You are here

Protective limiter with the Master Control Fader at 0dB?

All about the tools and techniques involved in capturing sound, in the studio or on location.

Re: Protective limiter with the Master Control Fader at 0dB?

Postby Wonks » Wed Feb 06, 2019 5:26 pm

The main point about calibrating your monitors when using K-metering is that when swapping between different K-meter settings, say K-14 and K-20, then the 0dBFS point is the same listening volume on both scales.

So at K-14 you set the monitor volume knob at one position, and for K-20 you'd set it to a position that had 6dB more gain (as your working 0dB point is now 6dB lower).

You probably won't need to do this in a home studio if you always make the same type of music, but if you work on differnt styles of music for commercial release, then it's something worth doing.
User avatar
Wonks
Jedi Poster
Posts: 10881
Joined: Thu May 29, 2003 12:00 am
Location: Reading, UK
Correcting mistakes on the internet since 1853

Re: Protective limiter with the Master Control Fader at 0dB?

Postby The Elf » Wed Feb 06, 2019 6:19 pm

If any of your source tracks are peaking over -10dBFS then gain them down right from the start. You shouldn't be going anywhere near clipping once that's done.
User avatar
The Elf
Jedi Poster
Posts: 14242
Joined: Tue Aug 14, 2001 12:00 am
Location: Sheffield, UK
An Eagle for an Emperor, A Kestrel for a Knave.

Re: Protective limiter with the Master Control Fader at 0dB?

Postby Matt Houghton » Wed Feb 06, 2019 7:00 pm

Hugh Robjohns wrote:Well, firstly any modern active speaker will have it's own built-in driver protection system

True. But we haven't all upgraded to 'modern active speakers'.

Hugh Robjohns wrote: the protective limiter being discussed was only ever going to clamp the signal a smidge below full-scale digits, so it wouldn't be hugely protective of the speaker in the event of a DAW meltdown, anyway really...

I hadn't read it like that. Master fader at 0dB could mean lots of things. I took it to mean leaving the fader at unity gain. Not to have the master stereo bus meter hitting 0dBFS. And the limiter is described as a 'protective' limiter, hence my thought about ears/speakers. This could surely have a threshold set where you want, in which case it could be as protective as you chose to make it. But perhaps I just misunderstood the OP...

Hugh Robjohns wrote:Back in the olden days of analogue, it wasn't normal practice to strap a protective limiter across the (monitor) output of the console -- we maintained a headroom margin to make it unnecessary -- so why do it with the digital equivalent?

It's precisely because you (sensibly) leave lots of headroom in the digital domain that full-scale noise can be so bloomin' loud in the real world when it happens by accident! And I have a hunch that full-scale digital noise was less of an issue in the (g)olden days of analogue :headbang:
Matt Houghton
Frequent Poster
Posts: 1002
Joined: Wed Aug 08, 2007 12:00 am
SOS Reviews Editor

Re: Protective limiter with the Master Control Fader at 0dB?

Postby Jack Ruston » Wed Feb 06, 2019 7:12 pm

Matt Houghton wrote:I hadn't read it like that. Master fader at 0dB could mean lots of things. I took it to mean leaving the fader at unity gain. Not to have the master stereo bus meter hitting 0dBFS. And the limiter is described as a 'protective' limiter, hence my thought about ears/speakers. This could surely have a threshold set where you want, in which case it could be as protective as you chose to make it. But perhaps I just misunderstood the OP...


I think the point is that the OP is trying to prevent clipping on the mix bus...therefore, regardless of the position of the master fader, the signal would be full scale.

As mentioned above, there's a nice pref in Reaper, which cuts the signal if a channel exceeds full scale for a given period of time. It's handy if something freaks out!
Jack Ruston
Frequent Poster (Level2)
Posts: 3803
Joined: Wed Dec 21, 2005 1:00 am

Re: Protective limiter with the Master Control Fader at 0dB?

Postby Hugh Robjohns » Wed Feb 06, 2019 7:18 pm

Matt Houghton wrote:But we haven't all upgraded to 'modern active speakers'.

Yes, fair point. If converter overload is likely and could create damaging levels to the speaker it might indeed be wise to introduce some form of external protection... But something appropriate in the analogue domain would make much more sense than peak limiter in the DAW... And I'd still argue that working with a generous headroom margin obviates the need anyway.

Master fader at 0dB could mean lots of things. I took it to mean leaving the fader at unity gain.

Me too! And I think that was the intention. I read the need for a protective limiter as something to avoid clipping the DAW mix bus or converter outputs, presumably because of mixing with minimal headroom. ...but I may have misunderstood too. But if that was the real concern, mixing with headroom avoids the problem and has other benefits too...

It's precisely because you (sensibly) leave lots of headroom in the digital domain that full-scale noise can be so bloomin' loud in the real world when it happens by accident! And I have a hunch that full-scale digital noise was less of an issue in the (g)olden days of analogue :headbang:

:lol: Yeah, okay... You got me there -- although full amplitude +24dBu analogue howl rounds were/are still possible! But if damage from full-scale noise is the over-riding concern, a limiter in the DAW will only be a help if the DAW remains functional, and could give a rather false sense of security. If the computer or interface freaks out -- which are as likely if not more so -- the DAW limiter won't help at all -- hence really needing a protective limiter in the analogue feed to the speaker/amp where it will always be functional.

Whichever way you look at it, a 'protective limiter' in the DAW is a bit of a chocolate fire guard!

H
User avatar
Hugh Robjohns
Moderator
Posts: 26981
Joined: Fri Jul 25, 2003 12:00 am
Location: Worcestershire, UK
Technical Editor, Sound On Sound

Re: Protective limiter with the Master Control Fader at 0dB?

Postby Wonks » Wed Feb 06, 2019 7:27 pm

Hugh Robjohns wrote:Whichever way you look at it, a 'protective limiter' in the DAW is a bit of a chocolate fire guard!

http://www.ichthuswebdesign.com/product ... fireguard/
User avatar
Wonks
Jedi Poster
Posts: 10881
Joined: Thu May 29, 2003 12:00 am
Location: Reading, UK
Correcting mistakes on the internet since 1853

Re: Protective limiter with the Master Control Fader at 0dB?

Postby James Perrett » Wed Feb 06, 2019 7:28 pm

Matt Houghton wrote:And I have a hunch that full-scale digital noise was less of an issue in the (g)olden days of analogue :headbang:

So you've never had a performer hang their headphones on the microphone or plugged a line level output into a mic input? Accidents certainly happen in the analogue world too but that's why the monitor level control is often the largest knob on the desk.
User avatar
James Perrett
Moderator
Posts: 9191
Joined: Mon Sep 10, 2001 12:00 am
Location: The wilds of Hampshire
JRP Music - Audio Mastering and Restoration. JRP Music Facebook Page

Re: Protective limiter with the Master Control Fader at 0dB?

Postby Matt Houghton » Wed Feb 06, 2019 7:35 pm

James Perrett wrote:
Matt Houghton wrote:And I have a hunch that full-scale digital noise was less of an issue in the (g)olden days of analogue :headbang:

So you've never had a performer hang their headphones on the microphone or plugged a line level output into a mic input? Accidents certainly happen in the analogue world too but that's why the monitor level control is often the largest knob on the desk.

Not when mixing, no. Not much call for mics at that stage... and the further the performer is away from the mix room the better IMO :bouncy:

Though I do certainly value my monitor controller's level control and mute function.
Matt Houghton
Frequent Poster
Posts: 1002
Joined: Wed Aug 08, 2007 12:00 am
SOS Reviews Editor

Re: Protective limiter with the Master Control Fader at 0dB?

Postby Matt Houghton » Wed Feb 06, 2019 7:39 pm

Hugh Robjohns wrote:Whichever way you look at it, a 'protective limiter' in the DAW is a bit of a chocolate fire guard!

Chocolate is a tad harsh. It's more like a fireguard with slightly wider than usual spaces between the wires, in that it stops some of the problems but not all. It lowers the risk, without removing it. I have certainly had plug-ins spew out noise without crashing the DAW. Though I agree an analogue solution after the D-A converters would be more effective...
Matt Houghton
Frequent Poster
Posts: 1002
Joined: Wed Aug 08, 2007 12:00 am
SOS Reviews Editor

Re: Protective limiter with the Master Control Fader at 0dB?

Postby Hugh Robjohns » Wed Feb 06, 2019 8:07 pm

:thumbup: the headphones-hung-over-a-mic thing isn't the only way to create howl rounds, of course, and I'm sure I'm not the only one who, when setting up for mixing, made a patching error with the outboard which resulted in a squeak or two and a desperate dive for the monitor mute button...:-D
User avatar
Hugh Robjohns
Moderator
Posts: 26981
Joined: Fri Jul 25, 2003 12:00 am
Location: Worcestershire, UK
Technical Editor, Sound On Sound

Re: Protective limiter with the Master Control Fader at 0dB?

Postby hz37 » Wed Feb 06, 2019 8:36 pm

It depends a bit on the post processing you are willing to do.

With your DAW in floating point, it is usually okay to have peaks that are over 0 dBFS. As long as you bounce down to floating point, you can adjust the gain to be below 0 dBFS before you render your final file to an LPCM audio file.

But here's where things can become a little tricky. If you are mixing for delivery where there are rules about both loudness level and peak level (as is the case in just about all broadcast situations), you might end up with an audio file that violates those rules. For instance, here in Europe we have the EBU R128 loudness norm which specifies that the average loudness of program material must be -23 LUFS (a.k.a. 0 LU) +/- 0.5 LU (unless it's live sound, then there is a tolerance of +/- 1. LU) and a peak level requirement of -1.0 dBTP. Now if you mix your program material without a limiter, with a nice loudness average of about -23 LUFS, you might end up with a file that has the required loudness but has peaks that overshoot -1.0 dBTP. That file will be rejected by the broadcast company. Alternatively, you could put a limiter on the master bus (with a brick wall setting, maybe at -2.0 dBTP as a safety buffer), still mix at -23 LUFS and even if you end up half a dB too soft, you can still gain the whole thing half a dB and end up well within the requirements. The limiter might do very little during the entire mix, but it saves you from overshooting on one or two moments. This is a case where no-one will hear the limiter doing anything and you staying out of trouble with your client. In the US it's almost the same, except with slightly different loudness and true peak specs.

Have fun,

Hens Zimmerman
hz37
New here
Posts: 6
Joined: Sun Apr 16, 2006 12:00 am
Location: Groningen, The Netherlands

Re: Protective limiter with the Master Control Fader at 0dB?

Postby Tim Gillett » Wed Feb 06, 2019 9:20 pm

Re Matt's point about hearing protection, I have an analogue limiter patched into the monitor amp's insert point. It's post the amp's volume control so I never need to reach for the volume control in a crisis, and it reacts much faster than I ever could. The threshold is set to protect my hearing, but it also protects the speakers from clipped signals. The "limit" lamp tells me when it's working. Over the years it's saved my ears many times.
Tim Gillett
Frequent Poster (Level2)
Posts: 2049
Joined: Wed Jan 30, 2013 1:00 am
Location: Perth, Western Australia

Previous