Introduction

What is Nucleus?

At the heart of every Roon system is a Roon Server. It's the brain behind the entire Roon experience: it manages your music collection, streams to your audio devices, and stores your Roon database.

The Roon team developed Nucleus as a silent, high-performance, power-efficient appliance for running Roon Server. The same team that makes Roon optimizes every part of its hardware, operating system, and software. That makes Nucleus the best way to run Roon.

RoonOS 3.0 brings a redesigned Web Administration Interface and an HDMI Now Playing display to Nucleus One and Nucleus Titan. Nucleus and Nucleus+ (Rev A and Rev B) don't receive RoonOS 3.0. To check which you have, please see Which version of the Web UI do I have?

Roon account

Every Nucleus requires a Roon account with an active free trial or subscription. You can start a trial or purchase a subscription from your Roon account page.

If you're trying Roon for the first time, getting started is a snap. If you already use Roon on another device, you can migrate your Roon database to your Nucleus, or start from scratch.

Controlling Nucleus

You control Nucleus from the Roon app. Please download it on a Mac or Windows PC, iPad, iPhone, or Android device.

The Mac, Windows, and tablet apps give you access to all of Roon's features. Because of their smaller screens, the Roon apps for phones have a more limited feature set.

Playback

There are three ways to play audio with Nucleus, and you can use any or all of them at the same time:

1. Connect an integrated audio component, DAC, or headphone amp to one of the USB ports.
2. Connect the HDMI port to an audio/video receiver (AVR) or other multichannel HDMI device.
3. Most popular: stream over your network. Nucleus supports many networked audio devices, including AirPlay, Sonos, hundreds of Roon Ready products, and legacy streaming protocols from Devialet, Meridian, Squeezebox, and KEF.

You can see all Roon Ready partners here.

Storing your music files

You can use any or all of these storage options with Nucleus:

1. Connect an external hard disk drive (HDD) or solid-state drive (SSD) over USB.
2. Install an optional internal HDD or SSD. Nucleus Rev A, Nucleus Rev B, and Nucleus One support drives up to 4TB. Nucleus+ Rev A, Nucleus+ Rev B, and Nucleus Titan support drives up to 8TB. For details, please see Nucleus Internal Storage.
3. Store your files on a network-attached storage (NAS) device.
4. Connect your TIDAL, Qobuz, KKBOX, or nugs accounts and import your favorites.

On Nucleus One and Nucleus Titan, RoonOS 3.0 handles USB drives more gracefully. exFAT and FAT32 drives are repaired automatically when they mount, and large exFAT drives now mount. An NTFS drive that wasn't safely ejected mounts read-only instead of failing to mount, and you can run Check & repair on it from the Web Administration Interface. For details, please see USB Drives.

What's in the box?

Nucleus One Device Details & Back Panel Layout

• Power button and power LED
  • Press the power button once to turn the unit on, or to start a clean shutdown.
  • A dim white LED lights up when the unit is powered on.
  • Hold the power button for 4 seconds to force a hard power off.
• USB 3.0 ports (2)
  • Connect a USB storage drive, USB audio device, USB network adapter, or USB CD ripper.
• Ethernet port
  • Connect your Nucleus to your network with an Ethernet cable. Nucleus only connects to your network over Ethernet.
  • The port lights stay on and blink even when the unit is turned off.
• HDMI port
  • Use it as a multichannel audio output.
  • With RoonOS 3.0, connect a TV to use it as a Now Playing display. See HDMI display and diagnostics.
  • It also shows diagnostic information for our support team.
• Power connector
  • Connect the power supply here.

For a full list of device details, please visit the Nucleus One product page.

Nucleus Titan Device Details & Back Panel Layout

• Power connector
  • Connect the power supply here.
• HDMI port
  • Use it as a multichannel audio output.
  • With RoonOS 3.0, connect a TV to use it as a Now Playing display. See HDMI display and diagnostics.
  • It also shows diagnostic information for our support team.
• USB 3.0 ports: Type-C (2) and Type-A (2)
  • Connect a USB storage drive, USB audio device, USB network adapter, or USB CD ripper.
• Ethernet port
  • Connect your Nucleus to your network with an Ethernet cable. Nucleus only connects to your network over Ethernet.
  • The port lights stay on and blink even when the unit is turned off.

For a full list of device details, please visit the Nucleus Titan product page.

Nucleus and Nucleus+ Device Details & Back Panel Layout

Nucleus and Nucleus+ Rev A

• Power button and power LED
  • Press the power button once to turn the unit on, or to start a clean shutdown.
  • A dim white LED lights up when the unit is powered on.
  • Hold the power button for 4 seconds to force a hard power off.
• Power connector
  • Connect the power supply here.
• HDMI port
  • Use it as a multichannel audio output.
  • It also shows a status screen for our support team.
• Ethernet port
  • Connect your Nucleus to your network with an Ethernet cable. Nucleus only connects to your network over Ethernet.
  • The port lights stay on and blink even when the unit is turned off.
• USB 3.0 ports (2)
  • Connect a USB storage drive, USB audio device, USB network adapter, or USB CD ripper.
• Internal storage
  • Supports a 2.5" HDD or SSD with a drive height of 7mm or 9mm.

Nucleus and Nucleus+ Rev B

• Power button and power LED
  • Press the power button once to turn the unit on, or to start a clean shutdown.
  • A dim white LED lights up when the unit is powered on.
  • Hold the power button for 4 seconds to force a hard power off.
• Power connector
  • Connect the power supply here.
• HDMI ports (2)
  • Use them as multichannel audio outputs.
  • They also show a status screen for our support team.
• Ethernet port
  • Connect your Nucleus to your network with an Ethernet cable. Nucleus only connects to your network over Ethernet.
  • The port lights stay on and blink even when the unit is turned off.
• USB 3.0 ports (2)
  • Connect a USB storage drive, USB audio device, USB network adapter, or USB CD ripper.
• Internal storage
  • Supports a 2.5" HDD or SSD with a drive height of up to 15mm.

Choosing your Nucleus

The two Nucleus models currently available are Nucleus One and Nucleus Titan. You can compare their specifications at the bottom of the Nucleus page. For most buyers, the biggest difference is library size and how hard your system has to work to manage it.

Nucleus One is designed for libraries up to 10,000 albums (about 100,000 tracks). Nucleus Titan is built for libraries over 10,000 albums. These figures are a useful starting point, but the real picture is more nuanced than a track count.

What does the track limit actually mean?

The album and track figures on the Nucleus product pages are a convenient shorthand, not a precise technical ceiling. Roon won't stop working the moment your library passes 10,000 albums.

We use track count because it's the easiest way to describe library size, and most people know roughly how many tracks they have. What the figures really point to is how much work your Nucleus has to do. That depends far less on how many tracks you have than on how complex your database is.

Think of a notary's archive. The archive has a fixed capacity, but not every file takes up the same space. A one-page document and a multi-volume legal case both count as "one file", yet they're very different to store and manage. Your Roon library works the same way.

What actually makes a library complex?

Roon doesn't store music as a simple list of tracks. It builds a rich, interconnected database of albums, tracks, performers, performances, compositions, works, labels, venues, time periods, and the relationships between them. How much a release adds to your database depends on how much information comes with it:

• A single with one credited artist and minimal metadata is a compact entry.
• A symphonic work with a composer, conductor, orchestra, soloists, movements, and detailed recording information creates a much larger web of linked objects.
• A pop or rock album with extensive production credits, featured artists, or multiple disc editions can be just as demanding.

Two libraries with the same track count can place very different demands on a Nucleus, depending on the richness of their metadata.

How your database grows over time

Your database doesn't just reflect what you imported. It also grows with how you use Roon:

• Playlists, tags, bookmarks, and metadata edits
• Custom artwork and album groupings
• Play history and listening statistics
• Streaming integrations with TIDAL, Qobuz, KKBOX, or nugs

Someone who has run Roon for several years, with streaming services connected and extensive tagging, will have a much larger database. It can be far more complex than one from a recent import of the same number of tracks.

To keep your database healthy, run Settings > Library > Clean Up Library from time to time to remove unused data. To learn what it does, please see Clean Up Library. Please also keep regular backups, so you can restore your database to a clean state if needed. On Nucleus One and Nucleus Titan, set the Time Zone in the Web Administration Interface so scheduled backups run at your local time.

So the right question isn't just "how many tracks do I have?" but "how complex is my library?" Your genres, metadata richness, streaming services, editing history, and how long you've used Roon all play a part.

Setup

1. Connect and power up the Nucleus

First, connect power and your network, then start your Nucleus. For details, please see Power Up Nucleus.

2. Update Nucleus firmware

Before you use Roon with Nucleus for the first time, please make sure its firmware is up to date.

Not updating your Nucleus firmware could lead to data loss or a failed migration.

For steps, please see How to Update Nucleus Firmware and Roon Server Software.

3. Prepare your storage and audio devices

Nucleus discovers devices connected over USB, HDMI, and Ethernet at any time. Still, it's simplest to have them connected and powered on before you start. For details, please see Nucleus Storage and Audio Device Setup.

4. Start using Nucleus

Now that your equipment is connected, install the Roon app on your Mac, Windows PC, iPad, iPhone, or Android device. Then connect to your Nucleus. From here, you can also migrate an existing Roon installation to Nucleus. For details, please see Connecting to Nucleus.

If you have trouble updating your Nucleus, you can use Reinstall in the Web Administration Interface to reinstall the latest software. In Roon, go to Settings > Setup, click Find next to Find Roon OS, then click your Nucleus's IP address. On Nucleus One and Nucleus Titan, go to the Operating System row of the Overview tab. Click Update if an update is available, or Reinstall. On Nucleus and Nucleus+, click Reinstall under Operating System.

Maintenance

HDMI display and diagnostics

Nucleus One and Nucleus Titan: with RoonOS 3.0, the HDMI port can drive a TV as a Now Playing display, showing album art, track info, and a progress bar. To use it, go to Settings > Displays in Roon and click Enable on your Nucleus's RoonOS display. For details, please see Displays.

You can use the HDMI port for multichannel audio and the Now Playing display at the same time. To do this, connect an AV receiver (AVR) or an HDMI audio extractor between your Nucleus and the TV.

A diagnostics overlay shows your Nucleus's IP address, serial number, and software versions. When everything is healthy, it hides after two minutes. It reappears when HDMI or USB connections change. To show or hide it, press Esc on a keyboard connected to your Nucleus. The display returns to Now Playing 30 seconds after you press Esc.

The display also shows when Roon Server is starting, updating, or not running. When your Nucleus starts up, you'll see a splash screen instead of technical text, and you can press Esc to switch between them.

Nucleus and Nucleus+: the HDMI output displays a status screen with diagnostic information, including the IP address, build information, and server status.

Web Administration Interface

Every Nucleus includes a Web Administration Interface you can open in any web browser on your network. It works even when Roon Server isn't running. On Nucleus One and Nucleus Titan, RoonOS 3.0 adds new tools:

• Check the status of Roon Server, RoonOS, storage, Tailscale, and USB drives at a glance, and update RoonOS when a new build is available.
• Run Network Diagnostics to test every layer of your connection.
• Use Check & repair or Eject on USB Drives.
• Set the Time Zone so scheduled backups run at your local time.
• Choose how devices connect to your Nucleus's Data share with File Sharing.
• Collect diagnostic data for our Technical Support team from the Support tab, when they ask you to.

Support

Need help getting started with Nucleus? Please start a new topic in the Nucleus Support category on our community site, and our support team will be in touch.

Where to Buy

To purchase Nucleus in the US and Canada, please visit the Roon Store. Outside the US and Canada, please choose one of our official online distributors in your region for Nucleus One or Nucleus Titan.