KVR Audio

crazyfiltertweaker · Post by **crazyfiltertweaker** » Thu Jul 30, 2015 7:01 pm

Because soem nice High quality gear like some microphons and also high end monitors have only a frequency response of only up to 15.000Hz, I ask myself if I should make a roll off with 6dB above 13000Hz.

UltimateOutsider · Post by **UltimateOutsider** » Thu Jul 30, 2015 7:25 pm

Most reference monitors top out between 20-24kHz, and while I'm not familiar with the general spec for studio mics, microphones are not the only way of recording sound, and many processors add high-frequency content.

My own approach is to only apply filters where they're necessary- and if it's an important part I'm EQing, I often lean toward shelves instead of pure LPF (or HPF).

I 100% disagree with a general rule of rolling off at 13K like you described. Really, just try rendering out one of your tracks without an LPF and then re-render with the 6db LPF on your master at 13K like you mentioned and compare them. If you can't hear a difference, you might not have a lot of high-frequency hearing... or your monitoring environment might be lacking- but that doesn't mean the same will be true for your listeners.

aciddose · Post by **aciddose** » Thu Jul 30, 2015 7:27 pm

It isn't important unless you're recording content above that point.

Vocals typically do not have much content above 15k although they can have a little. If the content above 15k didn't matter we could just record everything at 30k or 32k rates, while we actually use more than 40k.

The spec may be limited to 15k, but that does not mean the response suddenly falls off above that point. For microphones aimed at recording vocals it makes sense to spec only to 15k, as I said there is little content in a voice above that point in most cases.

That doesn't mean there is no content. There is definitely content there and it is definitely important. Go ahead and try to use a steep filter (more like 24db/o) at near 15k and see if you can hear a difference.

Look at the spectrograph of a recording you've made, see any content above 15k? There is a lot of content up there, it just isn't as critical to get it perfect like the content below 15k.

Tarekith · Post by **Tarekith** » Fri Jul 31, 2015 5:49 am

It's VERY important IMVHO opinion. One of the biggest trends these days is the concept of low pass filtering the whole mix, and I will never, ever understand why people do this. Takes away a lot of the imaging and ambience cues in the song, and doesn't gain you anything in terms of headroom like you often hear people say.

One of the main things I find myself doing again and again when mastering people's songs is trying to restore this sense of depth and space, "air" if you will. When they get the tracks back, people are shocked how much more natural and spacious things sound.

toothnclaw · Post by **toothnclaw** » Fri Jul 31, 2015 6:56 am

Notice the Air band. Goes up to 40. Why?

Tarekith · Post by **Tarekith** » Fri Jul 31, 2015 7:11 am

Indeed. I have a Bandaxall curve using the Pultec High band in Equilibrium that I use all the time to replicate this same thing.

BertKoor · Post by **BertKoor** » Fri Jul 31, 2015 7:30 am

crazyfiltertweaker wrote:Is there any importance above 15.000 Hz?

If you're younger than 40 and finally encode to MP3 with bitrates higher than 128 kbps, then sure!

But just because older people can't hear it anymore and lower MP3 bitrates cut those frequencies off, doesn't mean you should totally exclude that part of the spectrum.

crazyfiltertweaker wrote:Because soem nice High quality gear like some microphons and also high end monitors have only a frequency response of only up to 15.000Hz.

Microphones: yes. But I'm yet to see monitors that don't go up to 20 kHz. Well maybe 18 kHz...

Tarekith wrote:doesn't gain you anything in terms of headroom like you often hear people say.

Indeed, it's the low freqs that eat up your headroom, not the high ones. Just look at a spectrogram: lots of low, gently sloping off to not that much high.

mixedmind · Post by **mixedmind** » Fri Jul 31, 2015 7:36 am

toothnclaw wrote:Notice the Air band. Goes up to 40. Why?

it is called the bat band

lfm · Post by **lfm** » Fri Jul 31, 2015 9:08 am

Remeber that cutoff shelving LP at 13k will start to inflict phase from 8k-10k or something like that. Harmonics in that area are moved a little bit from where it should be. That means sound of notes from instruments/voices in 1k-2k, their 4th-8th harmonic is moved.

Why do that if uncalled for?

If using poor quality EQ's maybe you should - the content in high end will not be that pleasent mixing EQ from all tracks if each do things to harmonics.
Some seem to think and digital EQ's are the same - they are not.
You can do surgical stuff with digital - but to our ears unpleasent sounding.

Keep it simple and do as good recording as possible not having to try compensate with EQ everywhere.
Good signal path mike->preamp->AD converters with a lot of consideration of positioning mikes.

I had the opportunity to visit a studio when recording a band long ago - and studio engineer were running like crazy back and forth moving mikes just a cm or so to get it right. Mostly in horn section where there is so much mids. This was before the days of digital audio, but still tells a story where to focus your efforts. A good recording need less mumbo-jumbo fixing afterwords.

There are linear phase EQ, but usually cpu hungry beasts as well as plenty latency introduced.
But if to do cut I would use linear on master and really do A/B testing with and without.

I did some mix profiles in Ozone many years ago, the one that accumulate a mix frequency content - and there is just about nothing at 15k. Vinyl stuff a bit less even.

Some other analyzers has that ability too, to set to cumulate indefinately from a reset point. It will give you visual feedback on what is there.

Aloysius · Post by **Aloysius** » Fri Jul 31, 2015 9:14 am

lfm wrote:...

I did some mix profiles in Ozone many years ago, the one that accumulate a mix frequency content - and there is just about nothing at 15k. Vinyl stuff a bit less even. ...

Eh ... reminds me of a video I saw years ago. Makes me wonder what kind of vinyl you're talking about.

http://www.youtube.com/watch?v=4eC6L3_k_48

simon.a.billington · Post by **simon.a.billington** » Fri Jul 31, 2015 9:34 am

Its mostly the shimmer on brighter instruments, and the air. Much in the same way that you mostly feel the bass once it starts going below the 40Hz mark, you mostly feel whats above 15kHz.

It's not need for every sound of course, but if you lost it your stuff will start beginning to sound more claustrophobic.

I think we also fell past the 20kHz mark as well, maybe somewhere between 25-30kHz??? I don't know, I haven't tested it but it does suggest why audio technology developing companies like Maag can go around sticking a 40K boost on their plugins?!?!?

aciddose · Post by **aciddose** » Fri Jul 31, 2015 10:18 am

The reason you can label it 40k is, well, the graphics artist can put anything they want there. It could've said "hotdog".

A filter has an effect across the entire spectrum from the smallest fraction above zero (not including zero) to infinity, or in software, nyquist (half the sample rate = infinity.)

low-pass amplitude low(hz, fc) = fc / sqrt(hz^2 + fc^2)
high-pass amplitude high(hz, fc) = hz / sqrt(hz^2 + fc^2)
decibels db(x) = 20 * log10(x)

For example if you have your cutoff at 40khz, the effect at 20khz for a 6db/octave low-pass filter is:

db(low(20, 40)) = -0.97db.

If the filter is steeper, it has more effect. Just raise the fraction to a power of the number of poles.

For example a 12db/octave filter:

db(low(20, 40) ^ 2) = -1.94db

So, the effect that a filter placed at any particular frequency above 20khz has within the audible range depends upon the slope and gain of the peak or notch, shelf and so on.

Setting the cutoff frequency (fc) = 40khz definitely has an effect at 20khz.

The fact the plugin has the option demonstrates the author knew this, which is more than you can say about the majority of plugin authors.

The reason the values are 2.5, 5, 10, 20, 40 is that the author decided to use decades beginning at 2.5. Normally you might use the same from 2hz, which would give you 2, 4, 8, 16, 32 which are far more practical values although obviously the author disagrees.

lfm · Post by **lfm** » Fri Jul 31, 2015 10:49 am

Aloysius wrote:
lfm wrote:...

I did some mix profiles in Ozone many years ago, the one that accumulate a mix frequency content - and there is just about nothing at 15k. Vinyl stuff a bit less even. ...
Eh ... reminds me of a video I saw years ago. Makes me wonder what kind of vinyl you're talking about.

It just happend that some reference vinyl tracks I moved to digital domain basically dropped above 14k, like zero zilch nothing there. I only saw such a drop, like a wall, when using digital filters in Waves H-EQ.

Following the -6dB/octave and the pink curve guides, for vinyl, in my case from 70's, also tended to follow -6dB very close. So less level of high end on older productions.

Modern CD production tends to go closer to the pink curve(-3dB/octave). So we tend to favor more content in hi end nowadays when mastering.

Aloysius · Post by **Aloysius** » Fri Jul 31, 2015 10:51 am

Makes sense.

tehlord · Post by **tehlord** » Fri Jul 31, 2015 10:57 am

My take is that in the digital realm, a lot of high end content builds up and can create a sense of harshness in a mix.

I've been experimenting with selective low passing, just allowing elements that I want to keep in order to maintain a nice airy top and and that works very well.