The streaming audio network – bits are bits?

Without a network, there is very little to stream. After all, the data must be able to go from “A” to “B,” and that requires a transport system. That system is a network.

The computer network is nothing new. We have had networks since the 1950s. In fact, the U.S. Army had set up an automated radar system with modems. Between the 1950s and ’73s, there were many trials and proprietary systems. However, in 1973 Ethernet was invented (and patented in ’75) which turned out to be a solid standard for the networking industry. (So know that Ethernet is a standard and not a type of cable). Together with the development of TCP in 1974, we may call that the basis of the modern network and Internet. .

However, from the turn of the millennium, things moved very fast. Broadband Internet became commonplace in developed countries, allowing more and more sharing online. And online streaming media also started to become a possibility. And therefore the need for solid home networks also grew. Around 2000, gigabit Ethernet also began to penetrate, which is still sufficient for many households today, although we see a shift to multigig technology (switches that support 1, 2.5 and 5 Gbit/s).

Definition

First, let’s define what a network is. We would define it as:

A collection of connected devices that exchanges (digital) data with each other. What that data is is irrelevant. What kind of device it is is also irrelevant. And exactly what medium is used is also not very exciting. What matters is that they are connected and can exchange data.

Components

To establish an Internet connection in a home network, you need at least a modem and a router. In many cases, these are integrated, along with a wireless access point (wifi access point) and a swicht for wired connections, and the Internet provider supplies that as one device: the modem router.

An average home network will therefore also consist of the Internet provider’s modem router with smartphones, tablets and perhaps laptops or other types of computers connected to it.

However, it can be even simpler: a phone in hotspot mode with another phone connected to it. Or a bluetooth connection between the phone and smartwatch. After all: a network does not always have to be wifi or Ethernet. It can also be built via bluetooth. (After all: the medium is not important).

Expand

Looking at a slightly more extensive network, a decent network could consist of a separate modem (for example, by putting the modem router in bridge mode), a decent router, a separate switch for the wired devices and a separate wifi access point for the wireless devices.

The advantage of a separate router, switch and wifi access point is that the network tends to be more stable and slightly faster AND – in the case of a separate wifi access point – you can place the devices much more strategically.

Many modem routers with wifi disappear in the meter cupboard or some other awkward place. As a result, Wi-Fi coverage is often very poor which often causes instability. This can be problematic with streamers connected wirelessly. By placing a wifi access point in a central location, in many cases you drastically improve the coverage and thus the speed and stability of the network.

In the case of streamers that are wired connected – something we definitely recommend – it may be very inconvenient to run a cable. This problem can possibly be solved by placing a network switch in strategic locations.

IP addresses

Just a bit of technology which is particularly useful for you to understand. You can think of a network as a kind of village, or city. There are neighborhoods, streets, houses… With a network, it’s no different. There are all kinds of networks, and those networks are again divided into subnets. Now we’re not going to cover that here, but know that within a network, addressing is crucial. Just like in the “regular human world. If something goes wrong with the addressing, the network simply crashes.

To know where to go, you obviously need to know the street name and house number. So it works the same way in a network. A data packet needs to know where to go and which door to knock on. That’s why a data packet contains a sender and a receiver. Both based on IP addresses.

IP stands for Internet Protocol. That IP address is unique within a network at that time. As long as a device is on, the IP address remains the same. With a device that comes and goes, the IP address may change once, because it has been outside the network for longer than a certain time (lease time). Often the lease time is 24 hours.

Such an IP address can look like this: 192.168.1.14. The first three “blocks”: 192.168.1, which almost never change in a home network. To compare with streets and houses: you could say that 192 is the country, 168 is the city, 1 is the street, and then come the house numbers. Within a home network, only house numbers need to be distributed.

Technically, a router often gets default settings from the factory that ensure that only the last block is distributed (that’s down to the so-called subnet mask). And with 253 addresses (192.168.1.1 or .254 is often the router itself), you have plenty of room, it seems to us. If you do run out of addresses, there are ways to free up more addresses.

Many streamers allow you to log in to the web interface by typing the ip address into the browser. And sometimes you can then adjust all kinds of useful things. Sometimes you can only do the firmware/software update by logging into the web-interface. So know that that goes through the IP address.

If you want to know where to find the address … it is usually through the router. You can log into the router (via the router’s ip address) and then go to the list of connected devices. Where that list is located varies by model. Some put it under DHCP leases, others under LAN / Local Network, still other models have it under Connected Devices or something similar.

Bandwidth

Networks have become extremely fast in a short period of time. In the 1950s we were still working with bits per second, in the 1980s we got 10 Mbit Ethernet and now in home networks we have been working with gigabits per second for a long time and are already seeing a transition to multigig.

But do we need all that bandwidth for streaming audio? No. It’s as simple as that. You can also just do the math: 16 bit / 44.1 kHz / 2 channels amounts to 1441 Kbps, or about 1.5 Mbit/s. That’s very little.

If we look at high-res audio and DSD, we see that even at 32 bit / 768 KHz / 2 channels, the bandwidth is just under 50 Mbit/s. That’s only ^1/20th of a standard gigabit connection. So even a lossless 32 bit / 768 kHz 5.1-channel multichannel recording could easily be done over a gigabit line.

You will now understand that studios are particularly pleased with developments in network audio. Systems like Dante, AES67 or Ravenna can transport around 200 channels with ease even at 24 bit / 192 kHz resolutions, since one channel uncompressed takes up around 4.6 Mbit.

Wireless or wired?

Now that you know how much bandwidth audio needs, the next question is, of course: wireless or wired?

Although wireless is getting better and better, we still don’t advocate a wireless connection for audio streaming. There are several reasons for this.

First of all, audio streaming requires a very stable connection. A connection without “dips” in bandwidth. While Wi-Fi can achieve very reasonable speeds, the connections are far from stable. There are dips and peaks in bandwidth because there are numerous other wireless networks operating nearby. These get in each other’s way.

Second, Wi-Fi does not handle multiroom audio well which needs to play in sync. In other words, multicast traffic. There are numerous “optimizations” that the industry has tried to implement, but the fact is: it is not bullet-proof.

Most problems with multi-room audio arise with systems that are connected wirelessly. As soon as enthusiasts use a cable connection, the problem is solved, which makes sense: a wired network does not have these “limitations” or problems. There is much more bandwidth, it is stable ánd it is bi-directional. All things that wifi lacks.

Impact on display

Does a network – switch or router – affect audio playback? Short answer: yes. Alpha Audio has done a lot of research into this. Down to clock measurements in streamers and measurements of (common mode) noise and switch noise. If you want to know the details of this, we refer you to the articles on Alpha Audio. There you can see the details of the measurement setups and the results of the listening tests.

In short, the bottom line is that there is a big difference in performance in network switches (and routers too). We are not talking about speed or functionality, but noise. They all send data perfectly, but there is a big difference in how “clean” they do it. How much switching and power supply noise comes along with sending the audio data?

This noise comes mainly from the chipsets and power supply of the device. Now, previously the thought was always: surely there is a ‘galvanic decoupling’ in a switch (and also in the streamer for that matter). Yes: that is correct, but they are not 100% tight. Some noise always leaks through. And that sails along with the data. So your nice streamer in. And that little bit of noise creates sound differences.

How is it possible that a little noise creates differences in sound? It’s all digital, isn’t it? Very simple: among other things, clock stability is affected by the noise that goes in with it. The better – read: the less noise – the switch, the smaller the clock deviations are. And thus the better the streamer performs.

Again: this is all fairly briefly explained. On Alpha Audio we will go a little deeper into the matter, also break down the various types of jitter and show the measurement results.

Something about CAT5, 5E, 6…7…8?

Ethernet cables come in many shapes and sizes. There are shielded models, unshielded cables, CAT6, 7… Models with thick plugs, gold plugs, and so on. But what does it all say?

CAT is not a quality designation in the sense that it has nothing, but nothing to do with audio quality. It indicates a CATegory and thus the suitability for a certain speed, sometimes at a certain length of cable. You should think about that a standard CAT6 cable is suitable for 10Gbit at lengths up to 55 meters. CAT6A can handle 10Gbit up to 100 meters, because the twist is slightly different.

So it’s not that a CAT8 cable sounds better than a CAT6 cable. The quality of the cable is only determined by the internal conductors and shielding. Even the plugs have minimal influence as we at Alpha Audio have already researched. So don’t be fooled.