Smartphone Audio Quality Testing
by Chris Heinonen on December 8, 2013 5:15 PM EST- Posted in
- Smartphones
- Audio
- Mobile
- Tablets
- Testing
Many readers have been asking for audio testing on phones and tablets, and we are happy to be able to deliver it now. Because I live far away from Brian and Anand, I can’t easily access units they are reviewing so audio data may not run the same day a review is published. I do hope to be able to add it on to everything in the future so that all of our reviews will be as in-depth as possible, from processor to software, display to audio.
I also have to thank Audio Precision for their loan of the APx582 and their access to their offices and support staff. Without that these tests would not be possible. I also wanted to use their equipment as it is the reference standard for the industry and there can be no doubt about its quality. As I do a lot of AV testing as well, I found that more generic sound card methods of testing are becoming limited as the capabilities of products exceeds what they can easily measure. There are no such worries with the Audio Precision.
I also look forward to feedback from readers on the information here, and what else you would like to see tested going forward. Hopefully this will provide another set of data to help you determine if a product will fit your needs, and which vendors are trying to push performance in all categories.
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Impulses - Monday, December 9, 2013 - link
Ehh, impedance curves for the headphones he suggested (Grado SR80, AKG K701) are easy to find (Inner Fidelity and others have decent databases)... Testing and providing output impedance for the phones would be very valuable indeed though, even if everything else in the chain performs alright that alone can affect the FR significantly with one pair of headphones and not at all with the next... And unfortunately there's never been a realistic standard for output impedance, (other than high quality solid state amps now aiming for >1 ohm), and it's often all over the place.ssddaydream - Monday, December 9, 2013 - link
I agree with this.I think of three main usage scenarios regarding the headphone output:
1.) Quality of HP output driving a high-impedance line-level input for a home or car stereo.
2.) Quality of HP output driving low-impedance, sensitive IEMs.
3.) Quality of HP output driving high-impedance, non-sensitive cans.
For #2 and #3, the output impedance should be known, as well as the amplifier power at a given THD level.
There reasons why the iPhones are able to perform well with IEMs, namely low noise floor and low output impedance. Also, iPhones perform well with larger cans because of the decent output power.
I think the usage cases I listed above are pretty common, so I think a good approach to testing is to think about the most important parameters for each usage case.
BTW, I am excited about AT doing these measurements- very good news, indeed!
Anand_user123 - Monday, December 9, 2013 - link
I use my phone most of the time as a music player. Audio quality and storage capacity for flac files are major factors in my buying decision. I hope we can have more widespread information on smartphones audio performancestepz - Monday, December 9, 2013 - link
If you actually cared about scientific measurements of audio performance you would use compressed audio instead of flac. ;) Given a decent amount of bitrate, compressed audio is indistinguishable from uncompressed in double blind tests. In my experience FLAC is mostly about the listener feeling good about getting the "correct" experience, like expensive speaker cables.Impulses - Monday, December 9, 2013 - link
There's a valid usage case for FLAC as far as ripping and archiving IMO, you might as well if you're ripping a large collection (or ripping often)... Since you can quickly re-transcode or edit files w/o a loss of quality... But yeah, I don't see why anyone would put FLAC files on a phone, transcoding is dead simple and super quick if you have a remotely modern PC. Managing FLAC & MP3 playlists or whatever shouldn't be a hurdle if you're putting the effort to maintain a FLAC library to begin with, just use the MP3 library for everything or use stuff like Media Monkey's smart filters/playlists.NaterGator - Monday, December 9, 2013 - link
The biasing of the amplifier in the Nexus 5 and LG G2 left channel appears incorrect. Note it is only clipping on the negative portion of the waveform.vshah - Monday, December 9, 2013 - link
Can't wait to see htc one results!jrs77 - Monday, December 9, 2013 - link
Could you compare the phones to an iPod maybe? This way we would've an comparisooon to a mediaplayer where there's no 3G/4G/LTE disturbance.Oh, and for the general audience discussing the DACs etc... The DAC isn't the cruicial part, never has been. The amp is what it's all about and how good or poor it's powered.
There's a reason why audiophiles still use tube-amps, or atleast digital amps with high quality toroidal transformers and good shielding to reduce noise distortion etc.
Oh, and btw... A good mediaplayer needs a microSDHC-slot or the possibility to use an USB-stick. A mediaplyer is no good if I can't carry my whole music-library with it (100+ GB).
Leezhunjin - Monday, December 9, 2013 - link
Hi Chris, very nice to see smartphones getting measured in terms of audio performance, as many of these phones are used as a music device as well. Personally, I think that an inclusion of output impedance measurements would really great be though, as it is one of the factors that would affect the earphone performance rather significantly.CSMR - Monday, December 9, 2013 - link
Very good start. Poor quality needs to be exposed and you've done this with the Nexus 5.I would like to see output impedance since low output impedance is a very important quality of a good headphone output.