Smartphone Audio Quality Testing
by Chris Heinonen on December 8, 2013 5:15 PM EST- Posted in
- Smartphones
- Audio
- Mobile
- Tablets
- Testing
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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Friendly0Fire - Sunday, December 8, 2013 - link
The Nexus S has some of the best DAC in the industry, actually... Most phones these days use the built-in Snapdragon DAC, but the S has a Wolfson DAC which is way superior.I think you either had a dud or you have another issue somewhere because the S was lauded for sound quality (just like the original Galaxy S).
tedders - Sunday, December 8, 2013 - link
I must have had a dud Galaxy S then too because my Captivate had abysmal audio.Samus - Monday, December 9, 2013 - link
The captivate and epic 4G (sprint variant) were substantially different from the galaxy s, although I remember the epic 4G touch (S2) having decent audio quality.tipoo - Sunday, December 8, 2013 - link
So I've heard, but I'm not the only one with shit audio on it, the running theory is they put in a good DAC but didn't bother properly making drivers or something for it.tipoo - Sunday, December 8, 2013 - link
Or perhaps improper shielding of the audio circuit from the radios, since the static seemed to be radio related. Even modern phones have some of that, even the best sounding ones like the iPhone 5S, but it's much much reduced.cheinonen - Sunday, December 8, 2013 - link
The DAC really means nothing without knowing everything else that goes into the circuit. Yes, the DAC might have superior SNR and THD+N but if you use an amplifier, or a volume control circuit, that are worse than other phones, you've now mitigated that advantage. It's there in the DAC but by the time it gets to the output stage it's been buried by noise elsewhere in the system.Using a better DAC is nice. But you can't just drop it in and get better results, everything else needs to be engineered around it as well.
Friendly0Fire - Sunday, December 8, 2013 - link
Using a higher end separate DAC hints that the manufacturer at least somewhat cares about sound quality. Using the built-in SoC DAC says that it's an afterthought.It's not a guarantee, but it's certainly an indicator.
Galidou - Sunday, December 8, 2013 - link
Totally agree with cheinonen, any high end audio stereo setup is as strong as it's weakest link. Take the excellent nuforce DAC-100 at ~1200$CAD, use it with a poor sub 400$ multi channel receiver and you won't get much out of it. The nuforce got plenty of amazing review, but it always depends on what it is paired with.The galaxy sure got a nice DAC but it's amplifier section is poorly engineered.
cjl - Monday, December 9, 2013 - link
Actually (and I know audiophiles everywhere will disagree with me on this, but whatever...), you can get audibly perfect sound with a dac worth only a couple hundred dollars at most, and an amp of similar cost. There's really no point in buying a >$1k dac, and the same goes for an amplifier (though expensive multi channel receivers can be justified, not for the quality of their amplifiers, but for the quality of their DSP, room correction, video upscaling, and variety of inputs and outputs). For an audio system, by far the most important component is the speakers. You should spend the vast majority of your audio budget on the transducers (speakers/headphones), then buy an amp with sufficient power to drive them to whatever level you need without distortion/clipping (which is almost always less power than recommended by audiophiles). The rest of the system can really be quite inexpensive - the built in DAC in most modern audio products is audibly flawless, and it's impossible to improve on 14AWG zip cord for the cables (from an audibility standpoint) unless you're running your wires over an extremely long distance.Now, that isn't to say that modern smartphones have reached that audibly flawless point yet - many of them haven't (especially when they have such blatant flaws as the single channel clipping shown in the review above), but many of them are a lot closer than people realize, and it really doesn't cost much to make a product audibly flawless. I remember seeing testing done on the latest iPod, and it was good enough to not contain any audible flaws. I would assume that the iPhone is similar, and the GS4 looks to also be audibly perfect in the review above (so long as 500mV p-p is sufficient to drive your headphones - this may not be the case for some less sensitive models).
speculatrix - Tuesday, December 10, 2013 - link
+1A lot of audiophile ideas simply don't stand up to basic engineering principles, and blind A:B tests show it.