#1 Volume goes to maximum when Roon has been set to “DSP volume” and back to the default “Device volume”.
Note: This problem can not be solved in our software at the moment. We did add a ‘safety volume reset’ in firmware v1.1.2 though: whenever the volume jumps to maximum, it is internally reset to minimum.

Bug appears when: Normal playing state → Enter Settings menu in Roon → Go to Audio → Go to Device setup for the MU1 output → Change Volume control setting to DSP Volume → Save and exit menu → Enter the Device setup menu → Change Volume control setting to Device volume → Save and exit menu.

What is wrong: Device menu is not operating as intended, LS1 menu goes to maximum (23dB). When volume is lowered it is set back to maximum when the next track starts. Warning: This can damage your ears and loudspeakers (depending on track loudness).

To get out of this state: Enter Settings menu in Roon → Go to Audio → Go to Device setup for the MU1 output → Press Load Defaults in the bottom left corner → Save and exit menu.

#2 After updating to Roon v1.8 my interal SSD Music drive is unavailable.

Roon update v1.8 introduced folder access restrictions to the MU1 Roon server. On some MU1’s this causes the problem that the HEAP disk cannot be added to Roon by browsing the local disk and selecting /mnt/sda1 or /mnt/sdb1.

Solution: mount the SSD disk as a network share. Please read this Internal SSD mounting instruction pdf >

#3 After a database reset the Extension disappeared.

After a June 2020 Roon update the Grimm Audio Extension becomes invisible after resetting the Roon database. This reset is sometimes demanded to solve Roon related problems.

Solution: if you had to reset your database, please contact us. You need to put your MU1 in Support Mode and our team will then solve the problem remotely. Our next update will address this issue.

#4 MU1 internal drive not visible under Windows.

In some cases the MU1 internal SSD drive is not visible under Windows 10. The reason is that the ‘Bonjour’ service is not installed by default under Windows. Bonjour is used for so called zero-configuration networking, and it enables automatic discovery of devices such as the MU1. It will then show up in the Network File Explorer section of Windows 10 as a named network entity like ‘MU1-00xxxx’.

Solution: First you need to install the ‘Bonjour Print Services’. A download can be found by following this link from Apple.

Next you need to enable ‘SMBv1’. Unfortunately in Windows 10 the SMBv1 protocol is disabled by default as Microsoft sees it as a security risk. Mark that this risk does not apply for the MU1 due to the way it is set up.

Read about MU1 >

Please follow the steps in the work instruction pdf below to install Bonjour and to enable SMBv1. Note that with every Windows 10 update the SMBv1 protocol may be disabled again. In that case please follow the work instruction again.