Crackling noise

[BrotherShamus]

I'm using an 8Pre with a 828 MK2 attached with an optical cable. The channels on the 828 produce an intermittent crackling noise which if I understand correctly, means that the sample rate isn't synched up to my computer (2012 Macbook pro running Cubase 10.5). My problem is that I can't seem to access any of the settings for the 828... when I open the MOTU audio setup or Cuemix, it only provides me with the settings for the 8Pre and reads the 828 as ADAT. Is there a way I can manually change this on the 828? The user manual doesn't seem to have anything for this and it took me a long time to get this all set up correctly so I'd prefer to not disconnect the two if possible.

(my apologies if this is in the incorrect forum)

[mikehalloran]

Could be buffer size — in fact, that's the first thing I would suspect.

The other is the clock. You have 3 clock sources including your Mac. Open the pdf of the manuals, ⌘f and search for clock. Scroll through the listings and see what applies.

Still sounds like buffer size if just crackling.

[BrotherShamus]

Thanks... someone else had mentioned buffer size as well. I changed it in Cubase (I'm not sure how to access it anywhere else) as much as I could without too much of a noticeable lag in audio and while the problem seemed to get better for a short time, it returned within a couple of sessions. I'm not very good at this so I may have misunderstood and done something wrong. Is there another buffer somewhere in the MOTU settings that I'm maybe not aware of?

[CharlzS]

If you don't have the 828mkII clocked to ADAT, you can try changing to that. You'll have to have both the ADAT in and out connected between the units. Clock source on the 828 is very easy to set from the front panel, check the manual. In order to use Cuemix with the 828 it would have to be connected directly to the computer. Is there a reason why you're using the 828 as an ADAT expander rather than the other way around?

[HCMarkus]

Is there a reason why you're using the 828 as an ADAT expander rather than the other way around?

This.

Use the 8Pre as and expander and clock it from the computer-connected 828mkII.

The 828 gets its clock from your DAW. The 8Pre must to be connected to the 828 by both Optical ports (In and Out, two optical cables) and slaved to Optical. Then, control all your I/O from the 828mkII CueMix control panel.

[bayswater]

I had a setup using a 828-3 and a 2408-2 linked by ADAT. I was not able to sync very well by ADAT, and had to use the word clock connections via a BNC cable to get it working reasonably well.

Even with that, I got a consistent out of sync glitch every few minutes in ADAT channels 7 and 8. You could see the jump in the signal level in an audio editor when this happened where a wave was missing a small part of its cycle. I never figured out what the problem was. I tried new cables, buffer changes, and other stuff I can't remember, but none of these things made any difference.

It wasn't a practical problem. It was only apparent in low frequency waves and simply redrawing the wave at the glitch point fixed it.

[HCMarkus]

Unfortunately, IIRC, the 8Pre offers no sync method other than Optical. I definitely prefer BNC-connected Word Clock if available and use it in my current setup

[BrotherShamus]

I actually set it up that way because I was using the 8pre on it's own and added the 828 because I had a mic'ed drum kit taking up all of the XLR in's. I just wanted to add some 1/4" inputs for various instruments and the optical connection seemed like the easiest route. I'm definitely not a techie guy so I was happy to have it working for awhile (was good for a year or so) and I'm not actually sure what's changed to cause this to happen, except that I updated my Cubase. I'll try to find the buffers and work with them first. Just so I'm clear here, I'm increasing the buffer size? If not, I'll look into the word clock. So... would I be wanting to swap them out (8pre as slave to 828) to access the word clock? I'm not sure what the difference is...

[bayswater]

As per HCM, you might find there is no BNC connector in the 8pre for word clock. Good luck with the buffer solution. Yes, just increase the buffer size in the DAW.