The Mjolnir 2 thread

Discussion in 'Amplifiers and Combo (DAC/Amp) Units' started by maxedfx, Oct 11, 2015.

  1. Thujone

    Thujone Friend

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    I expect that most would agree the Valhalla 2 is better than the Lyr 2 for all high ohm Sennheisers. Also, only the front two tubes are rollable.
     

  2. aufmerksam

    aufmerksam Friend

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    I agree with your statement about Val2 v Lyr2, but disagree about which tubes can be rolled. Technically, you can roll all four, and I have read plenty from people who have... I think you meant its only makes sense to roll the outinput (front) tubes.
     
    Last edited: Sep 21, 2016
  3. SoupRKnowva

    SoupRKnowva Official SBAF South Korean Ambassador - Friend

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    In the Valhalla 2 all four tubes are rollable, though there aren't many options for the output tubes, basically just older versions of the 6n6p. But the front tubes are the input tubes, the small ones, and there is obviously loads of options for them.
     
  4. aufmerksam

    aufmerksam Friend

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    LOL, fixed that.
     
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  5. Thujone

    Thujone Friend

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  6. Garns

    Garns Friend

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    I am in a fairly similar situation to you - looking for tubes with a similar presentation (esp treble) to the LISSTs, which I like a lot. I picked up some mid 60s Heerlen E88CCs (which would be similar-ish to your Orange Globes) and while I wouldn't say they are rolled off to crap they are certainly too dull up top for me. OTOH the Voskhods I have have too much energy round 5-6khz. I am waiting on some E188CC tubes from the factory in Suresnes, France, which are supposedly somewhere between the Russians and the Heerlen tubes in sound (in particular in terms of treble presentation). If this is true, it could be a good option. I will report back in a couple of weeks w/comparo's vs the LISSTs. (NB: I use 650s not 800s but I am very treble sensitive).
     
  7. Garns

    Garns Friend

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    OK, here are some thoughts on tubes I've tried for the Mjo2.
    Chain: RME9632 > SPDIF coax > Gumby > Mjo2 feeding HD650s (modded) and Klein + Hummel O300's.
    Methodology: I stuck each of 'em in for a week or so and listened to some stuff.

    The last pair listed are my most recent acquisition and I think I can now stop looking further. Have indicated the prices I paid; some are probably a bit high and some a bit low.

    LISSTs, came with Mjo2
    Very fast, detailed and neutral. Best bass quality and extension, and highs are smooth and non-fatiguing. Unfortunately something funny is going on in the mids. It's the aural equivalent of looking through a pair of glasses with a smudge on the lenses. Messes up layering and separation. Imaging is precise but no depth to soundstage.

    WE396a 1967, $100 (Brent Jesse) + $15 adapters (Ebay)
    The most "fun" sounding. Extra rich in the mids and lots of wet, tubey acutance. Great microdynamics but not the fastest. Soundstage actually has some depth (fairly flat with all my other options). Rounded bass which is very noticeably above neutral (probably about 2-3db) but with a compressed slam to it which makes it quite pleasing. The top end is not at all rolled off, but on mine sounds pretty rough, the roughest out of the tubes here, which is a deal-breaker. Might be a duff pair, or might need more hours on them (though I'm doubtful as they have already have ~60).

    Heerlen E88CC 1962, Valvo branded, $85 (HF classifieds)
    Relaxed in the top end, not exactly rolled off but definitely lacking some air. Solid, powerful sound with warmth in the mids. A bit slow, staging and microdynamics not the best, not very much tubey acutance. Well-rounded and enjoyable sound which doesn't do anything wrong, but doesn't do anything exceptionally well either.

    ----- Above this line I though the tubes were holding the Mjo2 back. Below I think they do not.

    Voskhod Gray Shield 1975, $65 (local seller):
    Fast. Not much warmth or richness. Good extension at both ends. Quite a lot of tubey acutance. These are pretty close to the LISSTs in terms of technicalities but without the smudgy mids. Tight bass (best of all the tubes I have) but very slightly hyped. The bad is that there is quite a bit of heat around 6-7khz which throws the tonal balance and makes things sound papery and without solidity. Note the top end is still pretty smooth, just too forward.

    Suresnes E188CC 1966/8, Dario Miniwatt branded, $120 (HF classifieds):
    Very well-balanced. These are not as rich as the Heerlen or the WE396a but still have a noticeable splash of colouration in the midrange. Frequency response is overall the most neutral of all the tubes, seems very flat through about 10khz with maybe a very slight boost in the top octave. The top end is noticeably excellent, the smoothest and least fatiguing here and with a sweet, airy character. Nothing much negative to say, these do everything pretty damn right, good technicalities, and (to me) just the right amount of distortion to give a realistic presentation.
     
    Last edited: Oct 7, 2016
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  8. Garns

    Garns Friend

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    Postscript to the above:

    Because I am a massive idiot I only just realised (after owning them for 8 years) that my Klein and Hummel O300s can dial in 24db of attenuation on the internal amp. Of course, the first thing I did was to try removing the Mjo2 from the chain and connecting the Gumby straight to the speakers. With full attenuation 0dbfs = 86 db which is pretty perfect. Conclusions:

    1) Wow, the Mjo2 is really not transparent as a preamp (even with LISST)
    2) Wow, the Gumby is a much better DAC than I realised
     
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  9. philipmorgan

    philipmorgan Member of the month

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    @Garns Your description of the WE396a pushed me over the edge to pick up some adapters and a pair of those tubes. They should be a fun alternate flavor for my Mjolnir 2, especially if they add some color to the midrange and some depth to the soundstage. If I want transparent I've got the Jot for that, so this should be a fun alternate sound...
     
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  10. westermac

    westermac Acquaintance

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    Very interesting to read your impressions, thank you for sharing...

    While I really enjoy tube rolling, my previous experience with tube amps tells me that I will go overboard and spend too much money on them, which I really can't afford right now. My hope for the Mjolnir 2 – may be a long shot, I know – is to find an inexpensive tube that is "good enough" which I can buy a quantity of and settle in knowing I am covered without having to worry about my favorite tube skyrocketing in price.

    Unfortunately the LISST (while fast and very detailed) is too lean for me to enjoy. The stock tubes I find a bit fuzzy/bloomy for my tastes and the Orange Globes I've found to be pretty good all around.

    I've ordered a pair of 5670/6N3 adapters as well as some small batches of GE 5-star 5670 and Reflektor 6N3P-E in hopes that one of them will match the performance of the Orange Globes to my ears (or better yet, to exceed them). We'll see.

    Meanwhile, the Mjolnir 2 has been doing a superb job of driving my modded HD650/stock HD600 (better than the WA3, WA6, Liquid Carbon and Corda Classic before it). I think I will be hanging on to this one :)
     
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  11. Ice-man

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    With a good set of NOS tubes, this is an excellent amp even with the hd800, which is a nice feather in it's cap.
     
  12. Garns

    Garns Friend

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    Sounds like a good plan. Seems like the 5670 family is relatively unexplored territory. Certain the WE's are really nice tubes. I am actually more positive about them than it may appear from my description above. If it were not for the rough treble on my pair I would recommend them without hesitation. @Luckbad has a good post over at HF comparing various 5670's. Not in a headphone amp but should give some indication of the various possibilities.
     
    Last edited: Oct 5, 2016
  13. WNovizar

    WNovizar Facebook Friend

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    Hi I have been using Mjo 2 Gumby stack for 4 months with stock tubes. And today I have a problem, my mjo2 sometimes skipping my music while playing. It was almost like it was suddenly turned off (even though it was still turned on). The music goes back again after 5-6 secs. What's wrong with my mjo2?
     
  14. KurtSvensson

    KurtSvensson Friend

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    Maybe you should ask schiits support instead of us. But I assume it isn't the gumby relay triggering when you go from different sample rate music, right? Cause if it's that, it's completely normal.
     
  15. WNovizar

    WNovizar Facebook Friend

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    You're right. Gonna ask them tomorrow. And no this is not about relay triggering. It happens as the music is playing, not after it
     
  16. PoochZag

    PoochZag The Shadow knows - Friend

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    I just wanted to follow up with something I said a while ago about how there's a bit of a noise floor with BA IEMs (Jupiter and K10 for me) from the SE out.

    I finally got around to making an XLR adapter for my 2.5mm balanced cables, and holy cow. Basically no noise floor, if not black it's at least...midnight blue. Much quieter than my Galaxy S7 even, if not quite as black as DP-x1 or GOV2+. Very acceptable though, I've never heard the Jupiter's sound so good (the balls of Mjolnir 2 down low don't do the K10's many favors, as I already find them too thick, but they still sound very punchy and dynamic through Mjo2). This is with a variety of tubes.
     
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  17. westermac

    westermac Acquaintance

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    Just wanted to share my brief and entirely unscientific experience with tubes thus far (cans used are stock HD600 and HD650 modded):

    - Amperex Bugle Boy 6DJ8 ('64, small O-getter): Warm and mellow, a bit rolled off in the treble but not by much. Could be great for leaner sounding headphones but for the HD600/HD650 I find them just a bit too warm. Gives you a nice cozy feeling though.
    - Amperex Orange Globe ('69, single post dimple getter): These are better balanced to me - still mellow but less than the Bugle Boys with better treble extension for a more engaging experience. A bit tighter and faster sounding overall. Really nice but I haven't been seeing any of these for sale so unfortunately not easy to come across I guess. Curious to try the A-frame ones for comparison.
    - Amperex USA 6922 ('66, green label, big O-getter): Now we're talking. Similarly well-balanced signature to the Orange Globes but more controlled and resolving of details with eerily lifelike spacial cues/imaging. My favorite so far. (Also have a pair of Beckman branded USA 6922's ('62) which sound the same but are terribly microphonic).

    With 6N3/5670 adapter:

    - GE 5-Star GL-5670 (50's, black plate, D-getter): Very close to matching the USA 6922's in performance; perhaps a tad leaner sounding (less bass/lower mids). Could just as easily be content with these. Really nice and clean but not to the point of being sterile. From what I understand non-5 star black plate GE 5670's are the same (5-star just had tighter tolerances), making this the best value in my opinion

    - Reflektor 6N3P-E ('75): Dirt cheap, readily available (provided you don't mind the international shipping wait) and quite good. They are the leanest/most solid state sounding of the tubes I've tried, so not quite my cup of tea but with some warmer/darker headphones (perhaps stock HD650) I could see these being just right. A bit like LISST with smoother treble and more natural midrange. Only drawback is that they are a bit bulbous and nipple shaped compared to their European counterparts, kinda awkward to look at.

    Hopefully someone finds this helpful. What's everyone's favorite tubes so far?
     
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  18. msommers

    msommers Almost "Made"

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    Nice tube analysis! I'm thinking about moving up to the T3 or trying new tubes for the Mjo2. Some of these tubes are insanely expensive, especially in CDN dollars...

    Given the deal I got on my Mjolnir 2, and our exchange rate, it'd be a pricey move up. Lots of temptations as of a late...
     
  19. WNovizar

    WNovizar Facebook Friend

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    Sorry for quoting a slightly older post, thanks for your evaluation. I also have HD800 with Sennheiser Balanced XLR cable (I got this for 50 USD by the way), which I hope is sufficient for my cable needs (Can't ever justify going more than USD 100 for cables). As for tubes, does Siemens Halske tubes good for driving high sensitive headphones? I have Z1R, and what do you think of NOS 75' Reflektor SWGP tubes?
     
  20. colorsquid

    colorsquid Friend

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    As a Mojo 2 user, I've enjoyed some tube rolling of my own. Short of the Lyr2, the Mojo2 is probably the premier test bed for tube rolling IMHO. My '74 Reflector silver shields are still my favorites, but the hunt continues for the '75 Reflector Holy Grail. Our own atomicbob really has the definitive Schiit tube review. This is from 2015, but very relevant and spot on.

    http://www.head-fi.org/t/761078/6922-tube-review-17-top-6922-6n23p-e88cc-cca-7308-e188cc-tubes

    Edit: Linked up RB. Get well soon.
     
    Last edited: Dec 15, 2016
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