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DAW output clips CONSOLE inputs, Help Audio Interfaces
Old 17th May 2018
Gear Head

Thread Starter
DAW output clips CONSOLE inputs, Help

Hi, greetings slutz

Not really a newbie per se, but I didn't wanna clutter up the gear forums with an engineering question. Hopefully the right folks will see this and be able to help me.

I'm familiar enough with analog/digital levels to think I understand that 0dBu analog is somewhere around -15dBFS in the digital realm, generally speaking. I also understand that the analog realm has headroom above 0dBu before clipping, varying per gear.

Presumably, I should be able to 'master' a track where its just tickling -0.5dBFS digital, and that should be hitting at about the maximum my analog console can take before clipping. I've used different consoles, and different DAWS, in different scenarios, and this has always held true (unless there's a correlation I'm missing, which is why I'm posting here )

So I have:

interface: Allen and Heath ICE-16D - balanced outputs on D-SUB connections, +4dBu nominal (+26dBu maximum)

connected directly to

console: Allen and Heath gl2800 - balanced line inputs, sensitivity -40dBu to +14dBu (don't start a hybrid debate please, and I know the console isn't exactly made for studio work)

Should be just fine, or so I thought. But whenever I play any sound anywhere near 0dBFS (sometimes as low as -6dBFS), anything from a single sine wave to a full mix, it clips my inputs on my console channels. Even at -40dBu on the gain knob.

What gives?

but seriously, am I missing something here? I've written out all the decibel abbreviations like I know what I'm talking about, but all that's literally just copied from the manuals of my gear. So... is there some weird addition in amplitude that I don't know about? Should I have gotten the unbalanced, -10dB version of my interface?

This problem only comes into play about 20% of the time. I mix through the console, so obviously I'm not sending levels out that hot during mixing. The problem rears its head when I'm 'mastering' or just listening to some commercial tunes thru my setup.

Obviously, the easiest solution to this whole thing is to simply turn down my levels in the DAW. This works, and its the current method I employ. But its sorta frustrating, and I usually forget on export and end up with a really quiet export on accident. I'm not demanding a solution, but rather would just really like to know the 'why' behind all this.

Thanks so much for reading, have a great day!
Old 18th May 2018
Gear Addict
Wizzomixer's Avatar
To give you an idea 0dbfs is +18db on the Vu scale, -18dbfs = 0Vu, so it's no wonder your console inputs are clipping.
Old 18th May 2018
Gear Head

Thread Starter
To give you an idea 0dbfs is +18db on the Vu scale, -18dbfs = 0Vu, so it's no wonder your console inputs are clipping.

A kind-hearted slut PM'd me and explained something to me. I'm paraphrasing here, but basically the previous experiences I had with similar boards and setups didn't clip because I was using 2-track inputs. The mono channel inputs have a preamp section (duh), and a hot signal from the DAW will definitely clip that circuit, before the gain knob even comes into play. 2-track inputs don't have the same circuitry, as they're designed for just such an application.

So now, I just have to physically get a patchbay close enough to my console inputs so I can route 2 daw outputs to 2-track when I want, or route them to channel inputs when I want. The dang d-sub cables only have about a 18" spread at the console end, and my patchbays are currently about 6ft away.

So yeah, problem solved, just gotta figure out the physicality of it now for my specific setup.
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