EQ Question: Any Mid Frequency Adjustments Messes Every Instrument Up

[Shadow_7]

Fair enough. I'm just so used to spaced stereo mics. MONO audio just sounds off to me. Almost painful to listen to. No sense of direction to it. But even with a matched pair of mics, the EQ differences between each can be enough to cause some issues. Edited or not. Perhaps not in the common speaker ranges (50Hz - 16kHz). But still problematic if left unchecked. Not that you'll know what is off, but you'll now something is off aka not quite right. With a whole chain of gear upgrades to try and correct something that is only a result of editing, or the lack there of.

 

[Farview]

But even with a matched pair of mics, the EQ differences between each can be enough to cause some issues. Edited or not.

No, if there were any measurable response differences, they wouldn't be matched. The type of problems you are describing have never happened to me and I never use matched pairs. The two mics I frequently use for overheads weren't even manufactured in the same year. Never a phase problem when summed to mono that isn't caused by bad placement.

Perhaps not in the common speaker ranges (50Hz - 16kHz). But still problematic if left unchecked. Not that you'll know what is off, but you'll now something is off aka not quite right.

Think about this for a second. If the speakers can't reproduce the problem area, there is no way for it to be a problem. You can't hear problems that the speakers can't reproduce. Just like you can't hear that you have too much 12k when you are only listening to your sub woofer.

If the problem is above 20k, it will be taken out by the nyquist filters.

I'm sure you are hearing what you are hearing, but the cause is probably something less exotic than phase cancellation caused by EQ's and/or the mismatched frequency response of mics.

 

[mixsit]

I got to say I opped out of this thread with some of the stuff said I don't get at all.
I'd be interesting -wondering I guess.. if Shadow and Mike are hearing/talking about the same thing or what?

 

[Farview]

I got to say I opped out of this thread with some of the stuff said I don't get at all.
I'd be interesting -wondering I guess.. if Shadow and Mike are hearing/talking about the same thing or what?

Ummm... What?

 

[mixsit]

(Perhaps) post 2, right off, took a detour. There's been no word back from OP who (I'm assuming is) grappling with some basics. Sence then some fairly esoteric(? ..maybe questionable) stuff on stereo/mono, eq and phase- (problems?.

 

[Shadow_7]

No, if there were any measurable response differences, they wouldn't be matched. The type of problems you are describing have never happened to me and I never use matched pairs. The two mics I frequently use for overheads weren't even manufactured in the same year. Never a phase problem when summed to mono that isn't caused by bad placement.

You do realize that mics are matched within a tolerance. For my Avenson STO-2's that's 0.3dB or something like that. Which probably degrades with age. For other manufacturers that could be as large as 1dB. And that's just for the matched pair of mics. And only when they're brand spanking new from the factory. Although it depends on ones own meaning of good enough I suppose.

Think about this for a second. If the speakers can't reproduce the problem area, there is no way for it to be a problem. You can't hear problems that the speakers can't reproduce. Just like you can't hear that you have too much 12k when you are only listening to your sub woofer.

My car can't go 200mph, but if I floor it, it will try. And fail, probably in more ways than one. Although in the right conditions, downhill, favorable wind, straight road, boosted octane fuel, it might actually do it (once). As the tires fly off and other limits of the gear become painfully obvious.

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What I was hearing that made me aware of these issues was phase drift between a stereo image. Granted that's probably much more substantial than EQ. But when your tracks start aligning in full phase reversal the effects are quite apparent. Especially if you have video of say a tubist and for half his gig you can't hear him, but your waveform and levels look good at first glance. And your gear specs within the known ranges needed to record and reproduce his performance. And you know it can do it, you can hear it in the other half that isn't mostly silent.

As for EQ, we don't have simple single pitched tracks. Even when we do. A tone is not just a singular pitch / sound. There are harmonics and other tones in there. If you mess with one, you mess with them all within the limits of the sample rate. Granted that most of the subtleties are inaudible to most folks. Or otherwise lost in the mix of the actual track or the listening environment.

But you can generate test scenarios that will be very audible. ID a pitch that's obvious in a recording. And notch out the pitch that is exactly one octave higher than it(2x's the Hz value). Notch is just another form of EQ, specific pitch (or pitch range) down to zero. And see if you notice something. Sure you'll notice the EQ that it is, but also notice what it does to the character of the sound. Does it even sound like the same instrument? Or even a related instrument. Suffice to say that less is more in a lot of ways when it comes to EQ and stuff.

 

[Farview]

You do realize that mics are matched within a tolerance. For my Avenson STO-2's that's 0.3dB or something like that. Which probably degrades with age. For other manufacturers that could be as large as 1dB. And that's just for the matched pair of mics. And only when they're brand spanking new from the factory. Although it depends on ones own meaning of good enough I suppose.

But that won't cause a phase issue of any kind. The frequency response of one mic vs. another will not cause a phase problem. Phase is a timing error. The phase issues cause by EQ happen because of the way an EQ is implemented. Since there is no EQ as such in a mic, there will be no timing difference even if there is a response difference.

My car can't go 200mph, but if I floor it, it will try. And fail, probably in more ways than one. Although in the right conditions, downhill, favorable wind, straight road, boosted octane fuel, it might actually do it (once). As the tires fly off and other limits of the gear become painfully obvious.

That analogy doesn't work in this context. If a mic can't pick up a problem frequency, the recording medium can't store it, the playback system can't reproduce it and the human ear is incapable of hearing it, it can't be a problem.

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What I was hearing that made me aware of these issues was phase drift between a stereo image. Granted that's probably much more substantial than EQ. But when your tracks start aligning in full phase reversal the effects are quite apparent. Especially if you have video of say a tubist and for half his gig you can't hear him, but your waveform and levels look good at first glance. And your gear specs within the known ranges needed to record and reproduce his performance. And you know it can do it, you can hear it in the other half that isn't mostly silent.

That reads a lot more like a mic placement problem. That is a timing issue or a refection issue. It has nothing to do with EQ at all.

But you can generate test scenarios that will be very audible. ID a pitch that's obvious in a recording. And notch out the pitch that is exactly one octave higher than it(2x's the Hz value). Notch is just another form of EQ, specific pitch (or pitch range) down to zero. And see if you notice something. Sure you'll notice the EQ that it is, but also notice what it does to the character of the sound. Does it even sound like the same instrument? Or even a related instrument. Suffice to say that less is more in a lot of ways when it comes to EQ and stuff.

Yes, notching out the harmonics of any instrument will make it sound like something else. The only difference between a voice and a flute playing the same note is the harmonics each instrument generates. If you take them away, you are left with nothing but a sine wave. Still, this has nothing to do with EQ or the phase goofiness that EQ generates. Which, if you are using notch filters that go down to '0', (impossible with analog gear) you are generating a ton of phase at the 'shoulders' of the EQ response. But that would be positive phase and will actually boost the frequencies on either side of the notch.