Thursday, 29 September 2011

Updates and Digital Audio

It has been an awful long time since my last post; but things have been pretty hectic of late. Primarily is our decision to relocate our family to another country, which will be taking place within a few months. This event, along side other life things, has meant very little, if any, time to blog. At the moment, I barely get any good audio sessions in...

In light of the relocation, this has spurred me to look into portable solutions. Having a good assortment of headphones already is a good start, but this has forced me to look into the weakest part of the chain. At present, all my music is run through iTunes (AAC Lossless) and played to the headphone amps via the standard audio out on my Mac Pro or Macbook Pro. Note an ideal solution. This then started to get me looking into improving the digital connection between the computer and the amp.

Welcome to the world of USB Audio... Initially, there were a catch up in the USB Audio technology. The way I understand it is, there is USB Audio 1 and USB Audio 2. USBA-1 only allows for 48kHz/16 bit. But the newer standard of USBA-2, can support high sampling and bit depth. The highest I have seen so far is 384kHz/32 bit. However USB1.1 can support stereo 96kHz/24 bit in terms of its band width, and USB2 can obviously go higher. On top of this limitation are the limitations in drivers in the various OS. Add further to this is whether or not the USB device is asynchronous or not. More technical terms and more technical information to digest.

The long and short of it, I decided that the best place to start would be a USB device that had RCA outputs that can handle up to 96kHz/24 bit. And in this market, there was plenty of choice. Being able to handle the higher resolution allows me to explore HD audio tracks, which would not be possible had I stuck with something simplier with only 44/48kHz at 16 bit. Through the various web pages, etc, I was able to gleem that there was an awful lot of South Korean and Scandanvian companies making USB audio devices. Alongside that, the standard Chinese offerings and others from US and Germany. Some of the companies that I came across includes: Calyx, Bel Canto, M2Tech, Lead Audio, Lindemann, HRT, April Music, Anedio, Bladeius, CEntrance, SoTM, Halide Design and a few otherse. Where possible, I tried to avoid the Chinese companies. When I get the change, I hope to write some notes about the various units that I looked at over the last few weeks.

Again, without boring everyone, I settled on a Calyx Coffee. An asynchronous 96kHz/24 bit USD DAC using a lower version of the ESS DAC Chips the ESS9023. I chose this because it was relatively good price (middle of the pack), had the ESS DAC chip, looked good and has external control buttons. This was brought from Wicked Digital and the unit arrived yesterday, and has started the burning in process. The main difference I can see from this chip and the top of the line ESS9018 is that it only has 1 DAC circuit for each channel (whereas the 9018 has 8 circuits that can be customised in various configurations) and it also has voltage output (as opposed to current output).

Well, hopefully, I can provide more insight into this DAC, which is currently hooked up to the Elekit and HD650.

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