Article Index
Audiolab Q-DAC
page 2 Sound Quality
page 3 Conclusion
page 4 Measured Performance
All Pages

Measured by our Rohde&Schwarz UPV, the world's most advanced audio analyser

Like the M-DAC tested in our Oct 13 issue, the Q-DAC has seven filters, three for optimal time domain response and the rest widest frequency response, with minor variations of behaviour within each filter set.
    Optimal time domain filters avoid ringing, including pre-ringing, and sound best, having an easier, more natural sound than traditional filters like Optimal Spectrum that give extended bandwidth, as used in CD players.
    In the Q-DAC Optimal Spectrum possessed the widest bandwidth of 43kHz with 192kHz sample rate digital, and a slow roll down in output all the way up to the 96kHz upper theoretical limit.
    The optimal time domain filters reduce bandwidth but this did not affect the audio band up to 20kHz with high resolution digital, using sample rates of 88.2kHz and above. It is with CD that the optimal time domain filters affect audible response, rolling off audio above 8kHz. This gives an obviously warm sound, but also a more organic feel than is common from CD, as the admired Chord DAC64 once did.
    Output at +4dB (maximum) on the output level control measured a high 3.25V, and 2V at 0dB. The maximum setting raised the signal well above the output noise floor, giving the best measured EIAJ Dynamic Range value, an impressive 121dB with 24bit digital.
    The TOSLINK optical digital input worked up to 176.4kHz sample rate, but would not accept 192kHz. The electrical input worked to 192kHz without difficulty though, as did USB.
    Distortion levels were low, especially with 24bit, where the Q-DAC managed a -60dB value of just 0.02%. Just compare this with CD at 0.23% and you get some idea why high resolution digital is so much better than CD – ten times better in this area.
    The Q-DAC measured well in all respects, possessing a wide range of useful filters. It is little worse in performance than the more expensive M-DAC, so it looks to be good value. NK

Frequency response (-1dB)
192k sample rate       2Hz-43kHz

Distortion (%)    16/24 bit
0dB                        0.002/0.002   

-60dB                         0.23/0.02
Separation (1kHz)          115dB
Noise (IEC A)                -120dB
Dynamic range (EIAJ)    121dB
Output                               3.2V


FREQUENCY RESPONSE, 192kHz sample rate


DISTORTION, 24bit, -60dB


DYNAMIC RANGE (EIAJ, –60.827dB – 60dB = 121dB)

Comments (1)
Philips Test CD
1Saturday, 06 September 2014 06:13
Michael Krauss
Dear Experts!

With great interest I read some of your tests on CD players. You mention that you use special Test CDs for CD and SACD performance measurements.

I wonder where I could buy such a Test CD. Can you give me a hint and advice where to buy these items?

Thank you for your help in advance.
Michael Krauss

Sadly, the answer is "no". Philips produced the best test CDs (Denon, Technics and a few others too) but these were never made available to the public, at least in any obvious manner. In the end Philips would not even release test CDs and SACDs to those they felt might use them to criticise the medium.

There is a modern solution. Use Audacity to generate test signals and burn them to CD. It works.

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