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Does a microphone hear a stereo image like a person?

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Re: Does a microphone hear a stereo image like a person?

Postby Sam Inglis » Wed Nov 25, 2020 12:20 am

blinddrew wrote:
In that case, going back to my original lucky break, I got even luckier than I thought. :)

Either that or your speakers are wired out of phase...
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Re: Does a microphone hear a stereo image like a person?

Postby shufflebeat » Wed Nov 25, 2020 1:46 am

Kwackman wrote:I remember an article or interview about this sort of thing years (maybe decades!) ago.
Where they used the speakers as you did with a mono signal, then swapped the wires on one of the speakers so it's polarity was reversed. Theory being there'd be a lot of cancellation at the mic.
I'm not sure if it worked, or even if I read it properly!
Dave Stewart & Annie Lennox maybe?
Anyone else with a better memory?

I've seen it done but room reflections spoil the effect. In a suitable space it works quite well but a mic with good rejection is probably more practical for mere citizens like us.

If memory serves it was an article on Rod Stewart where I first heard of it. Otherwise nothing of interest in the article as I remember.
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Re: Does a microphone hear a stereo image like a person?

Postby Hugh Robjohns » Wed Nov 25, 2020 1:50 am

Tim Gillett wrote:The difference being the vocal itself? What would be the benefit then over the vocal track?

James is describing the technique of performing to a backing track being replayed over the speakers in the control room.

You record the vocal performance + backing track spill, and then just the backing track spill on its own. Mix the two together afterwards with inverted polarity and the backing track spill is substantially reduced.

Well known and effective technique in studio circles.
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Re: Does a microphone hear a stereo image like a person?

Postby Tim Gillett » Wed Nov 25, 2020 3:38 am

Hugh Robjohns wrote:
Tim Gillett wrote:The difference being the vocal itself? What would be the benefit then over the vocal track?

James is describing the technique of performing to a backing track being replayed over the speakers in the control room.

You record the vocal performance + backing track spill, and then just the backing track spill on its own. Mix the two together afterwards with inverted polarity and the backing track spill is substantially reduced.

Well known and effective technique in studio circles.


Yes Drew had described the in the opening post but for a moment my brain temporarily forgot about the backing track played by the speakers. In my stupour It seemed as if James might be describing a method of attenuating random studio background noise which didnt make sense to me. It doesnt make sense because it wasnt what James meant.

Sorry James, just an elderly antipodean man's 4am brain fade.

But yes as I implied in reply to Elf the use of three separate types of attenuation - all using some sort of cancellation mechanism - is an impressive use of technique.
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Re: Does a microphone hear a stereo image like a person?

Postby The Elf » Wed Nov 25, 2020 9:31 am

shufflebeat wrote:I've seen it done but room reflections spoil the effect.
Which is where adding an opposite-polarity 'blank' pass helps to mop up this last bit of bleed.

It genuinely works very well.
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Re: Does a microphone hear a stereo image like a person?

Postby blinddrew » Wed Nov 25, 2020 10:50 am

Sam Inglis wrote:
blinddrew wrote:
In that case, going back to my original lucky break, I got even luckier than I thought. :)

Either that or your speakers are wired out of phase...
I did make the cables myself... ;)
But the mid and side signals check out correctly and I tested all the correct continuities at the time so I think I'm ok there.
Just got away with a bit of quiet monitoring and a high signal to noise ratio.

Thank you all for clarifying on the mic vs ears business. :thumbup:
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Re: Does a microphone hear a stereo image like a person?

Postby Hugh Robjohns » Wed Nov 25, 2020 10:57 am

The low level from the monitors combined with the cardioid mic pattern would have kept the direct spill level relatively low. And the acoustic treatment in the room behind you would have minimised any reflected spill reaching the much more sensitive front of the mic -- this is the part that causes most trouble in most home studio setups!
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Re: Does a microphone hear a stereo image like a person?

Postby blinddrew » Wed Nov 25, 2020 11:37 am

I have a few square feet of absorption and diffusion directly behind me so it's nice to know that it was worth the effort! ;)
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Re: Does a microphone hear a stereo image like a person?

Postby Arpangel » Wed Nov 25, 2020 12:21 pm

Hugh Robjohns wrote:The actual sound sources!

The phantom image is entirely a construct of our human sense of hearing being fooled by sounds arriving at both ears at the same time and amplitude. In real life, that can only happen if the sound is being emitted by a source on the median plane, so our brain invents a phantom image.

The sound waves from the two speakers will interact, of course, and produce a horizontal interference pattern, but there will be multiple peaks and troughs occuring at different angles for different frequencies -- not a single central lobe!

This does raise another issue regarding microphones and actual sound sources, and it’s relationship to mic placement.
Microphone placement is often spoken of like some sort of black art, a talent you have or you don’t have.
I used to think that if it sounds good where you’re standing, then that’s where the microphones should go, as the mic’s should pick up what I’m hearing.
I don’t think I’ve ever met an engineer that would agree with me, and the results are far from consistent.
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Re: Does a microphone hear a stereo image like a person?

Postby Hugh Robjohns » Wed Nov 25, 2020 12:30 pm

Arpangel wrote:Microphone placement is often spoken of like some sort of black art, a talent you have or you don’t have.

There is certainly a degree of art involved, along with a degree of science. It is definitely an acquired skill, and some people are more talented at it than others -- just as some people are more talented at playing the piano than others.

But it is a skill that can be learned, like any other, given dedication and effort...

I used to think that if it sounds good where you’re standing, then that’s where the microphones should go, as the mic’s should pick up what I’m hearing.

Yes... but microphones don't have the signal processing that your ears/brain apply automatically. We are incredibly good at ignoring things in the received sound waves that microphones still capture... So while placing mics 'where it sounds good' is certainly a good start, it's far from the whole story!
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Re: Does a microphone hear a stereo image like a person?

Postby Arpangel » Wed Nov 25, 2020 12:35 pm

Hugh Robjohns wrote:
Arpangel wrote:Microphone placement is often spoken of like some sort of black art, a talent you have or you don’t have.

There is certainly a degree of art involved, along with a degree of science. It is definitely an acquired skill, and some people are more talented at it than others -- just as some people are more talented at playing the piano than others.

But it is a skill that can be learned, like any other, given dedication and effort...

I used to think that if it sounds good where you’re standing, then that’s where the microphones should go, as the mic’s should pick up what I’m hearing.

Yes... but microphones don't have the signal processing that your ears/brain apply automatically. We are incredibly good at ignoring things in the received sound waves that microphones still capture... So while placing mics 'where it sounds good' is certainly a good start, it's far from the whole story!

I’ve been caught out big time by the ears/brain thing many times, embarrassingly so sometimes, it’s a bit like taking a photograph of a beautiful sunset, and you’re so carried away that you fail to notice that huge electricity pylon in the foreground!

:D
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Re: Does a microphone hear a stereo image like a person?

Postby Hugh Robjohns » Wed Nov 25, 2020 12:58 pm

Many years ago, after a long and difficult day of filming on the North Cornish coast I was returning to the overnight hotel with my cameraman in the crew car. We were driving West along the North Cornish coast road on a beautiful summer's evening and the sunset was absolutely spectacular! So we decided to pull over and shoot some GVs of it as they might be useful for the programme's end roller or something...

So we got the tripod out, set up the camera, got the sound gear connected up, and then -- so we could see what we were doing with the equipment controls -- we both took off our smokey-tinted sunglasses...

... at which point the gloriously rich, colourful, dramatic sunset we thought we were about to record suddenly looked very ordinary, flat and boring! :headbang:

Sadly, we didn't have any tinted lens filters with us, and although we tried filming through one lens of the sunglasses, it really didn't work well...

So we piled everything back in the car and headed on to the hotel feeling rather silly... :lol:
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Re: Does a microphone hear a stereo image like a person?

Postby The Elf » Wed Nov 25, 2020 1:56 pm

The 'mic masterclass' I attended at Maida Vale a few years ago (run by a few illustrious members of these fora! ;) ) was an eye(ear?!)-opener for me. Until that point I'd pretty much used trial and error, but I suddenly acquired the ability to not only think it through, but finally understand what I'd been instinctively hearing, but not understanding.

That day was easily one of the best investments I ever made in myself. I would do it again, if only to refresh my knowledge! :D
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Re: Does a microphone hear a stereo image like a person?

Postby Aled Hughes » Wed Nov 25, 2020 2:02 pm

The Elf wrote:The 'mic masterclass' I attended at Maida Vale a few years ago (run by a few illustrious members of these fora! ;) ) was an eye(ear?!)-opener for me. Until that point I'd pretty much used trial and error, but I suddenly acquired the ability to not only think it through, but finally understand what I'd been instinctively hearing, but not understanding.

That day was easily one of the best investments I ever made in myself. I would do it again, if only to refresh my knowledge! :D

That sounds very interesting, are they still running it?

I’m sure an in depth SOS article on mic placement would be very popular too.
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Re: Does a microphone hear a stereo image like a person?

Postby CS70 » Wed Nov 25, 2020 3:13 pm

Arpangel wrote:I used to think that if it sounds good where you’re standing, then that’s where the microphones should go, as the mic’s should pick up what I’m hearing.

It's a good starting point, but it works if "sounds good" is "sounds good thru monitoring or you are listening to a recording taken in that position"!

If you evaluate positions moving the mic with your headphones on, while well insulated from the room sound, it gives you a starting point quite quickly.
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