Output to Audio Interface Clipping +6 dB. Help please!

Hello everyone!

I’m hoping that maybe someone on here can help me with an issue that’s been driving me crazy.

For reference:
Version = Nuendo 10 (version 10.2.20 Build 396)
Interface = RME Fireface UCX (Latest firmware & Drivers)
OS = Windows 10
Computer = Custom Dell
RAM = 64 gigs
CPU = Intel Xeon Gold 6134 @ 3.20 GHz, 8 Cores
Graphics Card = NVIDIA GeForce GTX 1080

So I’ve been working on some explosions for a video game lately and a couple days ago I noticed that my sounds were starting to have this clipping, crackling sound but my VU meters in Nuendo showed no signs of clipping. In fact, my levels were at -1 dB because of the limiter I had my audio going through. I figured that maybe I was hitting the limiter too hard so dropped the volume of all of my tracks and it seemed to help fix the crackling. But, because I lowered the volume so much, the threshold of the limiter wasn’t kicking in and my explosions lost all of their punch.

Next, I decided to try exporting with the clipping to see what would happen and when I listened to the audio in VLC Player and Sound Forge, there wasn’t any clipping present!

Finally, I decided to create a new, empty Nuendo project and place one loud explosion SFX file (stereo file, 96k/24-bit, peak 0 dB) in it to see what would happen. It still clipped. The VU meters in Nuendo weren’t clipping but when I opened the level meters for my Fireface UCX, there was heavy clipping on the main output channel. And the only way to stop the clipping was to bring down the Master Stereo Out fader to -6 dB.

Lowering the levels on my Fireface didn’t stop the clipping. Lowering the levels from the windows speaker icon in the lower right corner of the screen didn’t stop the clipping either. I also tried turning off Control Room to see if that helped and unfortunately it did not. Only lowering the levels in Nuendo worked; either on the track or on the master fader. This makes me think that there is a setting in Nuendo that accidentally got switched on and now my output is being boosted by +6 dB.

I’ve looked everywhere to try and find what could be causing this and I’m just plain stumped. Any help you all can offer would be greatly appreciated. My temporary fix for now is to mix with my Master Stereo Out set to -6 dB and then when I’m ready to export, I’ll just raise the fader back to unity gain. Then I have to check all of my exports in Sound Forge to make sure I didn’t introduce any unwanted distortion or clipping.

Thanks for taking the time to read this!

+6dB kind’a implies that something is being routed to an output twice. Normally I’d suspect that to be Control Room taking the signal from your main output and sending it to your interface AND that same main output ALSO being connected to the same physical interface output. The solution to that is to NOT have the output connected in the “outputs” tab and only do it in Control Room.

But you turned CR off so I suppose that wasn’t the problem.

Either way I’d go through routing in Nuendo again to make sure you’re not accidentally doubling up your signal somewhere, either through a group or send or something.

Also check your Totalmix settings.


^^^^^^^^ This!



Thanks everyone for the replies! @MattiasNYC totally got it right. My signal was getting routed to the output twice which was causing the +6 dB gain. For some reason, after I updated Nuendo, my Analog 1 & 2 channels got routed to the Metering Channel in Control Room in addition to the main output.

Now here’s the kicker: Even though control room was turned off, the signal still got routed to the Metering Channel and caused the clipping. Not cool at all.

But I’m just glad that the problem is fixed. And thanks again to all of you who replied!

Makes sense to me. Feeding signal to the Metering Channel is always needed, regardless if you use Control Room or not.
Metering Channel Output is designed to feed an external Hardware meter.

Glad the problem is solved.



This is exactly the way a thread is supposed to work. High fives and hugs all around!

Gives me hope for our future and that of our children!

I really hope that you’re right … doesn’t look like it, though … 8-/

I might have been exaggerating a little…

Very true. You would definitely want the Metering Channel to always get signal. I guess my main issue was that when Control Room is off, all connections in that tab disappear. So, the only way for me to see if anything was hooked up to the Metering Channel would be for me to turn on Control Room. And I just ran with the assumption that if Control Room was off, that meant that it couldn’t get signal.

I guess I should just leave Control Room on by default and make sure that the Metering Channel is set to “Not connected”?

That’s what I’ve done for anything that shouldn’t go to a literal interface output. I just make sure it’s routed to nothing, regardless of if it’s in the “outputs” tab or in the “Control Room” tab.