Multiple input/output devices

I can’t seem to find a combination that’ll allow me to use my USB microphone for input while also using my built-in soundcard for output, while using a QE62 laptop like this one:
and a microphone like this one: with Ubuntu.

Frankly, if I’d understood the graphics card I was buying properly I wouldn’t have brought this laptop at all. It has been a free-software pain. Hardest Linux install I ever did, and I was Linux in like 1998.

But anyway…

Audacity lets me just select the Samsung USB mic and plays back fine, giving up now on trying to make Aurour do so in time to record tomorrow.

I suspect Jack is mostly to blame, but when I select the USB mic for Input it changes the output to “none” and when I select the output to the inbuilt it unselects the USB output.

Gonna have to just use Audacity for actual recording now. Which is disappointing, and will mean extra editing work and less ability to play the existing dialogue lines to the new actor recording the next set. Might have to use my phone for that second bit I guess.

Could probably make it work on my main machine, but it’s fans are way too loud.

Anyone got any clues for next time? Probably too late for tomorrow now. explains, if you’re using Jack. And it shows how you can get round the problem.

What are you using to configure JACK? qjackctl? Gladish?

Audacity only opens the device when it is using it, so it does not matter if the input and output devices are in sync or not. Ardour needs to have them both open from application start, it is a DAW, not an audio editor after all. So using a USB mic with internal sound or some other output audio will not work unless they are externally synced or there is SRC involved. Ardour and Jack do not do this by default though the sound servers in some OSs do. In the case of Linux with Ardour, you will have to use jack as the sound server and add either alsa_in or zita-a2j to add the USB mic as another port to jack before starting Ardour. With both of these utilities you can name the port that Ardour will see to something you can find easily (like mic1). In Ardour you will need to manually connect this input to the channel you want it feeding. You may run as many instances of these utilities as you have USB mics if needed. The zita-a2j version is better quality resampling and uses less CPU to do so, but alsa_in is already included with jack, so if you have jack you already have alsa_in. The zita package will be called zita-ajbridge if you wish to install it.

It is a microphone with a usb dongle for a cable, or a usb input device for Mic/line inputs? If the latter is true, it may be more trouble than it’s worth. Jack isn’t going to configure a microphone or any instrument. I’ve been that route before.

Ok, I think I understand the implications of using unsynced devices for recording at the same time, but if I wanted to use one device for recording and the other one for playing that problem would still exist? I would like to do a reamping and have available two interfaces with only a stereo out each. I have managed before to do this with one interface but monitoring is practically impossible due to feedback which makes it a rather uncomfortable process. So it would be having one device to handle the DI output, then from the amp to the second device input with normal monitoring. Could this work?

Yes. When recording a second track while listening to the first track, the two interfaces must be in sync. This is one of the most common operations in DAW use. The input and output need to be in sync. Unless you only use one device while recording and then switch devices and only use one device when doing playback (which may be a different device) The sample rate does need to be the same, of course. But recording without any output is not very usable. It is not that hard to set up jack for this purpose on almost any linux system. Feedback is no more of a problem than with any analog system and can be solved with mic/speaker placement and level control. I happen to have a mixer in my studio (from analog tape days) and monitor any mic or instrument that is being recorded before it gets to the input device, mixing in the playback to the headphone/speaker mix. Most even cheap audio interfaces allow mixing input to monitor audio as well.

Thanks Len. Just to clarify when I talk about feedback I refer to internal feedback produced by having an interface outputting a signal that is being processed by an amp and then recorded again by the same interface. As it only has one stereo output the only way to achieve the reamping goal is either to split the output signal so the guitar part runs through lets say the L channel while the R channel plays the input as well as the backtrack, the other option being just plainly muting the active recording track so it doesn’t play again in the output you want to record. Either way “normal” real time monitoring is not possible. Unless I’m missing something, but I have had my fair time of fiddling around with it.

I haven’t done anything like that. I have either recorded the amp I want (with a mic) or used a plugin to get the sound. Live with mic allows the better sound (in my opinion) while DI to plugin allows more changes afterwards. Using the amp as an external “plugin” effects module is allowed for and can be done by using left and right as you mention, or using jack with zita-a2j to allow a second interface. I have had some success with cheap (less than 1$) USB Audio dongles as second devices with the right plug.

In most cases, I have found that playing through the amp I want affects how I play in the first place, while playing DI clean and reamping means I play for clean.

At the moment I’m using the amp as you say like a plugin as I’m trying its “cabin emulation”, but most times I would just record the amp with a mic, having anyway the same feedback issue due to the limitation of interface outputs. Indeed playing for clean has a different feeling than playing through the amp, for that regard I usually setup a DI box that serves as a signal split, one out goes to the interface for DI recording and the other one to the amp.
I’ll look into the zita-a2j, thanks!