Well, be it a bug or not - Ardour (that is, QJackCtl) doesn't start
using all default settings in Ubuntu, while e.g. Audacity works
perfectly fine from the first try on the same hardware. I'm just
reporting what I'm experiencing.

I followed your instructions. My sound cards:

 0 [Intel          ]: HDA-Intel - HDA Intel
                      HDA Intel at 0xe4804000 irq 47
 1 [U0x46d0x8da    ]: USB-Audio - USB Device 0x46d:0x8da
                      USB Device 0x46d:0x8da at usb-0000:00:1d.2-1, full speed

(0 is my laptop's sound card and 1 is a usb webcam that also has a microphone)

After a restart and before I open anything (except Firefox), when I
start JACK using either QJackCtl (without touching any settings, so
the device is still set to "(default)") or your terminal command, it
works in both cases.

$ pasuspender -- jackd -d alsa -d hw:0
jackdmp 1.9.9
Copyright 2001-2005 Paul Davis and others.
Copyright 2004-2012 Grame.
jackdmp comes with ABSOLUTELY NO WARRANTY
This is free software, and you are welcome to redistribute it
under certain conditions; see the file COPYING for details
JACK server starting in realtime mode with priority 10
control device hw:0
control device hw:0
audio_reservation_init
Acquire audio card Audio0
creating alsa driver ... hw:0|hw:0|1024|2|48000|0|0|nomon|swmeter|-|32bit
control device hw:0
configuring for 48000Hz, period = 1024 frames (21.3 ms), buffer = 2 periods
ALSA: final selected sample format for capture: 32bit integer little-endian
ALSA: use 2 periods for capture
ALSA: final selected sample format for playback: 32bit integer little-endian
ALSA: use 2 periods for playback

I can start Ardour afterwards and record and listen to sound normally.
I cannot, however, listen to music in other applications - like
Rhythmbox. Even after I close the JACK session. To get music to play
in other apps, I have to kill -9 jackdbus like you said and pkill
pulseaudio (to get it to restart). After I do this, Rhythmbox is
singing, but JACK won't start with the old symptoms. This is what the
terminal starting method throws:

$ pasuspender -- jackd -d alsa -d hw:0
jackdmp 1.9.9
Copyright 2001-2005 Paul Davis and others.
Copyright 2004-2012 Grame.
jackdmp comes with ABSOLUTELY NO WARRANTY
This is free software, and you are welcome to redistribute it
under certain conditions; see the file COPYING for details
JACK server starting in realtime mode with priority 10
control device hw:0
control device hw:0
audio_reservation_init
Failed to acquire device name : Audio0 error : Device or resource busy
Audio device hw:0 cannot be acquired...
Cannot initialize driver
JackServer::Open failed with -1
Failed to open server
(s)kermit@hocus-pocus:~$

I am running the default pulseaudio 2.1-0ubuntu4. I guess this is a
duplicate of that bug you mentioned that got fixed in version 3. Hope
the fix reaches me in Raring. Thanks for the help!

On Wed, Mar 6, 2013 at 2:58 PM, Kaj Ailomaa <email address hidden> wrote:
> Actually, you didn't need to open qjackctl at all for doing this
> practical debug.
>
> --
> You received this bug notification because you are subscribed to the bug
> report.
> https://bugs.launchpad.net/bugs/1147405
>
> Title:
>   JACK won't start
>
> To manage notifications about this bug go to:
> https://bugs.launchpad.net/ubuntu/+source/qjackctl/+bug/1147405/+subscriptions