Grimm Audio MU1 and MU2 Music Players

[Eelco Grimm]

Please allow me to step into the discussion and help to avoid confusion. First of all: yes we are developing a 'MU2' streamer, which is a unit that has similar looks as the MU1, but a different target group of users. It will sit next to the MU1 in our catalog, and not replace it. The MU1 only has digital outputs, the MU2 only has analog outputs. So they serve different use cases. For instance, someone who loves his high quality DAC or active loudspeaker with digital inputs (like the Grimm Audio LS1 series) will choose the MU1, someone who likes full integration of functions and has a power amp and passive loudspeakers will choose the MU2. 

 

The MU2 is still under development. We do not work towards a release date but only release a product when it is finished at our intended quality level. We hope to introduce the MU2 in the first half of 2023, but this is dependent on how development proceeds, plus the availability and delivery time of components (that is still problematic unfortunately). 

 

Function wise, the MU2 carries a built-in noise shaped DAC of discrete design based on our FPGA technology. It has both digital and analog inputs and an analog (relais based) volume control. We choose an analog volume control since it offers volume control of the two analog sources without AD conversion. There is also a headphone output. Note that internally a MU2 is so much different from the MU1 that there is no upgrade path possible. The price of the MU2 is not yet set. It will be less than twice the price of the MU1, but no other ballpark figure can yet be offered. The 15-16k number that @Vincent des Champs mentioned is not confirmed. 

 

I am sorry to disprove the rumours. More info will follow once we are close to the (yet to be scheduled) release date.

 

Thanks all for your strong interest in our developments!

 

Best regards,
Eelco Grimm

[Eelco Grimm]

12 minutes ago, Vincent des Champs said:

Presumably the digital front end (Roon Core/ Audio device-streamer) plus all it’s sound enhancing functionalities will be adopted from the MU1, is this a correct assumption?

The 'Roon Core side' and most of the internal control data software will indeed be the same in the MU1 and MU2. So the user experience with the two is similar. The fpga upsampler of the MU1 will be 'integrated' with the DAC of the MU2.

[Eelco Grimm]

4 hours ago, Nicholas Dong said:

Eelco,When will the next version of the firmware be released, can I add the standby or shutdown function to the Grimm GUI interface, so that I don't have to go to the front of the machine and press the golden disc every time, the golden disc has a very beautiful appearance,  I don't want to smear this perfect golden disc with my damn handprints 😛

The next firmware update will indeed add a 'go into standby' function from within the GRUI. It is not possible to wake the MU1 from standby however, you will still need to turn or click the big knob.

[Eelco Grimm]

11 minutes ago, PYP said:

Roon and Qobuz sometimes lose their handshake (or whatever it is) which requires logging out of Qobuz, rebooting the Roon core and then logging back into Qobuz.   To reboot the Roon core, is there an alternative to powering off/on the MU1?  If not, might there be a way to include this functionality (eventually) in the GRUI?  Thank you.  

Interesting suggestion. We will discuss this option, thank you.

[Eelco Grimm]

10 hours ago, pmorali said:

Hi All,

 

Quick question about the "Zone settings" in Roon related to the MU1, specifically the "Zone options", before getting to the "Audio device" setup: How do you recommend the "Volume leveling" options to be set up, Off, Auto, Track or Album?  Have you tried it and detected any impact on the SQ?

 

Thank you,

 

Philippe

We recommend to not use this feature and keep it on 'off'. Support of volume leveling in the fpga is on our road map (we have too, since I am 'mr Loudness'). But we need to cooperate with Roon on the metadata exchange part and this takes some time. 

[Eelco Grimm]

12 hours ago, PYP said:

I wonder why Roon Labs doesn't show Grimm Audio as a partner on their homepage?  Obviously a trivial issue vs. all that Grimm Audio is working on, but it would be free marketing.  

The MU1 needs to (also) become a certified Roon End Point for that. That's in the make... No worries, the people at Roon are very much aware of us and big fans.

[Eelco Grimm]

Dear TheAttorney, the IR issue you mentioned is known and has been fixed with later hardware. With the first few batches (that apparently includes your unit) you should indeed not plug or unplug the IR cable while the MU1 is on. Excuse us for the inconvenience.

[Eelco Grimm]

Dear aangen, Issues like this are usually related to Roon. Sometimes it solves itself after a while (probably related to indexing or so). Sometimes a Roon database reset is needed. Always make sure to regularly make Roon database backups so you can restore it after such a reset. If you need further assistance, please use the support form on our home page. I rather not use this forum to deal with private support questions.

[Eelco Grimm]

10 hours ago, pvanosta said:

I just had a first listening session on MU1 FW 1.5 and Roon 1182. I have an issue with DSD and DSF files. Before, any DSD and DSF file in my library played without and issues. Now, any DSD.DSF file shows as playing in the Roon UI, but no sound is produced by the Mu1 / LS1 system. This goes for DSD64, DSD126 and DSD256 (auto-downsampled to DSD128 due to the limitation on the LS1 speakers). Everything else plays fine (24/192 etc).

 

Update: this issue only occurred when I switched the MU1 from 4x to 2x oversampling. I just switched back to 4fs oversampling and everything plays again...

Good catch, that's a bug... We will look at it soon and solve it in an interim update.

Please note that DSD256 is converted to 4fs PCM natively by the MU1. Only rates higher than DSD256 need downconversion by Roon (which we do not recommend). 

[Eelco Grimm]

On 2/18/2023 at 11:12 AM, pvanosta said:

I think I fixed it. In the MU1 settings, I activated 'second out' to LS1, by pressing the bronze knob twice. Music playing is restored.

 

Not sure why it needed that. Also not sure that setting was active before.

Anyway, playing DSD64 in native lossless as I type this... phew...

If you do not use the 'second out' option (for instance to switch between your LS1 and a headphone DAC), it's better to turn the option off to avoid the effect of 'double clicking' by mistake. 

 

Best regards,

Eelco Grimm

[Eelco Grimm]

9 hours ago, Mike123 said:

Did the Grimm Reaper pay a visit to my Mu1? This morning Roon could not lock the Mu1. Mu1 was off with black screen. I usually leave the mu1 on -never turn it off. Unplugged and plugged back in - turned on. Got the scrolling three dots for about 4 min - then nothing.  Any thoughts? Very much appreciated

Dear Mike, if your problem persist, please contact us via the support form https://www.grimmaudio.com/support-form/ and we will look at it asap. All the best, Eelco

[Eelco Grimm]

@Nicholas Dong The next firmware update is a _huge_ amount of work since we write most of the code ourselves. And we prefer to do it right the first time. Please remain patient for a few months. It will be very much worth the wait...

[Eelco Grimm]

2 hours ago, J. Vitus said:

We tested the MU1 in our system along with the Taiko Audio Extreme. We also own an Aurender N30SA and tried it with a new clock also offered by Aurender (MC10).

 

For my listening tastes we preferred the Taiko, then the N30, and lastly the Grimm. However, such a comparison isn’t really fair to the MU1, as the N30 is almost twce as much and the Extreme is app 3x much. For the money the MU1 is an excellent value. 
 

This said, all of us hear differently. We also have different systems. So, everyone’s opinions can vary. 

 

 

 

Did you use the AES (or S/PDIF) outputs of the MU1 or did you play via the network (like with the Taiko and Aurender)? As a network source the MU1 is not very special (just a computer with a very high quality power supply). Its special qualities are only available via the AES and S/PDIF outputs.

[Eelco Grimm]

13 minutes ago, J. Vitus said:

Hi,

 

Our testing of the MU1 and the N30SA + MC10 Clock was done with AES cables. The N30SA (without a MC10 Clock) sounds better with USB to me and so does the Taiko. 

Great, so you did a proper comparison. I was just checking to be sure, some people miss the point that the MU1 should be used with AES or S/PDIF.

[Eelco Grimm]

Dear Playtron, if you have an issue with your MU1 playback, please make a support ticket at https://www.grimmaudio.com/support-form/. We will try to help you as soon as possible.

[Eelco Grimm]

@Vincent des Champs All MU2's of the first batch were shipped in the past weeks and the second batch is on schedule for early 2024, so I am happy to report there are no delays. The MU1 SW update is waiting on Roon Labs to finish their 'Roon Ready' certification tests. We will therefore release an intermediate firmware update within 4 weeks or so with small bug fixes plus 16 and 18 bits support for some types of Audio Note DACs. UPnP etc support will be added in a few months. Thank you for your patience.

[Eelco Grimm]

@playtron Please send a support request to https://www.grimmaudio.com/support-form/.

[Eelco Grimm]

@TheAttorney DSP functions are not planned at this moment, other than volume offsets per source. On the wish list is for sure loudness normalization, which will become possible after we have received a Roon Ready compliance. Cross-feed for headphones is also on our wish list. Tone control perhaps in the long run. You need to know that we have used almost all available space of the (powerful) FPGA to achieve the highest level of upsampling, leaving almost no space for extra features. But I will note your DSP wishes. 

[Eelco Grimm]

@aangen I am sorry but we will not support read/write on USB drives. Since there is no mechanical lock on a USB connector it is 100% guaranteed that people will unplug the drive at some point without unmounting. We do not want to offer support on that. The workaround is simple: just write files to the MU1 via the network. Tip: make sure to use a wired ethernet connection between the computer and the network when copying files to the MU1. That gives a big speed increase.

[Eelco Grimm]

@aangen If you did not manage to solve this by following the instructions of page 16 of the Software Manual, please send a support request via https://www.grimmaudio.com/support-form/.

[Eelco Grimm]

@Ronnie112 Can you please try mounting the internal SSD following the instructions on page 14 of the MU2 software manual?

[Eelco Grimm]

Re. the Roon SQ discussion: we regularly check if Roon is still bit tansparent, and it is - as long as you turn off all possible DSP and volume control etc it offers. Please read the MU1 and MU2 manuals about how to do this. SQ differences between bit transparent player softwares are related to the CPU activity and the ability of the device to isolate a possible impact of that activity via the CPU power supply on the audio clocks. It is our specialism to design high quality SMPS supplies, shunt regulators with high isolation (130 dB...) and oscillators with the lowest possible sensitivity to external interference. But then still we need to use a high performance jitter analyser to check if the design turned out right. And it does. We believe that combining knowledge and measurements is the best way to high performance audio quality. Does this make the MU1 and MU2 totally immune? That is hard to tell since first of all the increased resolution allows to hear even smaller differences. And secondly, it is not just the MU1 and MU2 that are subjected to for instance inavoidable ground loop currents, but also the downstream equipment of which we have no control. But we do hope to have achieved a level of immunity that satisfies the vast majority of listeners. 

 

Eelco

[Eelco Grimm]

FYI, we just tested the latest Roon version and it is (still) bit transparent, as long as you turn off all processing.

 

Please note that in very rare cases the memory of our FPGA can get partly corrupted (it is a bug of the Xylinx hardware). You may hear that as a lower SQ than you're used to. The only way to solve this is to turn off the MU1 (or MU2), disconnect the power cord, reconnect it after a few seconds and turn the unit on again. This is a hard reset, the FPGA memory is then reloaded. We are working on an intermediate firmware release that both solves this problem and (to be sure) adds an automated test to frequently test if the problem exists. Until then, whenever you have the feeling that something is wrong, it never hurts to follow the unplug procedure.

[Eelco Grimm]

@stevebythebayYes, this is totally independent of any user settings and it has nothing to do with Starbleed. It is an obscure hardware bug of the FPGA that popped up a few times now. Like I wrote, we have solved it in the upcoming update, the workaround is to do an unplug procedure. 

[Eelco Grimm]

@kakaThe MU2 internal intermediate rate is 8FS @ many bits.