Smartphone Audio Quality Testing
by Chris Heinonen on December 8, 2013 5:15 PM EST- Posted in
- Smartphones
- Audio
- Mobile
- Tablets
- Testing
Maximum Level
The maximum output level is derived from the 1kHz test tone used to determine THD+N. The higher the output from the headphone jack, the louder it can drive a pair of headphones. More importantly, having more power available means when you have dynamic music passages that call for power you are less likely to clip the waveform.
There is no chart to show here, just a number that the Audio Precision gives us. In our test data, the most powerful phone was the iPhone 5, at 32.46 mW of power. Next is the Nexus 5 at 22.24 mW, though we can’t drive it that high. Then the Note 3 at 11.81 mW and finally the Galaxy S4 at 3.895 mW. Doubling the power, from 4 mW to 8 mW, produces a 3 dB increase in volume level. 3 dB is the smallest change in volume levels we can easily hear. So even though the iPhone 5 produces 32 mW vs. 4 mW, that is only a 9 dB difference in volume. 10 dB is doubling the volume, so it isn’t even twice as loud. If you have demanding headphones, you will want as much power as you can get.
Frequency Response
To measure the frequency response we measure a set of 61 tones from 20 Hz to 20 kHz. All of these are then equalized to 1 kHz so we can see the maximum deviation from that level. An ideal phone will be perfectly flat here and allow you to adjust this with an EQ setting, or though your taste in headphones. On this test our best performing phone is the Galaxy S4, as seen here.
The total variation from 1 kHz is only 0.014 dB which is very good. The worst performing phone is the iPhone 5, but its variation is only 0.089 dB.
The iPhone 5 also picked up the 20 kHz tone while the Samsung and many others missed it. If we dropped this tone then it might be just as flat. The iPhone 5 test was run slightly differently, as it can't run the Android test program, which might account for this. For a phone with a different response, here is the HTC One with Beats enabled. Other HTC One testing is still in progress as I write this article.
Here we see that Beats is adding a +3.5 dB boost from 60 Hz to 90 Hz, but the deviation from 0 dB goes from 30Hz to 300 Hz. Past 6.5 kHz we also see a rise in the treble. People often mistake boosted treble for extra detail, which is likely the reasoning behind this. As we see it is far different than the other two examples we looked at.
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dylan522p - Sunday, December 8, 2013 - link
Just because you have a good DAC,doesn't mean you have great audio. S4 has a great DAC but it can't even power high impedence headphones.cjl - Monday, December 9, 2013 - link
The S4 powers moderately hard to drive headphones just fine - sure, it won't drive something like an HD650 adequately, but the majority of consumer headphones out there will go plenty loud driven straight out of an S4. That having been said, it would be nice if it had a bit more power for hard to drive headphones.oktrav - Monday, December 9, 2013 - link
I can't believe how many people on the internet are singing this song... Does it really matter who makes the DAC if the output sounds like crap? The DAC is just one of many components that affect the sound quality. You can have the best components in the world and still produce absolutely dreadful sound. Ask any wannabe audiophile who's dabbled in assembling home systems out of separates. This is akin to saying that your car must be very powerful BECAUSE it has Bosch coil packs --and Bosch makes the BEST coil packs (just play along for the sake of the analogy, I'm not actually asserting that Bosch makes the best coils --I don't know).nomopofomo - Sunday, December 8, 2013 - link
So glad you went into such depth.Best case scenario, the public and manufacturer are both made aware of the flaws.
drwho9437 - Sunday, December 8, 2013 - link
This has been needed badly for some time. Phones displacing media players this matters a whole lot. To me far more than actually anything else about a phone.probedb - Sunday, December 8, 2013 - link
You also have to remember with some measurements about what is actually audible and what isn't. It's crazy seeing people moaning about nanoseconds of jitter on DACs yet they're quite happy with milliseconds of the equivalent of jitter on vinyl. Then again some of these companies sell ethernet cable at £1600/m and claim it makes a difference to sound ;)matagyula - Sunday, December 8, 2013 - link
Great to see something like this on anand!I would like to see some older high-end phones compared to the ones we have now - for example the Nokia N900, or maybe even some of the ooold Sony-Ericsson Walkman phones (W810 and up). I'd find such comparison interesting ^^
chubbypanda - Monday, December 9, 2013 - link
Great stuff Chris!I was also wondering if it's possible to add some ancient phone with cult following from audio geeks. You know, Nokia N91 and similar. According to some, sound quality on the phones were never better, so that'd be nice to see what is really happening.
wrkingclass_hero - Sunday, December 8, 2013 - link
So, how long before Arstechnica "discovers" the audio problems with the Nexus 5?crabperson - Sunday, December 8, 2013 - link
YES! Thank you so much for doing this, its awesome. I didn't realize audio/amp quality was a huge thing until I upgraded my headphones. Being able to hear the difference between the same audio file on two different devices made me realize how little manufacturers care about audio quality.Then using an FM transmitter in my car showed me how some devices can't pump out enough power over the headphone jack. My Galaxy Nexus has pretty good audio quality (and does optical audio out through the dock, also awesome) served me fine for pumping up music through the FM transmitter. The Galaxy S3 I'm temporarily using does not though, and produces noticeable clipping at max volume. It also isn't properly shielded and when charging there is interference on the headphone jack (something you should also test if you haven't thought of it). I'm looking at upgrading if I can't fix my Nexus, and hope the HTC One is as good as it in terms of audio quality (with Beats disabled of course).