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

Status
Not open for further replies.
Ditto. This thread has been fantastic, and I've learned more from it than I ever could have imagined possible. Thanks in large part to your advice, my recordings now all sound 10 times better than before. Thanks. I'll be waiting with enthusiasm for the conclusion.
I'll add another ditto. :D

-tkr
 
OK, let's finish up stereo mic techniques and move on.

I'm not gonna go thru all the pictures with circles and arrows this ,since most of these techniques are listed in detail with pictures at the DPA Microphone University site at:

Mic University Stere Techniques

But we'll discuss all of the techniques here. We've already covered "coincident" stereo mic techniques (M-S, X/Y, etc.), all of which involve stereo from phase differences between the sound sources. The mic diaphragms are spaces close together, and the angle between the mics is used to control the phase differences.

Near Coincidence Stereo Techniques:
These use time and level differences between the two mics to achieve the stereo effect. The mic diaphragms are spaced at different distances or something is put in between them to approximate the way the human ear hears stereo. The near coincidence methods include:

ORTF (France): A pair of cardioids at 90° (pointed away from each other), spaced 17 cm apart. Looks like this: \ / (except the actual angle is 90°.

DIN (Dutch): A pair of cardioids at 90° (pointed away from each other), spaced 20 cm apart. Looks like this: \ / (except the actual angle is 90°.

NOS (Netherlands): A pair of cardioids at 90° (pointed away from each other), spaced 30 cm apart. Looks like this: \ / (except the actual angle is 90°.

Jecklin: A pair of omnis spaced 36 cm apart, with a disk between them, like this:


.....||
|....||....|
.....||


Binaural: A pair of omnis, usually mounted in an device which approximates the dimensions a human head.

All of these near coincidence techniques depend on time and level differences to get the stereo image. Which you would use depends on the source of the sound you want to capture, the room and equipment you are using, and the accuracy of the stereo image desired.

A-B (Wide-Spaced Stereo Techniques):
A-B techniques all use time and/or level differences to get the stereo effect. For large groups, a third (center) mic is often used. The standard A-B miking uses a pair of omnis spaced about 40 to 60 cm apart, facing the sound source. Cardioid can often be used instead, and a third mic in the center can be added to fill in any hole the wide spacing causes.

Stereo Wrap-Up Thoughts:
The effect of all these different stereo miking techniques will vary, depending on whether playback is for speakers or for phones, and the width of the source being recorded.

Generally, you'll get more accurate stereo effect using the coincidence or near coincidence methods, especially for smaller single instruments or small groups, like a string quartet or bluegrass band.

A-B wide spacing usually works better for loudspeakers and wide sound sources, like choirs, orhestras, and pipe organs. But M-S, Blumlien, Jecklin, and binaural can also work well on large sources.

All these stereo techniques are time-tested tools that work well on a lot of different things. As the person doing the recording, it's important that you understand how they work.

The choice of which to use for a given project is up to you, but now, you at least know all of the techniques that are normally used on a lot of records that you've heard.

Still to come: Drum miking, piano miking, percussion miking, and how to read (and understand) mic specifications.
 
Ribbon Mics

Harvey,
A big part of my interest last few months or so has been in ribbon mics. How are they better/worse, etc. I hear they make great room mics, overheads, and get a huge dirty guitar sound. Maybe its just the Royers. Been wanting to check out the Beyer ribbons and find some comparisons against the Royers.
Peace,
Paul
 
Paul,

Ribbon mics are a wonderfully simple, yet elegant, solution to a number of mic design problems. Using a single strand of superlight corrugated aluminum ribbon, they eliminate a large part of the resonant, transient, and axial difficulties of other microphone designs. They have the disadvantage of being fragile, having very low output, susceptable to hum fields and wind blasts, and the older ribbon mic designs were heavy as hell.

I own four ribbon mics, and I'd sell almost everything else in the studio BEFORE I'd part with them.
 
A few more thoughts about stereo miking.

First, I want to add a few pointers about stereo miking that might help clarify some terms for people that are new to recording.

Coincident Mic Techniques
That's a fancy term for any stereo mic technique where the two matched capsules are as close together as possible and only the phase differences are used to get the stereo image. The advantage to these techniques is that they collapse to mono very well, sound good on speakers, and amazing on headphones.

Near-Coincident Mic Techniques
Another fancy term for any stereo mic technique where two matched cardioid (or omni for some techniques) capsules are wider apart, pointed parallel (or away from each other) and use level differences and time delays to get the stereo image. The different spacings determine the stereo image spead. The advantage to these techniques is that they sound excellent on speakers, and very good on headphones.

Wide Spacing Mic Techniques
A term for any stereo mic technique where the two or more similar cardioid or omni capsules are wide apart, aimed parallel to each other(or angled in) and use level differences and time delays to get the stereo image. The advantage to this technique is that the sound is amazing on speakers, but not very good on headphones.

So which technique should you use for your recording? It depends on what you're recording, and what part it plays in the final recording. If it's an acoustic guitar part for a full rock band, forget about stereo and just use one mic, usually. For a singer/songwriter, try M-S or coincidence recording.

If the recording might get a lot of FM radio play, coincidence recording will give the best mono signal when you get into weak signal areas. String quartets, bluegrass groups, barbersho quartets might work better with near-coincidence mic techniques, while all three techniques might work well for larger groups.

You hafta ask yourself some question when choosing a stereo mic technique; How important is mono?; how much spread do I want; how important is one element in the stereo field (like a soloist in a choir)?

Like everything else in recording, experience comes with time, experimentation, and failures. We learn from our mistakes. And sometimes, our mistakes save our asses. Record, listen, then analyse:

What's missing? Why?
What's too loud? Why?
What's too boomy? Why?
What's too muffled? Why?

If you constantly hafta reach for eq to correct things, it usually means that the mic is:

1. in the wrong place, or
2. the wrong mic for the job.

Any more questions about stereo recording techniques, or does this about cover the subject.
 
Re: A few more thoughts about stereo miking.

Harvey Gerst said:

Any more questions about stereo recording techniques, or does this about cover the subject.

yes! why is it that in classical recordings the mics are very often set up above the orchestra/ensamble, while the audience normaly sits below? wouldn't it be more logical to put them where the listeners ears is?
The other question: how important is mono compatibility nowadays? I mean, how many % of the population (even in 3rd world countries) uses a mono playback device? I haven't seen one since many years.
thank you
Harald
 
Many orchestras DO put two mics in the listener's position, but it often captures too much of the hall's reverberation, so they use spot mics to cover different sections of the orchestra, and then they blend the various sections together during mixdown from a multi-track recorder.

Mono capability is still important in two separate areas - Television, and FM radio. There are still a lot of TVs out there with only one mono capability. And when you get into a lower signal strength area, your FM radio automatically switches to "mono receive" mode.

Now, let's say you recorded your rhythm guitar track on the left channel, and then ran the same track thru a short delay to the right channel - to make the guitar sound bigger (a common home studio technique). It'll sound fine in stereo, but the guitar will DISSAPPEAR COMPLETELY when summed to mono.
 
Harvey Gerst said:
Many orchestras DO put two mics in the listener's position, but it often captures too much of the hall's reverberation, so they use spot mics to cover different sections of the orchestra, and then they blend the various sections together during mixdown from a multi-track recorder.

But have you ever seen a decca tree at listeners position? As far as i know they are usually hung about 2m above the conducters head, aren't they?

Now, let's say you recorded your rhythm guitar track on the left channel, and then ran the same track thru a short delay to the right channel - to make the guitar sound bigger (a common home studio technique). It'll sound fine in stereo, but the guitar will DISSAPPEAR COMPLETELY when summed to mono.

OK, but would you avoid to use a spaced pair of omnis to record an orquestra if you knew that the concert will be transmitted on TV? Or maybe I should ask: Can you achieve satisfactory mono-kompatibility (what a word) with that kind of setup? Or would you prefer a coincident technique, even if the soundstage doesn't translate that well?

Harald
 
Originally posted by h kuhn


But have you ever seen a decca tree at listeners position? As far as I know, they are usually hung about 2m above the conductor's head, aren't they?

Yes, and that's mainly because the listener's position would have too much of the reverberant field present. You must also account for the fact that the end listener will probably be listening to the final product in their own reverberant field (i.e., their living room). The conductor's position would (or should) be the most balanced spot in the hall, since he controls the level of each section of the orchestra.

OK, but would you avoid to use a spaced pair of omnis to record an orchestra if you knew that the concert will be transmitted on TV? Or maybe I should ask: Can you achieve satisfactory mono-kompatibility (what a word) with that kind of setup? Or would you prefer a coincident technique, even if the soundstage doesn't translate that well?

When you hafta get it right quickly, you go the safest possible route, which means a coincident pair, if you're restricted to using two mics and you need a recording in a hurry without a soundcheck beforehand. M-S would allow you to adjust the soundstage in post production, and it would be mono compatible.

The "Making Of 'The Producers' Soundtrack" is going to be on PBS tonight and I'm looking forward to finding out how they recorded it. But, to answer your question, yes, a pair of spaced omnis would probably work fine, but most commercial orchestral recordings are usually made with each section miked.
 
Recording Drums

Drums - the "king" of rock instruments; so many different sounds, so many different textures, so many different sources.

Where do we start? How many mics do you "really" need to record a set of drums? One? Two? Three? Four? Eight? More? And what are the best mics for drums? Ribbons? Condensors? Dynamics? Small mics? Big mics? Where do you put them for best sound?

How big a room is right? What's too small? Is there a such a thing as too big a room? If drums require a big room, why do many major studios use a small drum booth?

If some of these questions sound familiar to you (because you've asked them before), then this next section is for you. I'm gonna dispel some myths, and show you how to get a good drum sound in any room. It's gonna be a big section, but it has to be. It's similar to miking a guitar; classical guitar is different than steel string guitar is different than electric guitar.

We'll cover drum tuning, music styles, mic selection, room considerations, and mic placement - all in detail.
 
*Picks jaw off floor* :eek: :D

Drums are my main instrument so I'm REALLY looking foward to this section. Can't wait.......

Thank you sooooooo much. :)

-tkr
 
Harvey Gerst said:



Yes, and that's mainly because the listener's position would have too much of the reverberant field present. You must also account for the fact that the end listener will probably be listening to the final product in their own reverberant field (i.e., their living room). The conductor's position would (or should) be the most balanced spot in the hall, since he controls the level of each section of the orchestra.


Harvey,
I think I found a different answer (which coincides very well with what you said about radiation patterns): I recorded a violin player last week. The venue was a fairly big theatre, I decided to try xy from about 2m high and 3m away from the player. The acompanying piano (a 6ft steinway, sigh..) had the lid half closed and was directly behind the violinist. The violin sounded great from above and only so and so from aprox 1m height and the same distance, while the steinway sounded better. I guess that the violin is simply radiating upwards/sidewards, very similar to the cymbals of a drum set. And much of the orchestral sound comes from the strings, while they seem to be the weakest part concerning spl, so it makes sense to accentuate them a bit. Are these very stupid ideas or am i on the right track?
Harald
 
Harvey, I recently took some pictures of our kit for just this purpose. I'll upload them and get it posted here to see what you have to comment on them; it's pretty much a dynamic-mic special. I'll get them on tomorrow PROMISE.

Thanks, btw. This is gonna be GREAT!
 
Harald, you're exactly on the right track. Now that you have a good idea about radiation patterns, some different positions open up to you and you begin thinking "outside the box" - a fancy term for avoiding most people's preconceived notions of how something should be done, based on limited experience, or just reading "how-to" books.
 
Drums, Here We Go.

This is gonna be a pretty big addition, so I'll break it up into several sections. Obviously, recording drums depends on a lot of different elements; the actual drums used, the drummer, the room, the style of music, the mics available, mic placement, number of tracks available, stereo or mono, and how important the drums are to the particular song. Let's look at each of the above elements in a little more detail (although I'm gonna go into a "lot of detail" about kick and snare right now):

The Drums
Bad drums will never sound great. The drums hafta be in good shape, tuned correctly, and properly set up.If they sound bad in the room, they'll probably sound bad on tape. A good engineer sometimes has to be a good intrument tech. I've had to tune drums many times, intonate guitars and basses, rewire pickups, etc. Just because the drummer knows how to play drums is no guarantee that he/she can tune them.

Every drum has a natural resonance. You can hear the note by lightly tapping on the side of the drum. That's usually what you tune the top head to, with the bottom head tuned a little lower. There's a range of about 2 or so notes each way from that natural resonant frequency that will work fine, but you need to stay in that range to get the power out of the drum. Drums are usually tuned in fourths, starting with the high tom. If you're not knowledgable about drum tuning, it would be well worth it to have a good drummer come in one time and show you how to tune drums.

I'll get into drum tuning in another post if anybody's interested in that, but right now, just make sure the drums are tuned correctly, and they sound good in the room. We usually use Ambassador coated heads for our drums and they record very well. We avoid the oil-filled heads (too dead-sounding), and we stick with the single ply, coated top heads for everything, with clear heads on the bottom.

The Kick Drum
The kick, along with the snare and electric bass, is usually the backbone of the song - these instruments provide the "groove" and "drive" of most rock music, and they require the greatest attention. For rock, especially metal, the kick also provides another element - the beater "click", needed to hear the speed or complexity of the bass drum patterns.

Most rock drummers have a hole cut in the front head (the head facing the audience), but few drummers understand the hole's function. Most do it for looks, because "all the other drummers do it".

The hole is for mic access to the back drum head (the head being hit by the foot pedal), to let the mic get close enough to pick up more of the beater "click". The hole should be 4 to 6" in diameter, and located above the center line, to make it easy to get the mic (mounted on a short stand and boom arm) inside the drum.

I usually have the drummer loosen and turn the head till the hole is in the upper right quadrant, and I'll bring the mic in, angled toward the floor tom, about 3 to 4" away from where the beater hits the head. Angling the mic towards the floor tom reduces the amount of snare bleed, which will help later on if I need to gate the kick drum.

For drums without the access port, I'll also try miking the kick from the pedal side of the drum. If I need a really "huge" sounding kick, I'll construct a tunnel from a packing blanket off the ported head and add a large condenser or ribbon mic about 3 to 4 feet away (inside the "tunnel"), just to pick up the low end. I've even made a "tunnel" by removing the front head entirely and placing a second kick drum in front of the first (removing the back head from the second kick, and miking the second kick at the hole.

I avoid gating or compressing the kick during the recording stage, but I might do it during the mix. I usually add a few dB of boost between 2 and 4 kHz to emphasize the beater click. I'll crank the boost all the way up, and then sweep till I find the desired click sound, then back off on the boost. For tape based systems, this should be standard procedure, since boosting top end later on will also add hiss.

I'll scoop out a big hole down low, using a parametric, anywhere from 250 to about 800 Hz, eleminating the "boom" frequencies. I don't usually add any low bottom boost during recording, since it's easy to add later during mixdown.

The Mics For Kick Drums
For rock drums, the mic choices are usually: AKG D-112 (older recordings use the AKG D-12E), ElectroVoice RE-20, AudioTechnica ATM-25, Sennheiser 421, Shure Beta 52, and the new Sennheiser 602. These are all dynamic mics, either cardioid or hypercardioid, and pretty large diaphragms. The Shure SM-57 is also used for kick, and will work ok, but not usually as well as the mics listed above.

Mics for use in a kick tunnel or for distant kick miking are usually either large diaphragm condensers (the Neumann U-47fet is the most popular choice), or ribbon mics like the Royer 121, the RCA 44BX, or the Coles 4038 - all high dollar mics. Some good low-cost choices would be the Marshall V67G and the Studio Projects C1.

That should do it for a while. I'll continue the rest of this a little later.
 
I build my kick tunnels out of couch cushions and throw pillows.
For some reason, it gave me an odd idea that I think I might try as a weird effect, with lots of boomy spacy reverb, maybe sample it for use later... turn a 55 gallon drum sideways with the lid off, and put a kick beater to it, with a mic at the end. :)
Maybe a double kick pedal and have the drummer do some wild triple beats and shit on it. :)
If you think thats weird, well... go see the blue man group. Bad ass. www.bluemangroup.com
 
tubedude said:


a 55 gallon drum sideways with the lid off, and put a kick beater to it, with a mic at the end. :)


That's basically the description of a 'Bass Pan', the low frequency instrument in a steel drum band. Of course they tune the top of the drum and play it upright with a sort of rubber mallet.
 
Just a quick note to say, I've been lurking in this particular thread since the day it started, and I find Harvey's input invaluable. I gave a vote of "5 -- Best" for the thread. Wasn't enough to bump the overall rating back up to 5 stars, apparently.

Thanks for all the tremendous hard work you've put into this, Harvey. I'd be thrilled to see you keep it going.
 
Status
Not open for further replies.
Back
Top