Hard to the Limiter

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karma17

Well-known member
Just finished reading Dean Miles book on Location Audio Simplified, and in it, he recommends what he calls recording very hot or hard to the limiter. He recommends frequently activating the limiter or very close to it. He acknowledges that this is not standard operating procedure but swears this is the way to go.

I was just curious if anyone else uses this approach because he's the only one I've ever heard espouse it.

Just curious.
 
I think it is an over reaction to the other extreme of some people recommending extremely conservative levels like peaks not surpassing -12db or even less.
Unless you have high end devices you have to find a medium between recording too hot and introducing too much noise.
 
It's been a while since I have done a lot of production sound, but I liked the limiter to kick in on the big transients. As an audio post guy i HATE overly limited production sound.
 
I don't know much about Dean Miles? Is he talking about production dialog for movies, docus or TV? I would recommend books by others, Ty Ford, Jay Rose for instance. Personally I like to record hot levels but keep the limiters in-check, usually setting the threshold around +16dBu (w/ +20dBu being slightly below digital clipping 0dBFS) and the limiters indicate activity on 'unexpected' peaks. Different scenarios require different amounts of headroom as well.
Music recording & mixing on the other hand is different. For instance, I just love the trashy sound (distortion) a 'certain limiter' gives to drums when it's hit hard, but that's usually down in the mix stage. It was also quite common (at least in NYC studios) to calibrate R-R tape machines 6 dB hotter than 'normal' (@ 250nWm) to add some tape saturation/compression (distortion).
 
I do mostly corporate and doc production. Lots of verite/direct/hard doc stuff where we levels are unpredictable. I'll tickle the limiters once in a while without worry, and if things get unexpectedly loud for a bit, I end up hitting the limiter kinda hard for a while. Good modern limiters seem to handle the hits without flinching; at least those on my Sound Devices mixers and recorders do. I'd assume Zaxcom and other similar quality kit will do the same.

Don't know first hand about low-cost audio recorders; not a slag, but I'm not sure...I've heard plenty of tracks recorded on low-quality stuff that had issues/clipping/etc...but perhaps the users didn't set up their recorders optimal. Or perhaps their limiters weren't fast enough or something...

But since limiters are basically compressors with a high ratio, I don't think I'd want to ride the limiters all the time because I want to preserve some dynamics (e.g., level changes) to my dialog. Perhaps in a news situation with no post, things are different and riding limiters could be handy...

I guess I'd say, don't be scared of good limiters, but if you have a decent grip on you levels, don't just ride the limiters all the time.

What do others think?
 
karma17 said:
Just finished reading Dean Miles book on Location Audio Simplified, and in it, he recommends what he calls recording very hot or hard to the limiter. He recommends frequently activating the limiter or very close to it. He acknowledges that this is not standard operating procedure but swears this is the way to go.

I was just curious if anyone else uses this approach because he's the only one I've ever heard espouse it.
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The results of doing this are compressed peaks. If this is what you want, why not just run the damn thing through a compressor, which will do a better job?

Typically the point of dialog capture is to capture all the dialog that's there -- all the nuance, all the dynamic range of the performance, all the texture, etc. All this so that post has all they need for the processing they think needs to be done to make the dialog fit the sound track in such a way as to support the story being told. Artificially compressing the peaks with a limiter seems counter to this mission. So... what mission does it make sense for? That's not a rhetorical question -- I just can't think of a reason for Mr. Miles to advocate this.

Personally I like to record so that I hardly ever engage my limiters. I typically record so that my dialog peaks are running around -10 to -12 dBFS. And yes, this means that they are typically raised a few dB in post. I'd rather have a little noise that is in reality below the noise floor of the total sound track, than to artificially compress the peaks in a way that makes it difficult for post to recover. Crazy, I know.
 
I have used hard limiters most of the time but with care as slamming into them defeats the object of them being there to prevent overload.

My mixers are all set up to come in at -12dbfs to ensure that I don't go above -10dbfs or +8db PPM.

Most limiters have a peak indicator light and levels are always set to have this just flashing every now and again as the limiter catches the peaks whilst recording.
 
There's a fine line there. If the Limiter kicks in, you're reducing dynamic range. Record too low, and the noise floor may become an issue.
 
I suspect people are over reacting and his point is to record hot as long as you have really good limiters to add a safety net. Most books etc. will tell you to record with a lot of headroom so you don't clip. The problem is a lot of people take that to an extreme and post gets levels that are way too low. IF you have really good limiters like the Sound Devices (and maybe the Zoom F series) you can record a lot hotter and not blow the take when some loud sound suddenly happens. If you set up like this you are not loosing dynamics on the vocals you are just protecting against the sudden blow out sound. Those are usually an actor deciding that slapping the table mid take will be cool, or a door slam or some other short transient sound. With a real sound post you will be replacing that sound 99% of the time so if it lacks a bit of dynamics it's not an issue, and you get more meat in the dialog to work with.
 
The problem with the budget gear is, the limiters are after the preamps and such (and this applies to the filters as well).. So at best, they're only good enough to catch an occasional 'over' so input stage distortion is still a possibility.. I recall this is a caveat with the Zoom F series as well, though I've never used one in a real world situation.
 
Jim Simon said:
There's a fine line there. If the Limiter kicks in, you're reducing dynamic range.
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True, but it seems to me that most people are not particularly concerned about maintaining the original dynamic range, apart from some classical music or things like bird sounds who releases anything that is not compressed?
 
When I was a dubbing mixer 20db was about it for the dynamic range for most things and now I do live sport 6db is about the norm.

Some radio stations and music have a dynamic range of about 2db so it is all relevant and unless you are doing cinema with a 20kw PA system of playback or classical music limiter and compressors are defacto for most media delivery.
 
I let my limiters do some work for me. I do a lot of corporate web delivery and I figure it needs to compete with music, computer sfx, and advertising video. Dynamic range is not my friend. In post, I limit and compress, but I don't have any reason to start with having the full dynamic range of somebody laughing or smacking their hands together. I will even let me limiters kick in on people who like to start with a hard attack on their first word of a phrase and then drop air pressure as they continue speaking. Also, my ears thank me at the end of the day that I am not constantly hitting them with loud transients while I am monitoring.
 
Cary Knoop said:
True, but it seems to me that most people are not particularly concerned about maintaining the original dynamic range, apart from some classical music or things like bird sounds who releases anything that is not compressed?
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Well since we are talking film, quite a lot of people. Pop music is compressed to hell and gone but some compression maybe on dialog but very rarely on anything else.

Though I guess it depends a bit on your definition of compression. Mixing in general "compresses" the dynamic range of dialog. And certainly a lot of folks have limiters tossed in and depending on how hard if at all you hit them it's compressing the dynamics. But compressors in film work are pretty much never used like they are in music.

I agree with what I think your point is that obsessing over dynamic range is kind of silly.
 
Rick R said:
The problem with the budget gear is, the limiters are after the preamps and such (and this applies to the filters as well).. So at best, they're only good enough to catch an occasional 'over' so input stage distortion is still a possibility.. I recall this is a caveat with the Zoom F series as well, though I've never used one in a real world situation.
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I read something, and I can't remember where, by Zoom explaining how their limiters work and it was very close to the way SD does it. They are digital but they control mic trim. It kind of makes sense since the demos I have seen have the limiters working a lot better than I thought they would.
 
Noiz2 said:
I read something, and I can't remember where, by Zoom explaining how their limiters work and it was very close to the way SD does it. They are digital but they control mic trim.
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Hi Scott,

This is a very recent summary of the Zoom F4/F8 limiters - https://www.youtube.com/watch?v=1P_ZAcSkfHI: whether you want a limiter that works in this way (i.e. apparently applying a 10db reduction in the analogue preamp, then boosting by 10db digitally - unless the signal requires limiting) will depend on use. I don't know where you got the idea that SD's (analogue) input limiters work in this way! Both companies could do with clarifying more about how their devices work - e.g. including sufficiently detailed block diagrams (older SD manuals, like that for the 552, used to have them).

Cheers,

Roland
 
Interesting link, really aimed at folks with very little sound knowledge so I'm a bit skeptical on the absolute accuracy of the explanation. But I suspect it's close and it did get me to do some research on the SD limiters.
Early boxes like my MixPre are all analog, but later models are a mix of analog and digital.

What I had read probably was a bit of a misunderstanding of the differences, but hard to tell because as you mention neither has been super transparent about the exact process.
The big difference I found is that SD does not use one limiter but one on every gain stage of each channel. The diagram they had on one of their mixers had a limiter on input trim, fader gain, and output, the later being digital and the first two analog. THere does seem to be agreement that part of the limiting scheme for the F series is knocking 10dB off the input trim to give the digital limiter some working room. The reason I'm skeptical that that is the only thing going on are some tests I have seen where the input should have shot over that gap and the waveform still didn't clip. So they may also be doing a trick FinalCut Suite used of using floating point in the digital domain to reposition "0" so that you never digitally clipped. The F series mic pres have a lot of headroom so you could get a really large amount of effective limiting that way. But?

Anyway I didn't mean to imply that they were the same just that the F limiters were not having the issues that instantly come to mind when they are described as "digital" and in practice the results of every comparison test I have seen has the performance of the F limiters very close to the SD limiters. So whatever "magic" they are doing is working pretty well.
 
Noiz2 said:
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Anyway I didn't mean to imply that they were the same just that the F limiters were not having the issues that instantly come to mind when they are described as "digital" and in practice the results of every comparison test I have seen has the performance of the F limiters very close to the SD limiters.
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Hats off to Zoom.
 
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