How does diaphragm size/polar pattern relate to mic applications?

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Re: *raises hand*

Kelly Holdridge said:
Ok, I've been going off of John Sayers' approach to drum micing, which includes putting the snare in the middle of the stereo overheads by offsetting the axis of the stereo spread. Here's a picture of what I understand John to be talking about:

Ok. What I'm wondering is why worry about phase cancellation with precise measurements if you can get the diaphragms close enough together in an X-Y config? Is it because of the middle tom (or whatever sits below this offcentered axis) being louder than anything else? Is there a distinct problem with this setup? (the snare and hi-hat both have the same off-axis position to the 57's)
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Well, I think with the john sayers approach he's talking more about spaced pairs, not coincident pairs. With spaced pairs (refering to your picture) you might put one overhead over the drummer's left shoulder and the other one in front of the kit on the side with the crash and high rack tom. That way, both mics will get the snare at approximately the same level so it will be centered when panned and (if you measure the distance to the snare) the snare will be in phase.

Ben
 
Thanks Harvey. Sorry for the delay, been out of town...
So, if the mics are close together above the drummers head, you've got sort of a narrow XY stereo set up, except the mics piont out instead of across? I definitley like the idea getting a little behind the kit.
I used to do XY above the kit, but switched to each side near the drummers sholders when I went to Earth omis. It got me closer to the drums (skins), more isolation from the other instruments and farther from the cymbals. Almost never see the need to close mic the toms. The hat being a little too loud and left seems to be the main disadvantage (but that's usually because he's playing it too loud. :)). In keeping with the mics being equa-distance from the snare, the left mic gets pulled back a bit which also helps.
 
I prefer using wide spaced omnis (Audix TR-40, MXL603S, or Oktava MC012s w/Omni capsules), or cardioids (Shure SM-81 or Oktava MC012s w/Cardioid capsules) for overheads. It gives me a feeling of greater control over the stereo image, but it's all about whatever works for the music.

One last note about drums before we move onto the last section of this whole mess:

I usually stand in the drum room and listen to the drummer and watch him for a while BEFORE I start picking or placing mics. I watch where he hits each piece of the set and try to establish a feeling of where the mics are gonna be out of the way, AND it helps me decide on which mics to use.

If he's heavy on the high hats, I'll position the overhead to pick up more crash, or switch him to a 12" set of high hats to soften them. Heavy on the snare? Pull the snare mic back a little (and maybe angle the kick mic away from the snare side a little more). Light on the snare? I'll move in closer. Lots of tom rolls? I'll double check the sound of the tom mics against the overheads for possible phasing problems. Lot's of light cymbal work? I might move the overheads in a little closer to pick up the delicacy and shimmer.

But really listening and understanding how the drummer approaches the drum set is very important to getting the right sound.

Ready for the next part?

OK, if we're done with drums, we can move on to understanding mic specs (and I promise you that there will be a lot of surprises there). Polar patterns are NOT what they "appear to be", "fudge factors" are major parts of most spec sheets, and microphone frequency response curves are often meaningless, misleading, or worthless, either by accident or by intent.

Stick around - it's about to get real interesting, real quick. :)
 
I just found this string yesterday and dear god it has got to be the most intense well of information I have ever found. I'm only about halfway through it, but I just had to ask something.

Harvey, are you very close to Austin? I would looooooooove to come to and hang out with you for a day or two...or three... or... and learn everything I could from you.
 
I'm about 5 hours north of you, near Denton, TX. You've got Mark McQuilken down there (FMR Audio), inventor of the RNC compressor. He's an untapped goldmine of information.
 
Hi Henry.

I wandered in here after recording my acoustic and finding out it sounds pretty bad. Was going to ask about mic placement in hopes of an answer. That was about three and a half hours ago.
Man, what knowledge your sharing.
You've answered my question, and many more questions I didn't know I had until I began reading this thread.

How's your back today? I noticed a few months/posts ago it was rankin' on ya.
Mine went out a few weeks ago. I can relate to your problem there.

Thanks for all the info you've posted.
 
badgas said:
Hi Harvey.

I wandered in here after recording my acoustic and finding out it sounds pretty bad. Was going to ask about mic placement in hopes of an answer. That was about three and a half hours ago.

Man, what knowledge your sharing.

You've answered my question, and many more questions I didn't know I had until I began reading this thread.

That's why I asked Chris on the first page of this thread if he was "really" sure he wanted to learn all this stuff. A good engineer has to know a lot more than just put up a mic, and hit record. I'm trying to give the people here a quick course in the theory behind the equipment they will be working with. It's taken me a lifetime to learn all this (and I'm STILL learning).

My son Alex is a good engineer with about 10 years plus of experience, but every so often, I hafta laff when he shows me a cool trick he's learned, and it's something I did about 40 years ago. He's not big on theory, so I hafta help him when it comes to radiation patterns, standing waves, or some of the techy stuff, but he's got killer ears - far better than mine ever were, for some things.

I guess this is my way of passing on some of the things I've learned over the years, so it doesn't hafta be rediscovered all over again.


How's your back today? I noticed a few months/posts ago it was rankin' on ya. Mine went out a few weeks ago. I can relate to your problem there.

Thanks for all the info you've posted.
Click to expand...
You're welcome. My sciatic nerve problem diasappeared as quickly as it appeared. After weeks at the back doctor, I took a few leftover Vioxx pills I found laying around here, and the pain went away almost overnight.
 
Microphone specs ("I don't think we're in Kansas anymore, Toto")

I know a lot of you read the specs of mics very carefully to help you make decisions before buying, but that could cause you some serious problems. Here's why:

Let's just look at two manufacturers that are highly acclaimed here; Marshall and Studio Projects. Keep in mind that I think very highly of both these lines, but their web pages show some serious inconsistancies. For example:

If you go to www.mxlmics.com and you want to find out about the 1000 series, you click on it and up comes a nice, very impressive specs page, complete with a frequency response curve that you can click to enlarge. When you move your pointer on top of the frequency response curve, it says it's about to show you "1000b.gif" (the big version of the picture). Now go to the 600 specs page (the 600, not the 603) and look at the frequency response curve. Hmm, looks very similar doesn't it? Let's slide our mouse pointer over it and see where that would take us. When you move your pointer on top of the frequency response curve, it says it's about to show you "1000b.gif" (the big version of the picture). Same damn curve. Is that accurate? Hell no, these two mics sound nothing alike. And that curve doesn't look anything like what either of the mics sound like.

Now let's wander over to the Sound projects page at www.PMIaudio.com. Let's click on the "Specifications" section at the top of the "Studio Projects" page and then let's click on the T3 specs. Curves look interesting, but not exactly what I was expecting, judging from the sound. Let's look at the polar patterns. The upperleft polar pattern is the omni mode obviously, and it's pretty smooth. Let's really study that curve for a minute. Notice the litte variations from perfectly round? Remember those.

Now go back and look at the omni polar pattern for the C3 mic. What's this. According to this these two mics are IDENTICAL in omni mode. Same little variations. So which should you believe? Well let's go look at the C1 for a minute since that's the mic most people are interested in initially. Hmmm, that doesn't look like a cardioid pattern polar response. Wait a minute, I know this curve. I've seen this before - just a minute ago. It's the same omni curve that's being used for the other two microphones.

So are Alan and Brent liars? No, they're not. But the specs sheets are wrong. If you're basing your decision on the specs, you're not getting the right information. I'm not picking on Brent or Alan - most microphone companies don't provide the specs you need to make an honest evaluation of the microphone's performence - and that includes all the big guys too. Speaker manufacturers are just as guilty. I just used Alan and Brent's pages to show you some pretty obvious screwups - some of the other manufacturers' screwups are less obvious ("downright sneaky" would be a better term).

In my next post, I'll get into how they create frequency response curves, different methods of measurements (steady tones, warble tones, white noise, pink noise, 1/3 octave, impulse, etc.), how they control the final results (pen speed, chart speed, smoothed, averaged, etc.), and what the curve REALLY means.

Stick around - it's gonna be fun. You're gonna hear about what manufacturers really DON'T want you to know.
 
...and another voice is added...

I've been visiting the homerecording.com boards for advice on sound cards, keyboards and monitor speakers for a home recording system I've been setting up. Recently, I decided to head over to the microphone forum to ask a question about Shure SM57 vs. SM58 microphones and their uses.

I posted the question, then decided to see what else was on the board. I noticed a thread with 200+ replies and thousands of views. This I had to see. So I clicked on the topic and began reading.

An hour or so later, I took a break from reading and deleted my post.

The information presented here is amazing. I don't even plan on micing instruments in the near future, yet I've scrolled through and read 11 pages of information, questions and discussion, much of it on that very subject. It is, to summarize it in one word, fascinating. The information is of a caliber that, when you ask someone where they learned it, you would expect to hear "music school", "book", or "seminar" (which, in a way, this is), But certainly not "internet discussion board".

Kudos to Harvey, and to everyone else who has contributed to this post so far. Keep it up! :)

(...and, in hindsight, it's a good thing Chris F didn't answer Harvey's original question "do you really wanna know?" with "Yeah, but don't go into too much detail." ;) )

P.S. - Harvey: You seem to be heading towards wrapping up the thread with a discussion of microphone specs, but had you planned to discuss micing pianos in detail? You had mentioned that drums, grand piano and microphone specs were yet to come a few pages back, and piano is an instrument that I am very interested in hearing about.
 
I have question, Harvey.

I blow alot of blues harp. I use Special 20s.
I use a Green Bullet 520DX.
When I play on stage, I run the GB through a small 30watt Marshall amp and mic it into the PA sys.

If you have the time, could you give out some tips on how you'd record a harp? Anything. Just anything.
Thanks.
 
HomeRec, did I miss pianos? I'll get to it before we finish. I know I wrote part of an article for miking upright pianos for Recording magazine.

Badgas, sounds like a typical blues harp rig. I'd just put a mic in front of your amp and take that signal into the board. Possibly a short plate reverb and that's it. Hard to improve on your basic setup.
 
Thanks Harvey.
I've been sitting here drawing diagrams, measuring, making phone calls, driving myself ragged trying to figure a way to record my harp.
Simplicity.
Thanks.
 
Harvey Gerst said:
HomeRec, did I miss pianos?
Click to expand...
I think you fielded a couple of questions about pianos at one point in this thread, but I don't think you've done a section on them yet.
I'll get to it before we finish.
Click to expand...
Excellent. Looking forward to it. :)
I know I wrote part of an article for miking upright pianos for Recording magazine.
Click to expand...
Which issue was the article in? I'm guessing that several participants in this thread (including Chris F) would be interested in picking it up.
 
It was for Electronic Musician, and here's what I wrote:

Pianos and Mics - No Simple Solutions

Just as with most acoustic stringed instruments, the bulk of the sound is produced by the sounding board to which the strings are attached. In guitars and violins, it's the top of the instrument; in pianos, it's the sounding board. You don't mic the picks, the bows, or the hammers - they produce very little sound.

There are several considerations when placing mics for piano recording. Foremost, will the instrument be recorded by itself, or with other instruments playing at the same time? Those two situations require different mic techniques. Is it a grand piano or an upright piano? Each requires different mic techniques. Finally, where will the recording take place? That may also require different mic techniques.

If the purpose of the recording is accuracy, and you're micing a solo concert grand piano, then you'll need some good, small diaphragm condensor mics, placed some distance from the piano, usually around 6 to 8 feet away. You can use an x-y setup for cardioids, or a wider spaced ORTF setup with omnis or cardioids.

The piano lid is used to direct some of the sound towards the mics. IF the piano is part of a group of instruments, you can get better isolation by micing the underside of the instrument, using a sightly wide spacing with omnis or cardioids. Mics placed inside the top of the instrument can also be used, but it's harder to achieve a good balance or isolation since the piano lid will also reflect sounds from the other instruments into the mics.

Large diaphragm mics can also be used, but the response changes as the sound enters from different angles and the larger mics add coloration (which can sometimes add an unexpected richness to the sound).

Upright pianos should be miked from the back of the instrument, but try to avoid having the soundboard too close to a wall. The distance from the wall will create a standing wave which will interfere with the sound. If the piano has to be near a wall, angle the piano so that it doesn't sit parallel to the wall. Be especially attentive to a ringing sound when micing upright pianos.

This ringing is caused by resonances within the piano, and usually can be solved or reduced by moving the mics around till you find a dead area, free of the ringing. Just as with a concert grand, close micing is not advised, but since an upright piano is usually part of a group, it's not possible to mic from a distance and still have isolation.

To sum it up, first choices for recording a piano would be small omni or cardioid condensor mics, but don't be afraid to try large condensors, ribbons, or dynamic mics (if that's all you have). Mic from a distance if possible. Second choice would be under the piano, and finally, from the top of the piano, but watch out for ringing and reflections from that position.
 
Thanks again for a great thread, Harvey. BTW any thoughts on using a couple of PZMs taped to the inside of the lid of a grand piano?

- Wil
 
Wil,

PZMs taped to the the underside of the lid wouldn't exactly be my first choice for miking a grand piano. It might be ok if the piano was being used in a rock setting, but even then, I would probably try some mics under the piano first.
 
Hello Harvey,

I’m a late comer to this post,I just wanted to thank you for all the great info .
I saved them all for later reading.

Sorry to hear about your back,I have the same problem and when it goes out I’m usually out of work a week(construction).

The only things I found that help are stretching my lower back and thighs,and laying on the floor with a rolled up towel and sometimes a big book under my lower back.
Also there is a product called Momentum,hard to find ,only sold in the big chain pharmacies.
Works pretty good.
Well I hope your feelin better soon!

I had a question if you don’t mind,

I read what you said about recording both acoustic guitar and vocals at the same time with three mics.
I own 1 good large diaphragm mic and have tried to do this many times with no success.
I’m looking now for a small mic or mics to accomplish this.

My question(s) is,I record in a small room and am concerned about having the two mics for the guitar within the proximity of the body,will I get to much boominess(is that a word?)

I was looking at either a pair of 012s or a single SM81,because it has a 3 position bass roll off,which I thought might help with this.

How much difference do you think would be between stereo and mono for this type of recording?Most of it is going to be mixed with other instruments later,bass drums ect.

Do you think an 81 is the best way to go for a single mic?

If I go with the 81(or another mic you can recommend ) do you think Shure or other manufactors are consistent enough where I can purchase another one later and use them for a stereo pair?
And if you or anyone else knows,is Octave the only one who sends their seconds to GC or could I run into problems with other mics bought there?

Thanks for any advice.

I noticed you live in Texas,I lived there many years and loved it.

(overheard between the new guy from N.J.and the Sargent from Texas,

"Boy there’s only two kinds of music”,

“Whats that Sarge?”

“Country and Western ”

You know he had a good point.

Thanks,
Pete
 
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