Hi Oliv
There doesn’t appear to be any way to set master or slave devices in pulse audio volume control:
I noticed that both interfaces are ticked as fallback devices and this cannot be changed here.
The terminal startup command
$ ARDOUR_ALSA_EXT=“hw:2” Ardour8
and then the Ardour audio/midi setup window control the relationship
Thanks for your interest
No, not expected to work with USB interfaces if you expect sample perfect coherence across all four channels.
It can be usable if you have two two-channel interfaces and make sure that the inputs split across the interfaces do not need extremely tight matching, e.g. no stereo microphone configurations split across interfaces, but you could have a close guitar mic on one interface, and e.g. overhead drum mics on the second interface. The acoustic delay of sound through air is approximately 1ms per 1ft/0.3m so the variation in latency between the two interfaces is on the order of moving microphones around a short distance, or moving musicians slightly in the room.
2 Likes
That’s a good point Chris, definitely worth a try. Come to think of it, there could be times when the phasing could be used as an effect to fatten up certain sounds as well.
Many thanks.
I had a brief try on Mac yesterday, without much luck. Both interfaces were recognised but ran into problems trying to record onto tracks even though there were signals visible on the meters, I guess routing issues. Also kept getting midi error msgs. May be this was because one interface has midi and the other doesn’t.
Might try again next week if there’s time
I think Mac is a different situation because the CoreAudio libraries handle compound devices.
The equivalent on Linux would be using Pipewire to manage multiple devices instead of the Ardour ALSA backend, or having to manually setup jackd resampling clients.
1 Like
Hi! I’ve been playing around with this sort of 2 interface config for a little while but in my case, I own one pci and one usb soundcard (Delta 1010 and Komplete Audio 6). After running some test, I came across the same offset/delay you mention.
As Chris mentioned…
So, I think is definitely usable but not quite sure if it would be my “permanent” set up. I’d love to hear some comments of other “multiple interfaces” users, their configuration and experience with latency, clock sync, stability, etc.
(I’ve once read about multiple pci cards in @jrigg webpage)
Yes. I panned the vocal I recorded hard right and left. It was originally centered in both tracks so I could hear if it was phasing.
However, when panned hard each side the vocal sounds much bigger and with no noticeable phasing. The effect is like on the guitar melody in the James Bond theme.
Or a similar idea to the varispeed technique @Robin talked about in his 50 things you didn’t know you could do with Ardour presentation.
It’s not something I would always use, but another useful method of making recordings sound larger.
Now I’m glad I did the experiment. 
1 Like
Thanks Chris
I was wondering if Pipewire would be coming with something like that.
Once it is available out of the box in an audio distro like AVL, I will be interested to see what can be done.
Meanwhile, as I have said to @L_Pro, I now think under ALSA it can be a useful widening technique for mono sounds when hard panned each side.
You have to be careful about the correlation, and I have found that reversing the phase on the track which the slave device recorded gives the least antiphase amount, in this recording anyway.
A happy accident, but you might be better using a plugin or even manually shifting one track by a little. It’s likely to be more reliable and predictable.
Cheers,
Keith
1 Like
Yes I may have been romanticising a bit. I thought, if only the technique
could be adapted to create an effect like late 60s tape flanging, as Ive
never heard a plugin that comes close!
Hey, if it works, then why not. Happy accidents are a gift.
Cheers,
Keith
This topic was automatically closed 91 days after the last reply. New replies are no longer allowed.