The Mjolnir 2 thread

You can find the compact for £125 new from some ebay sellers. There's also a version that's claimed to be modified for audiophiles, with a price bump and without any indication as to what those changes are

EDIT: Looks like the £125 ones are different, probably an older model. The other ones starts at £145

Furman have a couple of rackmounts that are cheaper than the compact, with many more outlets. The Mjolnir may stack on top well, it does with my DEQ2496. The links to the datasheets are down so I cannot compare them (I notified them, so hopefully they'll fix it soon). Can anyone comment on the rackmounts vs the compact?
https://www.scan.co.uk/shop/pro-audio/studio-hardware/all#filter=1&manufacturers=Furman_
http://www.furmanpower.com/products/all/component-power/classic-series-240v

EDIT: From one of the UK distributors: http://www.cuk-audio.com/uploads/files/Brochures_Furman/Furman_Catalog_2013.pdf

 

To the best of my knowledge (e.g. looking at pictures of the internals) Furman uses the same SMP/LiFT/EVP circuit in all of their products advertised with those specific features. That last part is important - if those three technologies aren't mentioned, then it isn't the same electronics providing the protection and filtering.

So, in this case the cheaper models don't appear to have the same internals as the AC210.

 

Yes, as mentioned above in a discussion of RF filters. You can also get the 220V four output Tripp-Lite Isobars in the UK, as a cheap and cheerful alternative, if you're just after RF filtering.

Not so fast there, zebra-face!

Mains iso transformers are for more than just DC offsets. They're also useful for hard-to-pin-down ground loops, which do manifest as a low hum through the outputs of a piece of equipment (as opposed to mechanical coil hum characteristic of DC offsets). This approach is particularly useful when you don't want to put anything directly in the signal path, or can't work out where the f**k the ground potential difference is happening in a chain.

In this situation, it's important to have only one item on the mains iso transformer- care should be taken. Here's a bit more blurb:

http://www.epanorama.net/newepa/2013/02/07/mains-power-isolation-for-ground-loop-solving/

It's also important to remember that if a bit of gear has a hum in its outputs, there can be a variety of causes, including problems in its power supply. It's nice to have an isolation transformer around, to allow slightly more comprehensive tests before arranging to have the suspect gear serviced.

That said, for an amp suffering a suspected ground loop, the best test is to simply disconnect everything except power and passive transducers, then slowly bring the volume up, to see if the hum is still there. Obviously, this is slightly harder to do with a typical DAC or similar.

(Edit: Not everyone needs a mains isolation transformer- probably most people don't. However, I do like to have one around.)

 

I've only just been able to find some mains plug 230v Isolation Transformers. Not entirely sure that the Edwards Audio one is actually an isolator, and not just a filter. The other three are heavy AF, and the last two are enormous and fuuuuugly.

Edwards Audio ISO1 mains isolation filter
http://www.talkelectronics.com/iso1-mains-isolation-filter/

Carroll & Meynell Single Phase Safety/Isolation Transformers:
http://uk.rs-online.com/web/p/safety-site-transformers/4368827/
http://uk.rs-online.com/web/p/safety-site-transformers/2604238/
http://uk.rs-online.com/web/p/safety-site-transformers/4368798/

 

You might like to ponder the phrase "it offers galvanic isolation" from the page you just linked.

EDIT: Though remember Mike Moffat's rant about the sloppy use of "galvanic isolation", so it's a fair question. Googling turns up lots of people calling it a transformer, mind.

(It's overpriced, and not all that powerful, but it's shiny, and if it makes a buzzing sound, you'd be quite justified in returning it, as it's marketed as a shiny audiophool toy.)

Yeah, if you can find a good industrial transformer, they're often really good bang for buck. The problem is that you don't know for sure how mechanically noisy any particular model is- if it's for non-audio use, a bit of mechanical hum is no big deal. If you can try a few, then you could end up with something really decent.

I considered borrowing one of the industrial grade transformers from work, but I couldn't easily pick any of them up one-handed. Given that I'd be coming home on a crowded train, something the size of a lunchbox that weighs that much is problematic.

 

Bring a 4-wheeled cabin bag with you to work, load up, go home ?

 

It's been around a couple of months with the MJ2.

I made some effort with the Yggdrasil and MJ2 to avoid a ground loop. They are plugged into a Furman AC215A (yea not the best value with only 2 outlets, but it's small and I have no plans to plug in anything else), and use of TOSLINK (optical so no ground), or USB via the Intona box (this thing does just one thing, galvanic isolation, no ground back to the computer that runs off a different wall socket).

Mostly I use the HiFiMan Edition X V2, and though these are not in ear headphones, with a sensitivity of ~103 dB, if there is any noise from the amp, I cannot hear it. Some reviewers felt these headphones were too polite, but that is why I keep coming back to them. Nothing in particular stands out. That planar delicacy and attack is still there, but nothing shrieks hey listen to me! Some feel Yggdrasil is on the analytical side; could be why I find it to be a very good match with these headphones.

Yes I am using tubes. In fact I still have not plugged in the LISST cans I ordered. Curious but this amp sounds good with tubes. One day, but I selected the MJ2 over Ragnarok because I wanted the tube option.

Another bit of praise for the MJ2 here (and Yggdrasil in part)... if the recordings have any intentional or unintended background hiss, pops, noise of any sort, that also comes through with clarity. Pause, and back to utter dead quiet.

I really enjoyed the Lyr 2 for almost 3 years, but the MJ2 has a brighter (without being nasty in your face) presentation. Details are revealed, and yet there is just a touch of lush richness (vs the Lyr 2's darkness) to the sound that makes it so pleasant hour after hour.

Recommend for anyone considering this option.

 

I think in a balanced setting the easiest way to ensure there is no ground loop is to ensure the grounds aren't connected in a loop. Note I do NOT mean using a ground lifting main plug, which is not safe, but rather, disconnecting pin 1 of your XLR interconnects at the male end. I have not yet found a situation where this makes the sound worse, and most of the time it seems to improve things. It might be bad if you live right next to a radio transmitter as you may get RF interference.

 

As a Gungnir Multibit/Mjo2 owner and enjoyer of a few months I wonder what the natural upgrade path might be in terms of keeping the Gungnir Multibit and upgrading the Mjo2. Would a Cavalli make a noticeable difference or would someone need to go to EC/DNA to hear a real difference?

 

My Mjolnir 2 wasn't working for quite a few minutes, even with different tubes, and I thought it may have had a blown output transformer like others have commented upon in the past. But then randomly, about four minutes after turning it on with LISST, it started working again.

???

Anyway... it's so much better with the Emotiva CMX-2 power conditioner, like a different amp than it was before. No pain, no fatigue... just lushness with a bit of sweetness and dem dynamics. Powerful and smooth. My upgrade itch is gone. Considering how it's an all-in-one that can do dynamics, planars, or whatever I may want in the future... it seems like this bit of tech could last someone many years. Definitely recommended.

Torn between the Miniwatts and WE396A tubes for king of the hill. I think the WE396A have the advantage despite the relative (but slight) lack of detail on things like piano notes because they simply make the listening experience more fun. Magical tube immersion... like the nitrous version of a Valhalla 2.

 

A quick impression of Schiit Mjolnir 2 (stock tubes):

Mjolnir 2 is one aggressive sounding amp! I don't know which is more aggressive, this or Jotunheim. Both work well with modded HD650 but I would still choose Jot, while M2 is the better amp modded HD800.

The M2 is clearly warmer and lusher than Jot. M2 has more power than Jot, but both have little to no problem powering most power-hungry cans. They would be a good choice for hard-to-drive planars, but I think I would choose M2 for neutral-to-bright Hifiman headphones. Soundstage is comparable, assuming both are driven balanced, but nothing to write home about. Compared to DNA Stratus, a TOTL tube amp, their soundstage lacked both width and depth. This was evident when using Darin Fong's OOYH and K1000.

Now, speaking of K1000, I've said that while the Stratus is a decent match with K1000, it fails to provide ample power to reach sufficient SPL for enjoyable listening with a rather significant portion of my music collection. M2, on the other hand, can drive the K1000 to ear-splitting levels with nearly every music I listen to. It still leaves some soundstage depth and finesse to be desired compared to Stratus, but if I had to choose one amp for K1000, it would be M2 for sure. Jot is okay too, but given that K1000 is a slightly bright headphone, the lushness of the M2 helps.

I'll try picking up some vintage Telefunken tubes for M2 and see where it leads me.

 

@songmic I would say the Jot's soundstage is clearly "compromised" compared to the Mjo. There's a very distinct two-dimensional window effect on the Jot that used to drive me crazy and necessitated adding a tube stage. The treble could also be piercing hot with certain cans (like the HE-400i) and tracks. The Jot is slightly crisper and blacker, but more sterile sounding in comparison (the classic tube vs SS conundrum I suppose). I hear the Mjo as more aggressive in the bottom end due to the fullness of the sound and increased bass extension and quantity, whereas the Jot is more aggressive up top.

I think at the prices used Jots have been going for it's a great value, but the Mjo 2 is overall the more enjoyable amp (IMO) because it offers tube goodness without the loss of detail or texture that usually implies. Imagine a hot day, with the sun bearing down... with the Jot you're walking through concrete city streets; hustling, squinting at times. With the Mjo, you're sitting at a sidewalk cafe and can relax a bit more to soak it all in. (With the Valhalla you're laying in the grass and there's a cooling breeze which vaguely obscures what you hear.)

 

Hmm, my tubed headamp has waaaaaaaay more inner texture than my Jot, it was the first thing I noticed when I compared the two. Not all tube amps are smeary, you know

(Happy to keep the Jot around though- for non-critical stuff like youtubage and gaming, it's sometimes better than burning tubes. It gets the job done well for the price point.)

Also, does your Mjo2 normally fail to start up when cold now, or was it just that once? If it happens a lot, it could be a bad joint/connection that is made after it heats up and expands..

 

Something about SS amps, not that I've heard them all, but I find myself needing to repeatedly turn up the volume to try and get past that sense of 'sounds dead and lifeless'. No doubt the Jot is a good SS amp, but for me, while SS amps often impress initially, give it a little time and then I can't help but feel 'this sounds sterile'.

The MJ2 is enjoyable at lower volume levels, and I even find myself turning it down at times. With tubes, it may or may not be less accurate than SS amps like the Jot, but it is a pleasure to listen to for much longer and at lower volume levels. My impression is the MJ2 has most of the benefits of SS without that final impression of 'hmm everything sounds the same, lifeless'; instead the opposite 'everything sounds good, one more song!'

 

^^^ Nailed it. If amps were 1970s drum sections, the Mjo2 would be John Bonham, Jot would be Kraftwerk, and the Val 2 would be Supertramp.

 

Furman state that their power conditioners should go directly into an outlet.

I wonder what could happen if I plug the AC215/210 into a power strip (where there's other stuff plugged into, but not too much for the outlet)? I only want to use Gungnir Multibit and MJ2 with the Furman.

 

Probably nothing so long as the power strip isn't overloaded. Besides most power strips don't do much but provide more outlets and maybe a basic surge protector.

For whatever it's worth, my AC-215a plugged into a wall socket, along with a generic power-strip plugged into the same socket. Not chained as you are pondering, but anyway...

I have a desktop fan here plugged into the power-strip, and when I turn that on, the Yggdrasil+MJ2 sound fuzzy. The AC-215a probably does provide some protection, and the Yggdrasil+MJ2 are dead quiet when nothing is playing, so no hum, not a ground loop issue, but yea, I am doubtful how good it really is at filtering noise on the AC line.

 

Considering the Furman AC210 for my Schiit Stack. Have you heard any improvement from your AC215 vs power straight a wall socket, sound quality wise?

 

I'll just get a Furman PL-8 CE, probably ordering today. Bet bang for the buck in Europe, I guess.

I don't expect to hear any difference, but who knows...

 

I'm not sure. I made two changes simultaneously. When I received the AC215, I also plugged into a different wall socket; previously the Yggdrasil+MJ2 were plugged into a power-strip with a lot other computer gear, lights, etc. So not sure which change mattered. In total it did help, though it's a minor improvement (or significant depending on how annoyed someone is by low level noise). The MJ2 is now dead quiet.

It's a nice enough device, though my main goal was to protect this end game gear.