[pulseaudio-discuss] whistle on Ubuntu 10.04

Alexander E. Patrakov patrakov at gmail.com
Wed Jul 7 09:34:06 PDT 2010

rulet1 at meta.ua wrote:
>   Anybode knows how to solve this bug?
> https://bugs.launchpad.net/ubuntu/+source/pulseaudio/+bug/475997?comments=all

No. It is even not known whether this is a hardware or software bug. 
Back in 2004 or 2005, I have tested several sound cards before buying 
one of them, and found some to have the whistle bug even in Windows. 
However, the origin of this bug varies. So let's start from the obvious 
(for me) and rule out one particular hardware issue (the analog 
amplifier not liking the capacity of the cable). You'll need headphones 
with a very short cable (< 80cm, the ones from an iPod are fine), and a 
long (5m or so) extension cable.

Make sure you know perfectly how to switch this whistle on and off (it 
seems that you do). Configure the system so that it is on. Then, unplug 
the speakers, plug in the headphones. Do they whistle differently? Does 
the tone of the whistle change if you connect your speakers or 
headphones to the sound card using a long extension cable?

Now, configure the system so that the whistle is off (or in the 
ultrasound frequency range - who knows without an oscilloscope). Try all 
combinations of connecting speakers/headphones with/without the long 
cable. Does at least one of them bring the whistle back on?

If you find that the length of the cable does have an effect on the 
whistle, then it is certainly a hardware bug in the output amplifier.

Alexander E. Patrakov

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