Music w/ lots of level under 30hz. Highpass across Printmaster out?
 

Hi folks -

Been mixing for a long time, some of us know each other.

I Just ran into a low frequency issue & would love to hear what folks think .


A composer delivered tracks which use heavy amounts of low frequency for dramatic effect, with fundamentals in the 10hz - 30hz range.

The filmmaker loves it in the studio, but I'm worried about how this will reproduce in theaters. For one, it's the rare theater w/ subs below 30hz. For another, it'll just eat up headroom.

I'm thinking to slap a filter across all this music, sharp HPF at 30, maybe some gentle shelving between 30 and around 60, 70hz. Maybe some band-limited compression in the zero to 60hz range.

I'm a little concerned that I'll miss something in the mix, and some extreme LF energy will be present on the master and cause trouble. But on the other hand, I like to keep the phase of my low frequencies intact by not having a powerful filter right next to them.

Thoughts? Approaches? Caveats?

-jeremiah

Re: Music w/ lots of level under 30hz. Highpass across Printmaster out?
 

I don't work cinematic music but Waves Rbass not only allows you to generate harmonics that can mimic those super low frequencies at a higher register but it also can mute the original freqs and leave only the psychoacoustic representation of them.
I discovered this while running Rbass through Q-Clone to make this video:
https://youtu.be/Z0ppAXU8jdo

Re: Music w/ lots of level under 30hz. Highpass across Printmaster out?
 

Yes - MaxxBass is a good idea.


A little more info: my director did a screen test of our mix, which I did not attend, and had distortion problems which I traced to excessive energy in 10 to 30 hz. It sounded good on my Genelec 7070 (mixing in small room), but bottomed out in the theater. So I'm trying to figure out how much to dial back, and at what frequencies.

One issue I'm dealing with is the size of my room doesn't allow these frequencies to fully develop. But the other issue is that my system has lots of headroom and extends to about 15hz, whereas cinema subwoofers are spec'ed with a higher 30ish hz rolloff

Sometimes composers are using samplers and synths that can generate enormous amounts of energy at very low frequencies, the kind of sound that sucks up the amplifier headroom in all but the most heavily spec'd sound systems.. and I'm thinking about how to contain my mixes to the technical constraints of ordinary theater systems, hence my questions.

What I'm getting at is: For folks who mix on a cinema stage regularly:

- how much low frequency do you allow in the track?

- Do you High-pass your LFE channel below, say, 30hz?

- Do you High-pass your mains at some frequency, say 40, 50, 60?


I'd really like to feel free to be creative including with low frequency energy, but have safeties and checks in place to know that I'm not exceeding the capacity of the medium, especially as directors get excited about the LFE channel. (yes I keep it contained, but sometimes it's fun to let loose.)

Yes I know about getting the mix into a proper stage to make tweaks, but generally stages are well calibrated and have good gear. This distorted test screening gave me a scare, and I don't want to have that happen again.


As I have to ship this particular fix, I'm going to highpass the LFE here at 35hz, and the music tracks > mains are getting some gentle shelving starting at 80hz, a little maxxbass on certain moments, and a little less Lo-Air, which is generating subharmonics in a few moments.


-jeremiah

Re: Music w/ lots of level under 30hz. Highpass across Printmaster out?
 

I think the only way you'll know is by getting the mix to a proper dubstage. Seems like you'll just be shooting in the dark otherwise.

Re: Music w/ lots of level under 30hz. Highpass across Printmaster out?
 

Yes - of course.

The point however is: Many proper stages also can’t reproduce sound below 30hz.

At this point I feel my best option is to place HPF’s on my stem masters, and filter sounds below 30hz.


...With tiny festival-bound documentary shorts, the entire budget is frequently less than a day on a quality stage... nevertheless a DCP must be made.


-jeremiah










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Re: Music w/ lots of level under 30hz. Highpass across Printmaster out?
 

My thought is that there are better more effective ways of creating dramatic effect than by hammering frequencies in the 20hz-30hz range. I'd roll those off down there. Especially if you are doing a short film that will probably be played on the internet or home streaming for a good portion of it's life on setups that can't reproduce 20hz signals anyways. It sounds like it's already causing you screening troubles. Roll off the lowest of the lows and figure out better ways to create inherent drama in score.

And as others said, mix checks on proper dubstages are the way to go. Even if you can't afford a full day see if you can book an hour just for playback and take notes.

Re: Music w/ lots of level under 30hz. Highpass across Printmaster out?
 

Yep. No question of value of mixing in a proper stage.

Just wondering if folks regularly place HPF on their outputs.

It’s pretty common w/ design elements to pitch down, or similarly w/ use of sampled instruments in music, and achieve large amounts of subsonic/infrasonic information. This can make it to the master unheard, in the absence of filtering, even on properly set up mix stages...

I seem to be answering my own question:

Do what it takes. If the project needs HPFs, insert them.

Just seeking confirmation / or other approaches from folks who’ve been there.

-jeremiah


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Re: Music w/ lots of level under 30hz. Highpass across Printmaster out?
 

I want to propose a different way of asking this question. Is there any reason you should NOT roll off below 30hz? I can't think of one.
Even a 4th order roll off at 30hz leaves a fair amount of signal in the 20hz range. Band limited compression may be an option that gives you more control.
I'm sure you can control the low end so it won't create down stream problems without losing the impact the composer was going for.

https://wanderingear.net

Re: Music w/ lots of level under 30hz. Highpass across Printmaster out?
 

I've gotten flamed for my use of the Lfe track (BTW I've seen the light and have added some filters in my chain), BUT here's my $0.02:

I often use fairly aggressive dynamics on low frequencies. I can't remember mixing music from a composer who played below 30Hz, but it's very common for me to use a high ratio compressor on everything below 120Hz with a relatively slow attack and slow release so the bass notes have a strong attack and then get out of the way. It takes some fairly detailed running of the release to match the tempo of the bass track, and it doesn't work on drones which this may be.

On drones, I'm likely to use a low shelf to manage it. But I tend to agree that below 30Hz is more trouble than it's worth. Even if the bass sounds good in theaters, or on a mix stage, it's pretty likely to run away on a lot of home theater setups.

(I say this is pretty common, but it really depends on the music mix. Most of the composers I love working with tend to deliver mixers that are well bass managed to begin with, so the more I get to work with my favorites the less I reach for this tool in the box.)

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Re: Music w/ lots of level under 30hz. Highpass across Printmaster out?
 

I don't to get to mix on a stage often but I was in this same predicament recently and I think your instincts are spot on.

My solution ended up being combination what of you've already mentioned above. I had a roll-off at 10Hz and band limited compression with a low shelving filter at 140Hz. FabFilter Q3 handled it quite well as the slope can be as steep or gentle as you need. With the inclusion of per band dynamics built in and surround support it became an easy one stop fix. I strapped this across the entire 5.1 MX stem and let it handle all of the low end. I tested settings across all reels and found a sweet spot that allowed the composers intent to translate and yet stay in the pocket enough to prevent any distortion at our tech screenings. We also had a day to print master on a dub stage (after the tech screenings) and the music held up there too.

I think if you go with your gut it'll be fine.

-chris