I’m using Ardour on Ubuntu Studio 20.04 with a Behringer U-Phoria UMC1820 + ADA8200 for 16 channels. I’m usually recording at 1024 frames but for monitoring overdubs down to 128.
However, regardless of frames and so on, I’m getting cracks in my recordings – permanent to the audio files. Cracks or pops or rather like gaps. Sounds like xruns. BUT! qjackctl or Ardour aren’t reporting any buffer over/underruns. I get it regardless of 128, 256, 1024 or 2048 frames.
I’m going to post an audio example and maybe someone could help analyze it.
Could it be electrical interference unrelated to Ardour? What does it sound like to you?
Had a similar problem with the UMC1820. Pops were irregular and appeared randomly in left or right channel (but never in both at once). Eventually tracked it down to a bad USB cable. Dunno if this is the case, but it’s worth checking simplest things first.
Looking at the wave with audacity (spectrum view, and then back to wav view) shows a “click” at sample 87554.
It does not look like an xrun, because the “center” sample between the two slopes and the respective sample left and right of it look like that they are not coming from the original signal but were “digitized” that way by the interface, however that happened.
Hard to say, what’s actually causing this.
You wrote that you use an “UMC1820 + ADA8200”. Does that mean you use both interfaces at the same time? If yes, what happens, when you only use one of them?
@slash is on the right track, I suspect this is a clock sync error between your UMC1820 and the ADA8200. They are likely not locked to a single clock. Confirm that first.
If they are connected via ADAT both ways and the SYNC switch on the Ultragain is set to ADAT In they should be and the SYNC LOCKED led on the Ultragain should show it.
Hah! Having not worked with TOSlink before, I unwittingly had the plastic protection on the new cable I attached. No wonder things went crazy.
ADA8200 slaving to UMC1820 and connected both ways, things … seeem to be working. I’ve not yet observed any pops in the recorded audio. I will keep recording and we’ll see.
