Core of the MU1 technology is an FPGA processor board of our own design that offers the highest quality oversampling and de-jittering possible. The amount of work and knowledge that went into this project can hardly be overestimated.
Interface description Front: On the left you find the MU1 activity LED in the ‘i’ of the Grimm logo. The display shows all user information. The MU1 activity led shows the current activity of the MU1 system. Table 1 below shows the modi.
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Please use high quality cables intended for use with computer systems and avoid cables with claimed special qualities for audio. The MU1 makes use of DHCP. To use a static IP address in the MU1 please consult the manual of the network device that acts as DHCP server within your...
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5. Dual USB input. These two general purpose USB3.0 connectors may be used for connecting an external USB drive (flash drive, SSD or HDD) for extending the disk space of the MU1 system. You may play music files from this drive. The MU1 supports the following filesystems: FAT32, NTFS, HFS+, exFAT, EXT2 and EXT4.
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Warning: Do not connect a network cable to this connection! Although a normal RJ45 connector fits, this output may only be used for LS1 control connection. Grimm Audio is not liable for damage to a local network system as a result of incorrect wiring by the user.
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Top: The top of the MU1 carries the main control knob. It is used for all user input of the MU1 via turning and pressing. Depending on the state of the system and the menu selection this knob changes functionality.
Roon remote control software for a tablet, smart phone, PC or Mac to get access to the Roon Core server in the MU1. Please visit the app store of your OS manufacturer, or use this link: https://roonlabs.com/downloads.html. For general operational guide lines of the user interface, we refer you to the Roon Labs documentation: https://roonlabs.com/support.html.
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Volume settings We put in a safety limit on the volume control. Whenever you turn the MU1 main control or the Roon app volume fader quickly to the maximum position, the volume will jump back to the lowest level (the fader will stay at the max position though).
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While you are in the Device Setup page, please set the “DSD playback strategy” to “Native” if it is not already. The MU1 FPGA processor has a superior quality DSD downsampler and we recommend to use this feature to play DSD files to the LS1 system or other PCM DAC’s. You may also open the “advanced”...
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Background analysis speed In the Library page of the Settings menu Roon offers several options for the ‘Background Audio Analysis Speed’. We recommend to set this to “Throttled” and not to one of the “Fast” options. This makes sure most of the processing power of the CPU is dedicated to audio playback. You may also set it to “Off”, Roon will then calculate the waveform of a new file on the fly when it is played.
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100% gapless by design, which means that a soft glitch can be heard at the start of a new track. This glitch is in the master files and cannot be solved in the MU1 or Roon software. Also, a short moment after playback of a DSD file has stopped, Roon will switch to a ‘silent’ PCM stream and this also causes a soft glitch.
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Internal disk The MU1 optionally has an internal disk for music files. Adding music to the folders of this drive is done via the network, how to do this is described below for Windows and Mac-OS. First of all, open the help page of the MU1 menu (see chapter “Control”) and note the hostname and IP-address.
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Enter the hostname and press Connect. The hostname of your MU1 is indicated on the second page of the MU1 menu, see Menu View in chapter 7 of this manual. Connect as “guest” to the Music share folder. In the unlikely event that connecting to the hostname does not work, please enter the IP address of your MU1, which is found on the same menu page of the MU1.
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Roon database. The database folder contains all settings, log files and database items. The MU1 mounts this folder in the network under the share name “roondata”, and it is password protected to prevent accidentally resetting the database. The credentials are as follows: Username: mu1-user;...
• A short press is shorter than 2 seconds, a long press is longer than 2 seconds. Below is an image of the screen you get when the MU1 is fully booted and there is no Roon remote connected yet.
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When a Roon remote such as a tablet is connected to the MU1 Roon Core and music is playing, the track information and progress bar is shown as in the picture below. In Music View, the display offers the following information: Sample rate and format •...
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If an LS1 is connected, the MU1 will send volume control data to the DSP of the LS1 via its proprietary cat5 cable. If volume control is activated for one or more digital outputs, the FPGA chip performs a volume attenuation at high precision for these output(s).
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For users who connected a third-party DAC to digital output 1 or 2 and have no LS1 connected, the scale automatically changes to 0 dB max, which reads as “100” in the Roon app. Source selection By pressing, holding down and then rotating the main knob you enter the source selection menu. Here you can select sources.
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The MU1 will remember the selected source when shutting down the system. When you power up the MU1 it will try to select this memorised source. If it was a source on the LS1 (Analog or Digital) this source will be selected as soon as your LS1 is detected. Note that if you operate the MU1 before the LS1 is detected, the MU1 will automatically fall-back to the ‘Roon’...
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Always turn off the system before unplugging the power cord to prevent damage to your MU1 computer system! Hint: The white LED on the front indicates if the device is in stand-by (LED ‘breathes’) or if the MU1 is shut down (LED off).
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MU1. If the IP address shows ‘unknown’, there is no network connection and in that case the MU1 cannot be found by the Roon App in your tablet or smart phone. Please check the network connection of your MU1.
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Audio that is already 4FS will be left untouched. This option is the default and recommended setting for the MU1. Note: FPGA resampling to 2FS is supported up to DSD128. When switching to the 2FS option the live preview of DSD256 and higher will cause noise as long as you’re in the menu.
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Volume control of the LS1 output is always done in the LS1 and can not be switched off. Hint: when using the MU1 as a source for a ‘digital’ loudspeaker that has on board digital processing such as crossover filters, it is recommended to disable the MU1 volume control so that the speaker will receive the audio with widest modulation.
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“DoP” is brief for “DSD over PCM”. It is a standard for transporting DSD64 audio over an AES3 or S/PDIF PCM digital audio connection. Some DACs support this format and the MU1 is able to forward DSD64 material unaltered to these DACs. Mark that volume control is impossible on DSD signals, hence the DoP option is disabled when volume control on digital out 1 or 2 is turned on.
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LED: The brightness of the LED on the front of the MU1 can be turned down with this option. This influences the brightness both in operation and in stand-by mode. Turn the main knob clockwise to increase the brightness and anti-clockwise to decrease the brightness.
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Use a short press with the main knob to start programming the highlighted function. The dot will turn orange until the MU1 receives an infrared command. Press the desired button on your infrared remote to connect this infrared command to the selected function. When the MU1 receives an infrared command the dot will turn green and it returns to the infrared selection menu as shown in the previous image.
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One button of the infrared remote can only be paired with one function of the MU1. If you use the same button of your remote for another function, the previous function is overwritten and the new one is paired. The dot of the previously paired function will turn red and the new function will become green.
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The software versions of CTRL (Control software), FPGA and UC (Microcontroller) are also shown in this menu. When you experience problems with your MU1 we may ask you to send us this information. Turn left to go to the fourth menu, turn right to go to the sixth menu.
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Updates for third party software like Roon is not included in the MU1 software update, this is done separately via the Roon App.
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When you activated Support Mode and wish to return to normal mode, press the power button on the back of the MU1 to turn off the device, and press the power button again to boot the MU1 in normal mode. Grimm Audio has no access to your MU1 any more as soon as you powered off the...
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