By now, I expect every music enthusiast has heard about Master Quality Authenticated (MQA) and how the high-frequency content is folded, origami fashion, into the low-frequency region. An MQA decoder (DAC) unfolds the highs back to their proper spectral location. The theory sounds great but because we can’t directly hear this upper register, how do we know what’s actually there?
I played my source file through an MQA DAC (Meridian Explorer 2) and a non-MQA DAC (TEAC UD-301) to another computer running the TrueRTA spectrum analyzer set to a 20 Hz to 50 kHz display, and exported the spectral data to two text files for plotting. The results are graphed in Figure 1 with the black line detailing the MQA decoding. There is definitely more MQA energy in the 22 kHz to 50 kHz region—10 dB to 20 dB above the system noise level.
My source, a FLAC MQA file, was the “From a Distance” track from the album Distance written and performed by Martin Tingvall, chosen because I enjoyed listening to it. The album is available as a download from www.highresaudio.com. (The tracks are MQA in a FLAC container file: 24-bits and 48 kHz)
The Explorer 2 is a bit “fussy.” It seems to work fairly well with drivers such as Direct Sound, WASAPI, and “Speakers” (the default for many sound cards). But an ASIO driver is required for bit-perfect playback and the Mode LED stays white if this need isn’t met. Meridians’ tech support sent me an email detailing the setup for the free foobar 2000 media player. It’s also worth noting that it’s easy to make a file non-bit-perfect. It is best to use the original downloads without changing the bit resolution, sample rate, or even the file name.
The Next Step
By using the magic of a product developed for listening to bat sounds, we have a tool to view and listen to what is produced by a high-frequency speaker (tweeter). This product is the model M500 USB ultrasonic microphone and BatSound Touch software from Pettersson Elektronik AB in Sweden. (This software is available only for Windows 7, 8, and 10.) The M500 is shown in Photo 1 along with the tripod adapter that I added to make it more useful for my measurements.
The Measurement Setup
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