I cannot find any info online to get it working with Jack so I just post a howto here to help others.
I am replacing my Presonus 1818VSL with a UMC1820.
The successful 1818VSL jack string was:
The Presonus was very intermittent, would work well for months, then just crap out for no reasons. Bought another one and the same problem exists./usr/bin/jackd --sync -P80 -ndefault -dalsa -dhw:VSL -r441
The UMC1820 on the other hand was immediately recognized without any song and dance as compared to the Presonus.
Just the Midas preamps is such a huge improvement above the Presonus preamps. I hear quite a stark improvement.
The presonus looks better but looks dont count regarding this howto.
All that is needed is -dhw:XYZ entry for the UMC in the string posted for the Presonus.
To get that for the UMC or any other interface: Run the following in a user terminal.
In my case with the UMC connected, I noticed$] aplay -l
Therefore the alsa hardware name to use is UMC1820card 4: UMC1820 [UMC1820], device 0: USB Audio [USB Audio]
The resultant required Jack/alsa string is therefore:
Execute the latter in a terminal: The output will read something like this if successful and wont return a prompt in the terminal. If it returns a prompt the string failed and jack did not start:$] /usr/bin/jackd --sync -P80 -ndefault -dalsa -dhw:UMC1820 -r441
Now start Patchage.$] /usr/bin/jackd --sync -P80 -ndefault -dalsa -dhw:UMC1820 -r441
jackdmp 1.9.12
Copyright 2001-2005 Paul Davis and others.
Copyright 2004-2016 Grame.
Copyright 2016-2018 Filipe Coelho.
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 80
self-connect-mode is "Don't restrict self connect requests"
audio_reservation_init
Acquire audio card Audio4
creating alsa driver ... hw:UMC1820|hw:UMC1820|1024|2|441|0|0|nomon|swmeter|-|32bit
configuring for 441Hz, period = 1024 frames (2322.0 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: 24bit little-endian in 3bytes format
ALSA: use 2 periods for playback
You should see a system Input with 10 inputs and a system Output with 12 outputs. you should alsso see two midi input/outputs.
Once that appeared in patchage it is all done and you can route the ins and outs with Jack to Mixbus/Ardour or any other Jack enabled program.
If all works to your satisfaction you can add the jack string as above to your rc.local or as I do I use execute it with an ampersand to spawn it and it is all good.
I intentionally started the interface with jack at a sample rate of 44100 (the -r option in the string)
You can now try higher sample rates to the maximum the UMC can handle.
For the highest sampling rates, it is important not to use any hubs. Try to connect the interface as directly as possible to a pc USB port.
SUGGESTION:
My expereince is such that I DO NOT and WILL NOT use Qjackctl and Cadence to start Jack. All these fancy nested interfaces do is just to construct the string I showed you how to do from first principles above. Qjackctl eg will do other unwanted time wasting things like switching on a2jmidid without your knowledge. You will spend weeks wondering why suddenly when jack runs (which you started with the the two examples of bloatware above) lots of midi controllers and applications fail to work unless you shut down jack. Dont start a2jmidid if you use controllers with applications that do not comply to a2jmidid. a2jmidid confiscates control and is not advised to use unless you have no other option as a last resort.