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.

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  • JasonQG - Monday, December 9, 2013 - link

    I'll be curious to see how the iPhone 5s compares to the iPhone 5. I noticed a definite improvement when I upgraded, at least to my ears' perception.
  • ClockHound - Tuesday, December 10, 2013 - link

    Nice to hear you're taking sound semi-seriously with devices that have a semi-important audio task. At least for those who use smartphones for aural communication and music playback.

    Nice to see the Audio Precision in action. Great unit. However, please, consider putting a little more thought into the scaling of your FR graphs. What appears visually as a huge peak in the htc Beats graph barely has a 3dB rise. That's not a huge peak.

    A 1dB rise at 10k is not much of a rise and since it doesn't display enough data, we can't tell if it's a low Q event or not.

    The Audio Precision can scale the vertical axis to make plots more informative rather than sensational.
  • pandemonium - Tuesday, December 10, 2013 - link

    Awesome stuff. Keep it up AT!
  • kreacher - Tuesday, December 10, 2013 - link

    Great article, would it be possible to test audio input (the mic) in this much detail. Noise cancellation as well as how it does in speakerphone mode / video recording. I know earlier reviews / articles have mentioned this are but it would be great to have detailed numbers like this article.
  • Cyleo - Tuesday, December 10, 2013 - link

    This is awesome. I truly love this, please continue this work ;)

    Any change one of the more recent Sony models makes the test (Xperia z comes to mind)
  • Pastuch - Tuesday, December 10, 2013 - link

    Chris, fantastic article, way to bring me back to Anand. Please include results of the Iphone 4s and any other phones you get your hands on. My girlfriend and I are phone whores, she's Apple, I'm Android. I'm constantly playing with all of our phones and cans trying to find the best audio combo.

    I run Sennheiser HD-25s, Sennheiser Momentums, V-Moda Crossfade M-80s, and Koss Porta Pros (Awesome since the 80s!).

    Best sounding phone I've ever heard:
    Iphone 4S sounds way better than the new Iphone 5. It's definitely louder and fuller. Too bad the 4s doesn't have APT-X codec for Bluetooth.

    Runner up:
    Samsung Galaxy S with Voodoo sound Rom (Note, you need to load a non-standard rom to make it sound great)

    The rest:
    SGS2 (International Model): Too quiet, poor quality, disappointing dynamic range.

    SGS3 (North American Model): Poor quality, lots of cross talk, disappointing dynamic range.

    HTC One (Beats Audio OFF): Sounds great, really no complaints. A step above most Android phones. Still miss the Wolfson DAC though.

    IPhone 5: Still sounds great but it doesn't live up to the 4S. I'd say it sounds slightly better than the HTC One but the difference is really marginal.

    Nexus 5: Sounds better than the SGS2 or 3. The V-Moda M80s sound good because they aren't hard to drive. The Sennheiser HD25 needs the top volumes and the clipping is obvious. The HTC One sounds a little better.
  • vision33r - Tuesday, December 10, 2013 - link

    HTC One audio is a joke. Which features a software sound enhancer AKA Beats Audio which any custom rom can cook into their roms.

    I've had the S3 with the Beats Audio software and took it off flashed a better DAC amp app.
  • Traum - Tuesday, December 10, 2013 - link

    As a head-fi audiophile, I want to THANK YOU for doing this!
  • MWisBest - Tuesday, December 10, 2013 - link

    Nice article, definitely curious as to how my Galaxy Nexus would fare in this, as I'm a bit of an audiophile.
  • hrrmph - Wednesday, December 11, 2013 - link

    Awesome topic and write-up :)

    Keep these coming, please.

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