Roaring Cube

Receivers are much like cars in some respects: While the world is busy talking about networked, autonomous, and electric vehicles, cars that simply drive reliably from A to B seem to be completely antiquated. Likewise, the HiFi amplifiers still found in many living rooms might deliver outstanding sound to your speakers, but their strong suit is not playing a digital music collection. In the end, you need to network your HiFi system. In this article, I show you how to build such a system with a Raspberry Pi and HiFiBerry.

In my case, I started out with a Philips FW362 [1] compact system built in 1999, with a twin cassette deck and a CD player (Figure 1). Even at the time of purchase, the stereo system was definitely not for audiophiles. The CD player died years ago, but the cassette deck now radiates retro charm.

Figure 1: If I'm honest, this Philips FW 362 compact system from 1999 with a defective CD player is electronic scrap.

Nevertheless, expanding the system by simply adding a network player is not the best idea; rather, I want to integrate a networked receiver with an integrated power amplifier. You can find a quite large selection of both device types today. The question therefore arises: What features do I need, and which devices offer them?

This question is not easy to answer for many products because of the numerous features and standards on offer: WiFi, Ethernet, Bluetooth, USB, DAB (Digital Audio Broadcasting), DLNA (Digital Living Network Alliance), FlareConnect, DTS Play-Fi, MusicCast, Dolby Atmos, Spotify, the HEOS App, and so on. You might think you are equipped for any digital case, but only at first glance (see the "Commercial Receivers" box).

Commercial Receivers

With the first test device, an Onkyo R-N855, I noticed that the first impression can be misleading (Figure 2). To its advantage, the R-N855 does not necessarily require an app for operation. All you need is the remote control and the buttons on the device. The network connection can be configured in a web front end. However, the use of WiFi and local area network (LAN) together are limited: If you disconnect the network cable, you have to enable the WiFi connection manually again.

Figure 2: The Onkyo R-N855 is a typical network receiver with only a few front panel controls.

The device has only a few controls. The small LCD lets you scroll through the NAS folders for music tracks, but control is very limited. Only after a firmware update could I fast forward through titles, although I could not stop a track with the fiddly menu button. Only the remote control or a smartphone offer really useful control.

Not surprisingly, the few switches and buttons and the display are obviously not designed to operate the receiver. Instead, a smartphone can be connected to the R-N855 by Bluetooth to stream music to the device from various apps such as Spotify.

When connecting an external solid-state drive with the USB port, though, I noticed that the R-N855 failed to identify the drive. The reason is given in the operating instructions: "The unit is also compatible with USB storage devices using the FAT16 or FAT32 file system formats. Other formats such as exFAT, NTFS, and HFS cannot be played by this unit" [2]. Because my hard drive was exFAT-formatted, the receiver could not read it.

The device has its own Bluetooth button on the front, but you can only connect Bluetooth devices that send their data to the receiver. Outputting the data to a Bluetooth headset or earplug does not work. Moreover WoL is only a pipe dream, which means the Onkyo R-N855 is out of the running as a network receiver for my purposes, despite a price of just under $800 (£500, EUR455).

I repeated this process with other test devices. The Denon AVR-X1400H ($450/£500/EUR300) has basically the same functions with the same weaknesses. The receiver can only play FAT16 and FAT32, and output via Bluetooth is again impossible. The device has a few more buttons than the Onkyo receiver, but using them is finicky, so you cannot start or stop tracks. The receiver is primarily designed to produce a cinematic sound in your living room with its 7.1-channel surround system. Additionally, the device can play music on various loudspeakers in the home with the HEOS WiFi multiroom sound system (Figure 3).

Figure 3: The Denon AVR-X1400H has more buttons than the Onkyo R-N855, but they hardly make operation any easier.

What seemed best suited to my purposes was a compact system like the Denon CEOL-N10 ($400/£360/EUR400). It has a slightly larger display and a CD player (Figure 4). Even Alexa voice control is possible. Like the AVR-X1400H, the CEOL-N10 can distribute music to several rooms through the HEOS system. Various music services can also be streamed to the system from an app, but almost the entire industry seems to have agreed not to support Bluetooth headphones with their receivers.

Figure 4: The Denon CEOL is a compact system with a CD player.

One exception is the Yamaha RX-A670 receiver (now discontinued, but available used), which has all imaginable features and even an integrated Bluetooth audio transmitter, as does the somewhat older RX-V681. However, the newer R-N803D, also with good connectivity but at even more expense, sees Yamaha drop this feature. Again, though, all the Yamaha devices only support FAT16 and FAT32.

Requirements

For my purposes, the receiver needs to meet at least the following requirements: It has to play my music collection from the home network-attached storage (NAS), recognize files on USB media, and transmit sound to a Bluetooth headset. Additionally, I want to be able to operate all the basic functions without an additional device, such as a smartphone app. For example, navigation of the integrated displays and buttons must be so convenient that titles on the NAS can be found and played. The icing on the cake would be a Wake-on-LAN (WoL) function for the NAS.

The rationale behind these requirements is that audio receivers are a long-term purchase that should normally continue to function reliably after several years. Whether they will still be able to communicate with the latest devices in 10, 15, or even 20 years is another matter. If not, they would be electronic scrap again, even if they are still working flawlessly. I find additional Bluetooth adapters that plug into the headphone jack cumbersome to use, and they constantly need to be plugged and unplugged. Pairing can also be very unreliable.

HiFiBerry

Buying a brand new receiver feels somewhat like buying an electric car. You can spend a large amount of money without even getting close to the range of the cheapest gasoline model. The alternative to a complete receiver is an independent network player. You can connect it to an existing system and then, for example, play music to the amplifier through a Bluetooth adapter. Other network players can in turn be integrated into the home network via DLNA. One good example of this is the Yamaha NP-S303. It can play music on headphones and speakers via Bluetooth and is otherwise very well networked, but without remote control and an app, nothing happens. The two-line LCD display supports very limited use without the MusicCast app.

In a test, the German Frankfurter Digital Newspaper [3] pointed out another way to network your stereo system with the help of a Raspberry Pi computer and a plug-in sound card like the HiFiBerry [4]. Even in terms of sound quality, this combination is said to keep up with the easily more expensive test devices.

HiFiBerry offers a small box for combining with the Raspberry Pi, but I am looking for a standalone model that can be operated without an app, which would require a touch-capable display and thus a larger housing.

Because my Philips CD player is broken, a network drive removes the need for CDs anyway, and the player sits right at the top of the case, I had no problem freeing up some space for the display (Figure 5). More than enough space is still available below the plastic hood to accommodate the Rasp Pi and HiFiBerry. If both boards are positioned correctly in the corner, all outputs can be used. The thin plastic also makes it easy to cut out the recesses for the display and connections (Figure 6).

Figure 5: A seven-inch touch display and the Kodi media center make it relatively easy to browse a music collection.

Figure 6: The Rasp Pi comes with at least four USB ports. It can be networked over the network drive and WiFi.

On/Off Switch

Because the Raspberry Pi does not have an on/off switch, I will be adding another board with that function to the two boards already in place (Figure 7). The now unused button that previously operated the drawer of the CD player can be used for my purposes. You can find a number of how-tos on the web for on/off switches, some of which need a complete microcontroller. However, I designed a circuit with a simple resistor-capacitor (RC) circuit and a transistor-controlled self-holding relay, which allows me to power on and boot the Rasp Pi (Figure 8).

Figure 7: The circuit diagram for the on/off switch. The former eject button of the CD drawer serves as a button.

Figure 8: The Rasp Pi and its peripherals can be switched on and off safely with an additional circuit board.

Additionally, the same drawer button can be used to call several functions, which I query with a Rasp Pi GPIO input (Figure 9). Depending on the number of operations, the Rasp Pi can then be shut down or rebooted with a small Python script. The Raspberry Pi's USB output, unlike the 5V GPIO pins, is switched off at shutdown. The capacitor of the RC circuit then discharges, and the self-holding relay interrupts the power supply again.

Figure 9: The Rasp Pi and HiFiBerry boards fit into the corner of an unused CD housing with a metal plate underneath.