Pimping The Schiit Out of The Mjolnir 2 - Tubes & Power Conditioners

My original reasoning for buying a Mjolnir 2 was it’s versatility in powering any kind of headphone, be it high impedance, low sensitivty, or incredibly efficient. Along with it’s reported competitiveness with amplifiers worth twice as much, lack of major weaknesses, and ability to try out vacuum tubes as well as solid state. Eventually I went about reading through the Mjolnir 2 thread, and later the one on power conditioning, to see how much further I could take it. I’m yet to have the opportunity to compare it to other high-end amps, and would like to see other peoples comparisons if they have. Everything written is with stock as the baseline, and a 20 minute warm up before each tube swap.

Chain
Tidal -> Audio Hijack & TDRNova -> Modi Multibit USB -> Mjolnir 2 -> TH900/HD650/HD800

Terminology
Micro-detail - Plankton, low level information
Macro-detail - Overall detail, resolution
Micro-dynamics - Small gradations of volume, like reverberations
Compression - Total range of volume, or lack thereof
Slam/Impact - How hard bass hits, how much air pressure you feel on your ear drum.
Clarity - Lack of veil, purity
Speed - Separation, clearly defined individual sounds, how well you can hear each individual string in the strum of a guitar
Texture - The detail within individual sounds
Tactility - Solidity of presentation, tangible feel
Ethereal - Ghostly nature of presentation, low density
Air - High frequency ambience/presence
Closed-in - Lack of air, high range treble cut-off
"Magical" - Defies expectation in a pretty way, vague random nonsense buzzword, self-endulgent twattery, don't trust anyone who uses it



Power Conditioning
230v version used in a 140+ year old house in London, UK.

Given that this was my first experience with a high end amplifier I was a little bemused by how much the chassis vibrated around the transformers. This increasingly appeared as though it was due to mains power quality issues. So that was the original motivation to try out some power conditioning. The DC blocker especially reduced vibration, but not entirely. I expected little to no audio performance gain, but expectations are meant to be broken. Caveat Emptor, any improvement you may hear will be entirely dependant on your mains quality so it's very much a case of YMMV. You may even find that it makes things worse overall.

Primarily done with Stock Tubes, with a little Western Electric 396a time to confirm my impressions.

I used two short run C14 cables to chain everything together.

DC Blocker
Purchased from ATL Hifi with C14 input and output. Very helpful customer service
http://www.atlhifi.com/shop/fully-assembled-devices/dc-blocker-trap-filter-assembled-in-case/

My immediate reaction was to the bass, it was tighter, and more impactful by a healthy amount. Every aspect had improved. Particularly in speed which has a profound effect on layering of soundstage and the crunch of a guitar. I also heard notable improvement in micro-dynamics and micro-detail.

Outside of technical performance the soundstage had tightened up and everything gained a lot more physicality and engagement. Vocals took on a clearer sweeter quality as well. Removing the DC blocker from the chain the sound went back to it’s soft floaty brittle character.

I didn’t know it yet but I’d gotten my first taste of texture.

RFI/EMI Filter (in chain after the DC Blocker)
http://www.furmanpower.com/product/10a-two-outlet-power-conditioner-export-AC-210A E

Texture, texture everywhere. Music felt different, the amazing increase in purity and clean sound had revealed all the nuance within each individual sound. The burrr of electronica bass, vocal coarseness and the subtle changes in pitch, and the flow and rhythm of guitars. This brought out more of the emotion, it was like using candles at night instead of a lamp, it revealed the mood.

This jump in clarity along with an increase in speed seriously brought out everything that was not in the foreground. Not only was all this background and ambient audio brought forward but I was also hearing it with all the nuance I was now hearing in the foreground. It lit the corners of the room, and brought them level with everything else. Soundstage also increased in size a little.

Continued Listening & Swapping The Power Chain Order
First I removed the DC blocker entirely and the result was as expected based on the impressions above, the end result being worse with only one in the chain but reflecting the differences noted above. Then I put the DC blocker after RFI/EMI filter and went back and forth a few times. What I found was that whichever unit was first in the chain had the more significant impact on sound quality changes.

Swapping them back I found things overall clearer, more alive, and more engaging. The vocals a little smoothed and softened.

The touch of veil over the vocals were noticeable when comparing, but I stopped noticing it after a day or two, and with the tube upgrades it wasn’t something I’ve thought about until I just looked at my notes. It was due to the DC Blocker. The benefits outweighed the cons here, YMMV.

Since then I have kept the DC Blocker first, and the RFI/EMI Filter second. This easily produced the best results. I’ve had no temptation to tweak or play around.



Vacuum Tubes
This is less about the individual tubes and more to see what tubes might do for you, and the sorts of differences one might expect between them.

Each of the NOS vacuum tubes were up to 2.5x better in most areas of technical performance vs stock, depending on what headphone I used. There generally wasn't a lot between them performance-wise, the major differences were really in character and presentation. So don’t go crazy, the amp is the amp. Tubes will only do so much. Particularly, I presume, in a hybrid.

Socket Savers
Seller: xulingmrs
“2pc B9A Gold plated tube tester saver for 6CG7 EL84 12AX7 ECC83 12AU7 6BQ5 ECL86”
http://www.ebay.co.uk/itm/2pc-B9A-Gold-plated-tube-tester-saver-for-6CG7-EL84-12AX7-ECC83-12AU7-6BQ5-ECL86/191550535290?ssPageName=STRK:MEBIDX:IT&_trksid=p2057872.m2749.l2649

Adapters
Seller: xulingmrs
“2pc Gold plated 5670 6n3 WE396A TO ECC88 6922 6DJ8 tube adapter for you amp”
http://www.ebay.co.uk/itm/2pc-Gold-plated-5670-6n3-WE396A-TO-ECC88-6922-6DJ8-tube-adapter-for-you-amp/191636111735?ssPageName=STRK:MEBIDX:IT&_trksid=p2057872.m2749.l2649

LISST - Schiit Solid State “Tubes”
LISST possesses more clarity, is comparatively un-colored, gives a more tactile sound, slams harder, with tighter bass. They’re also super-duper compressed sounding in a variety of ways. Micro-dynamics have been stripped out of existence. Micro-detail is there but it just doesn't stand up and make itself known. The mids are irritatingly blurred, separation is a bit of a cludge, and stage width is smaller. Macro-detail of everything not at the forefront just falls to the background in a mild haze. All the nuance is lost, there's no space between sounds. Decay, reverb, air, volume gradations all get squashed out. And there’s a wonderful sweetness about the high frequencies with the stock tubes that you just loose.

LISST's higher noise floor really picks up a lot of hiss and noise if you're using sensitive headphones on high gain. This is due to the high voltage for the vacuum tubes not being ideal for solid state components.

Power conditioning may have alleviated the mid range blur, I had to ship them off to a buyer the next day so wasn’t able to spend enough time with them to confirm this.

Western Electric 396a
Much tighter bass, more like LISST. Around 1.5-2.5x improvements in micro-dynamics, speed, micro-detail. Upper mid/lower treble glare made them really unpleasant in most cases. Cooler, not particularly engaging compared to stock, closed-in sounding/lacks air. Deep soundstage, also results in small/distant mids. Clearest out of real tubes. Thinner presentation than others.

With the HD800 specifically I found them more engaging, with a more cohesive staging, tighter bass, and all around much improved performance. The harsh upper mids weren't really evident with these headphones.

This pair need adapters, info above.

Telefunken E188cc
Best speed and micro-dynamics. Magical soundstage that gives you a little depth whilst also making the vocals image bigger, with good texture. Tighter bass vs stock, a little behind the other tubes. Darker tonality. Hazy as all hell.

These had the most profound effect on the HD800 bringing the mids more forward and creating a more cohesive soundstage. They made them almost tolerable, shame about the haze

Ahead of the others on technicals but not by much at all, hazy nature seriously takes away from it.

Did I mention the haze?

Siemens Halske CCa (Late 50s)
When first hearing them I was somewhat non-plussed, I was reminded of solid state’s straight clean presentation. Only they had all the benefits of tubes too. They really do nothing wrong, and have that rare quality of being unexceptionally exceptional. They don’t bring attention to one particular trait, but with time they show how capable they are in all areas. They were the cleanest and most engaging, having much more solidity in their presentation. Utterly real and engaging, with an incredible purity of sound producing gorgeous textured vocals. A nice touch of smoothness, which brings the technicals slightly behind the other two. Nice tight bass. Not much if any depth, and a little bright.

The character of this pair is incredibly engaging and just so vibrant. It reminds me of listening to the Sennheiser HE-1, tonality aside.



Everything Else

A Note on Headphones
Most of this was half or a third as relevant for the HD650, the TH900 with equalisation (and later pad mod/change) I have found to be the most revealing character-wise of upstream gear due to it’s physicality, clarity, and engaging nature. Whereas with the HD800 it was their general technical performance, and HD650 the micro-dynamics, which were out of this world with the upgrades.

Buying Tubes
eBay is relatively useless. Pretty much every “NOS” tube I looked at really didn’t look like new-old-stock to me. The pins were always bent or out of alignment with one another. Pins showed teeth marks, many with residue on them. This was how it appeared to an amateur anyway, I invite those with more experience to suggest buyer tips so that I can add them here.

To get you started there's a list of reputable vendors that @Setzz put together.
https://www.superbestaudiofriends.org/index.php?threads/list-of-tube-vendors.2750/

Balanced vs Single-ended Outputs
The SE outputs are all summed. I’ve found that the SE headphone output to be dulled and smooths over everything, putting out much less power. It’s a balanced amp by nature, I avoid them.

http://schiit.com/public/upload/PDF/mjolnir_2_manual_1_0.pdf
“Mjolnir 2 is an inherently balanced amplifer. Do NOT use any balanced-to-single-ended converters on the balanced headphone OR preamp outputs. That’s what the single- ended summed outputs are for.”

High vs Low Gain
According to @schiit's book the low gain setting on all their amps barring the Rag appears to be implemented by increasing negative feedback. My impression was that micro-dynamics and micro-detail suffered, enough for me to avoid it even if I had to put up with background noise as with LISST on efficient headphones like the TH900. If you're using vacuum tubes in the same scenario, that aren't creating noise of their own, then the background noise is minimal.

Schiit Happened by Jason Stoddard
Chapter 27: Twilight of the Gods—Ragnarok from 2009 Until Today
"As far as I know, Ragnarok is the only gain-switchable amp that uses the same overall feedback for all gain levels—which means that the sonic impact of switching gain is effectively nil."

Chapter 39: Unto the Second Generation
"Then it was time for the eeevil feedback. Yes, again. Lyr 2, like Valhalla 2, uses some feedback even at high gain, and more at low gain. The reason is also the same: because it sounds better. As with Valhalla 2, Lyr 2 is an inherently very linear circuit, so low amounts of feedback don’t result in appreciable re-entrant distortion."

Creaking & Popping Chassis
With mine an hour or so after switch off and once it has cooled down starts to intermittently creak and pop with a quiet snap. It settles down after awhile. Doesn't seem to be common but a few people have experienced it.

Mjolnir 3?
Make of this what you will.
@baldr aka Mike Moffat, January 10th 2017.
https://www.head-fi.org/threads/schiit-mjolnir-2-listening-impressions.778250/page-108#post-13159851
“At Schiit, Jason does almost all of the amp design (except Mani), and I do all of the digital design. All I will say is the following - I love my Mule2 - it works very well with all of our digital gear. Also, there are no current projects under development to improve, upgrade, or replace the Mule2. As for the future - Who knows? - I am sure that Jason will get to it when it is time.”



Conclusion
It’s worth trying power conditioners in your home to see if they are helpful to your setup, there’s potential for significant improvement and they’re much simpler to deal with than tubes. With tubes you’re gonna need patience but you can certainly release more of the Mjolnir’s performance with them, but keep in mind that after a certain point it’s about character and presentation. A good one to start with seems to be the GE or JAN 5670 Tube, the uprated 5-Star version is reportedly better but not by much, and 4x the price.

Thanks to everyone in the Mjolnir 2 thread, and the wider SBAF community.



Follow Ups

Focal Utopia
To be written upon further listening (As of now the CCa were not up to the taskt and have been removed. The WE396a have been inserted and are providing the clearest sound, much like solid state, with the dynamic advantages of tubes. The upper mid glare is not evident with the Utopia, though I am now 100+ year old house in another part of London, so there's a possibility of it being power related).



Moderator Mercy
Please direct general discussion to the Mjolnir 2, Tube Rolling, and Power Conditioner threads. Please keep discussion here to questions, corrections, suggestions, comparative experiences, insults, and copious amounts of flattery.
http://www.superbestaudiofriends.org/index.php?threads/the-mjolnir-2-thread.208/
http://www.superbestaudiofriends.or...ration-surge-protectors-ups-yadayadayada.282/
http://superbestaudiofriends.org/index.php?threads/i-hate-tube-rolling-but-lets-discuss-tubes.801/

EDITS
05/08/17 Various nips and tucks.
06/08/17 Added entry on chassis noises. Some touch ups.
07/08/17 Corrected some errors in the WE396a entry.
08/08/17 Added "Magical" into terminology..., LISST noise addition, Gain setting entry

 

Good work, thanks! It's interesting, I couldn't get the ATL DC blocker to sound acceptable anywhere in my audio chain. There is a palpable, like "something's wrong" degree, drop off in dynamics. It does seem to fix up sibilance but mainly by making everything sound like it's a filtered through a sock. I can only handle a few minutes before I have to take it out.

Given the chassis still vibrates you could try some vibration control. Just a few hundred grams mass on the chassis top could make a difference. Consider the Herbie's stuff too. Rx tube dampers and/or 3x tenderfeet. I hesitate to recommend this as it is real last 5% stuff but it sounds like you have everything else tuned up enough to notice any effect. It can take an edge off the top end and/or clean up the bass a bit. YMMV etc.

 

Good to hear that even the Mjonlir benefits from using tubes other than stock, I've almost always found that the stock tubes are never the best. There is almost always an upgrade that improves the sound for your system, and even in the US power conditioners go a long way! I've had one since 2014.

Did you notice any difference with and without the socket savers? Or were they more for convenience,

 

@BenjaminBore - in your opinion, what are the best tubes for the Mjolnir 2 ?

 

Nice to see the 1950s CCa in action, well written post as well ! The best tube pair I've ever heard in Mjolnir2.

 

@Mshenay Nah, they're just to save wear on the amp's sockets. Didn't compare.

Thanks @Garns . My original concern about the vibration was really just for it's dependability. Glad I gave it a try, I was warned about a year ago that that stuff may not be entirely positive for sound quality. I'll have to re-assess every time I move, I guess. Oooo, dangerous waters there. I might look into it once the project is complete and have a Gungnir Multibit, if I can ever find one.

@Changeling Thanks. I am tempted by the rest of your CCa tubes, actually. I mean they're no good for anything of course, and no one should even consider buying them. The post could have done with more work but I needed to get it out now before things got busy again, I'd been nipping at it for a month now.

@The Alchemist CCa all the way. But I wouldn't go to that cost for the HD650, not worth it. The CCa tubes take the cost right into TOTL price territory. I'd really like to know how the combination compares to the Ragnarok and the EC and DNA stuff, though.

 

@BenjaminBore WE396a's good for HD800's? And can you give me a link to a good pair? I already have the link to the sockets on eBay you posted

 

I'm selling two great pairs buddy.

 

I forgot I already have a pair I bought from you, I meant the WE396a

 

Weren't those E88CCs?

 

actually I think they were

Edit:

Yes you are correct, they are E88CC

 

Yes, better than stock tubes. With a standard HD800 I found them more engaging, with a more cohesive stage, tighter bass, and all around much improved performance. The harsh upper mids weren't really evident with these headphones.

I got mine from @Changeling and they were in terrific shape, and he got them from here: http://www.mcshanedesign.net/tubes.htm


EDIT: Made a few corrections in the entry for the WE396a tubes.

 

Yeah @Changeling is awesome with tubes, he knows his stuff and offers great prices.

 

You know where to find the tube slut

 

@BenjaminBore, thank you for putting together a complete and honest review of the Mjolnir 2 and its strengths and weaknesses.
I think this should be pinned to the top for the Mjolnir 2 thread as well as @Changeling's MJ2 HD800 tube write-up.

It is well-written and I hope, if you keep your MJ2, you will write more as you expand your system (especially with Gungnir Multibit as you mentioned above). I used to have a Modi Multibit, but never heard it on the MJ2, only with Jotunheim. I use a Gungnir Multibit, and I wonder if some of your perceptions about the WE396a (closed-in feeling) and LISST (the mids, decay and reverb) are influenced by the sound of ModiMB? I think as Changeling mentioned somewhere that this amp is a great holding place before jumping up to EC or DNA level. I wonder about spending $250 on a pair of tubes to roll in is a wise investment for this amp no matter the headphones. I think you wisely point out that it is not wise if you are only using HD-6X0 series. I have a TH-X00 and feel the LISST is a better match for them.

Again, I greatly appreciate the time and effort you put into this write-up. Excellent work!

 

+1 @BenjaminBore

 

Thank you, I appreciate it. In terms of the value proposition it entirely depends on the tube and the headphone. If you're in TOTL territory then, based on my limited experience above, I'd definitely say it's worth it. Especially if you can get a CCa for $250!


EDIT: Added "Magical" into terminology..., LISST noise addition, Gain setting entry