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I saw a product demo that had an EQ plugin that would detect all the octaves associated with the particular octave that was trying to be removed.

Could someone explain how octaves work and why you would eq out the "other" octaves? Is there a method behind that?

Comments

rockstardave Sat, 12/22/2007 - 01:03

Halifaxsoundguy wrote: I saw a product demo that had an EQ plugin that would detect all the octaves associated with the particular octave that was trying to be removed.

Could someone explain how octaves work and why you would eq out the "other" octaves? Is there a method behind that?

here's my guess:

most timbres have harmonics of sorts. these active harmonics are what help you establish what you are listening to (ie - your mothers voice versus your sisters, etc). some audio sources activate harmonics in rising octaves.

another case where you might consider this is in the field of live sound. many rooms ring at octaves of a fundamental wavelenght. for example, a room that "fits" 1 400Hz standing wave can fit 2x 800Hz waves, 4x 1.6kHz waves, 8x 3.2kHz waves, etc etc.

so notching out these octave harmonics is something that might be necessary anyways.

any one else want to correct me?

anonymous Sat, 12/22/2007 - 13:56

Briefly explained, an octave is the space between one musical note and another either half it's frequency or double it's frequency.

To give you an example, if you pluck the top open string of a guitar with standard tuning this is an E note. If you move up and octave (12 frets) this is where the next E note is. This is still the same note but it is double the frequency of the open string E.

hope this helps;)

dementedchord Sat, 12/22/2007 - 15:56

perhaps it's the context in which it's being used... but this sounds "funny"... but the info you've been given is acurate in that the harmonic series is based on even divisions of a freq and multiples (doubles and halfs) are the strongest... also a room that rings a given frq tends to ring at it's multiples so at a base level it might help some people to know where those "octaves" are...

natural Sat, 12/22/2007 - 22:48

Is it just me, or is the obvious answer:
Please post more info about the product of which you speak so that we might better know what we're talking about?

The only thing that comes to mind here is removing 60hz hum. Which will have a component at 120hz and 240hz.
If there is a plugin that will detect how far that particular sound extends (as well as it's volume), it might be interesting.

Cucco Sun, 12/23/2007 - 13:58

It's important to understand that it's not just a matter of octaves. It has more to do with the harmonic series than with just octaves, otherwise, each of the even multiples could be removed and the whole note and its residuals would be removed. (BTW, this is useful in removing 60Hz hum and other similar noises such as RF bleed from old TV tubes...)

The harmonic series goes something like this:

Fundamental
1 Octave up
1 Fifth up
1 4th up
1 major 3rd up
1 minor third up
1 smaller than minor third up
1 greater than major second up
1 major second up
1 slightly smaller than major second up
1 slightly larger than minor second
minor second...minor second...smaller than minor second and so on and so on ad infinitum.

You're welcome to do the math on this, but I'm afraid the "smaller than" and the "slightly larger than" statements will make that kinda hard.

The real question is, other than treating errant line or RF noises, what exactly would be the purpose of doing this since it would have profound (in a negative way) effects on most recordings (unless done specifically for effect...)

Cheers-

J.

dementedchord Sun, 12/23/2007 - 14:16

Cucco wrote: The harmonic series goes something like this:

Fundamental
1 Octave up
1 Fifth up
1 4th up
1 major 3rd up
1 minor third up
1 smaller than minor third up
1 greater than major second up
1 major second up
1 slightly smaller than major second up
1 slightly larger than minor second
minor second...minor second...smaller than minor second and so on and so on ad infinitum.
J.

hi jer... i find it interesting that you describe the overtone series this way... am i remebering correctly arent you a trumoet player????forinstance the second 8va you describe as a 4th from the previous which is true enough but is better understood as that *va relationship.... and then all those thirds and seconds... instead of the 3rd 5th b7th 8va 9th etc... oh well happy holidays man...

Cucco Mon, 12/24/2007 - 14:07

dementedchord wrote: [quote=Cucco]The harmonic series goes something like this:

Fundamental
1 Octave up
1 Fifth up
1 4th up
1 major 3rd up
1 minor third up
1 smaller than minor third up
1 greater than major second up
1 major second up
1 slightly smaller than major second up
1 slightly larger than minor second
minor second...minor second...smaller than minor second and so on and so on ad infinitum.
J.

hi jer... i find it interesting that you describe the overtone series this way... am i remebering correctly arent you a trumoet player????forinstance the second 8va you describe as a 4th from the previous which is true enough but is better understood as that *va relationship.... and then all those thirds and seconds... instead of the 3rd 5th b7th 8va 9th etc... oh well happy holidays man...

Yeah, I was thinking from one note to the next, not from the fundamental.

Besides....horn player...not trumpet player. GRRR... :evil: (JK)

JoeH Mon, 12/24/2007 - 14:32

From the sound of things, I originally thought he might have been talking about Algorithmix's reNOVAtor. This is a spectral editor that will let you (in some cases, with isolated tones, etc.) not only hightlight the fundamental, but all of the related overtones. (Root, Octave, Fifth, and so on...)

Removing "octaves" per se isn't any way to tune a room or fix a problem, but it's always good to see what you're hearing.

redbort Thu, 12/27/2007 - 10:09

this type of EQ is used to correct instrument flaws
the same way a room can have resonate frequencies with overtones, so do poorly built instruments.

you may come across instruments that resonate certain frequencies LOUDER then others... the musician who's been playing it forever will tell you it's part of the instruments character and tone. Sometimes it's just annoying and instead of compressing, you can "fix" it by using this sort of EQ.

you can hear it the most in monophonic stringed instruments, (violin, bass)

rockstardave has it right also

JoeH Thu, 12/27/2007 - 10:23

Nonsense. If the instrument is "poorly built" - replace it or find someone who can play it properly.

You don't "Fix" the sound of a bad instrument by messing with its overtone series, there are too many other variables involved - overall intonantion, noise vs sound, mechanical noises, etc. Overtones are NOT the problem alone. YES, you can create interesting effects and nicely warp a sound this way, but you don't fix serious music like like this. You re-do it with a better instrument or mic or EQ setting.

If I caught an engineer trying to "Fix" a problem this way - barring any other option - I'd have a serious sit-down with them before showing them the door.

I think until we find out exactly WHAT this plug-in is, and what it's stated purpose is, we're just blowin' smoke. :roll: