Odd harmonics? WTf is that?

YanKleber

YanKleber

Retired
The other day along a quick conversation a guy mentioned about the importance of take care of odd harmonics from some tracks, but didn't explain me what they are and how to find/remove them. So it remained in my mind as a 'WTF' thing. So...

1) What are those odd harmonics?
2) Will they be really harmful to the mastering or it is more like a meaningless 'hocus-pocus' thing?
3) If they are really someting to care about when and how to chase/detect/remove them? If not, just ignore this!

Thanks!

:thumbs up:
 
I think this question should go to the dude who mentioned it to begin with. Kinda impossible for us to know what he thought he was talking about.

Did he mean "odd" like "funny, strange, unusual"? In that case, I'd imagine you listen to what you've got and if anything sounds odd then you try to fix it.

Or was he actually trying to talk about odd (numbered) harmonics. Most real world instrument sounds consist of a fundamental frequencies and the harmonics which are integer multiplies of that frequency. Those harmonics where the integer is even are called "even harmonics" and the others are "odd harmonics". If he's talking about trying to cut the odd harmonics out of an instrument sound then he's just fucking nuts.

Distorting a signal also creates a series of even and odd harmonics of all of the frequencies in the original sound. Different ways of distorting the signal might create more even or odd harmonics. Most folks tend to think of even harmonics as more natural and musical sounding because, well, they are actual notes in the scale. Odd harmonics tend to be more dissonant and more harsh. Many folks are of the mistaken impression that tubes make evens and solid state makes odds, but it's just not that simple. If your boy was talking about trying to control the distortion and avoid adding too much odd order harmonics it might be something to consider, but if again he's talking about trying to remove the odd harmonics from an already distorted signal then he's completely fucked.

I think either way it's not some hidden monster that's going to suddenly jump out at mastering time or really much of anything you need to think much about. Turn the knobs til it sounds good. If something sounds odd (funny, strange) then replace, remove, or repair it.
 
ashcat_lt said:
Most folks tend to think of even harmonics as more natural and musical sounding because, well, they are actual notes in the scale. Odd harmonics tend to be more dissonant and more harsh.
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It isn't an even/odd thing per se. For instance, the 3rd harmonic is a just perfect fifth, and the 5th harmonic is a just major third.

But yeah, the idea of removing odd-numbered harmonics makes little sense, so the best thing to do would be to ask the guy what he was talking about.
 
Stop talking to that guy.

A long time ago, people were claiming that digital audio accentuated the "odd harmonics", which is why it is harsher sounding than analog. It's complete nonsense, but it is easy to find outdated i formation on the internet and even easier to find people parroting it.

Either way, the number of "odd harmonics" in your signal is nothing you can do anything about, so there is no point worrying about it.

You had another thread about dc offset and other noise issues with digital audio. Those sorts of things happened a lot more often in the 1990's. Now you are coming up with the "odd harmonics" thing. Where ever you are mining your information from is about 15-25 years out of date. Stop looking there.
 
Sorry guys... I didn't want to piss you off with my silly questions. I am just a stupid newby that do not know what is pertinent matter and what is out-to-date stuff. I will try to not ask too much often anymore!

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Naw, man. I think this is a pretty good place to post the questions. How else are you going to sort out all the bullshit? Maybe keep the real newbish questions in the newbie section, but it is at least part of why this place exists. [edit] Just don't come around claiming your absolute bullshit is solid gold truth!

Course it's possible that everybody here is full of shit. ;)
 
I notice my friend's ISA Two adds harmonics - tried it out on his bass this weekend and there's definitely some harmonics going on.
 
There is a definite purpose and intent to bringing out harmonics that sound good and suppressing the ones that sound bad.
 
YanKleber said:
I will try to not ask too much often anymore!

thumbs_up_smiley.jpg
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Don't stop asking questions. My post might have come off harsher than I meant it to. I just noticed a pattern and wanted to point it out, just in case you were getting all of this info from one source. I was just trying to steer you away from that source, not away from asking for clarification.

Keep it up, at least you are trying to understand all of it and weed through the bullshit.
 
If you get a chance to play with a Hammond organ, you can hear what adding harmonics does for the sound. Odd and even harmonics also explain why a cylindrical bore instrument sounds different from a conical bore instruments. One emphasises odd numbered harmonics, so a soprano sax sounds richer than a flute or even clarinet, which is a mix of conical and cylindrical. It's clever stuff, and it explains why a decent top end response is important, even on a bass instrument.
 
I've read somewhere that the 7th harmonic can be problematic as it doesn't fit in with the 12 semitone scale system (or something like that, I'm not up on musical theory). I've never noticed an issue myself, but if you're playing an A at 440Hz, then all this means you'll get a discordant sound at 3,080Hz (7 * 440Hz).

At the end of the day, though, use your ears to detect if there's a problem. Only take corrective action if you find an issue.

Actually, here's a link: -

Avoiding the 7th harmonic
 
Of course, in that article, it is telling you how to avoid it while playing an instrument. You really can't get rid of it in a recording, because it will be part of the sound of the instrument. Even if you try to EQ it out, the frequency would be different for every note.

Again, this is worrying about stuff that you really have no control over.
 
Yep, totally agree. The notion of sucking out individual frequencies without spoiling the sound just doesn't work. If it was that easy to turn a cheung piano into a Steinway, we'd all be doing it!
 
Another thing about removing odd-numbered harmonics-- it makes no sense unless you also remove most of the even-numbered harmonics, too. That is,

6th harmonic = 3rd harmonic raised 1 octave (6 = 3 * 2^1)
12th harmonic = 3rd harmonic raised 2 octaves (12 = 3 * 2^2)
24th harmonic = 3rd harmonic raised 3 octaves (24 = 3 * 2^3)
etc.

10th harmonic = 5th harmonic raised 1 octave (10 = 5 * 2^1)
etc.

etc.

Every even number can be factored as a product of some power of 2 multiplied by some odd number-- even 2 can be factored as 2 = 2 * 1, and 1 is odd. But of course we don't want to remove the 1st harmonic or fundamental. So unless you remove every even-numbered harmonic that isn't a power of 2, it's seems kind of pointless to try to filter out the odd-numbered harmonics, since leaving in harmonics like 6, 10, 12, 14, 18, 20, etc. just lets the odd-numbered harmonics "sneak in" at higher octaves.
 
Farview said:
Even if you try to EQ it out, the frequency would be different for every note.
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That's a good point - but automatable, I would imagine. Anyway, the main thrust of my post was to only take corrective action of any actual issue detected. I've never noticed any issue with harmonics on any recorded sounds.
 
jonny deep said:
That's a good point - but automatable, I would imagine. Anyway, the main thrust of my post was to only take corrective action of any actual issue detected. I've never noticed any issue with harmonics on any recorded sounds.
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I suppose iy could be automatable, if you hqve a lot of time on your hands and like doing math.

The thing is, the harmonics of an instrument's sound are the things that make that instrument recognizable as the instrument that it is. If you were to take all the harmonics away, you woukd be left with sine waves.

You really havr no control over the harmonic content coming from an instrument, unless you are willing to take the instrument apart and redesign it.

The discussion of even/odd harmonics always revolved around distortion characteristics. In recording, you generally want to avoid distortion, which avoids the issue completely.
 
Farview said:
The discussion of even/odd harmonics always revolved around distortion characteristics.
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Yes.

In recording, you generally want to avoid distortion, which avoids the issue completely.
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Except when you're deliberately adding distortion. Leaving out the thing about guitar (and other deliberately distorted instruments), everybody seems to be adding distortion to everything all the way through the recording process these days. You can call it warmth, or character, saturation, whatever the fuck, some even call it just "harmonics", but it's all really just distortion. In these cases you (as developer of the product/plugin adding the distortion) really can do things to accentuate some harmonics and downplay others. You can, in fact, generate more even harmonics or more odd, or whatever. You (as engineer) then usually choose these devices/plugins based on how they sound without knowing or caring what's going on under the hood.

The big thing is that you just don't have to think about this at all. Turn the knobs till it sounds good. If it sounds harsh, figure out where it's coming from and do what you can to remove or de-emphasize whether that means going back to the instrument and performance, swapping out a pre-amp or "saturator", and/or tweaking some EQ at some point along the way. There most certainly won't be any harmonics (even or odd) hiding somewhere waiting to jump out and bite you in mastering! Well, I suppose that assumes that the playback system in your mix room is worth half a damn...
 
I meant automatable by detecting the dominant frequency, multiplying it and notching with eq, all automatically. Such a plugin probably doesn't exist and probably doesn't need to!
 
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