Sunday, January 12, 2014

Management of Digital Music. Part 2: Hardware

Here's Part 2 in the series. Part 1 dealt with the modern history of musical replay and the transition from analogue storage (vinyl LPs, cassette tapes, etc) to digital files managed by a computer of some type. In this article I'll go through the basics of the hardware required to set up a genuine hi-fi system. Let me stress that this is a not a guide for the audiophile  -it's intended for (i) individuals who've been collecting digital music libraries and want to know how to manage them better and get better sound quality than their desktop sound dock or (ii) people like me who grew up playing LPs and CDs on decent hi-fis but are uncertain as to the best way to integrate these formats. Anyway let's get into it...

The replay of digitally encoded music in hi-fidelity form requires three basic components:
  1. A sound source (in this case a computer hard drive)
  2. A pair of speakers
  3. An amplifier
I'll deal with these items in reverse order. Needless to say an amplifier and speakers are universal for any system and I'll try not to labour over their descriptions. The set of the sound source is tricky and quite a bit more complicated than in the day when we just chucked an LP on a turntable and let it play.


My own amp is an Italian made Unison Simply Two integrated amplifier.  For the techies, it's 10w per channel of pure class A current. Really all you need to know is that it looks and sounds wonderful

An amplifier's job is to, errr, amplify the signal from the sound source to the speakers. It's necessary because an iPod/iPad/computer doesn't put out enough of an electronic audio signal to power a pair of speakers; they'll drive a pair of ear buds but that's about it.  Even modest bookshelf speakers require quite a lot of power to get the speaker cone flapping and moving air (which is what sound is all about).  Crudely, it makes the sound louder. A powerful amplifier can amplify the signal in a very lazy way and introduces very little distortion into the music.  There are lots of types available and a discussion of pre-amps and power amps is beyonds the scope of this article: suffice to say that an amp that integrates the pre and power stages (logically described and an "integrated amplifier")  is more than sufficient for most purposes.  The same goes for solid state electronics vs valves. As a rule-of-thumb, amps using old school "valves" or "tubes" usually sound warmer than their solid state cousins. In my humble opinion they have a retro-cool look but that's a matter of individual taste. Electrically they are pretty inefficient and tend to run hot (as in temperature). Decent amplifiers cost anything from 100 dollars/pounds/euro to something that looks like a NASA budget.


Speakers: this is where the sound comes out. They come in all shapes and sizes and should be selected for the room size, listening habits and musical taste. Don't confuse these with self-amplified computer speakers; they need an amplifier to drive them -this is a source of confusion with many young people brought up with sound docks and computer speakers. They also need to be connected to the amplifier with high quality cables (sound quality out of Bluetooth-connected wireless speakers is usually poor).  Speakers shown are my own British made Rega RS-5s.

Speakers are what the sound comes out of.  Generally the higher the quality the better the sound. The same rule applies to their cost as amplifiers i.e. anything from 100 units of currency to "how much?  -you're having a laugh!".  Quality and price are not necessarily correlated. Bigger and lazier usually sounds better (lower distortion) but requires a more powerful amplifier. Pick the size to suit your room and your budget. Space them correctly (the listener and the speakers should ideally form an isosceles triangle) and don't use them as plant stands (it looks naff and ruins the sound).

Sound Source (the important part)

Some Notes on Terminology
Now we are getting to the nitty gritty of the system. Before I start off on technical details, I think it's worth dealing with some commonly encountered terminology which can be quite confusing (it was for me when I started on the digital music pathway and I'm a technophile) or even a deterrent for anyone considering a digitally managed hi-fi. Here are some of the confounding terms:

"Home Entertainment System" A fuzzy term that reminds of the integrated music centers of the 70s and 80s. Essentially a computer box controls the TV for multiple functions including broadcast programs, streamed movies, DVDs, CDs, games, internet access etc and in addition can act as storage for music and games. The Xbox is marketed as such a device. Like the music centers of old, it's a convenient concept but the Jack-of-all-Trades approach means that nothing is done particularly well (particularly in terms of high fidelity playback) and component failure brings down the whole system.

"Home Theatre"  This is exactly what it says, namely an audio visual center for the home and usually comprises a large plasma or LED screen TV connected to a large amplifier and 5-7 surround speakers.  A home theatre can be a home entertainment system. Such systems are great for providing dramatic soundtracks for movies but most are not that good for hi-fi even though many have inputs for iPod-resident music. My advice is to keep hi-fi and television systems separate (more about this below).

"Music Server" A slightly pretentious way of describing the computer which stores and plays your music. In the context of true high fidelity replay, music servers should be dedicated devices.

"Network Attached Storage (NAS)" This means any music library that is connected to your wi-fi network and visible to other computers. A NAS is usually a hard drive on or attached to your music server and used for the purpose of storing your music library.

"Streaming" Nothing to do with plumbing although it's a wretchedly vague and confusing term. Essentially it means that music resident on one device is visible to, and can be played on, another device via some kind of wireless network, usually wi-fi although it can include Bluetooth. For example music from a master library on, say, a desktop computer can be played on  a laptop if both are on the same wi-fi network and sharing is enabled on iTunes.  In other contexts, streaming can mean playing internet radios such as Pandora or Spotify (i.e. music is streamed rather than broadcast) or movies are streamed from sources such as Netflix. With the exception of internet radio, I'm going to advise against streaming on genuine hi-fi system as sharing music over a wi-fi network invariably leads to sonic degradation (movies are ok streamed but just put them on a separate system).

A Computer or iPod?

My music server components (clockwise from top left): 246Gb solid state drive, Mac Mini with CD/DVD slot (c2010), 1 Tb Seagate disk drive, Cambridge Audio DACMagic 100 DAC, bluetooth mouse, bluetooth keyboard, 2 x 4Gb RAM chips

There are several ways to store digital music files. After quite a bit of thought, I opted to put them on a computer hard drive rather than an iPod for the following reasons (i) the user interface on an iPod is fiddly and limiting (ii) I'd be restricted to using iTunes as a music player which has multiple disadvantages in itself (I'll describe these in detail in Part 3 of the series), (iii) storage space: the iPod with the largest amount of space available is 160 Gb on the "classic" model -this sounds like a lot but actually is very easy to fill when using lossless files (again more detail on this in Part 3) and finally (iv) to get music onto an iPod, first it has to be resident on a computer.

All things considered, a computer seems by far the most logical choice as a base for one's music library. Any reasonably well-powered laptop or desktop can be used but I suggest that lower powered notebooks be avoided as their limitations will eventually cause problems. The selection is largely a mix of aesthetics and what computer you might have lying around.  The operating system (Mac OS or Windows) is optional: both will  support iTunes, which is hard to get away from, as well as other music players (see Part 3). I don't know about the suitability of Linux or Android operating systems in terms of their compatibility with iTunes. Just about anything can be made to sync with anything else these days but my five cents worth of advice is to stay mainstream in order to reduce compatibility issues.

Computer Hardware
First, I bought a used Mac Mini on eBay. It came with a wireless mouse and keyboard (necessary). I picked the mid-2010 model of this computer because it was the last one that came with a built in CD/DVD slot. An external drive would be ok but aesthetically it's not a clean a solution. I'm aware that the system is not future proof and at some point I'll have to upgrade the computer but as its primary task is just to replay music, it should be good for quite awhile. I expect at least 5 years. The processing power is more than up to the task and the solid state hard drive I've fitted (see below) really speeds things up and should increase reliability.

I made two physical upgrades to the Mac Mini: I increased the RAM memory from 2Mb to 8Mb (I purchased two 4Gb RAM chips from Crucial Technologies) and I changed the original electro-mechanical hard disk drive to a solid state 256Gb flash memory drive (again from Crucial). The purpose of the solid state drive was to make the computer's primary function as fast and as electronically and acoustically quiet as possible. As a side note, the flash drive also speeds up the computers speed amazingly  -a reboot takes seconds instead of a minute or more and apps launch almost instantly.  The increase RAM also helps prevent any lag in the computer's function.

I then attached to the Mac, a one Terabyte (Tb) external Seagate hard drive (thanks again, Crucial). This is the primary storage for the music library or NAS. Now before you ask why didn't I use a solid state drive, the answer is that 1 Tb drives are not yet available, at least at consumer-affordable prices. However the picture is changing fast and when they are offered at a reasonable price the old whirring hard drive will be replaced.

The final box I added to the system was a Digital to Analogue Converter (DAC), specifically a DAC Magic100 from Cambridge Audio. A DAC, as the name suggests, converts the digital output of a music player (this can be music files played with iTunes or the signal from a CD player) into an analogue form for the amplifier. Most CD players contain a DAC of reasonable quality but computers and iPods have a very limited sound card that performs this function. The DAC magic connects to to the Mac Mini by an (audio quality) USB cable and intercepts the digital signal before it is processed by the computer's sound card. The increase in audio quality is striking.

A HD computer screen completes the hardware list. My apologies for the flash glare but these things are difficult to photograph without the use of flash

Then just to enable me to see what I was doing I added an LED high definition computer screen. It's a nothing special brand from Amazon but was very inexpensive and had great reviews.

Finally, I'll pre-empt the question "why don't you just buy a music streamer?". The reason is that the technology is still evolving. Many streamers perform a variety of home entertainment functions and are neither fish nor fowl. As mentioned above, the Xbox is a good example. There are certainly some excellent music-dedicated systems on the market but they tend to be very expensive and don't have the flexibility of a computer hard drive. If for example I want to upgrade the Mac Mini I can always use it for another purpose such as a back-up drive or photo storage. This would not be possible with a high end dedicated streamer, many of which will become expensive doorstops after a few years. Also I didn't buy a streamer because I reasoned that many people would have a spare PC/Mac lying around that could be gainfully employed to storing a music library.

In summary, I've described here the equipment needed to replay digital music at a high level of fidelity. It's intended as a guide for the perplexed and shows one way to go about building a dedicated music server. For audiophiles roaming the internet I should say that this article is not for you. I certainly don't want to be told by Absolute Sound readers that because I haven't spent $2000 on a DAC (easily done) or that I'm not using interconnects made of solid iridium that the system is only fit to be used as a car stereo.

The final part in the series will deal with music file formats and player software.

To be continued...

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