Unwanted frequencies when using Mastering effect

[StarlightSky]

Hello everybody,

I discovered the effect Mastering (Effects->Special) and one of its options caught my eye: It's the one which let's you control the stereo balance.

I need it to focus the sound in my songs on the center channel. So if I put the slider on - 100% it does a good job but I noticed that this adds unwanted frequencies. I'll explain it with an example: A song has vocals, piano and strings. The strings and piano are on the left and right channel (they are recognizable as stereo sound when listening with headphones) while the vocals are on the center channel.

If I use that stereo balancing effect from the Mastering option on -100%, I hear the high frequencies of the outer channels (in this example it would be the strings and piano) in the center channel. The frequency section of that sound starts around 1500hz.

I do not have this problem when I put the slider on +100%.

Can I prevent this by changing some settings in the Master window? Or what else can I do to prevent bringing a frequency part from the outer channels to the center channel?

[SteveG_AudioMasters_]

Hmm... this sounds a bit like the person who went to the Doctor's, and said "Doctor, when I put my hands behind my back, grab them and pull hard, it hurts. How can I stop this happening?" The Doctor says "Try not doing it in the first place..."

If these are your songs, then presumably you have each part available separately. If this is the case, then you will be able to position them in the stereo field correctly without any recourse to the mastering effects at all. You have to bear in mind what Mastering is about; it's not a 'production' tool as such, but a way of evening out slight differences in the overall mix, usually of several songs to give them a degree of 'homogeneity', if you like - it's not something you should be using as an effect, or part of a mix of an individual track.

The other thing you mention is headphones. With the best will in the world, you can't make production decisions using them - you need a pair of loudspeakers, better yet proper monitors. But even average-sounding ones will give you a better idea of stereo positioning than any headphones ever will. Mixing only on headphones = big no-no!

The bottom line is that you set the positions of sources in your mix using pan controls - or if you have a stereo recording of a particular part, you can vary the width and positioning of that part separately so that it ends up in the correct spatial position. You get that part right at source, not afterwards. The chances are that with any given source that you don't need to pan it fully right or left anyway, and not doing this will tend  towards a better blend of sound in the centre anyway.

[StarlightSky]

I'm sorry I didn't mention that I mainly use Adobe Audition for mixed songs by different artists, like Justin Timberlake, Rihanna, etc. just to name a few.

This is a snippet from a song (only vocals and piano) to show you what I mean. This screenshot shows only the snippet without any effects or edits:

The next one is the same snippet where I used the Center Extraction effect:

I used for the next screenshot this setting:

I used on the unedited snippet this mastering settting twice and then I used the same Center Extraction settings as I did for the second screenshot:

When I use the mastering AND center extraction I get a clear result for the center channel, in this case the vocals (they start around 0:07 on the screenshots and end between 0:15 and 0:16).

But as you can see in the last screenshot the piano from the side channels are suddenly in the center channel due to the mastering effect.

I would love to use this mastering setting to get the best result when I extract the center channel but this is not possible when you can hear the higher frequencies from the side channels (in this case, the piano).

Is there a setting to avoid this?

[SteveG_AudioMasters_]

StarlightSky  wrote

But as you can see in the last screenshot the piano from the side channels are suddenly in the center channel due to the mastering effect.

I'm afraid that I can't tell anything at all from any of those screenshots, as they're all mono spectral displays, and we're talking about an effect that manifests itself in a stereo field.

The stereo width control converts the stereo signal to a sum and difference form, and simply reduces the difference level to make the sound-field narrower, or increases it to make it wider. If you reduce it to zero, then all that remains is the sum - which is both channels added together. It is inevitable that if you do this, frequencies that are present in either channel will be summed together in the centre. The only way they will not be present is if the signals are in completely the opposite phase in the other channel, and cancelled out. In a normal stereo recording, this simply doesn't happen, so what you've got is inevitable.

The center channel extractor works differently though. It's a FFT process that looks only at the sound occurring in one spatial position, and either boosts or reduces it just at that point. As such, it disregards anything to do with the stereo field at all - which is why, when you use it as a vocal extractor on a vocal with stereo reverb, the reverb remains afterwards as a sort of 'ghost' vocal that you'll never get rid of. Also it will get rid of anything else in that spatial position, regardless of what it is - so quite often it will make a material difference to the bass as well.

Any attempt at all to combine the two effects is likely to result at best in an unpredictable result, and there are no settings that will get around that, as the effects work in significantly different ways.

[ryclark]

I am not at all sure what you are trying to achieve using both of the effects in your description above. As Steve says the two effects tend to cancel each other out to some extent due to the way they work and what they are intended to do.

[StarlightSky]

I found out that if I combine the two settings (first mastering effect, then center extraction) I can get a really clear extraction of the center channel. When I use the center extraction on its own, either the result is ok or there are too many sounds left from the side channels.

But if I use the mastering setting as shown in the screenshot, the extraction result sounds crystal clear and the only sound left from the side channels are its high frequencies which have been placed in the center channel due to the mastering effect.

I really would like to show you with short audio files what I exactly mean.

Anyone has a suggestion where I can upload the snippets so you can play them online without downloading (Soundcloud doesn't work for me right now.)? This way might be a better one to show you what I am talking about.

[SteveG_AudioMasters_ · Accepted solution]

Even if you showed us what you are on about, there's nothing we can do about it - the way those effects work is fixed. Any HF left from the sides that ends up in the centre channel will remain there, whatever you do. And yes, it will almost certainly be at a higher level than if you just used the center channel extractor on its own, which would exclude them from the extraction anyway, as they weren't originally centre artifacts. The reason that some extractions will sound cleaner is simply that you've removed some of the sound from immediately adjacent to the extracted spatial position - but whatever you do, anything at the extremes that isn't cancelled out will be included in the centre position - which, as ryclark says, is the two effects cancelling each other out.

[StarlightSky]

Alright, guess there's nothing that can fix that. But thank you all for taking your time. I guess Adobe will improve their effects at some time more and more, so who knows, maybe their Center Extraction tool will give us better results in the future. Have a nice day.

[ryclark]

Unfortunately Adobe are unlikely to be able to improve the Centre Channel Extractor any further. That is just down to the physics of stereo audio recordings. Audition's version of the Centre Channel Extractor is one of the very best implementations that there is anywhere.