[SOLVED] JACK and Lexicon Alpha on Ubuntu Studio 16.04 LTS

[rrotoli]

Hi everyone.
It is my first time here and, first of all, I would like to apologize if an answer to my issue was already available and I failed to find it. Let me explain my problem: I've been using a Lexicon Alpha with Ubuntu 14.04 for some time and all was more or less ok. It was recognized by both ALSA and PulseAudio, and it was possible to assign inputs and outputs on JACK; all of this "out of the box", I simply had to plug the soundcard and go.
In order to reduce the latency, thanks to the low latency kernel, and have a better experience with all available plug-ins I decided to install, in dual boot, Ubuntu Studio 16.04 on my PC. Unfortunately, the Lexicon Alpha doesn't work on this distro and I'm really going crazy, trying to understand why. I've launched Alsamixer on the terminal and Lexicon Alpha is available among the soundcards, the commands arecord -l and aplay -l both show the Lexicon Alpha as an available device but, when I try to connect its in/outs on JACK, using QjakCtl, simply the soundcard doesn't exist. Since, on QjakCtl, the only available soundcard was the one integrated in the motherboard I also tried to disable it on the UEFI, in order to see if the problem was related to some kind of conflict between the cards when JACK server was started. The result is that now there are not inputs and outputs available, launching QjackCtl. I never had the possibility to listen to a single sound coming from my PC, when Ubuntu Studio is running, since neither PulseAudio seems to work... As far as I understood on Ubuntu Studio PulseAudio and ALSA work together.
Thank you in advance for your help.

[Pablo]

I've launched Alsamixer on the terminal and Lexicon Alpha is available among the soundcards, the commands arecord -l and aplay -l both show the Lexicon Alpha as an available device but, when I try to connect its in/outs on JACK, using QjakCtl, simply the soundcard doesn't exist

qjackctl has not detected your Lexicon card out of the box. This seems like an issue of qjackctl the first time you run it but I hope jack audio server itself is fine.

Note that the "interface" field is editable, just type there the name of your card. It could be something like:

hw:LEXICON
or
hw:USB
or, in general:
hw:NAME

where NAME is what you see between square brackets in the output of
cat /proc/asound/cards
that you can also see via aplay -l or arecord -l.

The following times you run qjackctl the lexicon will be there, I guess.

[rrotoli]

Thank you, Pablo for your reply. Reading your post, even if I didn't understand where to find the editable "interface" field you wrote about, I had a suspect and, taking a look to JACK historical data, I had the confirmation I was looking for. Simply, the JACK server failed to start due to some kind of error during initialization. I tried to change some parameters on QjackCtl and, finally, the server was started and, now, all is running properly. Unfortunately I am not able to say which is the exact parameter I have changed that allowed the server to start.

[Pablo]

Glad you solved your problem!
I was referring to the selection of the audio card (aka audio interface) in qjackctl's setup.
I am attaching a screenshot. In my case, hw:UA25EX is the short name that alsa gives to my Edirol UA-25EX, as shown in the terminal output of "cat /proc/asound/cards". It will normally appear in the drop-down list but you can always type it up if it didn't.


https://imagebin.ca/v/3mVy9xaZGTg3