Hi guys and gals...

Apologies for any typos...

Well I have a major problem and I don't know how to take it further so I need your advice AND help...
Found from the AudioScope.sh calibration method(s)...

I think I have found a HW bug in Apple gear...

This has been checked so far on a new iPhone 5S,
a 3 month old iPad Air and my Macbook Pro...

As a confirmation I have tried it on my old Blackberry Phone, Windows Vista and XP on various machines
Debian Linux and PCLinuxOS 2009 on an HP laptop and an Acer Aspire One netbook these work perfectly as
the sound _card_ should...
It has even been checked as a RAW file in /dev/dsp too and is correct.
(Will check CygWin tomorrow.)

Consider the code below:-
It was written to set up the vertical amplifier polarity and works as designed BUT........

Code:

#!/bin/bash --posix
> /tmp/pulse.wav
printf "\x52\x49\x46\x46\x24\x00\x01\x00\x57\x41\x56\x45\x66\x6d\x74\x20\x10\x00\x00\x00\x01\x00\x01\x00\x40\x1f\x00\x00\x40\x1f\x00\x00\x01\x00\x08\x00\x64\x61\x74\x61\x00\x00\x01\x00" >> /tmp/pulse.wav
for n in {0..8191}
do
	printf "\xFF\xFF\x00\x00\x00\x00\x00\x00" >> /tmp/pulse.wav
done
afplay /tmp/pulse.wav
exit 0

This works perfectly on the RANDOM gear as it should; a NEGATIVE going pulse NOT a POSITIVE one.
When pulse.wav is transferred to run on the Apple gear above the waveform is inverted, I.E. it is a
POSITIVE going pilse. AFAIK this is wrong.

What I would dearly like is for the interested on here to check the waveform from the earphone socket
against a known Oscilloscope and reply to this thread.

You can test on anything that plays a .WAV file. The quality of the wave is NOT important the polarity
IS however...

It should look something like this:-

Code:

 =-+  +-----------+  +-------  <- 0x00 Unsigned 8 bit.
   |  |           |  |
   |  |           |  |
   |  |           |  |
   |  |           |  |
   +--+           +--+  <- 0xFF Unsigned 8 bit.

Remember quality is NOT important, polarity IS...

I will be checking on other machines and phones myself over the WE...

Many thanks in advance...

NOTE:- I have not yet posted anywhere else and hope I am wrong. thanks guys and gals...

If this is consitent throughout Apple gear then I don't know how to take it further...

Barry.

EDIT:
Many thanks to my workmate Richard Carter for letting me test on his iPhone 5S and
his iPad Air...