New DAC

For some time I have been mightily disappointed in the DAC that I had in my music system. I built an amplifier using the excellent Hypex modules; chosen for two reasons, bandwidth (up to 50kHz) and low distortion. But I couldn't find a low cost DAC and had to fall back on what I thought was the best from HK, since I object to paying the ridiculous prices asked for by most audio companies. (I should explain. Wolfson in UK make the best ICs for building a DAC, there WM8805 SPDIF interface and WM8740 DAC are by far the best in the industry. And they cost less than 10$, so why should I pay 1000$ for a DAC?).

But then I found that some sensible HK supplier had taken the application note for the Wolfson chips and made a DAC, for £80! Complete in a nice box, with headphone amplifier also, and with an AC power supply. This DAC covers all bit depths (16 & 24) and all sample rates from 44.1 to 96kHz. So I bought one.

I coupled this DAC up in one of two ways:

1 Optical input from my Apple TV, and streaming music over from my iMac by WiFi. This was the response:



As you can see it cuts off sharply at 19kHz, this is due to the way Apple's Airplay handles the transfer, any file in iTunes is down sampled to 44.1kHz before being sent over the WiFi, and at the Apple TV end there is a low pass filter at around 20kHz. The idea being that music only needs a 20Hz - 20kHz bandwidth, an idea which I find ridiculous - for a violin to sound like a violin you have to pass all the frequencies it generates, and these stretch up beyond 50kHz.

2 Optical input from my MacBook with Audio MIDI setting to output 96kHz. This was the DACs response:



Well now isn't that better? A response out to nearly 45kHz - against the maximum you could expect from a 96kHz rate of half that or 48kHz. And note that the response goes down to DC, as do my amplifiers.

What is very exciting is that with "Home Sharing" turned on, so that I can access music on my iMac (some of which is 24/96) then playing a track through the MacBook gives the wide bandwidth, the same as playing directly from the MacBook!

Now I am sure that I am sending all the possible frequencies from the music files to my speakers. What they do with it is another question… but it sound much better.