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

[Chris F]

I won't bore anybody again with another "best mic for under $200" thread, but I'm curious to find out how you go about deciding which mic to use for which particular application... I understand that large diaphragm mics are often better for vocals, but what about other acoustic instruments? Most of the stuff I've read so far has pointed to small d. condensers for instrument applications, and yet most acoustic bassists I know seem to prefer LD mics in the studio. Is there a reason you would prefer a SD condenser over a LD for piano or double bass?

Also, I've done enough reading to understand (I think) what the different polar patterns are, but how do you make that choice when it comes time to record? Is there a FAQ on this subject that I could read up on, or some links to some other sources to study? Any/all opinions welcome.


Thanks,
Chris Fitzgerald


P.S. - I'm not trying to be a pest...I have actually been scouring the archives for the past few days on this subject, but would like personal opinions as well.

[Harvey Gerst]

Whoa, that's a lot to ask for. Are you sure you really wanna know? That could get pretty lengthy - almost book size. There's some information at http://www.phys.tue.nl/people/etimme...ordingFAQ.html in the FAQ, some good stuff on David Josephson's web site, as well as at Shure and other mic manufacturer's sites, but it would take a long, detailed post here to discuss everything you asked about. Be careful what you wish for....

[Chris F]

Am I sure I wanna know? Umm, yes. Can I digest it all at once? Probably not...but I make about half of my living as a teacher (college music classes), so I'm okay with the idea of slow absorption mixed with a good deal of trial and error. I'll definitely check into the sources you mentioned (I'll get started this evening), and supplement with whatever I can find here and at any other audio sites I can dig up. If you know of any good books on the subject, I'd be happy to order those as well - I give my final exams this week, and then there's gonna be some free time to be had!

Am I sure you want to go into all of that detail to reply to a post on an internet forum from someone you've never heard of? Well, no....and I wouldn't blame you if you didn't want to deal with it. But I'd be glad to listen to anything you might have to say, since I've read most of your posts while researching microphones and you seems to make a good deal of sense - the kind that even a recording newbie like me can understand - almost every time you post. The idea of being able to pick the brain of a professional recording engineer on this subject is too good to pass up, so if you have the notion, do your worst!

I can promise you that it won't fall on deaf ears, and that I have no inclination to start flaming anyone who says something that I don't agree with/didn't want to hear. I'm here to learn, and anything on the topic you might have to offer would be more than I know right now, and as such would also be greatly appreciated.

Thanks,
Chris

[Harvey Gerst]

Originally posted by Chris F
Am I sure I wanna know? Umm, yes.
Am I sure you want to go into all of that detail to reply to a post on an internet forum from someone you've never heard of? Well, no....and I wouldn't blame you if you didn't want to deal with it. But I'd be glad to listen to anything you might have to say, so if you have the notion, do your worst!
Thanks,
Chris

Ok, you're on. At 64, maybe the best thing I can do with my life is to pass on what I've learned from great people that taught me when I was starting out. I think that's why Al Schmitt, George Massenburg, Ed Cherney, and some of the other really big guns spend so much time on the net. We all owe the guys that came before us a lot, and this is our way of paying them back. And that's the only thing I have in common with all those guys I just mentioned - we all kinda drank from the same well back in the 50s and 60s.

I've got a band in the studio right now that's taking up most of my time till Wednesday, but after that I'm pretty free. I'll start off with some basic concepts till we're all up to speed, and then I'll try to fill in some holes.

I'll try to cover as much ground as I can, to give everybody a good basic understanding of the different mic designs, advantages and disadvantages of each design, how mic polar patterns are created, advantages and disadvantages of each polar pattern, and finally where each type might be used, along with advantages and disadvantages of each usage. How's that for a course outline?

[ametth]

I'm definetly looking forward to this!! There's alwasy something new to learn. Thanks Harvey.

[Harvey Gerst]

Originally posted by ametth
I'm definetly looking forward to this!! There's alwasy something new to learn. Thanks Harvey.

OK, now I have a question:

Is there an easy way to put images into a posting other than as an attachment? I'm thinking some hand drawn thingys (with circles and arrows) might be easier to follow than a jillion words.

[ametth]

I would be glad to host some pictures on my server. Email me.

[Harvey Gerst]

Originally posted by ametth
I would be glad to host some pictures on my server. Email me.

Putting them on my server is no problem. I was hoping I could actually show the pics in the body of the post so you could read the text while you looked at the pictures. Lemme see if this works:



This is the frequency response curve of a Neumann TLM-103. Not very flat, is it? Does that mean it's a bad mic? Before we can answer that we hafta know how to read one of these curves and how to interprete it.

[Harvey Gerst]

Ok, that didn't work. I'm open to suggestions at this point. Is it possible to directly show that picture in the body of my post?

[Chris F]

Originally posted by Harvey Gerst
Ok, that didn't work. I'm open to suggestions at this point. Is it possible to directly show that picture in the body of my post?

I can't help on that too much, being a music theory geek/cyber dummy, but on another forum I frequent for acoustic bass (which has exactly the same format as this one, BTW) people do it all the time. I'll email one of the guys who posts that way a lot and see if he can give me some clues. If he can, then I'll forward it to you, since I think both forums are running from the same software.

I'm looking forward to this. Thanks.

[ametth]

I think IMG code is off for this forum. I would just put links Harvey, this bbs open links up in a different window anyway, so I don think it will be a big problem.

[Chris F]

Testing...check....

www.talkbass.com

Well, at least the links are working...

[Gidge]

This is gonna be frickin amazing....Thanks Harvey.....

[pglewis]

Don't sweat the images, Harvey. Dragon or R.E. should be able to fix it. It the interim, I'm perfectly capable of copy and paste and watching this thread like a hawk.

[oh shit, now I'm a "genius" *LOL*. Never knew it was so easy]

[Harvey Gerst]

Originally posted by pglewis
Don't sweat the images, Harvey. Dragon or R.E. should be able to fix it. It the interim, I'm perfectly capable of copy and paste and watching this thread like a hawk.

[oh shit, now I'm a "genius" *LOL*. Never knew it was so easy]

LOL I suppose we could simply open two browsers at the same time and use the top half of the screen for the browser showing the image, and use the bottom browser to scroll the text from here.

[Chris F]

Harvey,

I just printed the recaudiopro FAQ, and it weighs in at 49 pages, even after I opend it as a Word document and made the font smaller. JELLYCOVERED HORNBLOWIN MOTHERLOVIN CHRISTMASTREEOFDOOM!!!! Now THAT'S a FAQ!

Uh, see you guys later, I'm gonna be a little busy for a while (heads for the WC, large stack of paper in hand)....I might be a little thinner the next time you see me.

[Harvey Gerst]

Go to: http://www.neumann.com/infopool/down...i=docu0002.PDF and download this pdf file. Don't worry if you don't understand the math. Just get out of it what you can.

[vox]

Hey Harvey, You Da Man!

[Tekker]

That's some good stuff there Harvey, but do you know if there is a way to convert it so that it can be opened up in word? I like to be able to highlight and underline stuff as I'm reading.

Thanx again and we all REALLY appriciate what you're doing here!!



-tkr

[Chris F]

Originally posted by Harvey Gerst
Go to: http://www.neumann.com/infopool/down...i=docu0002.PDF and download this pdf file. Don't worry if you don't understand the math. Just get out of it what you can.

Done. It's sitting beside the computer, 3-hole punched in a binder. And I hope you weren't kidding with the "don't worry about the math" part, because I can't say as I do understand the math at all. But the part about the shapes and ranges of the different polar patterns is clear enough.

Fire when ready.

[Harvey Gerst]

Okay, let's start this with some interesting history as a prelude to the whole mic discussion. "Why" will become pretty clear by the third or fourth paragraph:

In a way, the history of microphones and sound all started with Alexander Graham Bell, and Western Union. After Bell won the lawsuit with Western Union over the invention of the telephone, his fledgling AT&T company needed somebody to manufacture phones for them. Western Union had created a manufacturing division (Western Electric) to make telegraph keys and telegraph equipment. Bell bought the Western Electric division and they had the exclusive right to manufacture phones for Bell.

By 1910, Western Electric had the ambitious task of creating a coast to coast telephone hookup to tie in with the opening of the Panama Canal, but the problem of amplifying a signal over long distances was still unsolved. In 1913, Dr. Harold Arnold (of Western Electric's research group) saw that Dr. Lee DeForest's "Audion vacuum tube" was the possible solution, and they bought the rights to it and began work on a "high vacuum" tube.

This indeed solved their long distance problem, and led to another discovery - a "loud-speaking telephone". In 1916, they received a patent for what we now call a "loudspeaker". With the addition of the "high vacuum" amplifying tube, and another little patent for a device called a "condenser mic", they were suddenly in the P.A. business as well.

These inventions opened the door for radio, talking movies, and sound systems in general, and with their other patent for a high quality "amplifier" in 1916, they pretty much defined the science of sound. (It would be another 12 years (1928) untill a young Georg Neumann would start his own mic company in Germany. That same year, Western Electric received a patent for a "dynamic mic" design.

The designs Western Electric developed for movie speakers would eventually start companies like Altec and JBL making horns and loudspeakers for Western Electric, and eventually those Western Electric designs became the foundation for their own speaker lines.

Western Electric created their own Research and Development arm called "Bell Laboratories", which went on to create the transistor and a host of audio related products. It was Western Electric and Bell Laboratories who we must thank for the development and research into microphone design that we enjoy today.

Next, we'll look at some of the different types of microphone designs in terms of advantages and disadvantages. How a "dynamic" mic really works will definitely surprise you (hint: it's NOT just a small speaker in reverse).

[micmac]

Originally posted by Tekker
That's some good stuff there Harvey, but do you know if there is a way to convert it so that it can be opened up in word? I like to be able to highlight and underline stuff as I'm reading.

I don't know how to convert PDF's into Word documents, but there's a Text Select Tool on the tool bar in Acrobat Reader. You can copy text into Word with that. Of course, the pics would still be a problem... hmm, maybe not such a great idea after all...

Harvey, i want to say thank you for spending all this time sharing your knowledge: Thank you! Your posts are very much appreciated on this side of the Pacific Ocean!

micmac

[Chris F]

Originally posted by micmac

Harvey, i want to say thank you for spending all this time sharing your knowledge: Thank you! Your posts are very much appreciated on this side of the Pacific Ocean!

I'll go ahead and speak for the Ohio Valley while seconding that sentiment. I'm with you so far...

[Harvey Gerst]

By far, the most popular mic on the market today is the dynamic cardioid mic, so that's as good a place as any to start. "How does it work, what exactly is a cardioid, and how and where would you use it" will be our focus today. Let's look inside one and see what we find:

Well, it has a cone (like a small speaker), a voice coil (like a small speaker), and it sits in a magnetic gap (like a small speaker), so isn't it just a small speaker in reverse? Yes, and no. The operating principle is the same, but the execution is very different. When's the last time you saw a 3/4" speaker that went down to 30 or 40 Hz? Here's how it's done:

The system resonance is chosen for a mid band frequency. By itself, the capsule's response looks something like this:

......./\
....../..\
...../....\
..../......\
.../........\
../..........\
./............\ - just one big resonant peak, with the response falling off rapidly on each side of the peak. Now you can tame that peak by putting in a resonant chamber that's tuned to that peak, which will give you two smaller peaks on either side, like this:

..../\..../\
.../..\../..\
../....\/....\ And if you add two more resonant chambers, tuned for each or those peaks, you wind up looking more like this:

./\../\../\../\
/..\/..\/..\/..\ And if you make the chambers a little more broad band, the response starts to really flatten out:
._..._.._..._
/..\/..\/..\/..\ but remember, it's still a lot like a bunch of tuned coca cola bottles inside there.

Now ya gotta do all of this stuff JUST to get the response usable - never mind about the mic pattern yet!

A lot more to come!! Everybody still with me at this point? Any questions?

[Harvey Gerst]

Ok, so where are we at, gang? Is this too easy, too hard, just right? More than you need to know? Too basic? Too difficult? Gimme some feedback so I can tailor this thing to what you really want to know.

To quote a well-known, musical masterpiece, "Tell me what you want, what you really, really, want".