Clicks, Pops, and Squarewaves?

[Neil Eckstein]

I have a real problem here.

The first post that I put on this forum was in an attempt to resolve a clock issue between some external pre's using ADAT. I didn't know whether this belongs in the same place or not because it's a bit different.

Here's why: it's not the ADAT.

I've now got 2 500 series pre's and 5 710d pre's snaked to the DM's inserts as instructed by you all. It seemed like the perfect fix but I am still getting this horrible "squarewave-like" sound printed to my audio. I'm uploading a DI guitar track to let you hear: https://soundcloud.com/orange-whale-studios/gtr-06 (Cut to 2:30 and you'll blatantly hear it).

This is now happening on the board pre's as well--not just the externals. I tried for 4 hours last night to try and recreate the problem so that I could try and troubleshoot, but it just happens RANDOMLY.

Here's the kicker. When it happens, I can hear it in the live signal, even before it gets recorded! How could I be hearing latency in a LIVE SIGNAL?!

I found this post: http://www.tascamforums.com/threads/intermittent-loud-pop-crack-sound-in-dm-4800.469/

But the difference is, this guy said his channels were peaking out. Mine are not doing that at all; it just sounds like when I first started recording years ago and didn't know about latency.

Does anyone have any troubleshooting ideas here?
Am I monitoring a truly "analog" signal or is there some type of A/D happening before I hear it live?

I am at a loss here. I'm afraid to hit the record button because I don't know when the problem will jump up. I recreated the exact conditions where the problem happened last and couldn't cause the problem again.

H.E.L.P.

 

[cmaffia]

If you're hearing latency in a live signal it means that you're monitoring the signal through the DAW's mixer rather than direct from the DM. It's also possible that you're monitoring both (and depending on your routing schema, recording both). I'd start by making sure your DAW isn't monitoring the channel as well. In Cubase there's a monitor button for each track next to the record button. If your DAW doesn't have the equivalent, then just mute the channel.

From your description, it sounds like you're hearing this square wave sound live. Another test I'd try is monitor your guitar without the computer on (or your DAW running). Do you still hear the unwanted effect? If not, that would indicate that the DAW is routing something back to your DM. Are you sure there isn't any unintended routing that is duplicating the signal that is causing this effect? I'm putting my money on that being the cause.

Are you mixing "in the box" or returning DAW tracks to the DM and mixing through the console (out of the box)? It would be interesting to see all your DM routing and your DAW routing (I think your using Cubase, so that would be your VST Connections, both in and outs).

It's been said before, at first the DM's routing can be difficult to wrap your head around and it's quite easy to get overwhelmed by the console. You'll get it in time.

 

[Neil Eckstein]

I appreciate your input, as usual. This forum is awesome.

I think I understand the routing. And I am definitely NOT monitoring the live signal through the DAW--I've got my buffer size set to 3072 so that wouldn't even be feasible; there'd be an outrageous delay between the two signals.

I'm flabbergasted that you don't hear the corruption in that audio! I guess it's difficult to hear it if you don't have the volume up. Also, did you navigate to 2:30? It's after that when it becomes very apparent.

-------------------------
Just because I'm not very confident about it, here's my routing:

DM:

Input routing: Inputs 1-16 set to M/L 1-16 respectively; ch's 42-45 set to eff 1-l, 1-r, 2-l, 2-r respectively; ch's 47 and 48 set to Slot 1-1 and slot 1-2 for playback;

Output routing: all channels set to "Stereo" in the "Output Assign" section on the left of the board;

Output Slot: Output Slots 1-16 set to M/L 1-16 respectively; sometimes I also set Slots 17-32 to Bus/Dir 1-16 so that I can record dry and wet EQ/Comp, etc.

Cubase (Nuendo):

Device Setup: IF-FW driver selected; MIDI controls for motorized faders set to 5 and 6 (this was a funky setup but I got it);

Connections: Inputs set to "32x Mono;" Outputs set to Stereo "Out1" and "Out 2 (which I have routed to ch's 47-48 on the DM);"

NO MONITOR buttons are selected--I never use these because the DM eliminates the need for that.

Does this all seem normal?
--------------------------

Two follow-up questions:

Am I monitoring a truly "analog" signal or is there some type of A/D happening before I hear it live? For instance: aren't the DM effects Digital? If so, how are these applied to a live signal in real time? (Noob questions, I know, but curious nonetheless.)

Is there a factory reset on the board? Maybe I've got something silly going on that I can't find that could be eliminated this way.

 

[Neil Eckstein]

Also, remember: the only clock at play here is the DM and the computer. Everything else is "analog."

 

[cmaffia]

You said you're hearing latency. If you're hearing latency then you're probably monitoring through your DAW. To make positively sure you aren't, take your computer out of the equation. Turn it off and monitor your guitar signal through the mixer and see if you still hear the anomaly. If you still hear the anomaly then you have duplicate routing of the signal somewhere. Are you sure you're not sending your signal to an internal effect? Are you sure you're not monitoring an AUX somewhere? Arjan also suggested to look at the monitor levels to check for signal elsewhere besides the channel your guitar is plugged into.

I have to ask...why are your buffers so high? You should be fine at 256 or 512, especially with Cubase ASIO Guard.

All inputs (including your inserts) hit the ADC which is shown in the diagram Arjan posted in your insert thread.

 

[Neil Eckstein]

Well, that's the thing--I'm not sure it's latency; I don't know WHAT it is! I know for certain that I'm not monitoring through my DAW; but when the situation happens again, I will definitely try what you suggested.

So here's the thing I just noticed: it's ONLY the guitars! Not just the DI either, but the mic'ed guitar amp signal as well. The first track I showed you was ONLY DI, this one is ONLY the mic'ed guitar amplifier (sm57).

Can you please see if you can hear it in this track?

https://soundcloud.com/orange-whale-studios/gtr-clicks

(Soundcloud threw off the timing a bit--add .5 seconds to my notes on the track.)

I am totally at a loss here. I can't reproduce the problem when I want to so it's impossible to troubleshoot properly. My only solace is that at least I know it's only happening in the guitar tracks.

I truly appreciate your consideration on this. I have nowhere else to turn. Thank you!

 

[cmaffia]

Did you do any of the things I suggested? Not sure how else to help without knowing the results of every suggestion made by Arjan and myself. I'm not sure what I'm listening to. There is absolutely no reference point. There doesn't sound anything overtly wrong with these raw tracks.

 

[Peter Batah]

I listened to the audio snippet as well and was unable to detect anything out of the ordinary.