We spend a lot of time watching and listening to our smartphones and tablets. The younger you are the more likely you are to turn to them for watching a movie or TV show instead of an actual TV. For a lot of us it is our primary source of music with our own content or streaming services. Very rarely when new phones or tablets are announced does a company place any emphasis on the quality of the audio.

Display quality also used to receive very little attention. As more and more people reported on the display performance, more companies started to take notice. Now benefits like “Full sRGB gamut” or “dE < 3” are touted on new products. So now we are going to introduce a new set of testing for smart phones and tablets, audio performance.

To do this right we went to the same company that all the manufacturers go to: Audio Precision. Based out of Beaverton, OR, Audio Precision has been producing the best audio test equipment out there for over 25 years now. From two channel analog roots they now also test multichannel analog, HDMI, Optical, Coaxial, and even Bluetooth. Their products offer resolution that no one else can, which is why you will find them in the test and production rooms of almost any company.

Just recently they introduced a brand new set of audio tests for Android devices. Combined with one of their audio analyzers, it allows us to provide performance measurements beyond what has been possible before. Using an Audio Precision APx582 analyzer we set out to analyze a selection of Android phones to see what performance difference we can find. More phones and tablets will follow as these tests can be run.

The Test Platform

The test platform is the Audio Precision APx series of audio analyzers. For this initial set of tests I used an APx 582 model, which has two analog outputs and 8 channels of analog inputs. The outputs are not necessary as all of the test tones are provided by Audio Precision for playback on the devices. For each set of tests we can add a load, simulated or real, to see how the device handles more demanding headphones. For this article I am sticking with only a set of the updated Apple Earbuds. They are probably the most common headphone out there and easy to acquire to duplicate testing. For future tests the other loads will be AKG K701 headphones and Grado SR60 headphones. Both models are popular, and I happen to own them.

There are a few main tests we are going to use for all these reviews. Those key tests are maximum output level, Total Harmonic Distortion + Noise (THD+N), Frequency Response, Dynamic Range (as defined by AES17), and Crosstalk. These tests are the exact same ones that manufacturers will be running to verify their products. Most of these tests will be run at maximum output levels. Most amplifiers perform best at close to their maximum levels, as the residual noise compared to the signal decreases, and so that is what they are typically tested at.

We might add more tests as we decide they are relevant to our testing. I will also attempt to go back and fill in as much data as possible from previously reviewed devices as time permits. Now to look at the tests and see our results for our initial set of phones.

THD+N
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  • cheinonen - Monday, December 9, 2013 - link

    No, for the initial set I used basic Apple earbuds that everyone has. I do have AKG K701s to test them on as well, and plan to do so going forward. Reply
  • charltonv3x - Sunday, December 8, 2013 - link

    Curious how the test result gonna be for XPERIA Z, ZU, and Z1 against Lumias :)
    and...can it be used to test ASUS Xonar Vs Onkyo soundcards or other audiophile soundcards...
    Reply
  • cheinonen - Monday, December 9, 2013 - link

    It can test anything. I use it to test Blu-ray players, preamps, amps, receivers and more. The report it spit out for a receiver for me today was well over 150 pages. Reply
  • Impulses - Monday, December 9, 2013 - link

    Testing some other gear might be interesting context wise... i.e. How does a smartphone compare to a Xonar DGX or STX, or to some of the cheaper amps out there (O2? Magni?). Adding stuff like the venerable SanDisk Clip Zip might be even more relevant as far as comparisons go, since that's a great $30 solution for anyone with a phone with disappointing audio. Reply
  • lookit77 - Wednesday, December 11, 2013 - link

    +1 for using the SanDisk Clip Zip as one of the benchmarks. Reply
  • mrnuxi - Wednesday, December 11, 2013 - link

    Even better than a SanDisk Clip Zip is the older SanDisk Sansa Clip+, which can be found quite cheaply. Here's what will give you a fantastic audio experience:
    1. Add a 32gb microSDHC card to the Clip Plus with your music encoded as flac (the Clip+ supports flac [lossless] playback.
    2. Install the excellent RockBox (http://rockbox.org) replacement firmware.
    3. Add the superb FiiO E6 headphone amp. Note: beware of counterfeits on eBay!
    4. Use decent or better headphones (at work I use Grado SR60; cycling I use various good quality earbuds).
    5. Enjoy your music as you've never heard it on a phone or iPod.
    Reply
  • Morgifier - Sunday, December 8, 2013 - link

    This is great information, thanks!

    I have a Nexus 5 and when I plug headphones in I usually listen to level 6 or 7 (out of 15) and have found the audio quality to be to my liking (vs. my old Samsung Galaxy S2).

    However, typically when I listen to mobile devices via an amplifier I would turn the device up to MAX volume and then modulate volume via the amp - this does not seem to be the best case for the Nexus 5, I guess stop 12 would be the best volume.

    Is amplifier clipping a common occurrence for mobile devices? I consider this a design flaw, i.e. max volume available for the device should be prior to any clipping.
    Reply
  • ruzveh - Monday, December 9, 2013 - link

    To be honest i have heard many smartphones through one of the best earphones and headphones i dint like the sound quality from any of the smartphones that i have heard compared to the ones that my mp3 players deliver. This is where i hate my smartphone and still love my media players.

    Can mobile companies take a note on this?
    Reply
  • ruzveh - Monday, December 9, 2013 - link

    And the fun is we dont get quality DAC for the premium we pay for these phones Reply
  • shaolin95 - Monday, December 9, 2013 - link

    I hope we get to see how the Xperia Z Ultra performs even though I have not seen a review for the phone itself so I guess not much of a change there :/ Reply

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