Grimm Audio MU1 and MU2 Music Players

[PavelDosko]

3 hours ago, PYP said:

I had to power down the MU1 today (usually it is on 24/7).  When I rebooted, the sound was slightly richer.  I've experienced this previously, but this time it was very obvious.   After a few hours, the sound is truly exceptional.  

 

Anyone else heard this change after powering down?  I have read that some users of another streamer do regular reboots to maintain best sound.  

do you have the power supply treated in some way?

[skatbelt]

6 hours ago, fas42 said:

 

Interesting observation. I had this behaviour with my first CD player + power amp + speakers combo, decades ago. But in my case the effect was quite severe - chalk and cheese territory.

 

What's going on? I have never found a definitive answer, but my suspicions lie very strongly with some type of static buildup - somewhere in the chain. Causing an electrical operating point, somewhere, to be no longer at optimum. Powering down and then up again resets all the operating points - and the status of that key point in the component then very slowly starts to degrade, once again.

 

If I come across a system that sounds good at one time, but not so good at another time, that's one of the first things that I check ... does a power reset alter the SQ significantly? Experiment until a clear pattern of the behaviour is established - and then try to close in on the actual culprit.

 

 

Could it be 'parasitic' interwinding / inductive capacitance in transformer circuits? I have the same feeling of sound change (for the better) after a power down / up of mains power to the isolation transformer in my system.

[PYP]

2 hours ago, skatbelt said:

 

Could it be 'parasitic' interwinding / inductive capacitance in transformer circuits? I have the same feeling of sound change (for the better) after a power down / up of mains power to the isolation transformer in my system.

I prefer not to speculate since I don't have the technical knowledge needed.  I'm just curious.  The MU1 sounds great all the time.  In fact, I have tried it with a modest DAC and the result was very, very good.  This convinced me that for musical enjoyment, the MU1 is the foundation of my setup.  

[PYP]

6 hours ago, PavelDosko said:

do you have the power supply treated in some way?

the MU1 is plugged into a Shunyata power distributor (as is all my gear).  

[fas42]

10 hours ago, skatbelt said:

 

Could it be 'parasitic' interwinding / inductive capacitance in transformer circuits? I have the same feeling of sound change (for the better) after a power down / up of mains power to the isolation transformer in my system.

 

Parasitics anywhere could be an underlying cause of a charge buildup. But if the capacitance was allowing some high frequency noise to pass into critical circuitry, then some type of rectifying, or diode action needs to occur, somewhere, which allows an unwanted voltage offset to slowly build, and degrade SQ. The power cycling gives time for that voltage to drop back to zero, and quality is restored.

[TheAttorney]

On 3/16/2023 at 4:41 AM, PYP said:

I had to power down the MU1 today (usually it is on 24/7).  When I rebooted, the sound was slightly richer.....

 

When I first read this, I made the assumption that your "24/7" means that you don't regularly put your MU1 into standby, which means that the operating system and roon don't get regularly rebooted, which means that any s/w-related cobwebs don't get cleared away (e.g. gradual memory leakage). I don't know for sure if there are any s/w cobwebs that impact SQ, but some people have claimed so in the past.

 

Primarily for energy conservation reasons, both my MU1 and DAVE are put into standby every night, so any possible s/w cobwebs get regularly cleared out. I therefore wasn't sure if a full power down would make a difference, but last night I gave it a try, as follows:

 

System: Audience TSSOX (capacitor-based passive mains conditioner) feeding both MU1 and DAVE, to headphones. Currently no special grounding solutions used.

 

Normal routine: MU1 and DAVE on standby overnight > Activated early afternoon > Serious listening late evening (8-ish hours later).

 

Test routine: In late morning, power down the conditioner for several minutes (didn't time it, but guess around 15 mins). Then back to standby and normal routine.

 

Result: Well, I wasn't expecting much, but the sound did seem a bit "richer". I first noticed more bass, then a slightly more full-bodied presentation without any loss of detail.  As if some digital glare had been removed that I didn't know I had. Not night-and-day, but nice.

 

It could have been placebo and it's not possible to do a quick A/B/A test to confirm, So it's not definitive by any means. But based on this result, I think this idea does merit further investigation. In particular...

 

How long to shut down? (Some audiophiles claim long power downs result in extra long warm up times, or a re-burnin).

How frequently should this be done before SQ degrades again? Every day/week/month? Frequent power cycles are generally not good for long-term reliability.

 

I suspect that powering down everything including the conditioner (stuffed full of capacitors) would have exaggerated any effect of this phenomenon. Whatever, I don't recall my system ever sounding better than it did last night, so I'll repeat the test after a week or so.

 

[PYP]

2 hours ago, TheAttorney said:

 

When I first read this, I made the assumption that your "24/7" means that you don't regularly put your MU1 into standby, which means that the operating system and roon don't get regularly rebooted, which means that any s/w-related cobwebs don't get cleared away (e.g. gradual memory leakage). I don't know for sure if there are any s/w cobwebs that impact SQ, but some people have claimed so in the past.

 

Primarily for energy conservation reasons, both my MU1 and DAVE are put into standby every night, so any possible s/w cobwebs get regularly cleared out. I therefore wasn't sure if a full power down would make a difference, but last night I gave it a try, as follows:

 

System: Audience TSSOX (capacitor-based passive mains conditioner) feeding both MU1 and DAVE, to headphones. Currently no special grounding solutions used.

 

Normal routine: MU1 and DAVE on standby overnight > Activated early afternoon > Serious listening late evening (8-ish hours later).

 

Test routine: In late morning, power down the conditioner for several minutes (didn't time it, but guess around 15 mins). Then back to standby and normal routine.

 

Result: Well, I wasn't expecting much, but the sound did seem a bit "richer". I first noticed more bass, then a slightly more full-bodied presentation without any loss of detail.  As if some digital glare had been removed that I didn't know I had. Not night-and-day, but nice.

 

It could have been placebo and it's not possible to do a quick A/B/A test to confirm, So it's not definitive by any means. But based on this result, I think this idea does merit further investigation. In particular...

 

How long to shut down? (Some audiophiles claim long power downs result in extra long warm up times, or a re-burnin).

How frequently should this be done before SQ degrades again? Every day/week/month? Frequent power cycles are generally not good for long-term reliability.

 

I suspect that powering down everything including the conditioner (stuffed full of capacitors) would have exaggerated any effect of this phenomenon. Whatever, I don't recall my system ever sounding better than it did last night, so I'll repeat the test after a week or so.

 

Very interesting.  Especially considering powering down the capacitor-based conditioner.  My past experience with this topology indicated that it was best powered at all times.  

 

I don't put the MU1 in standby because I believe that the energy savings is negligible (and our solar cells are sufficient for our total load).  Good question about the frequency.  Between occasional updates and some power outages, I'd guess that every few months is sufficient.  

 

But these are just tweaks like any other.  As you said, a "nice" change, but not dramatic.  

 

There is also another path, which is playing a recording meant to clean out the cobwebs (if one believes in demagnetizing).  Something like IsoTek's disc:  

 

"The Full System Enhancer CD is an intensive ‘workout’ for your audio system. The disc includes specially developed signals to help ‘run-in’ new equipment, as well as demagnetising existing hi-fi components and rejuvenating your entire system."   https://isoteksystems.com/products/full-system-enhancer/

 

Or the "glide tone" from Ayre Acoutics:  https://isoteksystems.com/products/full-system-enhancer/

 

Haven't used these in years.  I'm not sure if the IsoTek helped speed up burn-in when I tried it, but our felines at the time got very agitated by the sound.  Maybe it was the very high-frequency sounds (even at modest, to humans, listening levels).  

 

[TheAttorney]

On 3/17/2023 at 2:56 PM, PYP said:

Very interesting.  Especially considering powering down the capacitor-based conditioner.  My past experience with this topology indicated that it was best powered at all times.  

 

There is also another path, which is playing a recording meant to clean out the cobwebs (if one believes in demagnetizing).  Something like IsoTek's disc... Or the "glide tone" from Ayre Acoutics

 

The pros and cons of powering down capacitors may be dependent on the length of down-time. There are too many variables for me to worry about, so if an occasional 10-15minute total system power down makes my system better, then that's what I'll do. In the meantime, after 3-4 days of my normal standby/active cycles, I haven't noticed any degradation in SQ, although it would be very hard to reliably notice any subtle degradation across a 24hr period.

 

Strangely enough, I have both the IsoTek and Ayre enhancements CDs, received as freebies decades ago. In the distant past, both did seem to subtly improve SQ, but I keep forgetting they're there. So I tried the IsoTek demagnetising track yesterday and I think it maybe did improve SQ a bit, but not possible to do an A/B test to confirm. If what I heard was real, then the power-down trick and the demagnetization tracks are doing different things and the benefits are cumulative.

 

I haven't compared which of the two enhancement CDs give the best results, but the IsoTek team have gone to much greater trouble to produce all sorts of complex test and enhancement tracks. In comparison, the Ayre team have been lazy and greedy to charge $20 for basically a simple glide tone (short and longer versions) and a few pink/white/brown noise tracks that can be got for free from the internet (although the out-of-phase brown noise track can be useful for burning in loudspeakers and headphones with reduced sound annoyance).

 

[PYP]

interesting experiments.  I've taken us off course...

 

Yesterday, I was enjoying the Grimm Audio Newsletter, particularly an essay on the origin of art.  Some truly fresh thinking (although was glad to see he cites his influences) and very well written.  Here is the teaser from the newsletter:  "In this fascinating essay, Eelco Grimm’s master student Wilko Schmidt-Dannert outlines the evolutionary forces that drive people to create and enjoy art. Warmly recommended!"    

 

I like the Grimm approach because it shows a broad set of interests and influences.  The result is original thinking and design.  To me, the MU1 represents the most economical (in all senses of the word) design to get from  A - data to B - music.  

 

Great to see that there is now a sales director for North America who shares the eclectic mix of interests and brings a lot of experience to the job.  After seeing a conversation with Eelco about the Grimm active speakers, I've been thinking about going in that direction.  So far, the US dealers advertise the MU1 on their websites, but not the LS1 speakers.  Perhaps that will change soon.  

[Low325]

Thanks for continuously sharing experiences within this awesome thread.  I  dont want to go down this rabbit hole either…but jeez I must say there are times, when I go …”hmmmm what just happened…” during a listening session…  But I was equating them to noise in the AC, of course I had no data to back it up, so I would chalk it up to placebo or just my mind so caught up with other distractions…

 

I do like to turn off my gear, and start up again.  ‘Rebuilding binaries…’ i always say to our customers ;-)

 

Anyway, I debated on adding this here on or on the tambaqui thread (but equally enough, credit to the tambaqui DAC too).  But does anyone else run SPDIF into the MU1 from their Tv out?  I do, and I have always been super impressed with just how full bodied, impact and clarity the sound of movies or even regular programming sound.  I know most of you have dedicated listening rooms, but I have a shared space, and with the MU1 being the hub, I downsized back to 2CH HT and packed u all my home theater components…!  For me, of course, I can only know technically how good its been sounding since, but just noticing how my family tends to just be more engaged at the material and catching them jump at those moments of surprise…perhaps just pure coincidence, too many variables.  That jitter-free special sauce is very addicting.  Whatever it is, I’ll take it!  

 

That said, with @PYP mentioning that the LS1 could be in his future…I just imagine how great that integration would be with the addition with the SB1s and 2CH HT.  Anyhow, i thought I’d just throw it out there as an added bonus to LS1 integration…as I understand it, even if you added 5 speakers, it wouldn’t translate Dolby or decode in that way, but just a small little added benefit for those of you who have shared spaces and are, like me, 75% 2ch listening and the 25% 2ch HT.

[PYP]

1 hour ago, Low325 said:

 

That said, with @PYP mentioning that the LS1 could be in his future…I just imagine how great that integration would be with the addition with the SB1s and 2CH HT.  Anyhow, i thought I’d just throw it out there as an added bonus to LS1 integration…as I understand it, even if you added 5 speakers, it wouldn’t translate Dolby or decode in that way, but just a small little added benefit for those of you who have shared spaces and are, like me, 75% 2ch listening and the 25% 2ch HT.

100% 2 ch here and don't see that changing.   But it is great to have the capability.  

 

The idea that the designer has control over all aspects (DACs, amps, drivers, dsp, etc.) and their integration just makes sense to me.  And that enables the designer to use what is needed rather than over-engineering, which I believe provides a lot of value for the money.   If I understand the design correctly, there is a DAC and an amp for each driver.  

 

Having the MU1 in front of the active speakers must make for a very musical system.  And that is really what matters to me.  Well, that and a simple (for the user) system that is easily placed in the room.  It is also an advantage to have dsp controls for HF and bass given how different rooms react differently to these.  I also like the look, which is also important to me.   So, excellent value, great performance (yet to be heard), compact size/versatile placement options and blends in with the existing decor = winning combination.  

[Low325]

On 3/20/2023 at 5:46 PM, PYP said:

So, excellent value, great performance (yet to be heard), compact size/versatile placement options and blends in with the existing decor = winning combination.  

 

To each their own, but I think the LS1 variant in white is beautiful.  Dont delay, I encourage you to buy now/soon! :D

[PYP]

13 minutes ago, Low325 said:

 

To each their own, but I think the LS1 variant in white is beautiful.  Dont delay, I encourage you to buy now/soon! :D

I like all the colors.  Thank you for helping me spend my hard-earned savings!  🧐 

 

If I do purchase, it will be the final molt before I become a butterfly and there will be no transformations after that.   Before the MU1, I thought I had my final setup, but it has thrown a curve in my expectations.  It is a special piece of gear as we know.  

[Low325]

17 minutes ago, PYP said:

I like all the colors.  Thank you for helping me spend my hard-earned savings!  🧐 

 

If I do purchase, it will be the final molt before I become a butterfly and there will be no transformations after that.   Before the MU1, I thought I had my final setup, but it has thrown a curve in my expectations.  It is a special piece of gear as we know.  

Yep.  I get it… been considering Grimm ecosystem for many things that can come full circle; the MU1 has heightened the level of transformation in my system like no other piece before it.  Simplicity/Design, and philosophy.  The drivers they chose bring back so many good memories.  There is something about a copper phase plug (get your head out the gutter you sickos 🤨) 

[FredM]

20 hours ago, PYP said:

I like all the colors.  Thank you for helping me spend my hard-earned savings!  🧐 

 

If I do purchase, it will be the final molt before I become a butterfly and there will be no transformations after that.   Before the MU1, I thought I had my final setup, but it has thrown a curve in my expectations.  It is a special piece of gear as we know.  

You can always ask your current dealer if an LS1 demo is an option. Perhaps it’s even a win/win, where the dealer can also learn more about the ability and performance of the LS1 😎. I can remember my first encounter with the LS1be/subs vividly 🙂

[Fourlegs]

I am considering dipping a toe into the MU1 water and see that there are a few second hand ones coming through to the market. Please can anyone tell me whether there have been any revisions to the MU1 during its life in terms of hardware or whether a second hand one will be identical to new (assuming that any firmware is easily brought up to date). Thanks.

[pvanosta]

@Fourlegs : My understanding (as a use MU1 owner myself), is that there have been minor hardware evolutions over time (some minor components switched out with updated versions) but nothing that should impact the proper functioning of the MU1 or differentiate that functioning from a newly bought one. The best thing to do, is get the serial number from the seller, as well as the current firmware it is on and contact Grimm support. They can tell you the device's full history, as well as which components might be upgraded/updated if any. Mine needed a new internal memory card installed, as it would not update from firmware 1.2 to 1.3 (it is currently on 1.51 without issues).

[soupcon]

1 hour ago, Fourlegs said:

I am considering dipping a toe into the MU1 water and see that there are a few second hand ones coming through to the market. Please can anyone tell me whether there have been any revisions to the MU1 during its life in terms of hardware or whether a second hand one will be identical to new (assuming that any firmware is easily brought up to date). Thanks.

 

the most obvious product change that i'm aware of was the addition of the SPDIF RCA output. I got one without it on the used market and have had no trouble, and I knew I would never need RCA digital connections.  the savings was to me worth it, and it was an easier decision process than the rather unwieldy experience i had with a couple of retail dealers with whom i tried to get home demos (that said, I understand changes to the dealer network structure are up on us). 

 

The MU1 is a marvelous piece of gear. It will be one of those pieces that I won't be compelled to swap out for a very long time. 

[Fourlegs]

@pvanosta and @soupcon many thanks for the replies. Having looked at photos of the rear plate I see that the spdif output had been added and also that there seems to have been a rearrangement of the usb and ethernet sockets.

 

I would be wanting to use the MU1 with my WAVE Storm spdif cables so I will keep my eye open for an spdif output version.

[skatbelt]

On 4/4/2023 at 9:50 AM, Fourlegs said:

@pvanosta and @soupcon many thanks for the replies. Having looked at photos of the rear plate I see that the spdif output had been added and also that there seems to have been a rearrangement of the usb and ethernet sockets.

 

I would be wanting to use the MU1 with my WAVE Storm spdif cables so I will keep my eye open for an spdif output version.

 

In his review, Christiaan Punter mentions the difference between the original and the updated hardware version the MU-1. See half way this page: https://www.hifi-advice.com/blog/review/digital-reviews/network-player-reviews/grimm-mu1/4/ 

[Fourlegs]

@skatbelt many thanks and that is interesting information in the link you provided. I hadn’t previously seen that the v1.3 incarnation sounds different to the previous ones. I will have a word with my dealer and see if I can get hold of one. 

[pvanosta]

18 hours ago, Fourlegs said:

@skatbelt many thanks and that is interesting information in the link you provided. I hadn’t previously seen that the v1.3 incarnation sounds different to the previous ones. I will have a word with my dealer and see if I can get hold of one. 

To be clear, 1.3 etc. refers to the software (firmware to be precise) of the MU1. Since then, there have been several updates to said software (we are now on 1.5.1 ). Just make sure that whatever MU1 you buy, is capable of running 1.5 or 1.5.1 and you'll be sure to get a model with current hardware.

[TheAttorney]

40 minutes ago, pvanosta said:

Just make sure that whatever MU1 you buy, is capable of running 1.5 or 1.5.1 and you'll be sure to get a model with current hardware.

+1

 

While most MU1's have had no trouble with firmware upgrades, there's been at least one older version that needed to return for a H/W-update in order to complete a successful firmware update.

 

Firmware 1.5 introduced the web user interface, which is a foundation for many future enhancements. So any age of MU1 should already be on the latest firmware version before being sold to a buyer. And if it isn't, you need to question why not?

[Fourlegs]

@TheAttorney thanks. I have a demo MU1 arriving on Wednesday from the dealer. I’m looking forward to it. 

[krass]

On 4/6/2023 at 12:50 PM, pvanosta said:

……… Just make sure that whatever MU1 you buy, is capable of running 1.5 or 1.5.1 and you'll be sure to get a model with current hardware.

 

Im not sure that is correct… the older Mu-1 without SPDIF hardware can also run software v1.5 - So it is not a guarantee that you have the “current hardware” (my unit is an example of older HW running latest software)

 

I recently bought a second hand Mu-1 and was helped by Grimm (Eelco himself !) to determine what equipment upgrades were ‘missing’.

 

What I learnt:

 

1) For serial numbers starting with 13.0.001.xxx: Intel i3-7100U 2.4GHz

For serial numbers starting with 13.0.002.xxx: Intel i3-8109U 3.0GHz

 

2) Serial 13.0.003.xxx are the SPDIF hardware updated models

 

3) Later models have 8Tb internal storage standard; earlier versions have less (my .002 has 4Tb)

 

4) very early models had a small hardware problem with the IR dongle capability. Minor issue and affects very few models. 

 

5) I think there are quite a few minor updates along the way. When checking my .002.xxx unit, the unit status was assessed and only one more critical HW update was identified by Grimm: “Most modifications were done on this unit, there are no critical mods needed. But there are a few that could be done (mainly to make reception of 4fs on digital inputs (XLR, RCA) stable).”

 

Hope this info is useful. For sure contact Grimm who are very helpful, and the cost of full check & revision was very, very reasonable…..