Samsung Galaxy S4 vs S3 Headphone Output Levels
May 18, 2013
This note provides measurements comparing the headphone output level of the Samsung Galaxy S3 (SGH-I747) and S4 (SGH-I337) superphones.
Measurements were performed on stock (not modified in any way) versions of the S3 and S4 superphones. A pure sine wave track at a frequency of 250 Hz (16bit/44.1kHz uncompressed .wav files) with digital amplitude almost full scale (32,000/32,767 = -0.77 dBfs)
were used for playback. Signal shapes at the headphone output were monitored on a dual-channel oscilloscope for 3 headphone PURE RESISTANCE loads: open output (no load), 33 ohm and 12 ohm loads on each
channel. The 33 ohm load represents a similar load to the impedance of the stock Samsung earbuds provided with the S3 and S4. The 12 ohm load represents a typical impedance level for many
balanced armature earphones. To standardize this measurement, the native Samsung Music player app was used with default settings (no EQ or special effects applied) which provides
a flat frequency response.
Summarizing, the results below indicate that the signal levels of the S3 and S4 smartphones ARE ESSENTIALLY IDENTICAL and this is verified in actual music listening tests.
However, the S4 (as discussed elsewhere) under 12 ohm load has a pronounced audio instability as displayed below at a volume level of 11/15 for pure sine waves at this frequency.
The instability is not a current-limit problem as
can clearly be seen by the fact that there is no clipping or obvious distortion at the highest level of 15/15. At a level of 15/15 under 12 ohm load, the headphone output
delivers a respectable unclipped peak current of ~ 52 mA. (More detailed RMAA tests show that for headphone impedances of ~ 16 ohm or greater, the audio quality of
the S4 is superior in terms of noise and residual distortion to that of the S3, but the S3 still has very good audio characteristics).
The setup used for measurement is shown below:
The first set of 6 plots below show results for the S4 phone.
An instability is observed at a Music player level threshold of 11/15 with a load impedance of 12 ohm, and manifested in actual music playback as a "crackle" or "buzz" for
player levels higher than this threshold level. This instability is not present at headphone resistance loads greater than ~14 ohm.
The second graph in this S4 set shows an expanded detail of the instability. This type of instability looks very similar to the "bottom side fuzzies", well known in audio output driver stage design.
Also, it was observed that for even lower load resistance values, the instability is manifest at several different volume level settings.
By comparison results for the Samsung Galaxy S3 superphone are shown below and are very similar to those of the S4 except that the S3 does not show the instability problem at any volume level for
the 12 ohm load:
