iPod Touch 5 hp out vs line-out via lightning (report c/w graph and audio clips)

Summary:

Since I started using my iPod Touch 5 after I lost my iphone 4S in Sep 2012, I felt that the audio from iPhone 5 headphone out isn’t as clear as that of iPhone 4S. In one particular video clip, the audible difference is very obvious. However, using lightning to 30-pin to LOD and amp, it sounded ok. Using a simple audio recording freeware, this difference can be “seen” and heard.

Report:

Equipment / software used:

Creative E-MU 0204

Ipod Touch 5

Lightning to 30-pin adapter

LOD

3.5mm to 2x 6.5mm Y-cable 

Audacity

Video:

http://www.mediafire.com/?413981xakazca16

(Kpop live performance. Area of interest: 0:50 to “la la la la”)

(Note: Content rights of this video belongs to KBS)

What I hear:

Using iPod Touch 5 headphone out, the “la la la” part suddenly become softer and muffled. It sounded similar on my mum’s iPhone 5 hp out.

Using  iPod Touch Line-Out via lightning and LOD, the “la la la” sounds coherent to the rest of the song.

It sounded similar via hp out of my E-MU 0204, laptop (3 nos), iPhone 4S, iPod Touch 4, iPad 2.

How I record:

Line-out direct to EMU 0204 L/R Line in

HP out to EMU 0204 L/R Line-in

Both aren’t volume matched, I tried to record hp out such that on the “-12db” indicator on the E-MU 0204 is lit, but not the “clip” indicator.

What I seen:

http://i255.photobucket.com/albums/hh160/kierai/hpvslineout_zps8bcdf658.jpg

What I hear and record (0:50 to “la la la la”)

HP out - http://www.mediafire.com/?bbo4czo8eaajirv

Line out - http://www.mediafire.com/?862ngnnaf3jrn7f

Video converted to mp3 - http://www.mediafire.com/?2dlxrjopd5dbqbb

Audacity Project file - http://www.mediafire.com/?pnoa1v5n10q9020

(Note: You do not need hundred/thousand-dollars equipment to hear the differences)

Conclusion / Remarks:

From what I recorded, there is seems to be real difference between using iPod Touch 5 hp out and line-out via lightning.  So, the difference which I perceive between my iPhone 4S and iPod Touch 5 hp out should be real.

What cannot be concluded:

Is  this difference is a “fault” on both on my iPod and my mum’s iphone ? Or does it occur for all iPhone 5 and iPod Touch 5 ?

What causes this difference ? See update below.

Does it affects other files (ALAC, mp3, mp4, mov, etc) ?   

Update:

It turns out to be a software issue. The video sounded correct when played on 3rd party app instead of Apple default video app. All along i thought it was a hardware issue because it sounded correct when using line-out via lightning. 

According to goodvibes, it looks like there's compression on the headphone out. 

It may either be a bug or something incorporated into the app by Apple. So, for those who watch video on iPod Touch 5 or iPhone 5, please take note.

(1st original post: http://forums.hardwarezone.com.sg/headphones-earphones-portable-media-devices-314/ipod-touch-5-hp-out-vs-line-out-report-c-w-graph-audio-clips-4067883.html)

Quote:

Originally Posted by goodvibes 

Looks like there's compression on the headphone out. May be a movie mode setting somewhere in the menus or simply incorporated to not blow out your ears with IEMs on explosions etc.. Would be interesting to see what happens with music which most seem to think is good on the new units.

You are right. It turns out to be a software issue. The video sounded correct when played on 3rd party app instead of Apple default video app. All along i thought it was a hardware issue because it sounded correct when using line-out via lightning. There is no related movie audio setting in the menu. So, it is either a bug or something incorporated into the app.

To me, when playing music, i can't tell any difference between 4S and 5. But based on RMAA results i have seen on both a korean and a chinese website, FR of iPhone 4S begins to roll off after 5kHz to -0.9dB at 20kHz. FR of iPhone 5 is flat. I'll leave these measurements to be done by the pro.