Two audio interfaces with Jack and Ardour? Your recent experiences?


#1

Hello everyone, I found this video very interesting. I remember in the past reading somewhere that this approach could be problematic but that was an old article and both Linux and Jack have improved a lot since then. Has anyone used this approach recently? Is there a problem or downside to doing this? A friend o f mine and I have 2 input interfaces each so plan is to try it for drum recording using 4 mics with Ardour. Thanks in advance.

Forgot to add the video link :joy: , here it is


#2

That might be problematic. As far as I understand the interfaces won’t be in sync with each other so you might get all kinds of phasing problems as the channels slowly drift out of sync from each other.

Four input interfaces are cheap and problem free, my recommendation is to always use only one interface with enough inputs for what you are doing. For example Behringer UMC1820 has 8 mic inputs and it costs less that 200 euros. By adding a Behringer Ultragain ADA8200 you can add 8 more Mic channels via Adat. I have both of these devices and this combination works in Linux and is dirt cheap. When talking about Behringer you need to add: the first device you get might be broken and you need to return it (this also happened to me :slight_smile:


#3

Its still interesting. I myself have 16 analog inputs (Scarlett 18i20 along with the OctaPre mkII via ADAT), but I have been looking for more MIDI inputs. This same method should work for a MIDI interface and something like the Scarlett, right? Thanks for sharing :slight_smile:


#4

yes that will work. It does take care of out of sync cards by using SRC to correct. However, I would rather use the zita-ajbridge package which has zita-a2j instead of alsa_in and zita-j2a instead of alsa_out. The advantage with zita-ajbridge is that is has better quality SRC while at the same time using less cpu power. It also allows not using the SRC if you have a word clock link between your devices and they are synced. Another note is that jackd 1 has this built in already though jackd 2 does not yet.

Any time SRC is used, there is no longer a sample for sample path. The difference for most cases is not audible but I would not use sources across two device for stereo or other surround tricks. Left and Right for any source should always be on the same device. A second left and right can be from another device.

SRC = Sample Rate Conversion

MIDI is a different animal. You can use as many MIDI devices as you like and jack with a2jmidid will show all of them with no problems. It is even possible to use a midi port on a card and not use the audio part. for example I have an old pciaudio card that has a joystick/midi connector that I use only for MIDI no audio.