Grimm Audio MU1 and MU2 Music Players

[FredM]

The digital front end has made a lot of progress in the last years. Besides the DIY solutions, it’s great to see innovative turnkey products hit the market. Just to name a few I guess Antipodes is long known for its DX servers and now CX+EX combo, recently Silent Angel has introduced an affordable Rhein server (~ €1.500) and -on the opposite side of the spectrum- the Taiko Audio SGM Extreme server has received the highest appraisal from users and reviewers (at €24.000, see recent reviewed at 6moons). It kinda surprises me that the Grimm MU1 server went under the radar here at AS, so -with more spare time at hand these weeks- good to share and introduce this server here.

 

Coincidence or not, in about 1.5 hour drive from Taiko Audio another Dutch high end manufacture is located: Grimm Audio. Currently mostly known for its ultra-low jitter clocks (aimed at studio’s with Guido Tent) and LS1 speaker system line up, Grimm Audio has recently launched its MU1 server (€9.800). In short the MU1 is a Roon core server with Grimms oscillators, the inhouse developed power supply, endpoint with an inhouse designed FPGA board as the magic ingredient (which converts / up- or down samples to the desired format). Like other Grimm products, the MU1 is upgradable overtime (upgrade of the existing components and placement of a internal DAC).

 

The most interesting thing for me is that the FPGA is aimed to match the outgoing digital signal with the ‘default/native’ bit depth/sample rate of the connected DAC. For me this was a new approach, only later I discovered that Auralic has a similar approach with the Sirius G2 Upsampling Processor (€ 6.300). I’m not an expert by any means so I prefer to link to an interview where Eelco Grimm gives a proper explanation (time stamp, English subs). Have I been sleeping for years, or have more servers/streamers applied this DAC matching-approach?

Quick links for a fast introduction/understanding:

MU1 Interview Eelco Grimm (English subs)
The “Pure Nyquist” filters of the MU1

Company overview Hans Beekhuyzen
Productpage and reviews (6Moon has also a review of the MU1 lined up)

 

[FredM]

Anyone reading this: Eelco Grimm wil take part in the Dynamic Range Day webcast in approx 1.5 hour. Please enjoy:

 

 

[FredM]

Besides Ian Shepperd (host) and Eelco Grimm, Bob Ludwig and Bob Katz are in the panel. Tool - Fear Inoculum has won this years award. Great discussion going on.

 

[FredM]

On 3/24/2020 at 12:00 AM, FredM said:

The most interesting thing for me is that the FPGA is aimed to match the outgoing digital signal with the ‘default/native’ bit depth/sample rate of the connected DAC. For me this was a new approach

 

As mentioned in the opening post, I was intrigued by the importance to match the source output format with the ‘native’ format of the DAC chip/module. An recent article from 6Moons goes in more detail, some snippets:

• “But when a DAC runs its own upsampler as the vast majority does but still allows you to defeat it, comparing it to the MU1's own filter can painfully reveal the resolution losses of generic on-chip upsamplers.”
• “ .. helps offload a DAC's heavy calculations when the latter converts music data from the digital into the analog domain.”
• “Throughout the listening period we switched between TotalDAC and T+A DAC 8 and each time found the TotalDAC in non-oversampling mode to be the preferred partner.”

 

Specifically regarding the Grimm MU1 server/streamer, for me it ticks all the boxes, and more. Perhaps in the Netherlands we’re spoiled, Grimm is well respected and the MU1 is reckoned as a state-of-the-art digital source (the Dutch site hifi.nl has even covered the MU1 in three in depth articles). Some other insights from the latest 6Moons review:

• "In Grimm's Eindhoven shop they spent a lot of time and effort perfecting a switching power supply which became a 2-storied affair. It is prepped for future expansions and was developed using jitter measurements on the audio clock.”
•  “The maximum sample rate for S/PDIF is 192kHz. USB supports 384kHz but eliminates a clock signal. S/PDIF's embedded clock signal meeting the MU1's superior clock is sonically far more relevant than sample rates above 192kHz!”
• “Compared to the Taiko SGM Extreme … the MU1 costs 2.5 times less, weighs 1/10th … and already stands out for its remarkably effortless listening quality.”

 

The Grimm MU1 in action, on top of a rather exclusive platform 😉

 

 

I’ve had the opportunity to listen at the MU1 on three occasions, leaving me (and others) nothing less than astonished with the impact of dynamics and accuracy and yet beautiful stress less sound (sets from €40k to well over €100k). Unfortunately it’s not my expertise to (even try) to describe a sound, I’ll just keep admiring those who can 😊.

 

For me the MU1 has all the advantages of an one box solution (synergy, in-house end to end design), without the disadvantage: upgrade flexibility. As I have no relevant electronic or software DIY skills myself, Grimm has a good track record supporting its customers with future upgrades for their products. This is very comforting in a digital area where new discoveries and improvements are a constant.

 

Oh dear.. I almost forgot, as @Nenon, @RickyV and @beautiful music have already requested, here's a link 😘

https://6moons.com/audioreview_articles/grimm/

 

[FredM]

Haha, no shares or affiliation, just intrigued. I haven’t heard the version in the 2018 XFI event, I believe it was their first prototype in public!? Sorry to hear you where underwhelmed.

 

I first encountered the MU1 at the 2019 XFI event, in the Grimm Roon (together with the LS1be’s) and in a room using Kroma speakers, Zanden amps and Mola Mola DAC. I really liked both! Later I listened at a dealer (BB&G).

 

Recently a firmware-update has been released, which apparently brought some improvements (haven’t heard this). When you live close to the Netherlands, perhaps you have a chance to listen to the current/latest version?

 

I’m keeping my fingers crossed for XFI / Dutch Audio Event this year, hopefully corona is on its return by then..

[FredM]

YMMV, personally the LS1 just stunned me, all good

[FredM]

On 4/12/2020 at 4:10 PM, nevillekapadia said:

I have a DAC with a USB input that upsamples everything to double DSD, but having trialled the Grimm 176.4 or 192 sampling via AES/EBU it will outshine the USB output due to it's FPGA card. 

 

Mixing and matching the server/streamer and DAC is growing on me. Good to see you echo the findings 6moons where they favoured the MU1 / TotalDAC D1 combination via AES/EBU without upsampling in the DAC:

 

“Throughout the listening period we switched between TotalDAC and T+A DAC 8 and each time found the TotalDAC in non-oversampling mode to be the preferred partner. “

 

With my limited technical knowledge on mixing and matching, as far as I now understand important point of attention are:

- connection type (USB, AES/EBU, I2S, ..)

- cable used for connection (connector, wire, shielding, ..)

- location and quality of the clock* and jitter level

- native ‘converter format’ of the DAC and output of the server/streamer

- upsampling and the quality of it

- ..

 

Very interesting to better understand these design subjects, but the more I read reviews or forums, the better I realise my technical insights are quite a bit under developed. I guess the list above is just a faction of the real world ‘matching criteria’. Bottom line that it’s all about synergy, and personal preferences of course.

 

* as an example, I even barely understand how this also relates to master & slave clocks and/or PLL & FLL. Way over my head I’m afraid 🙃 

 

[FredM]

On 4/16/2020 at 11:06 AM, McNulty said:

@FredM or you could wait for the MU2.

Thanks. For synergy between the steamer and the DAC, the MU2 could be interesting. In my situation I won’t need a DAC.

 

On 4/20/2020 at 3:42 PM, johnli said:

I think the MU2 is basically a MU1 with analog output

correct me if I'm wrong

cheers!

In the interview Eelco Grimm (see OP for link) gave some details on the benefits cutting of the ‘internal format converter’ in the DAC chip/module.

 

Ps. MU1 is installed at home and it’s freaking good, more later

 

[FredM]

15 hours ago, beautiful music said:

 

Did you mean you received MU1 at your home if so, looking expectantly your review soon.

Yes! 😃  Happy to share my journey and listening experience with the MU1. Please give me a day or two.

[FredM]

17 hours ago, beautiful music said:

 

😄 👌🏽

 

I'm not that hurry, take your time and give us a comprehensive review.

 

What is your previous server configuration?

 

Ps: don't forget to post some of photos as well😉.

Haha, don’t hold your breath for a comprehensive product review like @romaz, @austinpop and @Nenon occasionally share. My technical and writing skills less developed. Btw: On the Grimm site you’ll find several extensive reviews, with a little help from google translate you can read the full reviews. I’ll focus on my journey/reasoning and listening experience. 

[FredM]

Here you go, please let me share my journey/ process to decide for the MU1. In a follow up post I’ll attempt to describe the music experience with the MU1. Besides getting more familiarised with the MU1 at first, hopefully my enthusiasm is settled down (and my night sleep is also back to normal by then). Hopefully I’ve also thought of one simple word to describe the MU1, it isn’t only the qualities, there is more, hard to grab. 

 

As some of you might know, my quest for a decent digital front end started a while ago, to be combined with Harbeth speakers, Primaluna Dialogue amp, Metrum DAC in a medium sized room with some acoustic treatments. A joyful system, and very much to my liking. As part of my interest/this hobby I tracked the latest and rapidly changing front end developments. With Linn’s mantra ‘source first’ in my head, I decided the source should be the cherry on top.

 

As several source (related) products where launched: server, endpoint, OS, clock, switch, psu’s and cabling, eventually I preferred an one-box-solution. Having no technical knowledge or relevant DIY skills to build something myself, I reckon it would be difficult and time consuming to determine a good mix of devices/cabling/.. Most would become trail and error in my case. With already some devices in and on the hifi cabinet, I also wanted to avoid a plethora of source related devices/cables.

 

There where not that many servers on the market to my liking. When the hifi tailored AudioLinux software got more traction. I was eying a particular server with this kind of software onboard. Long story short: this appeared to be a dead end street, with a year waisted. Meanwhile -on the opposite side of the system- the idea of an active speaker system was growing on me. Similar to a one box source, an active speaker system is designed and tuned as one. The Grimm LS1, Dutch & Dutch 8c’s and Kii Three would be the usual suspects.

 

When hearing the D&D and Kii Three for the first time I was surprised with their performance. Later I listened at the Grimm LS1 at a Dutch audio show (XFI 2019), their statement LS1be speaker system was connected with the MU1. What an experience, like a goosebumps inductor, once 3 times during one song..! This really grabbed me. Of course I haven’t listened at all speakers in the world, although more than enough to know this was very special. A fair amount of the afternoon I just sat in the room enjoying song after song. I remember driving back home, ‘I’ve just found a gem’.

 

A while later at a dealer I had a direct comparison with the D&D 8c and two LS1 models from Grimm. The D&D and Grimm are both stunning speakers. I favoured the Grimm LS1a, where the LS1be with the dmf subwoofers in my experience where just magical. I was in love. Unexpectedly I was able to go ‘all in’ and sold my complete system and bought the LS1be’s. As much I liked my previous system, I never looked back. The LS1’s simply play in another league.

 

Regarding the source I still was at square one. Oddly the MU1 wasn’t on my radar at first. In fast forward I went thru a similar thought process as before, pondering about separates vs an one-box-solution. I even thought of building my own server. I did some research on fanless cases, motherboards, RAM, cabling, psu, internal cards/bridge, etc. Where I have utmost respect for those who are skilled and have the time to discover and create servers themselves and share their insights online (which I enjoy reading, many thanks @seeteeyou, @austinpop, @bobfa, @romaz, @Nenon and many more!), I reckoned a turnkey solution would be more appropriate for me. 

 

As the MU1 was well received in the Dutch hifi press I realised the answer could be right under my nose, with the additional advantage that speaker and source will match excellent. Then, the more I read about the MU1, the more fascinated I got, hence this topic. Not looking on Grimm MU1’s sound quality, there are some other aspects which I find appealing and are perhaps worth mentioning:

• The design approach, as first mentioned in the OP the importance of matching the format of the source with the ‘native’ format of the DAC. Also walk the talk by choosing for S/PDIF via AES/EBU as the single digital output which carries the clock (quite daring as USB is most commonly used for consumer products).
• Custom end-2-end design and build, only the NUC and (optional) SSD are of the shelve components. i.e. the psu of the MU1 is developed by jitter measuring at the clock. Track record developing oscillators (Guido Tent, Tentlabs), like a server build by jitter experts.
• Deep understanding how ‘music works’, with Eelco Grimm being a front runner for Loudness Normalisation (ie analysing more then 4 million albums on Loudness, which recommendations are implemented by Tidal)
• As with other Grimm products, the MU1 isn’t just buying a server/streamer. Upgrade possibilities will appear, making the MU1 a future proof investment. Sure it’s a lot of money, but with good value imho. The MU2 is already announced (MU1 with internal DAC). Grimm is also working on custom playback software, as a free alternative for Roon which will deliver a higher sound quality.
• It took the Grimm team of experts (with Eelco and Guido also being university lecturers) about 4-5 years to develop the MU1. No way I will be able to match that with source (related) devices, where I mix and match products myself.

 

So far my personal ‘journey post’, I hope it was interesting and perhaps useful for some. As I’ve enjoyed reading about the process and discoveries of others online, nice to share something in return. 

 

 

 

Oh, @beautiful music, here’s a nice picture, as requested 😋

[FredM]

28 minutes ago, RickyV said:

Excellent Fred, I think you made all the right choices, fantastic system.

 

What is the size of your audio room?

Happy listening 👂 

 

Thanks Ricky, it’s a dedicated listening room, 4x5,2m (approx 13x17 feet), with side and front wall panels and bass traps in the front corners.

[FredM]

Can't edit the opening post, here's another MU1 interview. Eelco Grimm and Guido Tent give some details on developing the MU1 (some go over my head), followed with a review by Jason Kennedy from The Ear.

[FredM]

Update: now that the MU1 is settled in, it’s time to share my listening journey with the Grimm Audio MU1. As mentioned earlier, please don’t expect a professional like write up where several hifi components are compared and carefully described with a rich hifi/ audiophile vocabulary. Even after about two months of listening I couldn’t catch the MU1 in an one word summary. There is more to it, which I’ll explain later. 

 

To share my personal thoughts with you, this ‘listening journey’ update has three perspectives. Please let me start with the first, and most important:

 

 

Objective listening experience 

 

Here’s a chart on how the MU1 objectively sounds:

 

This is probably the most fact based experience I can share with you*. The items on the bottom represent the listening sessions, the value per bar displays the number of goosebumps per session. I’ve never experienced this before, it’s great to have such an (emotional) connection with the music. With the MU1 I’m not listening technical and dissect a song, it’s about the joy of listening, where my foot starts tapping, etc. (*Disclaimer: I’m not a person with a notebook and pencil at hand during listening sessions, I would say it touches five on an average evening).

 

So perhaps the MU1 can best be described as a goosebump inductor, or as a pleasurability generator: “Canadian researchers have suggested that when humans are moved by music their brains behave as if reacting to delicious food, psychoactive drug, or money. The pleasure experience is driven by the chemical dopamine, which produces physical effects known as "chills" that cause changes in heart rate, breathing, temperature and the skin's electrical conductance. The responses correlate with the degree to which people rate the "pleasurability" of music. Dopamine release is greatest when listeners had a strong emotional response to music. "If music-induced emotional states can lead to dopamine release, as our findings indicate, it may begin to explain why musical experiences are so valued,” wrote the scientists.”

 

 

Listening impressions 

 

What impresses most during the first weeks is the lack of listening fatigue. Three, four, five hours without a problem, no limit. Great to listen song after song, album after album. Or just sit back and let Roon serve its picks and discover new tunes. This effortless comes with a warning, it’s addictive. Thanks to separated listening room (with no mrs M. around) listening till 2.00-3.00 AM is no exception, like having a candy shop at home.

 

New for me, the volume also doesn’t seem to trigger listening fatigue. Delicately soft or screaming loud with striking dynamics: it’s all good, where the volume slider in Roon is very convenient to simply adjust things on the fly (with peace in mind, thanks to a ‘comfort limit’ setting). When listening at low levels, there is still a sharp picture, details and image remain. I mostly listen at folk/vocal, jazz, electronic and pop/rock btw.

 

What could be a down side for some: great recordings sound great, exceptional recordings sound exceptional and lesser quality recordings show there shortcomings. I have the impression that the MU1 doesn’t overemphasis. Replay is transparent and honest, it’s fast with lots of details (with for example the beautiful gradually dying of a piano tone or the tip of a drumstick hitting a cymbal) but not in an overemphasised / in your face way.

 

Most difficult to describe is the ‘flow’ of the music, I don’t know if this is related with the LS1be also in play. I’ll try to explain what I mean with ‘flow’ in an other context: It like riding a rocking horse on a carousel. When sitting on a rocking horse (normal listening) is very entertaining, the extra joy (flow) is created by the carousel, where al individual pieces (instruments) seem to move in same direction, and each have their own character next to you: moving up and down, sideways and with their own pace on the carousel platform: All instruments towards the same direction, being surrounded and sucked into the music. I hope this makes any sense, please excuse me, I couldn’t think of an easier way to describe it. At least you now know the limitations of my writing skills 🙂

 

 

Relaxed listening 

 

Also worth mentioning is the impact on the hobby. After adding the MU1 in the set, it seems everything falls into place. I still occasionally read about hifi news and developments, but in a more distanced way. 

 

Despite knowing there are some (potential) upgrade possibilities, the ‘upgrade bug’ has left the building. With power cables, network input and perhaps vibration as the usual upgrade suspects, I don’t feel a desire to improve in a specific area (I’m currently using a white Walmart power strip, go figure). The chain seems very well balanced. Endgame? Yes. 

 

Who knows what the future brings. If I would change things, I reckon it’ll most likely be driven out of curiosity (not from a desire to improve or fix certain area’s). It’s also a comforting thought that Grimm has a reputation for offering upgrades on existing products, so why pursue upgrades: Better to relax and enjoy the music. A big thumbs up for the Grimm team, a stellar performance!

[FredM]

5 minutes ago, Kal Rubinson said:

How did you count the goosebumps?  Were your eyes closed?

Haha, I don’t know, both I think. Are you suggesting A/B comparison sessions, blind? Oh wait.. uhm.. 😁

[FredM]

On 5/14/2020 at 11:16 PM, FredM said:

Can't edit the opening post, here's another MU1 interview. Eelco Grimm and Guido Tent give some details on developing the MU1 (some go over my head), followed with a review by Jason Kennedy from The Ear.

 

 

Apparently the link has been changed, hope this one sticks:

 

[FredM]

9 minutes ago, RickyV said:

good review, Fred 😀. In a funny way I understand what you mean. Especially the description of flow of the music is brilliant . 👍

 

 

Thanks!

 

 

[FredM]

7 hours ago, Kal Rubinson said:

You did say "objectively."🙄

I understand, please don’t take it too serious, consider it as an alternative to share/indicate my listening experience (which is personal, etc). As we all know how it’s feels when we’re touched by music.
 

It’s even possible to move towards a more scientific approach to measure the (emotional) effect/connection if you want, I just found this goosebump sensor 🙃 (But please in an other topic, not keen to open a can of worms). 

[FredM]

15 hours ago, HeeBroG said:

Hi Fred,

 

Thanks for sharing your experience.

 

Can I ask why you use Roon volume control instead of that on your preamp?

 

Surely there is some loss in transparency using the software volume control.

 

Geoff

Hi Geoff,

I understand your question, I’ll try to answer. Please let me start saying that in case the MU1 is used in combination with a Grimm LS1 speaker system ( =my situation), the MU1 acts as the ‘pre-amp’. There is a proprietary connection, carrying both audio data and control data between MU1 and LS1’s  (I won’t go in detail how the LS1 work. On the Grimm’s site you can find a white paper with schematics etc and much more in depth information).

 

In addition to the proprietary LS1 output, the MU1 has two other outputs to connect a (3th party) DAC with. One of them can also output a volume controlled signal to the DAC. One of those might be suited for you.

 

I remember that in an interview Eelco Grimm has explained the design of the MU1 volume control. I believe the volume setting/calculation is done on the FPGA board and that it would be very difficult to hear a difference, if any compared with a external pre-amp/volume control. So with the Roon app you’re controlling the FPGA board directly, not Roon’s volume calculations. (I did have a quick look for you, but couldn’t find the specific fragment of the interview.)

 

The disc on top of the MU1 also acts as the volume control (I rarely use it, as the MU1 sits in a cabinet), I very much like the convenience of the app, everything at the touch of my fingers. 

 

In my experience I don’t notice a degree of anything using the MU1 to control the volume and very much fancy the convenience. I haven’t compared with a top notch external pre-amp/volume control device in between. I love the simplicity with the MU1.

 

Cheers, Fred

[FredM]

Nice Grimm Audio company overview by Alpha Audio. In this extended interview (1h50!) various topics are covered, like company history, background of Eelco Grimm and Guido Tent (both lecturers), what’s drives them, design philosophy, network company, new products, ..

 

On the MU1 the power supply, clock circuitry, jitter treatment, importance of up scaling via the FPGA board and the in-house software development are mentioned. 

 

https://www.youtube.com/watch?time_continue=2&v=6YPznUzSRB0&feature=emb_logo

 

The interview is in English (after ~30 seconds), for quick access you can use the timestamps in the description on Youtube.

 

[FredM]

34 minutes ago, TheAttorney said:

as the Extreme and (to a lesser extent) the Statement are too big and heavy for my downsizing aspirations.

Hi, given your size / decluttering preference, have you considered other options? (Antipodes, Pinkfaun,..?) If not, a straightforward route is to ask for a home audition directly. At home you can also better experience the effortlessness play of the MU1.

[FredM]

4 hours ago, matthias said:

 

I followed the discussion about the subpar Roon SQ after a certain release on the Roon community forum and the Taiko Audio thread on WBF and must say the Roon people are quite arrogant, I dislike Roon.

 

Matt

Personally I just love Roon, great experience and easy to have everything at the touch of my finger: Discovering new music with Roon radio, easy volume control, etc.. If Roon would impact SQ a bit (which I haven’t noticed with the MU1), I guess it would be okay given all benefits of Roon. Earlier you mentioned that you don’t fancy a product that is bound to Roon. Well, perhaps this approach is an advantage to create an optimised package.

 

Off topic: I’m actually kinda surprised that on the WBF thread Taiko owners report such an apparently big decrease in SQ with Roon (two recent: “Roon is barely listenable..” and “absolutely horrible..”). There could be a degradation using Roon, but I haven’t seen such extreme comments elsewhere. So perhaps it’s related for a specific combination of used hard- and software. Nice to read the users are happy with TAS btw, so all good.

 

@TheAttorneyWith the recent firmware update up- and down sampling to 2FS is now supported, this matches the AES input of your DAC (also both AES outputs are volume controlled since the last firmware)

[FredM]

19 minutes ago, matthias said:

 

Not for me, I appreciate the efforts of Taiko Audio to get rid of Roon and to get the best sounding SW.

SW has a similar or even greater impact on SQ as HW.

 

Matt

Everybody has their own preferences, all good

 

34 minutes ago, beautiful music said:

 

Is this firmware related to MU1 or to Roon?

Ah sorry, I was talking about the MU1 firmware

https://www.grimmaudio.com/news/new-firmware-for-mu1/

 

 

[FredM]

2 hours ago, TheAttorney said:

I've only just realised the significance of this.

My DAVE AES input's limit is 96kHz. And I've just checked that my M-Scaler doesn't even have an AES input!

Which severely restricts the options I have with MU1's AES output.

 

The proof of the pudding will be in the hearing, but these limitations (not particularly MU1's fault) mean that I may not get the full potential of the MU1 with my Chord equipment, so may need a Plan B sooner than I had expected ☹️.

 

 

In this fragment you can find an explanation what the FPGA does, and why AES-out is chosen. I don’t know how AES-96 will pair with the DAVE DAC. Indeed, the proof of the pudding is in the hearing 😀

 

 

56 minutes ago, lmitche said:

Greater, for sure.

Somehow I was quoted without typing the message 😁😁😁

 

[FredM]

Indeed, synergy is key.
From specs only it’s hard to predict, it’ll depend.

The proof of the pudding is..