Ticking sounds on stereo output DM4800

[Headroom]

The DM4800 of a friend of mine (not on this forum) suffers from ticks in the left stereo output channel. It sounds as if there's an electric spark somewhere, and it overloads the left channel. The frequency of the ticks depends on several audio levels. Without any input connected tot the DM there are no ticks. With just the FW cable connected, the ticks occur every few seconds. With audio through the FW the frequency increases up to several ticks per second, depending on the audio level of any channels. However, audio from any channel other than the FW inputs does not affect the ticking. What I have tried so far: I connected the FW to a DM3200: no ticks. I changed the FW card in the DM4800: no difference.
Summarizing: ticks/spikes on the left stereo output, depending on the level of channels connected to the Firewire.
Any help would be greatly appreciated!

 

[skier]

There may be several reasons for this problem from a ground loop to a poor ground, but
I've seen this before and traced it to a shielding failure of the FireWire cable. If you have another FireWire cable, especially if it's new and hitherto unused, try it.

Good luck!

Jerry

 

[Headroom]

Thank you Jerry for your suggestion. Unfortunately changing the cable made no difference.
I also noticed that the ticks/cracks continue after the audio has stopped. They fade out in about 0,5 to 1 seconds. Re-recording the stereo channel into the DAW also records the ticks.

 

[skier]

Ok, let's back up a bit. You said that you only hear ticks from the left stereo output channel. Have you tried individually muting each channel to see if muting one of them stops the ticks? Start first by muting those channels that are panned left. If you find it, then try panning that channel right and see if the ticks now come from the right channel. If so, you've found the source of the ticks and need to go further back up that branch to determine the cause of those ticks.

However, based on the other points of your description, it's also possible that the problem is in the DM4800s FireWire card and that sending audio through it causes the ticks to generate there. For example, a DC blocking capacitor could have shorted or a chip in the digital chain is oscillating and sending pulses out when a bias or level is disrupted. But I wouldn't try to go to that level, just try to determine if the problem is coming from a channel coming in via FireWire or if its a problem with the FireWire card itself. You already confirmed that it didn't happen on the DM3200, so that points to the DM4800's card. But it's fast and easy to check individual channels by muting them in case one of them is bringing the tick signal there.

 

[mixerizer]

Also - sometimes repeating ticks and overloads are caused by clock issues. Is there any chance that your specific clock setup or settings need to be adjusted somehow?

 

[Headroom]

The ticks were caused by a bad snapshot!
They are eliminated by recalling a different snapshot from the library. I don't know how the snapshot got corruped, nor can I explain how this could cause this particular errors.
Anyway, back to making music!

 

[skier]

Headroom, thanks for closing the loop on this! I have to admit that I'd not considered that, but it does make complete sense. It means that one or a combination of the settings saved in the snapshot caused the ticking sound. That also implies the problem occurred before the snapshot was saved, but was not noticed, perhaps because it was low-level and other parts of the signal or studio noise covered it up.

A too generous EQ boost, too high a fader or aux send level, too high a setting of a plugin amplitude, or anything else that can cause an over driven condition or oscillation, alone or in combination, could caused such a problem. If you know and still have the snapshot, it could be investigated and the problem found. OTOH, you now know how to avoid it, and other than academic curiosity, I wouldn't be inclined to spend too much time on an investigation.... though, it is curious...

Jerry

 

[Arjan P]

Very interesting, this one. Something to keep in mind, cause I wouldn't have thought of looking at the snapshot (and the settings inside it ofcourse).

 

[Headroom]

If you know and still have the snapshot, it could be investigated and the problem found. OTOH, you now know how to avoid it, and other than academic curiosity, I wouldn't be inclined to spend too much time on an investigation.... though, it is curious... Jerry

The bad snapshot was the only one that contained a delay in the aux1 channel. It turned out that the ticking/cracking starts when the delay in the aux1 is set at 64 samples or more. This happens just with the aux1 channel, all other channels are fine.

 

[mixerizer]

Whoa!

Just checked, my board doesn’t crackle on aux 1 with any delay setting.

I’m using 1-2 as regular auxes, tho - not as the monitoring pair.

Does the same thing still happen on your DM regardless of snapshot?

 

[Headroom]

It happens with any snapshot. I also created a new project, with the same result.

 

[mixerizer]

Aw man that sucks. I hope it self-resolves. Maybe it’ll subside w a re-examination/laying on hands of the cabling and/or after the next power down.