Using a stereo mic- are they your choice as a sound pro?
 

Greetings.

I thought I'd start a new thread. I've gathered an enormous amount very useful information thanks to the contributors in this audio forum.

I've owned my one and only mic, an Audio-Technica AT-822 Stereo mic for the past several years. I think it has served me well, but as you can tell, I am newish at the audio thing, but like I say, learning every day. (I was even a bigger PITA on the video and cameras forums, but learned so much that I now feel safe when confronted with most cameras, which I generally rent if I need something high end.)

It wasn't until playing around with the Shure FP 33 mixer that I realized that the 822 has a real drawback, or I am just not familiar with the idiosyncrasies or stereo mics.

Here is what I've found: If you position the 822 directly in front of the sound source I.E. a person speaking, the sound (gain?) is quite low. However if you position the mike to the left or right side of the mic, the sound really bumps up (sorry for my bad lingo here). This makes sense since the stereo mic would have a left and right channel.

So my question is: why the dead spot when directly in front of the mic? When and why would someone use a stereo mic in professional audio world? Or would someone in the biz choose separate mic(s), and then mix.

My gut feeling is that they are more hassle than just dealing with a "mono" mic.

Re: Using a stereo mic- are they your choice as a sound pro?
 

One important thing you missed when you gathered your audio info .. spoken voices should always be recorded in mono
and positioned in the centre in your video or audio production.

Sounds like you're running into phase problems with your stereo 822, so you need more research then practice with stereo.
It's used for stereo sound effects, music recording eg: small choirs.

Read Jay Roses book, available now on Kindle ..

Here, enter this you might win a good mono mic .. http://www.prosoundweb.com/sweepstakes

Cheers.

Re: Using a stereo mic- are they your choice as a sound pro?
 

Thanks Allan. I've just ordered the Jay Rose book. I've been really focusing on my sound stuff lately. Even if I have the luxury of hiring a sound person, I just want to know what's going on.

Re: Using a stereo mic- are they your choice as a sound pro?
 

I would guess that mic has an x-y configuration, each pointing 45-degrees to the side. For dialog, you could turn the mic 45-degrees and then select that channel as the source. (When you record on-center, both mics will have some mid and high-frequency roll off.)

Each mic component is probably cardioid though, which isn't ideal for dialog. One typically uses a lobar shotgun outdoors and a super- or hyper- cardioid indoors.

A stereo mic is best for recording ambient sounds and live music, though amplified bands are often mixed in mono so that the audience on the left and right extremes of the stage can hear the whole mix.

One can record Foley elements (footsteps, etc) in mono and place them in space using channel balance, delays, EQ, and convolution reverb. Even large orchestral scores are generally mixed to stereo or multi-channel from a large bank of mono mics placed near each instrument or group of instruments on the soundstage. (They will also typically have some mid and far mics that record the reverberant sound in stereo or better.)

A good rule of thumb is this: When recording one item, a mono mic works fine. You can place it and add the "space" in post. When recording multiple, concurrent items (like people and birds in a park), it's good to record in multichannel to capture them in their original space. That way, you don't move all the people and all the birds left or right as you pan/delay.

Re: Using a stereo mic- are they your choice as a sound pro?
 

I've used quite a few approaches to stereo mic technique; Jon's advice is good.

Frequently, for live performance, I'll have either a mono mix or multitrack recording of all the performer's direct mics, and a stereo mic in the audience both for their sound (applause!), and to mix in to provide some ambience and room sound. A directly miced musical performance can sound pretty dead without some reverberation/echo/delay mixed in. These can certainly be post EFX, but it's nice to have the choice of what it sounded like in the original hall with the audience.

IMHO, where stereo micing *really* shines, is as the only mic for a small acoustic ensemble where they have acoustic balance. Nothing beats it in a good room with this kind of performance, though some might reasonably argue with me about that. Placement is critical for this... I do quite a bit of this type of work.

And, as Jon suggests, general ambience recording...

But no, not for dialog recording. Here your best choices are a lav or a boom mic.

Re: Using a stereo mic- are they your choice as a sound pro?
 

Jonathan,

If the mic is really dead when perfectly centered, then you have something connected out of phase.

With an X-Y mic, each individual channel should be down about -3dB when the sound source is dead center, compared to when the sound source is off to the side by roughly 45 degrees.

Please give us exact description of every cable you are using between the mic and the mixer. For example, are you feeding that mic into just one channel of the mixer, or are you splitting it into two channels of the mixer? Either way, describe each cable in detail: type of connector on each end, as well as wiring details if you know them.

[I would bet that you are feeding the 822's XLR output, which is unbalanced stereo, into ONE of the mixer's XLR inputs, which are balanced mono. In that case, the mixer sees a signal which is the DIFFERENCE between the mic's left and right channels. When the sound source is centered, both mic channels are very nearly equal, so the DIFFERENCE is very nearly zero.] You need to cable it differently... OR use a mono mic for mono recording.

Re: Using a stereo mic- are they your choice as a sound pro?
 

The big issues here is WHAT are you recording and WHERE will it be used? As other have said, a stereo microphone is good for recording music (mostly acoustic music, not amplified bands) and for recording ambient background sounds.

Stereo mics are NOT a good choice for most of the sync sound we record with video. When you talk about putting the mic in front of someone talking, that is a PRIME example of where a stereo microphone is NOT appropriate. And you have demonstrated first hand why that is the case.

If I could have only one microphone and I were recording music and the occasional video, I would probably opt for a stereo microphone. But if I were doing primarily video, I would NOT choose a stereo microphone. I came to audio-for-video (and then to video) by way of many decades of audio experience, so I have many examples of both mono and stereo microphones. That provides me the relative luxury of never selecting an inappropriate microphone (like a single-point stereo mic) for something like dialog recording.

Remember that unless you are watching raw home-video of the nephew's 3rd birthday party, the track you are listening was almost certainly CREATED in post-production editing from multiple monaural sources.

Note also Mr. Miller's post. Without actually hearing and examining a sample, it is difficult for us to tell whether you are seeing the natural drop-off at dead-center on a stereo microphone, or whether you are seeing phase-cancellation from improper wiring and/or mixing. If the effect is only slight, I would say it is a natural phenomenon of most single-point stereo microphones. But if it is a profound drop (more than 6dB), then there may be other factors at play such as Mr. Miller is trying to walk you through. Of course, using the proper (monaural) microphone here would eliminate this potential problem altogether.

Re: Using a stereo mic- are they your choice as a sound pro?
 

Mr. Crowley:

He says when used dead on the "gain is quite low." To my mind, "quite low" is a lot lower than -3dB. I doubt that he'd even notice -3dB. (I'm betting that the dead-center sound quality is pretty thin, too, which would add to the "quite low" perception.) So I'm pretty confident that he's hearing phase cancellation between the two capsules. Remember that the 822 uses a 3-pin XLR for unbalanced stereo... to a neophyte who thinks "XLR = XLR" it would be easy to plug this into a mono balanced input and get "quite low" cancellation with a center source.

Re: Using a stereo mic- are they your choice as a sound pro?
 

Indeed. And Mr. Levin also says "It wasn't until playing around with the Shure FP 33 mixer..." which further suggests that he may have made the mistake of plugging the non-standard XLR output from the AT822 into a conventional XLR input of the mixer. He doesn't mention what cable (or camcorder) he is using.

But even wired properly (with the Y-cable that goes with the microphone), using a single-point stereo mic for something like speech/dialog is a significant compromise to optimal performance.

Re: Using a stereo mic- are they your choice as a sound pro?
 

Agreed, in regard to stereo recording of dialog.

Even if you create a proper mix of L+R, the pattern will be strange: cardioid in the vertical plane, but perhaps wider-than-normal cardioid in the horizontal plane. The actual result, I think, depends on whether it's an X-Y mic (like the OP's 822) or whether it's an M-S mic. In any case, there's no benefit to doing so, and it may well make the audio worse.

Besides, for a given price one proper mono mic should be better quality than a stereo mic (which is actually two mics in a single housing). So it's best to buy the proper tool for the job at hand.

Re: Using a stereo mic- are they your choice as a sound pro?
 

I tend to record all dialogue or speech in mono but use a stereo mic (sony ECM-MS957) for gathering stereo sound effects or buzz/wild tracks to add depth in post.

I also use stereo mics to do music or theatre/stage work but could just use several momo mics and pan them accordingly but as other people have stated it all depends on the job.

Re: Using a stereo mic- are they your choice as a sound pro?
 

Sorry for a very long reply.

First of all thanks for your time and patience fellows. I am realizing that not only good sound vital to any video/film production, it is also as complicated, or more so, than the video capture portion of a project.

Some of my colleagues believe that you just plug a mic in here, run a cable there, set a level and that's it. Obviously that's not true. I was always the kid who had to know how things worked, ended up with many clocks, motor things under my bed that I couldn't get back together, punished, but learned.

I take this approach to my production work as well, or at least I'm getting there. Up to now I've squeeked by with OK, sound, as you will see with my interview stuff with the Fearless Fernando video (see link below on my signature). I used the 822 mic for that and got lucky I guess.

I digress.

Let me describe how my initial set is:

As was noted by Richard and other contributors, the AT 822 mic came with a cable that was xor to mic, and the other end had 2- 1/4" mail plugs. I have never used those.

The mic was used initially to record solo acoustic guitar. I bought a standard Mogami 25' xlr male-female cable. (Man are these things expensive). I heard that Mogami was a decent brand with good warranty.

For my guitar stuff, I was running the mic, cable into a M-Audio Fastrack Pro USB interface to GarageBand on the Mac. Long story short, my audio kind of sucked, was never able to get consistent levels, final recorded material average....My head knows good sound, need to make the connect to MAKE good sound.

Fast forward to now, when a buddy of mine who is a sound guy for CBS lent me a Shure FP 33 to fool around with. And this is where I am now. The reason I am so into this is the realization of possibilities using a mixer, and not just for the added channels. Being able to feed sound in from another source is intriguing and the control aspect of each channel.

I digress again.

So to clarify, I have been testing the mixer with the stereo mic, a "standard" xlr cable to channel 1 on mixer. Pan dead center Gain set to 7 (2 o'clock) Master (unity?) set to 2 o'clock.

Left and right of mic a strong signal -3 but drops to -15 when dead center. Mic about 6 inches from me making steady sound (helloooooooo). Monitoring sound through headphone out on mixer.

So that drop is kind of in the center.

Apparently if I am doing interview stuff, this is not the ideal mic to use. I've read that cardiod or super cardiod or lav is the way to go indoors and a short shot gun outdoors. Mono all the way.

If any one has any additional comments, that would be great! My copy of Jay Rose's book will arrive in a few days, and spare your guys, hopefully, many more neophyte questions, and embarrassment.

I'm going to start a few new threads to address a few other basic ??'s if you dare.

Best to all.

Jonathan Levin

Re: Using a stereo mic- are they your choice as a sound pro?
 

If you are plugging the AT822 directly into a common XLR microphone intput, you will get extremely wierd results because the microphone was never intended to be connected that way.

Your AT822 microphone does not have a standard XLR output. It is a "stereo microphone". It is actually two separate microphones inside a common case. It has TWO outputs by definition.
It cannot be plugged into ANY standard XLR input and work properly. You have demonstrated that for yourself.
You MUST use that microphone with a properly-wired Y-cable to split out the left and right channels separately.

If you don't have a Y-cable with XLR male ouputs, then you must acquire or make one. Until you have the proper cable, you are wasting your time.
Note that you can't just buy any old "XLR Y-cable" it must be wired specifically for this microphone.
Or you could take your cable with mini phone plugs and use adaptors or re-wire it with XLR output connectors.

Re: Using a stereo mic- are they your choice as a sound pro?
 

Thanks Richard.

I think I've given up using the 822 for my intended purposes. I hear what you are saying about the x/y thing. From what I know pin 1 on the mic is the left and pin 2 is the right and the third pin is the ground.

I suppose in a pinch I could use the mic as is with the two channels combined thru my xlr cable with the Pan set to center on the mixer, but that still doesn't address the odd left-right issue with the mic.

I'm thinking this is like using a wrench to change a light bulb. Onto the right tool, right-time frame of mind.

All my channels and outputs thank all of you!

Jonathan

Re: Using a stereo mic- are they your choice as a sound pro?
 

I'm still not sure what your "intended purpose" is?

Please note that the AT822 is not a bad mic. But it must be used properly (with the proper stereo break-out cable). And it must be used for appropriate (stereo) applications. Speech/dialog/narration is NOT an application for any stereo microphone.

Pin 1 on any XLR (even for the AT822 non-standard wiring) is always ground. On a standard microphone, pins 2 and 3 are a differential/balanced pair of the (monaural) signal. The microphone preamp rejects any signal that is common to both 2 and 3. That is how a standard microphone system works to reject noise picked up by the cable.

But your AT822 has the independent left channel on pin 2 and the independent right channel on pin 3. And when you plug it into a standard microphone input, you are getting Left MINUS Right. That is why you are getting a big hole in the middle. What you are calling "the odd left-right issue".

No, you can NOT "use the mic as is with the two channels combined thru my xlr cable" because it is NOT "combining" them. It is SUBTRACTING them and giving you a very weird response.

Re: Using a stereo mic- are they your choice as a sound pro?
 

Hi Richard,

Thanks again for your help.

My intended purpose would be for interviews, indoor possibly out door. Single person. As you mentioned, not the right application for the 822 stereo mic. So the Y splitter from guitar Center wouldn't do it?

"I was unable to identify that product on the Live Wire website. There is no information disclosed about how it is wired, but I would wager 100:1 that it is NOT wired correctly for what you need. Repeating: this is a NON STANDARD wiring and you cannot use commonly-available adapters with it."

I'll look into Redco for an adapter. When I communicate with them, what exactly do I tell them I'm looking to have made?

I know that this is not the ideal mic at all, and that something like a Senheisser MK66 or 64 cardiod would be more suitable for my purposes.

I just found a ton of info that I really need to study here: Educational Articles - Online booklets and bulletins

My head is spinning.......

Re: Using a stereo mic- are they your choice as a sound pro?
 

Most microphones that use an XLR connector have what is called "balanced" signal.

Pin 1 of the connector is used for shield/ground, and carries no audio.

Pins 2 and 3 carry the audio. The two pins have equal voltage amplitude, but opposite polarity. If, some given instant, the microphone is seeing positive air pressure, and pin 2 happens to be +.003 volts, then pin 3 would be -.003 volts. If, at another instant, the microphone is seeing negative air pressure, and pin 2 happens to be -.027 volts, then pin 3 would be +.027 volts. Maybe you can visualize why it's called "balanced." (It's the same as the RF on a half-wave dipole antenna, but we won't go there...)

A typical mixer using an XLR connector has a balanced input. It subtracts the voltage on pin 3 from the voltage on pin 2, to obtain the total audio signal. In the first example above, the mixer would see
(+.003v) - (-.003v) = +.006 volts total (corresponding to a certain amount of positive air pressure at the mic). In the second example above, the mixer would see
(-.027v) - (+.027v) = -.054 volts total (corresponding to a certain amount of negative air pressure at the mic.)

The purpose of balanced wiring is to make the system immune to electrical noise. Let's imagine the microphone cable happens to be subjected to a strong electromagnetic field. Let's imagine that the field induces some voltage on the two microphone wires. (Actually, with shielded wire, noise is a minimal problem, but let's keep imagining...) OK, since the two mic wires are spiral twisted around each other inside the cable, they will receive the same amount of induced noise. Let's assume that both wires therefore pick up +0.077 volts of noise. The mixer sees
(+.077v) - (+.077v) = zero volts, so the system is immune to this type of induced electrical noise.

Now here's the problem with the 822. The XLR connector is used in a very non-standard way. Pin 1 is used for shield/ground. Pin 2 is used for left channel audio (not balanced) and pin 3 is used for right channel audio (also not balanced). If the two microphone elements are exactly and perfectly matched, and you record someone who is exactly centered on the mic axis, both elements will generate exactly the same voltage and the same polarity. So the voltage on pin 2 and pin 3 will be exactly equal.

So let's imagine both of the mic elements are responding to a positive air pressure, and both channels are generating +.045 volts. The mixer will see
(+.045v) - (+.045v) = zero volts. In other words, the mixer will subtract or "null out" the sound from the two channels of the mic, exactly as it nulls out induced electrical noise. Of course the elements are not perfectly balanced, and the sound source is not perfectly centered, so there is a slight difference in the left and right channel signals, and that difference is what you're hearing as "very weak" audio.

If you want to use the 822 only as a mono mic, feeding into a mixer with a normal balanced input, then the cable should be as follows:
MIC pin 1 >> MIXER pin 1 and pin 3.
MIC pin 2 >> MIXER pin 2.
MIC pin 3 >> MIXER pin 2.
Note that you're simply connecting the microphone's left channel (pin 2) and the right channel (pin 3) together, and feeding them to pin 2 (the "non-inverting" input) of the mixer.

You also need to be absolutely, completely, 100% certain to check, verify, and double-check that the mixer is not feeding phantom power to the mic jack. Phantom is used only for balanced condenser mics. If you feed phantom (which might be as high as 48 volts DC) to the 822, the mic will become an instant paperweight. And believe me, some day you'll be in a hurry, and you'll do just that. That's just one more reason to use a proper, balanced, mono mic for your application!

Note that if you use that cable some day for some normal balanced mic, it won't work at all and you'll end up pulling out your hair.

And of course if you wire the 822 as shown above, it really won't have the correct pattern for dialog, and the recordings will be less than ideal. (But hey... somewhere in the world, someone is trying to haul elephants in a Volkswagen. Some people just like to defy established experience.)

Re: Using a stereo mic- are they your choice as a sound pro?
 

Adding a note to Greg's excellent explanation, an ordinary XLR-F - > 2x XLR-M "Y" cable won't work to split the mic in order to send this mic to a pair of the mixer's conventional XLR inputs for stereo. The outputs of this mic are unbalanced and need to be treated as such. You'd need an adapter 'Y' cable made up that connects ...

XLR-F pin 2 to left XLR-M pin 2
XLR-F pin 3 to right XLR-M pin 2
XLR-F pin 1 to BOTH left and right XLR-M pin3
and
both XLR-M have their pin 3 shorted to pin 1 to unbalance the mixer's input.

Re: Using a stereo mic- are they your choice as a sound pro?
 

Steve, Greg, Gary, Richard, Seth and John.

Thanks so much for your input (no pun intended.)

I'm thinking of retiring the stereo mic for the time being. I'd just like to KISS (keep it simple stupid).

The difference between me and you guys is that you know what you are doing. I'm getting there.

I am even thinking of selling it if there is any interest, and get what I need in for my production purposes: interviews, and so on.

From what I've read, it sounds like I will be looking at both the following:

1) A hard wired lav of some sort. I do a lot of work in hospitals, and with all their equipment, I don't need the added RF headaches of wireless, at least for now while I'm learning and juggling and acting as a one man band.

2) Something like a Rode NTG-3, or Senheisser ME 66/64 Or some other Super Cardiod.

Jonathan

Re: Using a stereo mic- are they your choice as a sound pro?
 

It's quite possible that your stereo mic is capable of giving you really nice audio quality - so retiring it seems a bit counter productive - as having more mics to do different things is very useful.

You just need to get into your head the concept of stereo mics needing two mono channels, one usually panned left and the other right. Most non-DSLR cameras have had two inputs for many years now. If you use a stereo mic paralleled cable wise to make it 'mono' then that's fine. In fact, why not just make up two adaptors as people have detailed above (which anyone who can solder can follow as pin numbers are on the pins!) then you can have a short male to female XLR that can plug into any socket to give you mono. The other would have a female XLR one end and two male XLRs the other - this would go into a two channel (stereo) input device.

What you have accidentally done is produce something like the circuit inside cheap karaoke machines - these do exactly the same thing to a stereo signal to get rid of the centre components - usually the voice. If you listen again to your recordings you'll probably also detect that they sound very thin and on headphones, have a kind of 'hole' in the middle when you close your eyes and imagine what you can hear.

Most professional stereo one piece mics have a 5 pin XLR, not 3 - making the mistake you have less likely because ordinary cables don't fit!

Re: Using a stereo mic- are they your choice as a sound pro?
 

Ok. I'm really excited and making a bunch turkey noises like Curley on the Three Stooges!

I gave Redco Audio a call and spoke at great length with Chris. (Thanks for the lead, Richard Crowley!!!)

Very nice fellow, I went over what you guys wrote, and since I take decent photos, good video, good at woodworking and make really good BBQ'ed ribs, soldiering wires isn't something that I want to fuss with, especially since I'm dealing with sensitive audio stuff.

So, they are going to build me two types of cable, wired to the specs per Steve and Greg's suggestion. Actually, Chris knew straight away what I needed.

One cable will be a mono cable so that I can plug in to one channel, basically turning my stereo mic into a mono combined L+R input device.

The second cable, which he said is the preferred method, so that it can be used as a true stereo mic, is a Female xlr to dual male xor (two separate channels). I guess I would then use the pan controls for each channel and pan one channel hard left and the other hard right.

They know all the solder doodle stuff, and both cable cost me about $40.00US plus shipping. A bargain in my book to get this the way you guys have been so patiently trying to pound into my 56 year old head.

Agin, I thank you for your time and suggestions and if you have any more comments about what I just did, please post them.....here.

Happy holidays all.

Jonathan

Re: Using a stereo mic- are they your choice as a sound pro?
 

You don't use a putter in a sand trap. You don't drive with a wedge. An X/Y stereo mic is not a good choice for dialog for the very reasons you have described; square peg, round hole. If you want to use a stereo mic on dialog try a M/S mic with a front facing capsule and a side facing figure of eight. Still a bit of a challenge, especially when you're working the boom between two or more people because, if you intend to unfold the M/S into stereo, you have to be aware of left and right and swinging the mic can cause some really wacky sound field shifts.

The Neumann RSM 191 is a killer stereo mic, BTW. Here's a review I wrote some time back.
https://www.dropbox.com/s/haka1tz53c...nn_RSM_191.txt

Regards,

Ty Ford

Re: Using a stereo mic- are they your choice as a sound pro?
 

Greetings everyone.

Well my new cable/adapters arrived from Redco. I've had a chance to test them out with the AT 822 Stereo mic and Shure FP33 mixer and all I can say is WOW. What a difference! Best 30-40 dollars I've spent in a while!

The first thing I noticed with both the mono and stereo adapters is that there is no longer much of a dead spot when speaking directly into the mike!

The other thing I noticed is with the gain set at about 8, the meters only get to -10 to -7 with mike placement about 12" away from mouth. Does this seem normal? All inputs are set to MIC level.

Thanks to all of you, I now want to re-record everything I've ever done! I think I'm getting closer to better audio all the time, thanks to all of you.

I'll probably get the Y XLR-Mini output adapter so I can use this set up with my Canon HV30.

I am currently looking into Lav options and short shot gun and I think I'll be in real good shape, unless I get a camera that has xlr inputs, then I'll be in real good shape.

Jonathan

Re: Using a stereo mic- are they your choice as a sound pro?
 

PLEASE REMEMBER that this is a STEREO microphone!!! When you say "speaking directly into the mic" if you mean that you are in "front" of the mic ON AXIS with the microphone you are NOT "speaking directly into the mic". You are, in fact, speaking "off axis" into TWO microphones, NEITHER of which is aimed at you. You can experiment by slowly turning the microphone to discover what "directly" means for the left channel, and what "directly" means for the right channel.

Assuming you are referring to the channel level knobs on the FP33. Assuming you are talking about the meters on the FP33. Assuming you have good batteries or power for everything.

You didn't state whether you were talking about one or the other channel (or both) (REMEMBER YOU HAVE A STEREO MICROPHONE). You didn't state where the pan pots were set or the master level control. I agree that running the channel volume at 80% is NOT normal. But all of these issues are somewhat more complicated by using a stereo microphone instead of a conventional microphone.

Re: Using a stereo mic- are they your choice as a sound pro?
 

Hi Richard.

Loud and clear on the directionality of the mic. Definitely a left and right side. However with the new adapters, the "deadish" spot front an center seems to have gone away, or is at least Far less noticeable than before I got the adapters at Redco. I even hooked up the xlr cable without adapter, and there was that dead spot!

As far as settings on the FP3, when using the adapter that plugs into input 1 and 2, both pan settings set to center. And the gain (volume) knobs for both channels at 8. Batteries read well into test "good" area of VU. I may try a different AA battery in the mike itself to see if that raises level a bit. Interestingly enough, even though the meters read -10 or so, sound good through headphones with the headphone volume set to about 7

Re: Using a stereo mic- are they your choice as a sound pro?
 

'both panned centre' ...... what ? You have just made a stereo mic MONO.

The left output of the mic going to ch1 should be panned LEFT and right output of the mic ch2 should be panned to RIGHT.

Re: Using a stereo mic- are they your choice as a sound pro?
 

I am afraid we are not getting through to you. "Front and center" is NOT ON AXIS FOR EITHER CHANNEL!

I have to go back and ask what you are trying to record. If you are trying to record a symphony orchestra or a choir or a string quartet, or the sound effects down at the beach, etc, then a stereo mic is marvelous. But if you are recording someone speaking, then a stereo microphone is NOT the right choice.

Now you can make it work by picking one channel (left OR right) and aim that channel of the microphone at the talker's mouth and use just that side of the microphone. Certainly it is going to look "goofy" to have the microphone seemingly aimed at one of the talker's ears. But the microphone capsule INSIDE the microphone will be properly aimed directly at the talker.

But you keep combining two different microphones that are aimed AWAY from the talker's mouth. That certainly accounts for some of the drop in level that you are experiencing.

Please UNPLUG one of the channels. PLEASE discover what TRUE ON-AXIS means for your favorite channel and do the same experiments as a MONAURAL MICROPHONE.

Re: Using a stereo mic- are they your choice as a sound pro?
 

Brian,

That makes sense. Thanks for that. I'm getting it.

Richard, this mike will be used for ambience, maybe group of musicians and so on.

I really do get it about the purpose of this mic, and learning to get the most out of it.

Most of my sound work will be sit down interview so for me a good wired lab is in my future (mono of coarse), as well as a hyper or super cardiod short shot gun of some kind.

I believe this will set me up for some decent audio.

Obviously the stereo mic is not ideal for most of what I do, and I appreciate the help in just getting it set up correctly with the right cables settings and so on. I'll play around with the pan per Brian and your suggestion. I'm guessing with one channell panned hard left and the other panned right my little front on dead spot will reappear. And I understand that the mic is meant to be off access to talent I.e if I had two singers one would be just to the left of center of mic and the second singer to just right of center on mic. This would then render a stereo 2 channel recording. Hopefully I got it.

Thanks Brian and Richard!

Jonathan

Re: Using a stereo mic- are they your choice as a sound pro?
 

No. With the left channel panned hard left, and the right channel panned hard right, IF the talent is located on the axis of the mic body, you will hear him equally on both channels, and it will sound almost like mono. There will be no dead spot.

You got the dead spot because the two channels were originally out of phase, so they were cancelling each other. Now that you have the correct cables, and the two channels are correctly in phase, you will hear a correct stereo image.

But that's still not what you want for dialog (i.e. a single person's voice). Because with the mic panned to stereo, you will get stereo background noise, air handler rumble, etc.; besides, the voice will never be perfectly centered. For dialog, you want to pan both mic channels dead center; that will give you a mono signal. And you keep that perfectly centered for your final mix, even if the fx and music are stereo.

It seems you aren't grasping this yet. I suggest you carefully re-read the above posts, especially #6, #15, and #17. If it still doesn't "click" then ask more questions. You really need to understand this basic concept if you intend to do sound work.

Re: Using a stereo mic- are they your choice as a sound pro?
 

Greg,

You are absolutely right! Upon further testing with the pan controls in various position, things sound really quite nice. I'm finally getting a feeling for this stereo beast. Thank you so much.

I thank everyone for tearing their hair out for me on this.

Keep in mind that this whole thread started with me having a problem that I didn't even know I had: not having the proper connector (wiring) and being "out of phase". Both then new to me.

Before I go on to my next point, I want to let you know that I realize that the right equipment for the right job is what I'd adhere to. I (now) wouldn't use this stereo mic for a sit down one on one interview anymore than I'd use a 4x5 view camera to shot action shots at a football game. A lav for that, or properly placed/boomed cardiod mic.

HOWEVER: I was thinking that in a pinch, one could use the AT 822 Stereo for an interview if you had two people placed at the correct L/R angles to the mic. One person feeding mostly into chan 1 and the other mostly into chan 2, setting the pan appropriately of coarse, also allowing for some leeway in post.

Or I'll go out on a limb further and say (with a question mark) that if you were recording sound at a table where two three people were sitting across from one another (6 people total) you'd have 3 people on one channel and 3 people on the other. OR setting the pan to dead center and getting both sides but in MONO. I also bought a mono adapter from Redco that I'm now wondering if I'll need other than to free up an input on the mixer, which I suppose is possible.

Again, doing the above if you were in a bind and didn't have two separate (mono) mice pointing at opposing sides of the table. I also understand that with the separate mic situation, you have more flexibilty for positioning.

Thanks.

Jonathan

Re: Using a stereo mic- are they your choice as a sound pro?
 

Excellent. You have come a long ways and now have a good working stereo mic and mixer. You have demonstrated that you understand the strengths, weaknesses and peculiarities of stereo mics. We award you a solid "A" on this course! Congratulations. :-)

As you say, you CAN use the stereo microphone as a conventional monaural microphone by simply selecting ONE of the channels (leaving the other one disconnected) and aim the microphone properly to be ON AXIS with whichever channel you picked. Hopefully by now you have done the experiment and know what the "on axis" angle is for the left and right sides.

And indeed, I have seen some people use them in a hand-held interview situation where they keep one side pointed at the subject, and the other side aimed at the interviewer. That is kind of difficult to do effectively as it is NOT intuitive because you can't see the axes. You must remember to keep it in just the right position as you/they are talking, etc.

Re: Using a stereo mic- are they your choice as a sound pro?
 

Jonathan,

It's good to see that you are starting to grasp things; you've learned a lot in a few weeks.

Your last post asked some good questions; regrettably, the answers that you guessed at aren't quite right. So I'll try to shed some more light on the subject.

Let's consider a single mic, with a cardioid directional pattern. (50 years ago, very detailed patterns were published, and it was easy to see what was going on. Today, you're lucky if you get any published pattern at all. So you're not to be blamed for not already knowing this stuff.)

A cardioid mic is, of course, directional... it picks up more strongly directly in front of the capsule, and the pickup falls off to the sides. But what is not obvious is that the directionality is different at different frequencies! (And, incidentally, this will not be exactly the same for different model mics.)

Consider the attached set of polar response curves.

Start with the black line, representing the pattern at 250 Hz. Note the shape of the curve.

Now compare the dark blue line (500 Hz) the green line (1 kHz) and the red line (2 kHz). Note that as you go up through those frequencies, you start to get a little bit more pickup behind the mic. Subtle, not a big problem for most applications.

But look what happens to the cyan line (4 kHz) purple line (8 kHz) and especially the yellow line (16 kHz). The sensitivity at the sides of the mic starts to fall off significantly, as you go up in frequency! So when you're off axis to this mic, the high frequencies will be diminished and the sound will start to sound rather dull.

That's why you want to use a single cardioid mic element, pointed directly at the sound source (i.e. the talent).

Having said all that, let's consider the AT 822. Based on your questions, I think you're assuming that the two mic elements are each pointed 90 degrees off the physical axis of the mic body. That's very unlikely. They are probably each about 45 degrees off the axis of the body, in other words 90 degrees apart from each other.

When you seemingly point the mic (body) directly at your talent, he's actually 45 degrees off axis for each of the two mic elements. If the elements in your mic had the same polar response as that published diagram, then each element would be about -9 dB at 16 kHz, and your audio would sound dull as a result! (However, the sample curve is not for the AT 822; and I don't have a good set of polar curves for that mic; it will be somewhat similar but also somewhat different from the sample curves.)

Now, as far as your two-person interview scenario: If you could position the mic so that each person was off to the side of the axis of the mic body by about 45 degrees, then yes, you would get fairly good pickup on the two people. But it still would not be a great track. Because person "A" would also pick up on mic element "B" but with very reduced high frequencies. (He would be 90 degrees off axis for the other mic element.) You would have poor isolation: each person would be on both tracks. And if you made a continuous mono mix of the two tracks, it would sound dull, because you'd be mixing two versions of each person: one version "flat" and the other person very muddy. The only way to produce a really good finished result would be to edit, cross-fading between mics as the two persons alternated speaking (always using the correct channel for the given person).

And your scenario with three persons on each side of a table... bad. Again, the mic elements are not 180 degrees apart, they are only about 90 degrees apart. So there's nowhere that you could place that mic, that would even begin to get everyone on axis of one element or the other.

Unfortunately, as you learn more about sound, you'll learn that it's not as easy as you initially thought!

Does this make sense? Does the color image of polar response curves help?


PS: What's wrong with taking football action shots with a 4x5 view camera? I've done that. (Oh wait... that was 50 years ago.)

PPS: Can anyone tell me how to get an image up in the middle of the text field, instead of at the very bottom? Thanks!

Re: Using a stereo mic- are they your choice as a sound pro?
 

In further support of Mr. Miller's excellent discourse...
Here are two diagrams of the polar pattern of the AT822. One is the black/white original, and the other shows my crude attempt at highlighting the left cardioid pattern in green, and the right cardioid pattern in red.

As you can see from the arrows I have drawn, the cardioid patterns of the left and right capsules are each 45 degrees off-axis from the body of the microphone. This is a classic stereo microphone design. As we have said before, you actually have TWO cardioid microphones in a single body. Like a two-headed monster.

Re: Using a stereo mic- are they your choice as a sound pro?
 

And to go back to the original question this is why as an sound pro I prefer to use an M/S stereo microphone as the forward facing capsule is always on axis to the sound source!

Re: Using a stereo mic- are they your choice as a sound pro?
 

Guys,

You are truly amazing! But stop! I need to study especially your last few posts. Thanks you so much.

Jonthan

Re: Using a stereo mic- are they your choice as a sound pro?
 

Like Gary, I like M/S - BUT it really isn't suitable for a beginner. Unless you have a recorder with a built in matrix, you can't use headphones for anything other than making sure there are two separate channels live, and even using it in some editors is very tricky, unless you can cobble together a decoder - which isn't hard, but you have to now what you're doing, and able to gang together faders that track together accurately.

Orchestral and choral events are ideal for M/S systems where you really need to make adjustments back in the studio, rather than use a technique and discover the 'hole in the middle' too late!

To a large degree, basic audio is very simple, but more difficult to capture stuff shows where the recordist's weaknesses are. Quite different to camera work where the skill level increases fairly quickly and gradually. Sound often uses almost the same processes each time until you need to use a new one and have to admit your skills are paper thin.

Re: Using a stereo mic- are they your choice as a sound pro?
 

More info here and I personally use the sony M/S ECM-MS957 mics: Recording with the Mid-Side Microphone Configuration | BH inDepth

Re: Using a stereo mic- are they your choice as a sound pro?
 

There's a Sony 979 on ebay at the moment
SONY ECM-979 Broadcast Quality CONDENSER MICROPHONE # 3 + CABLE | eBay

These are quite old now - I had one back in 1994 and they're M/S and have the width control knob, but have a left and right output, NOT M/S, so you get the benefit of the stereo capability and no hole in the middle, but lose the ability to adjust stereo width in the studio. I used one with students and they proved to be pretty tough, and sounded rather good I thought.

I think Gary's is a much newer one - but I haven't used these ones.

Re: Using a stereo mic- are they your choice as a sound pro?
 

The ones I use are the prosumer version and they are very cost effective, I also have the small ECM-MS907 as well. They both output A/B signals so you don;t have to mess around doing any matrixing but I do have an M/S width plug in for my pro tools dubbing set-up so can adjust the width later if required.

That one on e-bay is the pro version and they were used a lot by the BBC on things like wimbledon and last night of the proms if I recall correctly, they also used the ultimate M/S type mic the Calrec soundfield.

The sony's are the only stereo mic's I own and have been used to record countless stereo effects and musical items for broadcast, I have made up XLR cables for the larger one and it sounds fab just on it's own but I normally add some AT875r as spot mics as well.

Re: Using a stereo mic- are they your choice as a sound pro?
 

Gary suggested the ECM-MS957 as a cost-effective M/S mic to me a few years ago on this forum. I've been very happy with it.

Small acoustic ensembles, single point stereo - it's good for that.
Audience ambience in larger rooms - it's good for that, too.

That's all I need a stereo mic for, and it does very well! Thanks Gary!

I too have made up 5-pin XLRF to dual 3-pin XLRM, and have run 100' or so with no problems.