HiFi nirvana

The staring point for HiFi nirvana is Apple's media solution. This stores your music on either a computer or on an iPod/iPad or iPhone.

AAC lossy and FLAC lossless

One thing that is important is to realise that the Apple iPod, iPad and iPhone rely on Apple's choice of AAC lossy compressed music files, recorded at 16bit/44.1kHz (CD standard), but compressed, and because these are lossy they are not as good as CD's for quality. So if you make up your music media centre using just an iPod, iPad or iPhone then you are limited to music purchased from iTunes Store in the AAC format. If you include a computer in the setup you have a much better chance to have HiFi reproduction, as iTunes running on a computer can store AAC lossy music files, CD AIFF ripped music files (plain uncompressed files) or HD audio download FLAC files at 24bit/96kHz. You will have to convert these to Apple's lossless format using a program like XLD but this is simple.

It goes without saying that a Mac computer is better in all respects than a Windows PC...

Media centre to loudspeaker

Now how to get the music from your iTunes/iPod library, running on the iDevice or on your computer?

I should explain, there are two types of amplifier, a plain analog one or an amplifier with a digital audio input and a DAC (Digital Analog Converter). If you have an analog only amplifier then you have two choices, connect the amplifier from the iDevice or computer with a cable, or use an Airport Express WiFi interface. If you have an amplifier with a DAC, either built-in or separate, then you have the choice of connecting by an Optical link (TOSLINK, SPDIF) to your computer, or over WiFi with an Airport Express or the new Apple TV 2.

I suggest the Apple TV2. For two basic reasons, it can also feed your TV with video over an HDMI output and it can handle audio up to 16bit/48kHz - which is a simple down-sample from even HD audio at 24bit/96kHz, thus preserving the audio quality.

So my choice is the Apple TV 2. Now comes the choice of DAC and power amplifiers. First the amplifiers. One of the issues about audio is that the bandwidth must be preserved to equal as much as possible the actual sounds made by the instruments. Many instruments make sounds well above the human hearing top threshold of 20kHz (actually I doubt if anyone can hear 20kHz, most likely the limit is 12-18kHz depending on your age). But to get the timbre and dynamics of the instruments right you do need a wider audio bandwidth. A good target is 40-50kHz to end, and at least 5Hz bottom end to get the breathiness of voices and the bumph from low notes.

So how to build such an amplifier? First the power supply, a toroidal transformer (cuts down stray magnetic fields and adds efficiency, rectifiers and good size condensers. I use these from HK (eBay) and a UK electronics distributor:





And then the amplifiers proper. Here a very good choice is the superb modules from Hypex. These are Class D and thus have low dissipation, they are available in various sizes from 180W to 700W! I chose the UcD180 version





Now what about a DAC? There are a millions DACs on the market some ridiculously expensive. There are a much more limited number of DAC chips from which most of them are made. There is also a lot of misunderstanding about DACS (more expensive = better syndrome). Frankly I am of the opinion that a good DAC can be cheap. I mean even the best chipsets in the world (Wolfson WM...) are less than £5, so why would a DAC cost £500? I chose to source from HK and I found one made by Muse using the TDA1543 chips, in fact the design uses 4 of them and sounds very good. Cost? About £40 only.



I built the whole lot into a fancy box and put a volume control in there and a pretty blue LED to show when its active. Total cost for power supply, amplifiers plus DAC around £200.

Now the interconnect

My choice is the Apple TV 2 so that I can stream both video and audio over WiFi. I can leave my computer in my study and have the media wirelessly sent to the living room. I can remotely control iTunes on the my computer using Apple's Remote App on my iPad or iPhone.



And the results are wonderful, I use a pair of Spendor loudspeakers which are small enough to please the wife, but have a sound big enough for me. HiFi nirvana.