To all who work with choirs - to high pass or not to high pass?

[george_vel]

Sorry for throwing lots of topics / questions lately, but you're so helpful that I'd be stupid not to ask and learn.

As you can guess from the subject, my question goes to whether a HP filter should be used or not in classical/choral music (from best practice perspective and from your personal experience).

This is a common technique for other genres to control the low energy, free some space for clear separation between the tracks as well as decreasing dullness/muddiness and after all, improve clarity and intelligibility of the audio.

But I also read somewhere that for the classical/choral genre this is a non-go approach and should be avoided, as it will affect the overall tonal and musical balance, because subharmonic frequencies have been removed and it will make things worst across the entire spectrum.

I saw a video that at some point explained a dull/muddy mix may appear also because it was mixed with headphones (and I am mixing with headphones) but I am not sure how true this is.

I do experience that only adding a shelf boost to the high end range is not enough to compensate and improve the balance. Also cutting a bit at 400 Hz not always gives reliable results.

What is your approach?
Do you use HP for this genre, and if yes - how do you apply it?
If no, how do you preserve the clarity and keep control over the low energy to prevent dull/muddy mix/master?

As always, thanks in advance for your help

[Drew Stephenson]

This is a common technique for other genres to control the low energy, free some space for clear separation between the tracks as well as decreasing dullness/muddiness and after all, improve clarity and intelligibility of the audio.

But I also read somewhere that for the classical/choral genre this is a non-go approach and should be avoided, as it will affect the overall tonal and musical balance, because subharmonic frequencies have been removed and it will make things worst across the entire spectrum.

The thing to remember here is an HPF in a DAW isn't a switch, it's controllable in frequency and steepness. So I would suggest that you do use them, but use them wisely and listen carefully to the output.

I saw a video that at some point explained a dull/muddy mix may appear also because it was mixed with headphones (and I am mixing with headphones) but I am not sure how true this is.

Pretty untrue I reckon! There are plenty of people on here who are capable of producing release quality material on headphones and plenty of us who are capable of messing things up on normal monitors!
Mixing solely on headphones does require a bit of adaptation, but like all monitoring set-ups you have to learn your system. If that system is headphones, then learn them by listening to your reference material and keeping an eye on the frequency analyser. There's no reason why any particular system, headphones or monitors, should result in muddy mixes.

[Hugh Robjohns]

Sorry for throwing lots of topics / questions lately, but you're so helpful that I'd be stupid not to ask and learn.

There are no restrictions here on questions asked!

...my question goes to whether a HP filter should be used or not in classical/choral music (from best practice perspective and from your personal experience).

Use of a high-pass filter -- or any processing really -- comes down to whether the material and/or the mix would benefit from its application.

There isn't typically a great deal of low-end in voices generally, so application of a high-pass filter wouldn't normally be required to reign in the wanted sound. Instead, it would be to reduce unwanted sound such as subsonic rumbles from traffic outside the recording venue, or vibrations reaching the mic through the stands etc. Or possible to reduce muddiness from organ pedal notes or something like that.

But I also read somewhere that for the classical/choral genre this is a non-go approach and should be avoided, as it will affect the overall tonal and musical balance....

High-pass filtering it tends not to used mainly because recording venues are chosen carefully, and mics are supported in shock-mounts... so there shouldn't really be any nasty deep LF to worry about.

Also, classical recording engineers like to use spaced omni-directional mics specifically because of their extended LF response and the greater sense of spaciousness that is acquired from their use... so to filter out all the low end so carefully acquired would seem rather counter-productive!

I saw a video that at some point explained a dull/muddy mix may appear also because it was mixed with headphones (and I am mixing with headphones) but I am not sure how true this is.

A dull/muddy mix is the result of a lack of talent and/or experience, not the use of headphones.

...how do you preserve the clarity and keep control over the low energy to prevent dull/muddy mix/master?

A dull mix implies a lack of content in the upper registers above about 5 or 8kHz. A muddy mic implies too much going on in the 200-500Hz area...

[The Elf]

I saw a video that at some point explained a dull/muddy mix may appear also because it was mixed with headphones (and I am mixing with headphones) but I am not sure how true this is.

Hogwash! Just because one person finds *they* can't mix on headphones doesn't mean none of us can!

[RichardT]

Hi George - I guess the question is - do you feel there is a problem at low frequencies in your recordings? Only if there is do you need to do something about it!

Low frequencies do contribute to the sense of space in a recording, so they can be valuable. They can often contain extraneous noise too, and that's one reason for cutting them.

However, there is a difference between cutting the lows and cutting the lower mids (200-400Hz or so). The lower mids is where muddiness occurs, so that's the region to pull back a bit if your suffering from that. But again, only do that if you perceive a problem.

Alternatively, if you're adding reverb, you can cut the lower frequencies you're feeding to it to get a cleaner sound, or increase the 'brightness' of the reverb (I often do that).

[george_vel]

...
A dull mix implies a lack of content in the upper registers above about 5 or 8kHz. A muddy mic implies too much going on in the 200-500Hz area...

Do you remember my other topic with the 2 pieces I’ve shared and you gave me feedback?
I find them well on any types of headphones and big speakers, but on small / portable speakers I can’t tell they are exactly dull or muddy, but somehow... lacking in intelligibility, in clarity. Like too much is going on in the lows.

Hogwash! Just because one person finds *they* can't mix on headphones doesn't mean none of us can!

For the record and for my story to be proven, pay close attention at 0:39

https://youtu.be/U_rxBinijKM

[Sam Spoons]

Hogwash! Just because one person finds *they* can't mix on headphones doesn't mean none of us can!

For the record and for my story to be proven, pay close attention at 0:39

https://youtu.be/U_rxBinijKM

Ah, somebody said it on YouTube so it must be true

[george_vel]

Ah, somebody said it on YouTube so it must be true

Actually, I’ve doubted to be true. And just double checking it with you here.

[Sam Spoons]

[george_vel]

...
However, there is a difference between cutting the lows and cutting the lower mids (200-400Hz or so). The lower mids is where muddiness occurs, so that's the region to pull back a bit if your suffering from that. But again, only do that if you perceive a problem.

Alternatively, if you're adding reverb, you can cut the lower frequencies you're feeding to it to get a cleaner sound, or increase the 'brightness' of the reverb (I often do that).

Richard, thanks for your suggestions.

I do really add reverb (FabFilter’s Pro-R) and it has and embedded EQ in it as well. There is a Brightness knob, so I’ll check what will happen dialing it up.

As for dull or muddy - I have some difficulties to translate correctly the nuances of these in my native language and be sure we have exactly the same understanding. The terms we use in my country can be translated in English more closely to “cloudy” and “unclear”.

Language barrier, what to do.

I’ll try to cut a little bit around 200 - 400 Hz area and see the effect, although my gut feeling tells me I should pay attention to either 1 to 4 kHz, or 5 to 8 kHz as per Hugh’s explanation.

[RichardT]

...
However, there is a difference between cutting the lows and cutting the lower mids (200-400Hz or so). The lower mids is where muddiness occurs, so that's the region to pull back a bit if your suffering from that. But again, only do that if you perceive a problem.

Alternatively, if you're adding reverb, you can cut the lower frequencies you're feeding to it to get a cleaner sound, or increase the 'brightness' of the reverb (I often do that).

Richard, thanks for your suggestions.

I do really add reverb (FabFilter’s Pro-R) and it has and embedded EQ in it as well. There is a Brightness knob, so I’ll check what will happen dialing it up.

As for dull or muddy - I have some difficulties to translate correctly the nuances of these in my native language and be sure we have exactly the same understanding. The terms we use in my country can be translated in English more closely to “cloudy” and “unclear”.

Language barrier, what to do.

I’ll try to cut a little bit around 200 - 400 Hz area and see the effect, although my gut feeling tells me I should pay attention to either 1 to 4 kHz, or 5 to 8 kHz as per Hugh’s explanation.

Cloudy suggest slightly higher frequencies to me than muddy, so yes, have a look at the frequencies Hugh suggested.

[george_vel]

Cloudy suggest slightly higher frequencies to me than muddy, so yes, have a look at the frequencies Hugh suggested.

Yeah, I’ll give it a try, although I’am afraid a little bit that the “sibilance monster” lurks there as well.

[Sam Spoons]

Would the feedback detecting trick help identifying the offending frequencies, set a narrow boost in a PEQ and sweep it up and down until the frequencies pop out the replace with a cut?

[george_vel]

Would the feedback detecting trick help identifying the offending frequencies, set a narrow boost in a PEQ and sweep it up and down until the frequencies pop out the replace with a cut?

Sam, I’ve already done it. It was my first step actually, after setting the general levels.
For different choral and soloist tracks I found different nasty frequencies and cut them a little with a high Q.
Particularly, 2737 Hz was extremely harsh and painful on all tracks, so I’ve cut it everywhere with 2 db. I guess this was some critical frequency of the church where recording was made.
Maybe the added to the mix location reverb mic (+10 meters away from the choir) + added artificial reverb contributed to what I feel needs to be tweaked for a better sound...

[The Elf]

Ah, somebody said it on YouTube so it must be true

Actually, I’ve doubted to be true. And just double checking it with you here.

I wasn't questioning you, my friend, just the source.

[Sam Spoons]

Ah, somebody said it on YouTube so it must be true

Actually, I’ve doubted to be true. And just double checking it with you here.

I wasn't questioning you, my friend, just the source.

I think it was a 'fly away' comment by the presenter and probably not meant to stand up to detailed scrutiny. The dialogue didn't sound scripted (accepted that the best 'scripted' dialogue doesn't sound scripted either) and, if it was, such a throw away remark probably wouldn't have made past the first read through.

[Hugh Robjohns]

Particularly, 2737 Hz was extremely harsh and painful on all tracks, so I’ve cut it everywhere with 2 db. I guess this was some critical frequency of the church where recording was made.

Not likely. Could be related to the mic(s) being used or, more worryingly, it could be related to your headphones/monitors/room.

Whenever you have a consistent problem like this it's important to cross check with an alternative monitoring system and, if possible, look for consistent peaks on a high-res FFT spectrum display or sonograph (to see if it's on the source).