Topic: Cardoid vs Omni

[dominar]

Can someone explain or point me to a description, in laymans terms the benefits/differences of cardoid vs omni mics?

In the simplest terms possible.  I've read alot of info on this site and quite honestly alot of it is over my head!

Thanks!

[Todd R]

Omni mics record sounds coming from all directions equally, cardioids record mainly sound coming from the front and reject sound from the rear.  So cardioids are better suited (speaking in very, very broad terms) of recording the music coming from in front of you and rejecting the crowd noise of people behind you.

With their rear-rejection, cardioids can easily be used in tightly-placed pairs to record in stereo and re-create a stereo soundfield.  2 Omni mics since the record equally from all directions, will need to be separated (say a meter or more) or baffled in order to record in stereo.

This all is highly simplified, but gives the gist of it.

Excellent information is available over at the microphone university at www.dpamicrophones.com

[dominar]

So, what's the point of stealth omnis?  Wouldn't they be too close together while recording a concert?

What is the prefered type of mic for stealth recordings?

I thought I read it was omni because it gave fuller sound with more room information, whereas cardoids were flatter.

[dorrcoq]

So, what's the point of stealth omnis?  Wouldn't they be too close together while recording a concert?

I think your head acts as the baffle.

[Gutbucket]

So, what's the point of stealth omnis?  Wouldn't they be too close together while recording a concert?

2 Omni mics since the record equally from all directions, will need to be separated (say a meter or more) or baffled in order to record in stereo.

In that case your head or body acts as a baffle.  You can make good recordings with closer spacings without a baffle too, but more space or a baffle is optimal.

What is the prefered type of mic for stealth recordings?

I thought I read it was omni because it gave fuller sound with more room information, whereas cardoids were flatter.

Because they pick up sound equally from all directions (unless you mount them on or near a baffle ), omnidirectional mics do record more room information.  That's great if the room information sounds good.. maybe not so great if the room sounds boomy or there are lots of people blabbering behind you.  Omni mics are easier to arrange properly since it doesn't matter as much if they are pointed just right, whereas it's important to point cardioid pattern mics properly.

When you say "cardioids are flatter" you are probably referring to the frequency response of the microphone which determines how sensitive the mic is to each range of sound from the lowest pitches to the highest treble sounds.  All mics are different, but as a very gross generalization, omni mics are usually flatter in frequency response, picking up all frequencies evenly.  Cardiod mics can be and are often very flat too for sounds coming at them directly from the front, but are less flat for sounds arriving from the sides.

However, a perfectly flat frequency response isn't always desired.  Many microphones are well regarded because they either impart a pleasant coloration to the sound or are less sensitive to 'problem sounds' like too much bass.

This all is highly simplified, but gives the gist of it.

[dominar]

So, if you're going to an event at a new location how do you know what you should bring?  I'm guessing omnis would be best for a beginner (like myself) since the pointing is not as critical as with cardoids.

[Gutbucket]

Very hard to say.  You learn your rig, you learn how different recording situations usually work, you determine if its a loud raucous bar or a quiet respectful audience, you ask questions here... figuring that out is half the fun.

You'll have to record a few things to figure out how to run your rig before you know how to use it well, so don't worry about throwing out your first few attempts.

[BC]

Very hard to say.  You learn your rig, you learn how different recording situations usually work, you determine if its a loud raucous bar or a quiet respectful audience, you ask questions here... figuring that out is half the fun.

You'll have to record a few things to figure out how to run your rig before you know how to use it well, so don't worry about throwing out your first few attempts.

agree here. I prefer cardioids, even with a quiet audience I like to try to reject ambient noise like coughing, page turning, etc.

[DSatz]

dominar, a cardioid microphone discriminates somewhat in its pickup of sound, since in the back of the microphone it has almost no response at all (in fancier terms it has a "null" in its response at 180 degrees). Any sound that arrives from the front or sides of the microphone will be picked up, though.

An omnidirectional microphone is similar except that it also picks up sound from the back of the microphone, in addition to the front and sides. Cardioid and omnidirectional aren't opposites, in other words; "directional" and "non-directional" would be opposites, but those terms aren't quite the same as what you asked about.

The directionality of a cardioid isn't nearly as sharp as many people seem to imagine. It isn't anything like a flashlight beam, for example; no conventional microphone has that narrow a pickup pattern. Even sound that arrives from 90 degrees off axis (all the way to one side or other, and/or above or beneath the mike if it is horizontal) is reduced only barely enough to notice. When people here talk about the use of cardioids to reduce audience noise, it is because they are recording clear enough stereo that the listener's brain can filter out some of the unwanted sound in playback. Beyond enabling stereo pickup to occur, though, cardioid microphones themselves don't really do much "filtering out" like that. Cardioid is still a big, round 3-D blob of a pattern.

In practice there are some things that go along with a microphone's being directional or not. Directional microphones are sensitive to wind, breath noise (popping on consonants with closely miked singing or speaking voices, for example) and handling noise or physical vibrations; omnidirectional microphones, if they are of a type known as "pressure transducers," are nearly immune to these problems. And directional microphones emphasize the bass and lower midrange of most sound sources that are in close proximity to them while pressure transducers don't have any such "proximity effect."

Just speaking of condenser microphones, since they're the type most commonly used for high-quality recording and broadcasting, directional microphones have a low-frequency rolloff that generally starts somewhere between about 50 and 100 Hz, while pressure transducers (remember, all pressure transducers are omnidirectional but not all omnidirectional microphones are pressure transducers) can have full sensitivity down to the lower limits of human hearing and even beyond.

Finally, for reasons of physics, "omnidirectional" microphones of normal size aren't omnidirectional at high frequencies, so you still have to take care which way you aim them--strange though that may seem at first.

--best regards

[Gutbucket]

^^^^
Well put and concise as usual.

Can someone explain or point me to a description, in laymans terms the benefits/differences of cardioid vs omni mics?
In the simplest terms possible...

[George]

So, if you're going to an event at a new location how do you know what you should bring?  I'm guessing omnis would be best for a beginner (like myself) since the pointing is not as critical as with cardoids.

Depends on where your seated or standing.  If your close up to the stage/pa, go with omni's...farther away (lets say 20 rows back or more, go with cards).  In my experience, omni's sound hollow and distant when taping from a great distance away from the stage.  If you plan on attending concerts where you can obtain good seats, go with omni's then, but I find cards to be more versatile.

[Gutbucket]

So, if you're going to an event at a new location how do you know what you should bring?  I'm guessing omnis would be best for a beginner (like myself) since the pointing is not as critical as with cardoids.

Depends on where your seated or standing.  If your close up to the stage/pa, go with omni's...farther away (lets say 20 rows back or more, go with cards).  In my experience, omni's sound hollow and distant when taping from a great distance away from the stage.  If you plan on attending concerts where you can obtain good seats, go with omni's then, but I find cards to be more versatile.

Regardless of mics, try to get in the best sounding spot in the room you can.  Generally closer is better, though if there are vocals over a PA, or if there is almost no stage volume and everything comes over a PA it is possible to get too close. Ironically, I was listening just last night to a recording I made of some acapella vocal harmonies made from the board position 4 rows from the very back of a theater with omni's that I figured would be way too far back at the time and it turned out very nice and foreward sounding.  Remember that these usage guidelines are just that, guidelines and you'll find exceptions to all these generalizations, whereas the info DSatz posted on the working principle of cardioid/omni mic types is factual info that describes how the mics function.

[Dede2002]

dominar, a cardioid microphone discriminates somewhat in its pickup of sound, since in the back of the microphone it has almost no response at all (in fancier terms it has a "null" in its response at 180 degrees). Any sound that arrives from the front or sides of the microphone will be picked up, though.

An omnidirectional microphone is similar except that it also picks up sound from the back of the microphone, in addition to the front and sides. Cardioid and omnidirectional aren't opposites, in other words; "directional" and "non-directional" would be opposites, but those terms aren't quite the same as what you asked about.

The directionality of a cardioid isn't nearly as sharp as many people seem to imagine. It isn't anything like a flashlight beam, for example; no conventional microphone has that narrow a pickup pattern. Even sound that arrives from 90 degrees off axis (all the way to one side or other, and/or above or beneath the mike if it is horizontal) is reduced only barely enough to notice. When people here talk about the use of cardioids to reduce audience noise, it is because they are recording clear enough stereo that the listener's brain can filter out some of the unwanted sound in playback. Beyond enabling stereo pickup to occur, though, cardioid microphones themselves don't really do much "filtering out" like that. Cardioid is still a big, round 3-D blob of a pattern.

In practice there are some things that go along with a microphone's being directional or not. Directional microphones are sensitive to wind, breath noise (popping on consonants with closely miked singing or speaking voices, for example) and handling noise or physical vibrations; omnidirectional microphones, if they are of a type known as "pressure transducers," are nearly immune to these problems. And directional microphones emphasize the bass and lower midrange of most sound sources that are in close proximity to them while pressure transducers don't have any such "proximity effect."

Just speaking of condenser microphones, since they're the type most commonly used for high-quality recording and broadcasting, directional microphones have a low-frequency rolloff that generally starts somewhere between about 50 and 100 Hz, while pressure transducers (remember, all pressure transducers are omnidirectional but not all omnidirectional microphones are pressure transducers) can have full sensitivity down to the lower limits of human hearing and even beyond.

Finally, for reasons of physics, "omnidirectional" microphones of normal size aren't omnidirectional at high frequencies, so you still have to take care which way you aim them--strange though that may seem at first.

--best regards

I've been following this thread since day one.
Lots of great tips and usefull information. Thanks for that. 

[George]

So, if you're going to an event at a new location how do you know what you should bring?  I'm guessing omnis would be best for a beginner (like myself) since the pointing is not as critical as with cardoids.

Depends on where your seated or standing.  If your close up to the stage/pa, go with omni's...farther away (lets say 20 rows back or more, go with cards).  In my experience, omni's sound hollow and distant when taping from a great distance away from the stage.  If you plan on attending concerts where you can obtain good seats, go with omni's then, but I find cards to be more versatile.

Regardless of mics, try to get in the best sounding spot in the room you can.  Generally closer is better, though if there are vocals over a PA, or if there is almost no stage volume and everything comes over a PA it is possible to get too close. Ironically, I was listening just last night to a recording I made of some acapella vocal harmonies made from the board position 4 rows from the very back of a theater with omni's that I figured would be way too far back at the time and it turned out very nice and foreward sounding.  Remember that these usage guidelines are just that, guidelines and you'll find exceptions to all these generalizations, whereas the info DSatz posted on the working principle of cardioid/omni mic types is factual info that describes how the mics function.

Yep, its definitely a generalization, but I seriously consider location and the size of the venue when selecting one of my mics to use.  It's a risk we take everytime though because you don't know exactly what will work best until after you hear your recording...I've had some duds with my dpa's and then some killer recordings with my dpa's. 

[dean]

dominar, a cardioid microphone discriminates somewhat in its pickup of sound, since in the back of the microphone it has almost no response at all (in fancier terms it has a "null" in its response at 180 degrees). Any sound that arrives from the front or sides of the microphone will be picked up, though.

An omnidirectional microphone is similar except that it also picks up sound from the back of the microphone, in addition to the front and sides. Cardioid and omnidirectional aren't opposites, in other words; "directional" and "non-directional" would be opposites, but those terms aren't quite the same as what you asked about.

The directionality of a cardioid isn't nearly as sharp as many people seem to imagine. It isn't anything like a flashlight beam, for example; no conventional microphone has that narrow a pickup pattern. Even sound that arrives from 90 degrees off axis (all the way to one side or other, and/or above or beneath the mike if it is horizontal) is reduced only barely enough to notice. When people here talk about the use of cardioids to reduce audience noise, it is because they are recording clear enough stereo that the listener's brain can filter out some of the unwanted sound in playback. Beyond enabling stereo pickup to occur, though, cardioid microphones themselves don't really do much "filtering out" like that. Cardioid is still a big, round 3-D blob of a pattern.

In practice there are some things that go along with a microphone's being directional or not. Directional microphones are sensitive to wind, breath noise (popping on consonants with closely miked singing or speaking voices, for example) and handling noise or physical vibrations; omnidirectional microphones, if they are of a type known as "pressure transducers," are nearly immune to these problems. And directional microphones emphasize the bass and lower midrange of most sound sources that are in close proximity to them while pressure transducers don't have any such "proximity effect."

Just speaking of condenser microphones, since they're the type most commonly used for high-quality recording and broadcasting, directional microphones have a low-frequency rolloff that generally starts somewhere between about 50 and 100 Hz, while pressure transducers (remember, all pressure transducers are omnidirectional but not all omnidirectional microphones are pressure transducers) can have full sensitivity down to the lower limits of human hearing and even beyond.

Finally, for reasons of physics, "omnidirectional" microphones of normal size aren't omnidirectional at high frequencies, so you still have to take care which way you aim them--strange though that may seem at first.

--best regards

Well done - thanks!

Can you expand on the "directionality" of omnis at high frequency?  Or perhaps point to a resource written in as close to layman terms as possible?  We have a raging debate amongst the MN Tapers on this exact subject.