Strange bursts of noise in my mix. Your thoughts?

[CurtZHP]

Was doing a little experimentation with a mix I'm working on for a friend.

Basically, I'm using SAW as the playback deck, mixing on my Tascam DM-24, and the interface is a MOTU 2408mk3. The clocking setup is simple. I'm using the DM-24 as word clock master and the MOTU as slave.

(Ordinarily, I'd just do the mix in SAW, but bear with me...)

The tracks were recorded elsewhere, using Adobe Audition. My friend Dropboxed me the .wav files. I flew them into SAW, did a few edits to clean up some timing issues at the end of the song, and got a mix set up.

So, I set about printing the mix. Took the stereo output of the mixer and routed it back into an available track in SAW and started recording. Everything was fine until the very end of the song. All the instruments stop except for one guitar that plays an arpeggio as it fades out. As I'm listening to that, I'm startled by a few short bursts of white noise.

I play it back again, and sure enough, it happens again, but not in the same exact spot. I check everything in SAW and don't see anything that could be producing it, like stray regions, etc. I pull up the metering screen in the mixer and see that it happens on several inputs simultaneously.

OK, I think; at least I've got it narrowed down to something going on between the mixer and the interface. That immediately gets me thinking of the word clock. I set the MOTU for internal clock (instead of slaving to the mixer) and it doesn't like that. So, I change the relationship, making the mixer slave to the MOTU. That took care of the noise issue to the point where I could at least print a mix.

I've done things like this before, albeit not very often, and never had this problem. Most of the time, I'm just running the first two channels of the MOTU into the first two channels on the mixer for stereo monitoring.

While it's likely the issue is the clock setup, since changing it seemed to solve the problem, I'm still wondering if there's another possibility.

Could there be something about the files he sent me that SAW doesn't like?

Anyone seen this sort of thing?

[Tim Miskimon]

It does sound like a clock issue.
Are all the tracks the same rate?
Is it happening just at the end of the song or are there noises through out the recording.
If you are doing any on the fly clock coversions in the multi track that could be the problem.
Since you're recording back into Saw are you setting up the record at the same rate?
I've made that mistake a few times and had this happen when the imported tracks were 24/48 and I was trying to record at 24/44.1 - you might want to double check.

You could also try building the import tracks to new files and reloading them into Saw.
That's fixed issues I've had with a few imported track that I've gotten from a few clients that didn't want to behave in Saw.
Good luck.

[CurtZHP]

Everything's happening at 44.1. I'll have to double check the audio tracks he sent me. Maybe even go back to Dropbox and check them.

No other noise during the song. Only during that last few seconds when the only thing playing is one guitar track. When everything else is playing, it's clean.

I had thought about doing something similar to what you suggested. I was going to take each track by itself and build a new file for each. Might still do that in a new session just to test the theory.

[CurtZHP]

I stand corrected!

After doing a little more digging, I discovered that the files are 48kHz, 32-bit (float). I guess that's what Adobe defaults to. And I'm running the SAW session at 44.1/24.

I can see where that'll cause some conflict. At the very least, it'll make more work for the software.

That's what I get for taking his word for it.

:o


Now, is the necessary conversion something SAW can do, or do I need something else?

[UpTilDawn]

...Now, is the necessary conversion something SAW can do, or do I need something else?

You should certainly be able to do the necessary sample rate conversion from within SAW. I would do all tracks simultaneously to make life simple.

You should be able to do this from the session you already have going, but I suppose you could create a new session just for creating the converted files and then import them into the other session and replace the old ones, if that makes it easier for you to work with.

1- So, make sure that your SAW session is set to the sample and bit rate that you want to wok in (24 bit/44.1k, right?).
2- Now, go to the Process/Mixdown menu and choose the highest setting for the BuildMix Conversion Quality (you can set this to a lower setting later for normal work speed).
3- Select all the tracks that need converting in the MT by left-clicking each channel number to the left of the name label and blacken them (just to be very clear about the process here...)..... I'd probably make sure that only regions that need converting are on those tracks.
4- Go to the BuildMix menu and choose Export Track To SoundFile - No Mixer Processing (unless you want mixer processing, of course).
5- Build Mix to the folder location and file name you choose and let 'er rip. SAW will acknowledge the sample rate conversion, while ignoring any mix changes, by the way.

The end result should be new converted files that all begin at zero and extend the length of the total regions on each track (or is that of the whole session?... I don't recall at the moment). You can then use the SAW Library to locate and import those tracks into your session.

There's probably ways that you can simply replace the old regions with the converted ones, but that might produce unpredictable results because of the different file length and any region edits and/or automation you might have already created for them. You CAN probably figure out a fairly simple method to transfer automation and region cuts from the old tracks to the new on a manual, track-by-track method.

Hope this helps and I didn't leave anything out....

[CurtZHP]

There's probably ways that you can simply replace the old regions with the converted ones, but that might produce unpredictable results because of the different file length and any region edits and/or automation you might have already created for them.


I was concerned about that too, especially since I'd made some timing critical edits already.

I think what I'll do for now is wait to hear from my friend. If he's happy with the mix, then that's that. I'll just need to remember to check anything he sends me from now on!

If not, then I'll try what you suggest.

[Bob L]

Instead of converting all tracks in the session... consider doing the mix at the 48k rate... then doing one more pass on the final mix to come down to 44.1k... that way you only incur artifacts from one conversion instead of multiple track conversions.

Bob L

[greeny]

Hi Cuzt
I have had this issue before, it seems to be something to do
with fragmentation on the hard drive.
however this might be a problem on the other drive if the file
was sent via dropbox.

Run the defrag just in case.

if you zoom in on the file you be able to see the corruption.

let me know how you get on.

Greeny:)