Whole-House Music Systems a.k.a. Multi-Room Music Systems

part of materialism by Philip Greenspun; written in October 2005, last update May 2022

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In setting up a system to play music in multiple rooms throughout a house, start by answering the following questions: [If you're pressed for time and just want to buy something, the author's current recommendation for most applications is the Sonos system (see below), pulling music from a Synology disk array or Western Digital My Book, and driving GoldenEar in-wall speakers or whichever bookshelf speakers fit your budget.]

Old-school Solution to the Whole-House Music Challenge

Get a $15 FM transmitter and connect it to your primary music source. Tune in the signal on FM radios elsewhere in your house.

Whole-House Music Approach I: Add Extra Speakers to Legacy Stereo

A simple approach to multi-room sound is adding a second pair of speakers to an existing home stereo system (the "legacy stereo"). If you have newer equipment, the receiver may already be able to broadcast wirelessly to additional speakers or receivers. Yamaha's MusicCast is an example of this approach.

If you're a throwback to the 1990s, you can run speaker wire in the walls and either terminate them in a second room or terminate them at in-wall speakers. The typical A/V receiver will have a second pair of speaker outputs and can drive a small additional pair of speakers without any challenge. Make sure that the cable is UL-rated but otherwise there is no trick to the wiring.

Problems with this approach include the following: (1) depending on receiver age, might not be able to control the volume of the rooms independently, (2) cannot control the volume from the second room, and (3) cannot control the source, pause, or move forward a track from the second room.

The classical solution to the volume control problem is to place an "LPAD" resistive voltage divider in the second room, which tends to look like a volume control knob on the wall. The LPAD converts a selectable amount of unwanted power amplifier energy into heat. LPADs compromise sound quality to some extent.

On the assumption that the legacy stereo is controlled via infrared (IR) remote controls there are various techniques for getting IR signals back into the room where the CD player and receiver reside. One technique is the wall keypad connected (more wiring) to an IR transmitter near the legacy stereo. This has to be programmed so that pressing the "track forward" key on the wall keypad will send out a "Pioneer CD player track forward" IR signal. If you're willing to carry remotes physically around the house you can get wireless IR repeaters or "extenders" that listen for IR signals in one room and rebroadcast them in the room with the legacy stereo.

Now you're set up but what if you want to add a third or fourth room? This will probably be beyond the capabilities of the 1990s stereo power amp and the old-school receiver manufacturers, such as Yamaha and Denon (with its HEOS system), have not set the world on fire with their multi-room systems.

Whole-House Music Approach II: Add a Multi-Room Power Amp and Control System to Legacy Stereo

Various companies make multi-channel amplifiers specifically designed for whole-house music. You plug your legacy stereo components into the multi-room amp and then run a bundle of wires from the multi-room amp out to each room. Each room has an in-wall speaker that takes a musical signal from the speaker wires in the bundle. Each room has a wall-mounted keypad and volume control that sends control signals back to the multi-room amp. The control signals tell the central amp to "reduce volume to the bathroom speakers" or "junior is in his bedroom and doesn't want to listen to NPR so change the source for this room from FM tuner to the CD jukebox" or "the Forward button was pushed; send an IR signal to the CD player asking for the next track".

These systems represent the state-of-the-art circa 1990 and work pretty well if the legacy stereo is where your content lives. In a McMansion the sound quality might be compromised to some extent by the long speaker wire runs. In a rental apartment you might not want to pay for all the hard-wiring that is entailed. Without a good interface among the components it would generally be impossible to see, on a keypad, the name of the CD being played or the freqency of the tuned-in radio station. Otherwise this is a reasonable way to go.

The best example of this kind of system ever designed was the B&W CASA system. They ran a single CAT5 wire (computer Ethernet cable) from the central brain to each in-wall loudspeaker. The CAT5 wire carried a balanced analog signal, low-voltage DC power, and digital control signals back to the brain. Each speaker had its own low-voltage DC power amplifier, like the amps found in car stereos (it would be against electrical code to mount a mains-voltage AC amplifier in the wall). Each speaker had an IR diode watching for remote control signals, which it would repeat back to the brain, presumably adjacent to the legacy stereo. Thus you could walk around the house with your, say, Pioneer remote control and point it at any in-wall speaker and have it work just as though you were in your living room. I said to myself "this system seems just about perfect, though it would sure be ugly if B&W decided to discontinue it and left you with a house full of orphaned in-wall components that only understand this proprietary CAT5 interface." Back in the early 2000s, while I was debating whether or not to install one, B&W discontinued CASA. This is a good example of why one needs to think long-term before cutting holes in walls.

Whole-House Music Approach III: Think Digital

In a world where content is increasingly digitized and sitting on a server, how can it make sense to place the legacy stereo at the center of the house? The legacy stereo offers high quality reproduction for critical listening but otherwise has little to recommend it. The PC or smartphone has access to millions of songs on subscription-based services such as Deezer and Tidal. The PC or smartphone contains MP3 files, podcasts, and videos. The PC or smartphone knows the names of the songs that it is playing and can show you a photo of the album cover. The PC or smartphone is part of a high-speed wired and wireless network.

One you place a computer at the center of the audio system, the whole-house music system looks completely different. Any computer or computerized device that can talk to the Internet can play any streaming track. Any computer or computerized device that can talk to your local disk storage can play any music file in your collection. The design challenges are user interface and software to enable access to vast world of music, both local and streaming, and to ensure that the digitally networked machines throughout the house are playing the same song in sync.

The rest of this article will be about building an Internet-centric whole-house music system.

Why aren't Bluetooth speakers sufficient?

Everyone has a phone that can stream music to a pair of headphones or a single speaker via Bluetooth. Why can't this be extended to stream music to 5 pairs of speakers in different rooms of a house? The Bluetooth standard is optimized for shorter range communication than the dimensions of the typical American single-family house. Also, hardly any phones implement a Bluetooth multicast protocol. Therefore, only one audio device can be connected at a time. (Two friends can't generally listen to the same song being played on a phone, for example, by both connecting their Bluetooth ear buds to that phone.)

For local files, first make sure that they're accessible

Other family members may not want the music to stop if you close your laptop and walk out the door. Thus, you'll need to keep any of your own music files on network-attached storage (NAS). The NAS box is a compact little machine that has enough electronics to talk to disk drives and the network. The NAS box has no audio, video, or keyboard interfaces. The NAS box has no CD or DVD drives. The NAS box may have a sophisticated RAID ("redundant array of independent disks") controller so that the failure of a single disk drive will not result in any loss of data or interruption in service.

Based on chassis noise and ease of setup, the best current NAS devices for the home are the Synology disk array and Western Digital My Book. Streaming digital music is not demanding by current computer communications standards, but Sonos systems can interact badly with some routers and switches. Netgear seems to make everyone happy.

How big a disk subsystem do you need? One hour of music on an uncompressed CD occupies 635 MB of space and therefore you can fit 1000 hours into each TB of disk. With a lossless compression format such as FLAC, this doubles to 2000 hours. Most people receive and/or store their music CD in formats such as MP3 that are much more space-efficient. An hour of music at 192 Kbps takes up only 86 MB, which means that 7300 hours fit into 1 TB.

As of mid-2022, I think the best disk drives to buy for a home NAS are 16 TB. Western Digital is probably better than Seagate.

Sonos

Founded in 2002, Sonos has endured while nearly all of its competitors have died, including attempts from huge companies such as Microsoft, Cisco (!), and Philips (Streamium). Sonos worked the problem of whole-house music backwards from the consumer's point of view. In the early 2000s, Sonos seems to have assumed the following: As originally conceived, each Sonos "Zone Player" is a little white brick that can talk to the computers in the house, can talk to other Zone Players, and can talk to a fancy Sonos remote control. These communications capabilities enable the Zone Player to show you, via the display on the remote, what music is available to play and, depending how you've set it up, to tell other Zone Players to play the same thing. Each Zone Player has line inputs and outputs so it can take a signal from a legacy stereo or a television and pump it into the network at CD quality for other Zone Players to play. Each Zone Player has a 55 watt/channel power amp that enables it to drive one or two pairs of conventional loudspeakers. The Zone Player presents a clean appearance with only one light and three buttons: volume up, volume down, mute.

The basic setup for a 3BR apartment would be as follows. You would have one Zone Player next to the legacy stereo, connected via the line inputs, so that you could play MP3s from your computer on the big speakers and so that you could play your LP records and SACDs through the rest of the house. This Zone Player would not have its loudspeaker outlets connected to anything. You would have another Zone Player in your master bedroom closet, driving two sets of speakers in parallel. The first set of speakers would be conventionally wired to the Zone Player. The second pair of speakers would be in the ceiling of the master bathroom, connected by wires that terminate in a wall-mounted jack inside the closet. You would have a third Zone Player in your home office, next to your computer, because although the Sonos Desktop software runs on a Windows machine or Macintosh, the computer itself won't play what the Zone Players are playing. You might have a fourth Zone player in your kitchen.

I set up a system as described in the previous paragraph in approximately 15 minutes, including informing the Sonos software of the location of my music library, which it indexed in a background process.

Its basic capabilities put the Sonos system far ahead of the alternatives in terms of compatibility with legacy stereos and TVs but the details make the system even more impressive.

Network Connectivity. Sonos wants at least one of the Zone Players plugged into a hard-wired Internet connection. Unlike almost any other product on the market, Sonos refrains from hogging the "drop". The back of the Zone Player sports four RJ45 jacks. If you previously had a computer plugged into a network drop, simply run a cable from any of the Zone Player's four ports to the wall and connect the computer to one of the remaining three ports on the Zone Player. A single Zone Player will find other Zone Players on the wired network and also any that are within range of its 802.11n Mbit wireless network transceiver. The Zone Players cooperatively set up an encrypted wireless network that requires no configuration by the consumer and is independent of any existing wireless network that might have been set up in the same apartment. The encryption ensures that your tech-savvy neighbors can't sniff packets and figure out that, while you've been crusading against rap music at PTA meetings, at home you enjoy Ice Cube's Death Certificate. An unadvertised features of the Sonos system is that it forwards packets it sees on the wired network. Suppose that, for example, you have a McMansion, where a single WiFi base station won't cover the whole house. If you have six or eight Sonos boxes they establish a mesh network where wireless packets need never travel more through one or two walls. You can then plug a laptop or desktop computer into the back of a functioning wirelessly connected Sonos box and it will provide connectivity for the computer.

Legacy Sources. The Sonos's analog line input digitizes signals from a legacy stereo or television at the standard Compact Disk sampling rate of 44.1Khz, 16 bits per sample.

Party Mode. Changing the source or the song for one Zone Player changes it for all. If you are sensible enough to live in a part of the country where you can afford a house large enough to support different music in different rooms, the Sonos will also let you play 32 different streams in 32 different zones.

Remote Control. Sonos used to make a wonderful hand-sized remote control unit that talks to whichever Zone Player is closest. Here's what I wrote about it:

The controller shows you album cover art, if available, what track is playing, and what track is next. Volume control gets dedicated up, down, and mute keys on the left. The controller has a wheel-style control like an iPod plus a huge display with soft keys. The rechargeable remote control has a motion sensor and wakes up if you pick it up, or if you touch any key. Sonos makes a charging cradle that you can mount on a wall and the remote is splash-resistant if you want to change tracks while sitting in the bathtub.
This was a perfect device. They don't make it anymore. Instead you install a free app on your Android or iOS device. Unfortunately, the typical Android or iOS device has 100 other apps installed and it takes a while to boot up the Sonos app. The touch screen of a phone or tablet is not as simple to operate as the volume control button was on the Sonos controller. Waking up a conventional phone or tablet and navigating to the Sonos app is simply too much work and takes too long for the desired operation of changing volume.

Subscription Music. Sonos works nicely with all of the subscription music services, such as Deezer, Spotify, Tidal, etc.

Boxes with built-in speakers. Apparently, plugging in speaker wire was too much trouble for most people so Sonos got away from making digital boxes with power amplifiers ("Sonos Amp" today) and into making many different types of powered WiFi speakers.

A Nit for Audiophiles The line input introduces about a 100 millisecond delay. If you hook up one Zone Player to your legacy stereo, for example, and play an LP record that is then broadcast to other zones, the music will come out of the speakers on those other zones just a little bit later than it came out of the main stereo speakers. This is very evident with percussion. If your legacy source is a preamp or receiver with a tape monitor loop, the solution is to connect the Zone Player via the tape monitor loop. When you want to play a legacy source throughout the house, set the legacy stereo on "monitor" so that you are actually playing from the analog line output of the Zone Player. Now everything is in sync but you've compromised the sound quality of the legacy stereo to some extent. Whereas before you had your $1,000 phono cartridge and $5,000 turntable feeding your $5,000 preamp, now everything must go through the Zone Player's CD-quality analog-digital and digital-analog converters.

Additional criticisms of the Sonos system:

Audio Pro

Straight outta Sweden... a Sonos-like system from a company that started by making powered speakers: Audio Pro. Vastly cheaper than Sonos if what you want to do is adapt legacy equipment because their Link 1 streaming player is only $129 (compare to $449 for the Sonos Port). It lacks any buttons to mute or adjust volume. Audio Pro does not make anything comparable to the Sonos Amp, which is unfortunate. Audio Pro makes a full line of powered speakers comparable to what Sonos offers.

Audioengine Multiroom

Another system that grew as a natural extension of making powered speakers, Audioengine has its own WiFi-based multiroom system. The little streaming box is $189 and doesn't seem to have any buttons. As with Audio Pro, there is nothing with a power amp other than complete speakers.

Bluesound

Bluesound is differentiated from Sonos in catering to high-end music lovers who want higher-than-CD quality. Unlike Audio Pro and Audioengine, Bluesound makes a streamer+amp. It is more expensive than the Sonos Amp (about $950) and, at least on paper, has less power (80 watts per channel).

Denon HEOS

Denon makes a "HEOS Wireless Amplifier" that is comparable in function to a Sonos Amp, but costs a bit less. It is 100 watts per channel. Denon can play higher-than-CD-quality recordings (up to 192 kHz/24 bits). User reviews are mixed. If your house was already wired with a lot of in-wall or in-ceiling speakers coming back to a central panel, the HEOS system includes an amp that will drive 4 pairs of speakers as potentially separate music zones.

Which Bookshelf Speakers?

With the Sonos Amp boxes, the latest of which push out 125 watts per channel (Class D power amp), you are free to use virtually any conventional (passive) loudspeaker. Audioengine makes some good ones for $250-400. Monoprice makes some medium-price speakers that are THX-certified for home theater and some dirt-cheap passive speakers.

If you're going to get active speakers, you might as well buy ones that are already part of multi-room music system.

Which In-Wall Speakers?

Choose in-wall speakers carefully. They are going to become part of your house and it will be expensive to change them. If your goal is to drive these with a Sonos amplifier, it works fine to hook two pairs up in parallel. I recommend the 14-gauge in-wall speaker from monoprice.com, which also sells two-speaker wall plates with 5-way binding posts. Get all of the hardware and any electrician can easily put the speakers in and run the wires back to the wall plates (don't forget to put the wall plates near a power outlet so that you can plug in the Sonos!).

Traditionally in-wall speakers are rectangular and in-ceiling speakers are circular. Functionally they are very similar, but most listeners find it more natural to face a pair of speakers and therefore in-wall speakers are preferred except for surround or background music. If the speakers are in-wall they're going to be passive (no amplifier).

For high-end sound, I recommend B&W in-wall speakers or GoldenEar.

If you're on a budget, it is Monoprice to the rescue. I played around with some of their first higher-end efforts, the Caliber speakers, back in 2013. They weren't impresive. Monoprice has some "Amber" in-wall speakers with ribbon tweeters and some not-very-cheap THX-certified in-wall speakers that are probably pretty good (no more than half the price of competitive products with similar-size drivers).


Text and pictures copyright 2005-2022 Philip Greenspun
philg@mit.edu