Intro

We've asked Francois Simond (supercurio), creator of the very popular project-voodoo and voodoo-sound  improvement packages, and Android hacker focused on sound, video, and image, to set the record straight on Samsung Galaxy S 2's sound quality. In addition, Francois will help us test smartphone and mobile-device sound quality and continue being a contributor as it quickly becomes an important industry focus.

Context

Galaxy S II comes with a lot of expectations in the audio department. Samsung’s previous flagship family, Galaxy S, (aka Vibrant, Captivate, Fascinate, Galaxy S 4G, Epic 4G in the US) set the bar high, using a good quality implementation of Wolfson Micro WM8994 codec. Existing custom mods which tuned WM8994 usage have even been able to push the quality higher than most expected, as well as the headphone output levels.


Yamaha YMU823 - Encircled in Red Above

For the Galaxy S II, however, Samsung changed audio IC suppliers, preferring the popular Japanese brand Yamaha making a big entry in the the low power codec for Smartphones area. The exact chip used in Galaxy S II devices is named C1-YMU823 (also refereed as MC-1N2).

Its datasheet is not public but it’s a chip designed designed to compete with latest Wolfson and TI offerings and probably a custom product designed to follow Samsung requirements.

As the growing interest of readers and recent HTC and Beats by Dre strategic alliance shows, smartphone audio capabilities constantly gain importance. Of course, solid voice call performance remains a major concern. Many smartphone owners now use their device as a primary music player, sometimes with high-end headphones. 

Audio Performance

Music

Demanding enthusiasts expected As music player Galaxy S II to sound at least as good as its Apple competitor: iPhone 4 and supersede its older brother Galaxy S performance.

Unfortunately, it fails at both.

As music player, Galaxy S II performance can be described as:

  • Average for a smartphone.
  • Below average for a high end smartphone.

Yamaha’s MC-1N2 codec has some nice theoretical specs, but the promised sound fidelity turns into a boring rendering affected by several outstanding issues, relegating Samsung flagship far from the audiophile category. Worse: only some of those issues can be remedied by using additional equipment like an attenuator or an active headphone amplifier.

Galaxy S II audio output as music player has issues

Audible CPU and Radio noise

Today most listeners enjoy music with isolating earphones, as they are useful for listening to music or podcasts in loud environments without having to pump the volume up and introduce listening fatigue. Most in-ear gear is highly sensitive. Combined with low impedance and 20dB isolation, hiss and other noise are quickly noticeable.

Galaxy S II is not recommended to drive directly sensitive in-ears because you’ll easily hear the CPU working. Fixing the CPU frequency to its maximum (rooted phones only) doesn’t prevent this annoying noise reminding us of cheap integrated audio codecs a dozen years ago. Admittedly, hiss and noise levels of Galaxy S II headphone output are a lot lower, but today’s standard mobile headphones reveal them easily.

If you’re using sensitive in-ear headphones, radio GSM / EDGE noise is as audible, indicating a probable hardware design flaw of the codec or the board. The culprit is poor EMI shielding.

Description

Galaxysii-cpu-edge-noise-volume1-volume0 by AnandTech

  • 0:00 to 0:02  sound card noise only.
  • 0:02 pop on codec power up, music start to play. EDGE activated, Volume 1/15
  • 0:02 to 0:35 music playing, you can hear GSM and CPU noises despite the signal
  • 0:35 Volume set from 1/15 to 0/15. Music keeps playing in background but is silent
  • 1:03 WiFi enabled, EDGE is automatically disabled. Moving some UI elements

Due to its bursty nature, this flaw is hard to expose in measurements and fortunately less audible with medium sensitivity headphones, not at all with low sensitivity ones.

You can solve this issue by using an attenuator or amplifier: maximizing digital Android output level and adjusting the volume to your need with the amp.

DAC Distortion

With today’s Android audio implementation, all kind of media are sent to the DAC as a 44100 / 16bit / Stereo stream. Despite the usage of a fixed rate, Yamaha’s codec is not able to provide a very clean output.

Galaxy S II DAC output quality is limited by several kind of distortions. So far, no firmware was able to fix those despite early Korean updates describing “audio clarity improvements”.

When playing music, those artifacts are perceived as “lack of clarity”, “reduction of stereo separation”, “loss of detail” and “lifeless sound” (opposite of lively).


From 20 Hz to 20 kHz, dB: -0.42, +0.04
Galaxy S II Frequency response: no load (line in)

Not the best ever but reasonably flat. The slight oscillation in frequency response starting at 1kHz gives a clue about what we’ll see in the next graphs.


Noise Levels
RMS power (A-weighted), dB: -95.1, -95.6
Peak level, dB FS: -71.7, -74.4


Dynamic Range

Dynamic range (A-weighted), dB: +95.4, +95.9

On Noise Levels and Dynamic range graph, I added measurements of Apple iPad and a reference sound card for comparison puposes.

What we see here is good performance. In theory and measured in ideal conditions Galaxy S II has low noise levels and very good dynamic range. However, if noise levels are remarkably low on high frequencies, they increase on lower frequencies which is not something expected nor a good sign as those are more likely to be heard.


Total Harmonic Distortion
THD, %: +0.0036, +0.0035
THD + Noise, %: +0.0390, +0.0388
THD + Noise (A-weighted), %: +0.0425, +0.0424
THD + Noise (A) equivalent: -67.4 dB
Same Graph adding iPad results

THD is calculated by measuring harmonics generated by the electronic circuits when a signal at 1kHz is played. As you can guess by this graph’s shape, there’s an issue here.

In terms of sound and perception, harmonics add colour to the sound; sometimes pleasing like the kind of distortion tube amps add.

This graph show all kind of distortions introduced by Yamaha’s DAC, ie:

  • Jitter-like frequencies distributed around 1kHz
  • All sort of unexpected spikes at higher frequencies

As the noise and other distortions are high, the THD measurement itself becomes kind of irrelevant. Unfortunately the value of  0.0036% is not of the actual performance here.

Other reviews might have use this THD value as base for invalid conclusions.


InterModulation Distortion 
IMD + Noise (A-weighted), %: +0.0655, +0.0655
IMD + Noise (A) equivalent: -63.7dB

What IMD + Noise means needs an explanation: I believe it’s safe to describe it as “all kind of noise and distortions happening when you play a signal” − at the opposite of the signal itself.

IMD + Noise importance is often underrated, like it was useless as we already have another distortion value (THD). Still, it’s often more representative of the general performance and of the sound quality perceived.

No matter how low is the theoretical noise floor, Yamaha MC-1N2 DAC has issue when playing signals. As you can guess by this latest comparison graph and the number of spikes indicating some sound that shouldn't be there. iPad DAC is not perfect either, still it provides a much cleaner sound. The reference DAC shows how the graph should be.

-63.7dB level for “noise and distortions” is far from the level of performance expected from a last-gen audio IC.


InterModulation distortion + noise (swept freqs)
IMD + Noise at 5000 Hz: 0.0108, 0.0109
IMD + Noise at 10000 Hz: 0.0108, 0.0109
IMD + Noise at 15000 Hz: 0.0108, 0.0109

This test consist of a single sine played going from a very low frequency to 22kHz.

Actually, when playing something as simple as a single frequency at one time result is not so bad; music is rarely made of simples sines.


Stereo Crosstalk.
dB: -82.3

My guess is that Yamaha’s codec internal behavior is perturbed by a jittery clock source (being Exynos AP PLL clock). If not? it  would mean the DAC design is flawed. The first hypothesis is more likely: implementation on small very low power board is always tricky.

You cannot avoid the distortions described here by using an external amplifier or any other equipment.

Exploring sound with spectrograms

A spectrogram lets you “see” the sound, why I’ll use this colorful presentation to show you some examples of Galaxy S II audio output.

Udial


Galaxy S II udial output sampled at 96kHz (FLAC sample)

Reference, re-sampled to 96kHz with sox
For comparison: Apple iPad udial output (FLAC sample)

udial is a very interesting sample circulating in forums for more than ten years. I didn’t manage to find its author to thank him for his clever idea. udial is a very efficient stress test that enables an easy test for clipping, re-sampling and some types of jitter.

Galaxy S II performance is not terrible but not good either. Artifacts are audible and can be seen in this spectrogram. I must admit some are a mystery to me like the “delayed” ones.

Bass sines

Simple bass sines allow to check a few things: clipping, unwanted EQ, Bass Boost or Dynamic Range Compression but also buggy DC Servo setups.

The sample used here contains 7 tones: 100Hz, 80Hz, 60Hz, 50Hz, 40Hz, 30Hz, 20Hz.


Galaxy S II bass sine waves output (FLAC sample)


For comparison, Apple iPad bass sine waves output (FLAC sample)

Once again Galaxy S II exhibits artifacts. If you download the associated FLAC record phone’s output you may be able to hear those appearing as lines on the spectrograph (more noticeable on last 2 notes).

But it’s not all bad: Samsung’s phone spectral representation exposes a nice hardware feature called Digital Noise Gate.

DNG analyzes the signal played and quickly shut down parts of the codec. It helps reducing the perceived hiss and reducing power consumption a little.

Eventually (after about 2 seconds of nothing played) the entire audio hardware is shut down by Android OS but the best part is that Digital Noise Gate feature is extremely efficient as anti-pop.

MC-1N2 performance is class leading on this regard.

Headphone amp

Galaxy S II built-in headphone amp is able to drive in-ears or full size cans to satisfying levels. I know for sure mobile devices are never LOUD enough. Samsung’s flagship is louder than iPhones, iPads, a first-gen Galaxy S.

This part may become a dedicated article but here are some facts already:

At Max level (15/15):

AC Tension, no load (line-in): 0.703V

Driving Sennheiser HD 650 (300 Ω)

  • AC Tension under load: 0.621 V
  • Power (left+right): 2.11 mW

Driving Head-Direct RE0 (64 Ω in specs, mines measured at 58 Ω)

  • AC Tension under load 0.381 V
  • Power (left+right): 4.14 mW

Question is: Is it loud enough? When driving HD 650, it reaches comfortable listening levels but won’t reach “loud” levels. For RE0 and most consumer headphones, yes it's loud enough.

Remember isolating headphones are recommended when in loud environments rather than pumping volume too high and damage your hearing.

To me the quality of the amp itself is average-to-okay. Its hard to speak much about it as it’s most of the time amplifying the signal sent by a flawed DAC.

As distortion amount rises at highest levels, its probably MC-1N2 amp power stage implementation on Galaxy S II board does not have much headroom. More measurements may be welcome here.

High output impedance

One characteristic of Galaxy S II's headphone driver is its relatively high impedance: higher than competitor chips. Power efficiency diminishes when the output impedance grow: energy lost in heat. This is why Yamaha’s choice of design is surprising.

I measured mine at 49 Ω.

A notable side effect of this characteristic is that the headphone output becomes less loud with low impedance cans. 

Output impedance doesn’t have much effect on 300 Ω gear, but on common 16 Ω earphones:

  • Gain is lowered, hiss level is reduced: nice bonus
  • Frequency response shift: less bass, more highs. Okay if the tiny speakers was too bassy, terrible if the headphones were bright already.

As a result, Galaxy S II might play well with some equipment but also reveal the worst side of other with harsh and aggressive rendering.

This output impedance is why opinions about Galaxy S II audio are so contradictory in forums: experience can vastly differ depending on your choice of headphones.

Appreciation note

There are many issues or flaws listed and demonstrated in this article. However it doesn’t mean Galaxy S II is unable to play music.

Compared to the average Android phone it probably sounds better already. Explanations mean to show where there’s headroom for improvement on the next devices.

We're more than willing to discuss audio testing methodology with manufacturers to help improve the next generation of phones.

Samsung Music Player

Samsung updated their Google music player replacement look and feel with TouchWiz 4.0.

It still supports FLAC natively, which is a nifty feature for audiophiles and its simple interface and efficient will satisfy most users.

This pre-installed music player still lacks a much desired gapless feature, which means listening to mixes, concerts records or classical music won’t be as pleasing as it should.

You’ll find an 8 band graphic EQ in settings as well as EQ presets and additional sound effects adding reverberation, spatialization or stereo enhancements. Some effects are interesting if you’re not looking especially for an hi-fi accurate sound reproduction. However I would suggest to stay away of the EQ presets as much as possible:

The way the EQ engine uses a suboptimal DRC implementation makes constant volume changes audible.

If you really need to use this EQ, one workaround in using the graphic EQ manually instead: only attenuate but never increase some frequencies, those you find too present. This is in general the best way to use an EQ and find a more balanced sound response to correct headphone or speaker response.

This tip will avoid triggering the DRC.


Typical graphic EQ setup using only negative gains for frequency response correction

As usual with Android OS, you’ll be able set an alternative music player as the default one without any restriction, adding gapless , more compression codecs  support or a different UI.

2.4 and 5 GHz WiFi, GPS, and Audience The Fastest Smartphone SoC Today: Samsung Exynos 4210
POST A COMMENT

132 Comments

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  • VivekGowri - Sunday, September 11, 2011 - link

    I literally cannot wait to read this article, and I similarly cannot wait for SGS2 to launch in the US. Reply
  • ImSpartacus - Sunday, September 11, 2011 - link

    You guys don't get early access to drafts? Reply
  • niva - Monday, September 12, 2011 - link

    I own an original Galaxy S, until it's been proven that Samsung updates to the latest Android within a month after major releases I will not buy anything but a Nexus phone in the future (assuming I even go with Android). By the time that decision has to be made I'm optimistic there will be unlocked WP7 Nokias available. Reply
  • Havor - Monday, September 12, 2011 - link

    Seriously , whats the problem, I was running 2.2 and 2.3 when they came out, could have them sooner, I just dont like to run roms with beta builds.

    So you never heard of Rooting and Custom Roms?

    Its the nature of companies to have long and COSTLY eternal testing routs, done mainly by people with 9 to 5 jobs, as delivering buggy roms is bad for there name, but then so is not updating to but its lots less hurtful, as most people dont care or know any better.

    Next to that if your phone is a phone is customized with extra crapeware by your provider it can be that it takes months before you get a update even do Samsung delivered one a long time ago.

    The rooting scene is totally different, its done by nerds with passion for what they do, and yes the early/daily builds have bugs but also get mouths quicker reported and fixed by the scene.
    And imho are the final updates just as stable as the factory builds.

    Dont like how your Android is working?
    Stop bitching and fixed your self, its not that hard, as it is a OS platform, just make sure you can root your phone, before you buy it.

    The following website explains it all.
    http://androidforums.com/galaxy-s-all-things-root/...
    http://androidforums.com/galaxy-s-all-things-root/
    Reply
  • vision33r - Monday, September 12, 2011 - link

    If it's your personal phone, you can do whatever you want. However like some of us here with jobs that let us pick phones. One requirement is the phone has to be stock and no rooting allowed.

    Samsung is about the worst of the 3 makers in terms of software updates.
    Reply
  • niva - Monday, September 12, 2011 - link

    Seriously calm down, I've heard plenty about rooting and custom roms but phone hackery is not something I'm interested in right now. I don't have the time or energy for it. I shouldn't have to manually go through rooting and updating my phone, especially when security issues are involved.

    I like the way 2.2 is working on the SGS. I bought this phone from a friend who upgraded and it's not something I would've paid the retail price for. I've not run into anything so far that's made me actually bother with the rooting and manual upgrade process. I've not read into rooting the phone or updating it, but I'm sure if I get into it this will take me a long time (hours/days) which I shouldn't need to sacrifice to run the latest version of the OS.

    From the political standpoint the blame is both on Samsung and T-Mobile apparently in terms of getting the new revisions out.

    From my personal standpoint I despise all companies who do not use the default Android distro, running skins and secondary apps, on the phones they ship out. While some of the things they do are nice, it slows down their ability to keep up with android revisions.

    On the other hand, my wife's Nexus (original one) updates faster than internet posts saying Android 2.3.x has been rolled out. It's friggin awesome. She had one problem with battery draining really fast after a recent upgrade but I managed to fix that after a couple of hours of forum searching and trying different things.

    So it's simple, if I will buy another Android in the future, it will be a Nexus phone, where I know from personal experience that everything works in terms of having the latest and greatest. Notice the Nexus S is made by Samsung, it's for the most part identical to the phone I have, yet gets the updates immediately and doesn't have the known security problems I'm exposed to.
    Reply
  • ssj4Gogeta - Monday, September 12, 2011 - link

    Well, the international version got 2.3.3 around ~3 months ago here (and earlier for other countries). Reply
  • poohbear - Tuesday, September 13, 2011 - link

    vision33r u dont know what you're talking about. People bitch and complaina bout software updates, but how are the quality of those updates? when its updated too soon there are bugs and ppl complain, updated later ppl complain about the wait times. I remember last year Motorola said they're not updating their XT720 to android 2.2., they're leaving it at 2.1. S korea Motorola was the only branch that decided to do it, but guess what? 2.2 was too much for the hardware in the XT720 to handle, and it ran slooooow! XT720 users all over complained about it, but the reality is the phone couldnt handle it. 90% of smartphone users want something stable that works, they dont care about having the latest and greatest Android build. So if Samsung errs on the side of quality and takes more time to release stable quality software, then all the power to them! Reply
  • anishannayya - Friday, September 23, 2011 - link

    Actually, if updates are your hard-on, then you'd likely be looking at Motorola in the future (due to the Google acquisition).

    The entire reason why the Nexus lines of phones are quick to get updates is because the are co-developed with Google. As a result, these phones are the ones the Google developers are using to test the OS. When it is ready to go, it is bug free on the device, so Samsung/HTC can roll it out immediately.

    At the end of the day, any locked phone is plagued by carrier bloatware, which is the biggest slowdown in software release. Just buy an unlocked phone, like this one, in the future.
    Reply
  • ph00ny - Sunday, September 11, 2011 - link

    It's awesome to see this article finally
    I'm glad François Simond aka supercurio contributed to the article

    Btw that slot on the left is for the hand strap which is very popular in asia for accessory attachments
    Reply

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