years ago but price kept going up to well over $100. I haven't seen it around anymore. I run Vali at "low" gain because mine is tweaked a bit to have a few db gain at the low switch, so think of it as medium gain.
     
  7. sorrodje

    sorrodje Carla Bruni's other lover - Friend

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  8. Qildail

    Qildail Facebook Friend

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    I know graphs aren't the whole story here (they never are), so this comes from an honest seeking of understanding:

    If I read this graph, and compare it with your previous thread's graphs, would it be fair to say the 6922EH-Gold is more of a... sidegrade(?)... from the stock Vali 2+ tube?

    Or is the better message to interpret is your summary that all of these are basically flavor-tuned sidegrades of each other, and there's only so far you can go in a small one-tube roll even in the crazy/unobtanium models?
     
  9. penguins

    penguins Friend, formerly known as fp627

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    ^ I made a post in the vali2+ or tube rolling thread, don't remember which, but long story short, some tubes were a very obvious upgrade over the others.

    On the flip side, as much as I use and like my 2+, it's not enough amp for me to use rare/limited WE396a, whatever $100 6922 family tubes, or $250+ Telefunkens. The Vali2+ doesn't become some super amp with these. Instead, my conclusion was to buy a small handful of cheap 6BZ7 tubes ($5-10 each shipped), plug them in, keep the ones you happen to like, sell or give away the rest. If you need a better amp, $500 on a new amp will go much further than $150 on a Vali 2+ with $350 in 2-3 good 6922 tubes.
     
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  10. Biodegraded

    Biodegraded Friend

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    @purr1n I think your Tele 7DJ8s (PCC88s) are Siemens made. On the left one in the photo (#1?) I see the embossed code near the bottom with what looks like the =|= mark indicating the Siemens Munich factory (I have a Siemens-Halske branded one with the same getter style and 'DJ8' embossed coding). On the one 3rd from right there's embossed lettering too, but I can't make out the symbol. Do those two have the diamond underneath?

    If it's the one second from the right, one of the Tele 6DJ8s (#2?) looks more like Telefunken Berlin or Ulm. It has 'squarer' shoulders than the one to its left.
     
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  11. Merrick

    Merrick A lidless ear

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    I use a 396a in the Vali 2+. It's the only 6922 type amp I have.
     
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  12. Azimuth

    Azimuth FKA rtaylor76, Friend

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    @Qildail, what I have found is that there are few downgrades from the stock tube, but still, don't expect miracles. Some might be upgrade in one are of the other of tonality or noise. That said, I have only found one that I might consider worse than the stock tube. Some may have great results to your system, some might not. And the level of upgrade is very likely subjective.

    After having this amp for quite sometime and trying many tubes, more vintage tubes rather than newer tubes like Marv, and mostly what I have learned is that the tubes may work with a certain chain, and others work with a better chain. Meaning source and headphones. Some of my headphones I like better with certain tubes, some I like others, and even might change depending on the type of music (loud bashing rock, prog, jazz, acoustic, etc.). I think the tube rolling is to find your particular flavor that works for you.

    Case in point, I really found a great square halo getter 5670 that I find sounds sublime that is probably really close to the 396A sound. My buddy heard it with pretty much similar source and headphones, and he found it too bright and boring. Same exact tube. This can happen.

    Right now I am rolling an RFT ECC84 with an adapter that some might found too tight on the bottom end. I love the RCA 6CG7, and some find that one a bit too bloomy on the low end. One of my other favorites is a Russian 6HN1 and some won't believe it because it is not a megabuck tube.

    I think this why Marv hates tube rolling threads because it can go on and on and on and everyone chiming on their ultra rare NOS oddball. Basically, there is no reason to spend megabuks for some of these rare tubes becuase you are not going to get the best performance out of these tubes in a Vali 2 or Vali 2+. There are plenty cheap tubes out there that can sound great.

    So I will echo what @penguins said and buy cheap and find works best for you.
     
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  13. Qildail

    Qildail Facebook Friend

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    Thank you. That was how I thought I was reading the summary: Don't treat a $150 amp like it's more than what it is; and stop overthinking it while you're at it.

    Now, if FedEx would be so kind as to show up with mine today, that would be grand.
     
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  14. purr1n

    purr1n Super Friend

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    Haha. Exactly. Part of this post was me being a dick-waving asshole showing a small part of my collection of unobtanium tubes. The other part was me being real. We don't need speshal tubes. A 6922 is a 6922, and even an exotic 6922 could have issues, many times on one of the two triodes in the same tube, if not be different from the same tube sub-model. And the finally, the bestest most unobtainium tube may not necessarily work well on any amp for your setup.

    My favorite tube to go with the Vali 2+ is none of the above. It's the WE396A on an adapter. And guess what, It's not one of my good ones I have stashed away (those will be matched into pairs and sold off to stupid httsp://orfas.org people.) It's one which has been almost used up that scores close to 0% emissions on tube tester and has high hum and higher distortion. This is how it measures:

    Horribad well used WE396a on adapter on Vali 2+
    [​IMG]

    The WE396A is warmer and richer sounding than the 6922/6DJ8 in the Vali 2+. Here is a measurement of a pristine one below. Note significantly higher second order and third order (15db and 30db) harmonics and an additional forth harmonic that the 6922 does not have. Granted these were done on the AverLAB, not the APx555 which has a super sine wave measurement mode; but if we give the AverLAB a 56-db handicap, the moar distortion is there.

    Pristine WE396a on adapter on Vali 2+
    [​IMG]

    THD is 0.05% and has a nice triode pattern. Nothing like the horrible distortion pattern (and similarly high distortion) seen in the plate amp of the JBL LSR305ii. The difference between Amir and me is that I will admit that I like certain kinds of distortion as long as it isn't too much (0.05% - think about that deeply - that number ain't that high) and Amir cannot hear distortion (and will not measure the distortion) if his company sells the product.
     
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    Last edited: Sep 16, 2021
  15. Tekker

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    Lol, so much so for Amir and his followers claiming that the only thing tubes do, is glow, and not have any sound difference.
     
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    Last edited: Sep 16, 2021
  16. jexby

    jexby Posole Prince

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    pssst. if this thread has inspired anyone to use old / extra tubes laying around in a new Vali 2+,
    mine shipped in 2 days not the 6-8 weeks as stated on the schiit web page.
     
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  17. Azimuth

    Azimuth FKA rtaylor76, Friend

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    I just put in an order late last night and this morning received a shipping notification.
     
  18. purr1n

    purr1n Super Friend

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    With respect to me disliking tube rolling, it's always context. I dislike audiophiles who roll tubes, go hem and haw, and proceed to discuss certain majikal properties of specific brands of tubes, the chrome flashing, the color and typeface of the print, etc. (a better way is to took at the internal structures, the plates, the electrodes, etc. because a lot of stuff got rebranded). The thing is, this stuff is so old that we have no idea of their condition. That Le Fivre toob with the bat ears antenna over the mica with partial flashing third-fours over one side the black glass and green print with the special wolf penis logo that identifies that it was made at the Indiana plate in November of 1958 - there's no guarantee that another one will sound the same.

    However... with the Schiit Vali 2+ or Garage 1217 Project Horizon, do what @penguins said. Buy a bunch of 6BZ7s and have fun, roll to your heart's content or until you get sick of it.
    PXL_20210916_171215328.jpg

    Anyway, I scored! I found this rare amazeballs Arcturus that really does put the Vali 2+ on another level.
    PXL_20210916_173851988.PORTRAIT.jpg

    Actually, it doesn't - or at least I don't really know how it sounds or measures yet. I'm messing with you. I just thought their logo looked cool. I picked it out because Arcturus tended to do their own stuff with different looking internals (don't know if this is true in the case either).
     
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  19. Azimuth

    Azimuth FKA rtaylor76, Friend

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    I was reading through Jason's Vali 2+ chapter (Chapter 14, 2020, you know where to find it), and he wrote that he wanted 6H1N as the stock Vali 2+ tube, but decided against it because it draws lots of heater current and gets fairly hot and he felt that might not be a good thing for new tube amp owners with an exposed tube. I find any of the 6H1N's great with good solid low end and sweet top end. Just a nice full spectrum with plenty of dynamics.

    I say that as I sit here and beside myself over a German made RFT ECC84 with an adapter., that came in a Tesla box, but everything, including the numbers and logo, point to RFT.

    And Marv, I don't find the descriptions bad. It is not like that terminology is used to sexify the tube, it is more of and indication of manufacture and period because tubes do not have excellent markings, labels that get rubbed off, 50's manufactures that kept bad legers and notes. I get what you are saying though...it kind of gets way into cork sniffing territory.
     
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  20. Zampotech

    Zampotech Friend

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    In the photo, the tubes 1,3,4,5 (from left to right) are very similar to the tubes 6N23P-EV. Perhaps these are old 6N23P-EV on which the plant has applied other markings. @purr1n i can send you 6N23P tubes (without letters) in two versions, with an open anode system and a closed anode system. This will probably expand your research.
     
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