The best way to experience Roon:
The Nucleus and Nucleus+ appliances were conceived to bring Roon to a wide audience of music lovers, particularly those who aren’t highly technical or interested in do-it-yourself (DIY) projects. By tightly integrating high-performance hardware with an optimized operating system and purpose-built software, they provide a simple way to get the richest possible Roon experience. They represent the culmination of an extensive product design and engineering effort, combining the Roon team’s years of experience designing media server hardware and extensive software development expertise.
The Nucleus product line was developed with several goals in mind:
- A turn-key Roon Core that does not require a Mac, PC, or NAS
- Computing power to support Roon’s requirements now and in the future
- Ease of use – little to no customer support required after installation
- Software and firmware updates downloaded “over the air” and managed by the end user
- Reliable and robust operation – tamper-resistant and nothing to service
- Audiophile-friendly – no fans or moving parts
This document provides insight into the design and engineering choices that were made during the development of the Nucleus product line in order to accomplish these goals.
It was tempting to try to design a single device that was perfect for everyone. But since its launch in 2015, Roon has evolved to include a variety of computationally intensive features like DSD upsampling, convolution, and support for music libraries in the hundreds of thousands of tracks; specifying hardware to meet the needs of the few people who use all those features would have driven the price of Nucleus up for everyone. We made the decision to produce two models, identical in every way except raw computing horsepower: Nucleus for the majority of users, and Nucleus+ for those with the most rigorous requirements in library size, numbers of simultaneous playback streams, and high-rate DSD.
When the first media servers appeared in the 1990s, storing large media files was their primary application. Large hard drives didn’t exist, consumer NAS appliances were not yet common, and the network speed (both LAN and WAN) required to stream high-resolution media content was extremely expensive.
The world has changed since then, as have the requirements for media storage. Some people store their music on a single USB disk, while those with large music libraries often have a NAS with RAID for redundancy and fault tolerance. Audiophiles may prefer SSD (solid state drives) over traditional spinning hard drives because they have no moving parts (and thus no mechanical noise) and a longer life span. A new generation of music listeners is increasingly relying on cloud-based streamed content rather than local media files, so they have little to no need for local storage.
Nucleus aims to address all these cases by taking advantage of modern storage technologies, most notably the introduction of low-power, high-capacity 2.5” hard drives and SSDs. Nucleus has an internal 2.5” drive tray, which can accommodate a single SATA SSD or HDD for dedicated internal storage. Two USB 3.0 ports can be used to connect one or more external hard drives with support for a variety of common file system formats: FAT32, NTFS, exFAT, and HFS+ (“Mac OS Extended”). Of course Roon has always supported connections to SMB/CIFS file servers, which includes most NAS appliances available today.
Wireless networking is ubiquitous, and often consumers expect that every device can and should be wireless. While Roon is often controlled over WiFi (using Roon Remote on a mobile device) and RAAT (the protocol used by Roon Ready devices) is designed to work reliably over WiFi, Nucleus is an infrastructure product. Because its primary function is to act as the Roon Core on a home network, reliability is a key networking requirement. We made the decision not to implement WiFi in Nucleus, and rather to require a connection to a router or switch via Gigabit Ethernet.
For users of early media servers, ripping CDs was a primary use case for customers. Our research indicates that these days, the majority of people have already ripped their CD collections. Among those who continue to buy and rip discs, there is often a strong preference for a particular ripping application (like EAC, dbPowerAmp, or XLD) which are only available for specific operating systems.
We also know from our experience that optical drives are inherently prone to failure over time. Rather than building in a CD drive and implementing our own ripping software, we decided to leave ripping in the domain of the PC. Media files from a computer can easily be copied to Roon by SMB transfer or via drag-and-drop to the Roon application.
Almost all music “server” or “streamer” products in the market have audio outputs of one kind or another, either digital or analog using a built-in DAC (digital to analog converter). With Nucleus, we have taken a different approach.
A cornerstone of the Roon product strategy has always been to support a wide variety of partner audio brands. Roon’s role is to be the best possible music source, leaving rendering to products from companies that specialize in audio. Nucleus extends that strategy by having no analog audio outputs at all. External DACs, receivers, integrated amplifiers, and speakers can be connected either directly via USB, HDMI, or over the network using RAAT, AirPlay, or Roon’s other supported protocols.
The Nucleus requires a 19V DC supply, which meant we had several options. The most elegant product choice was designing an internal AC-DC switching power supply board, which would have meant a single external AC power cable from the Nucleus to the wall. We rejected this approach, though, because we realized that in our target markets, one size doesn’t necessarily fit all.
Depending on whether the Nucleus is connected to audio equipment directly (via USB/HDMI) or indirectly (via ethernet) there could be advantages to different switching power supply designs, and the possibility of a DC filter might make sense in some configurations. In addition to those options, in the audiophile world there might be a preference for a linear power supply, which would require a different thermal design, substantial additional cost, and more safety certifications.
Taking all these variables into account, we took the pragmatic decision to include a simple external “wall wart” DC power supply with the Nucleus. The wall wart is an appropriate solution for the vast majority of users, and for those with different requirements, a wide variety of third party switching and linear supplies and filters are available.
Almost all modern computing hardware includes a fan-based thermal solution for maintaining internal component temperatures within safe limits. Unfortunately, fans are inappropriate for critical listening environments, so a completely fanless cooling system was an absolute requirement.
Together, Nucleus and Roon OS represent a leap forward for media server appliances. As a result of thoughtful product design, hardware engineering, and software development, they provide a turn-key solution for installing and running a Roon Core that is easy to support, high-performance, and robust.