Update 2017: Sadly, I am no longer using the Firewave device because Griffin have not updated the Firewave application to run on versions of OSX more recent than 10.6 Snow Leopard. I am currently just using 2.0 stereo, feeding my Quad 303 amp and Spendor BC1 speakers from the headphone socket of my 2011 Mac Mini. I am looking at USB external sound cards but am not yet sure which one would give me the same seamless solution I was enjoying with the Firewave.
This note discusses the use of a particular device - the Griffin FireWave surround sound decoder as a component in a Mac-based HTPC (Home Theater Personal Computer).
I and many other people use a Mac Mini as the hub of a very capable Home Cinema (for US readers: Home Theater). If you're not familiar with the basics of using a Mac as an HTPC, you should probably Google 'Mac HTPC' and read some background in the blogs and forums you'll find, before reading on.
In this note I'm going to discuss only the audio side of my home cinema, which feeds two classic hifi speakers of very high-quality (Spendor BC1s) for the front audio channels and two average-quality Yamaha rear-channel speakers. I don't use a centre speaker; the centre channel is synthesised and presented via the two Spendors, because two different medium-quality centre speakers proved less satisfactory in trials. The BC1s also have excellent low-frequency response so no subwoofer is required.
So my speaker setup includes just four speakers which is a little unusual for surround sound, but the reasoning below applies equally well to most speaker configurations up to and including a full 5.1 setup and a suggestion on following that path is made in the conclusion.
The system is used for classical music listening via iTunes, TV viewing with EyeTV software and 2 x Elgato FireWire tuners and DVD viewing with Apple DVD player or VLC.
When my Denon ADV 1000 home cinema receiver gave up the ghost a few months ago, I reasoned as follows:
1. Home cinema receivers do a lot of things that people who have a PC in their system don't need. In particular, they have many input ports, source switching and video output switching all of which are totally unused in an HTPC setup.
2. Their resulting complexity has two negative consequences:
3. The minimum set of components that I needed to produce surround sound from my Intel Mac Mini-based home cinema were:
I concluded that a simple component-based audio system could in principle provide this and would suit me a great deal better than a high-end receiver – if only I could identify the right components.
After a period of head-scratching and some intensive Googling I discovered the Griffin FireWave.
The Firewave is a small bus-powered FireWire device designed for use with a modern Mac. It receives Dolby Digital and Dolby Pro Logic II digital signals through its FireWire port and generates 2v (line-level) audio signals on six surround sound output channels that are physically routed through three 3.5mm stereo mini-jackplug sockets. The spec says it doesn't support DTS (Digital Theater System) but I have obtained satisfactory surround sound from DVDs with DTS sound - maybe the DTS signal includes a Pro Logic II stream - I'm not an expert on this. A FireWave application is provided which provides a range features for configuring the device to different speaker setups and room arrangements, etc.
The Firewave was the only Mac-compatible decoder that I could identify. The alternative would be a decoder designed for use in a component audio system connected to the digital optical audio port on the Mac, e.g. one of the decoders from Yamaha, That would have been considerably more costly and would have left me without the on-screen controls for the audio signal discussed in the next section.
The next question was: did I need a pre-amplifier? Clearly not for the amplification of the signals coming from the FireWave; its 2v output was more that adequate to drive a set of power amplifiers directly. The FireWave software offers control of front-back balance and time delay, but no control of left-right balance. It also offers a master volume control and of course the Mac offers plenty of ways to control the volume and iTunes and the other relevant Mac applications offer an equalizer for tone control. I therefore decided to forgo the left-right balance and tone controls that a pre-amplifier would offer for the sake of simplicity.
Hifi amplifier choice is of course a major topic of debate amongst audiophiles, so I won't presume to recommend anything, just describe my solution. My reasoning was that I wanted to feed the highest quality signal that I could afford to my front pair of speakers; the quality of the signal to the rear pair was less critical.
By now I had purchased a FireWave and was searching eBay and elsewhere for deals on a high-quality 5-channel power amplifier. There were a couple of Rotel products (e.g. the Rotel RMB-1565) that seemed to fill the bill and I was close to 'pulling the trigger' on a Rotel when I was serendipitously offered a classic Quad 303 stereo power amplifier of 1970's vintage which had been out of use for about 20 years. I hastily accepted it along with the matching Quad 33 preamp, but I stuck to my guns about the preamp and put it in my spare components cupboard where it remains.
After obtaining the necessary cable to connect the Quad 303 to the FireWave I set it up with my front speakers and fired the system up. Bingo! It was abundantly clear within seconds that its audio quality exceeded what I was used to from the Denon receiver by a comfortable margin.
I subsequently refurbished the 303 using a kit of modern replacement components offered by Net Audio and got a further noticeable improvement.
By now I was delighted with the quality and simplicity of the system I'd built. But of course without rear-channel amplification I didn't yet have surround sound. That was quickly solved with an eBay purchase of an AIWA P50 1980's vintage compact stereo amplifier.
This picture shows all the components of our HTPC system except the Quad 303 front amplifier which is behind the books.
The system is pretty unobtrusive. Video is fed to a 17" TFT monitor which stands on a coffee table or to a ceiling-mounted video projector.
We have ended up with an interesting 'minimalist' surround sound system that provides a pretty-well perfect solution for us. It offers:
George Coulouris, November 2008