Here's the info I wish was all in one place I began my quest for better audio. I periodically revise it for clarity and accuracy. Comments and corrections welcome.

Do I need an external microphone?
If you care about audio quality, yes. Although excellent video capability comes with all modern camcorders, good audio requires extra effort and investment.

Is that because all built in camcorder mics are "crap" as I have read?
Not exactly. When the sound you want to record fills the space around you, such as at an informal indoor or outdoor gathering, or an indoor concert (if it isn't too loud) the built in mic is often acceptable. By acceptable I mean that the audio will sound appropriate for the video footage and will not distract the viewer. It may even sound good to many ears.

But all built in microphones will give crappy audio in many circumstances. "Crappy" audio distracts the viewer from the video. It includes distant-sounding thin voices, unwanted background sounds, room echoes, and sometimes camcorder motor noise. The echo recorded during a kid's play in an auditorium or gym can be so bad that you have trouble hearing the words

Why would a good built in mic often give poor audio quality?
(1) because distance from the audio source matters tremendously, and the built in mic is forced to be at the same distance as the camcorder.
(2) because the built in mic is almost always a stereo mic, and stereo is not always the best choice. Sometimes you want the audio to concentrate more on what's in front of the camera and less on the surroundings.

Will one external microphone solve these problems?
No. You can start with one mic that will give much better sound than the built-in one in most situations, but the more you care the more you will invest in microphones and accessories over time. That's because you'll learn more about handling the challenges offered by different settings and subjects.

Then what should be my first microphone?
For tight budgets, one choice might be a better quality stereo mic like the Sony ECM-907 or ECM-908C in the $60-70 range. They will provide noticeably better fidelity and directionality even when camera mounted, but for dramatic improvement you have to get them closer to the subject using a cable. And they will still give a spacious (as opposed to intimate) sound, with ample pickup of surrounding background.

So a mono external mic, which is more different from the built in one, is usually the most logical addition. The most common choice is a "shotgun" (highly focused) mic like the $60 Audio Technica ATR55 (again, a decent mic for tight budgets) or the much better worth-every-penny $120 Rode VideoMic. Both of these are battery powered and will plug right into a cam's external mic jack. Another excellent and very popular choice is the $270 Audio Technica AT897, a battery powered XLR mic. Even when camera mounted, any of these, especially the latter two, will give dramatically better results for capturing the voice of a person in front of the camera than any stereo mic. As always, closer is better.

What is an XLR mic?
A microphone with an XLR connector at the end, designed to use XLR cable. Some are battery powered, but many require "phantom power" (described below). XLR mics tend to be higher quality mics and cost from several hundred to several thousand dollars (but the Rode VideoMic mentioned above is an exceptionally good non-XLR mic considered by some, including yours truly, to sound as good as the AT897). To use an XLR mic with a consumer camcorder's 1/8" mic jack requires a an adapter. This can be a simple cable, or a box with added features.

What is "phantom power?"
Some XLR mics can be battery powered. But many XLR microphones, and almost all of the high end ones, require that power (10-48 volts) be supplied to them over the same XLR cable that carries the audio signal. This is called phantom power. Many audio mixers, some wireless mic transmitters, and some camcorder XLR adapter boxes can provide phantom power. Standalone phantom power supplies are available also, in the $40 range.

What is XLR?
The term "XLR" comes from XLR audio cable. 3-pin XLR cable (the most common) is cable containing two inner conductor wires (L and R) surrounded by a conductive shield (X), all inside an outer vinyl covering. It's used with rugged snap-lock XLR connectors at the ends, each having three male or three female electrical contacts. The shield is usually grounded via the equipment it is connected to. Professional and semiprofessional audio equipment like mixer consoles, higher quality microphones, effects processors and, of course, camcorder XLR adapters (discussed below) are equipped with XLR connectors in order to use this cable.

Why?
Because it can transport sound signals over long distances (often up to 200 feet or more) cleanly and reliably. It was devised for sound studios, theaters and outdoor professional shoots where induced electrical noise and flimsy connectors cannot be tolerated.

Is XLR cable for stereo, or mono?
3-pin XLR cable is most often used as "balanced cable" to carry a mono signal. It can carry a stereo signal (hence the "L" and "R") but not in balanced mode. It takes two 3-pin cables or a single 5-pin cable to carry a balanced stereo signal.

What is balanced cable?
The audio term "balanced" means that a signal voltage is applied between two conductors that are both isolated from ground by the same electrical resistance. In XLR cable both inner wires are isolated from the shield (ground) by infinite resistance. Balanced cable helps eliminate electrical noise induced from the environment.

Then what is unbalanced cable?
Basically, cable that uses the outer shield (again, usually grounded) as one of the audio signal conductors.

How can I tell which is which?
A balanced mono cable must have three electrical contacts on both of its connectors. Usually it's 3-pin XLR connectors. But they can also be TRS (Tip, Ring and Sleeve) plugs like the ones used on headphones.

If a cable has any type of connector at either end that has only two electrical contacts, it is unbalanced. Examples are RCA connectors (the red and white ones on the cables that connect audio from a DVD player to a TV), coaxial cable connectors for cable TV, and any two-section plugs.

[Note: For special purposes, even cables with three-contact connectors at both ends can be internally wired to be unbalanced. Two conductors could be wired to one contact, and/or vice-versa.]

Should I use XLR cable?
Depending on how electrically noisy the environment is, you can usually use unbalanced cable for runs of up to 15-30 feet. Professional opinions on the maximum vary because peoples' personal experience in various environments vary. But longer runs become antennas that pick up electrical noise, and XLR cable should be used.

What is an XLR adapter and what does it do?
It is a small box with electronics on the inside, and connectors on the outside, normally two female XLR connectors for the inputs, and a short output cable with a 1/8" stereo plug that plugs into your camcorder's microphone jack. Not only does it allow you to connect an XLR microphone or (other XLR device), it allows you to connect two!

Why would I want more than one input?
You might want to use two mics placed to get good coverage of all the sounds going on in a room or at an event, or you might want a stand-mounted mic for general room coverage and a wireless lavaliere ("lapel") mic on a particular person, or maybe you would want to place a mic somewhere and also take an input from a sound mixer board. The two signals can be fed separately to the left and right channels of your camcorder, or mixed and fed to both.

Why would I want to keep the signals separate?
So that you can retain control on how they are mixed until you edit your footage on a computer later. You might want one louder, you might want to increase the bass in one, or you very well might want to eliminate a noise that's in one but not the other, etc.

Where does an XLR adapter go--does it "dangle" from my camera?
No, they are designed to either mount sandwiched between the camcorder and the tripod, or to clip to your belt.

What are the different types of XLR adapters?
(1) A simple short cable internally wired to connect one XLR mic to a non-XLR input like a camcorder's mic jack. They cost $10.
(2) A basic adapter box has two XLR inputs, each typically switchable for mic level or line level input voltage, and with a control knob for reducing the input voltage. Often there is a mono/stereo switch to mix or separate the signals, and a mini jack input that can be used in lieu of one of the XLRs. This adapter does not require any power or battery. About $150.
(3) For another $50-100, the next level of adapter does the above, and adds phantom power capability. It takes a standard 9 Volt alkaline battery and can send 48 volts or so through either or both XLR connections. A battery is typically good for about 4 hours of use.
(4) More advanced adapters may add preamplifiers in case the mics have weak signals, and/or limiters that automatically prevent "clipping," which is scratchy sounding distortion from a signal that's too strong. But at this level of sophistication you should probably be looking at an actual field mixer instead.

The major players in the XLR adapter market are Beachtek.com, Signvideo.com and studio1productions.com

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Fred

Thank you very much for the information. You have cleared the fog. I'm doing mostly sports videography with my GL2 but am also doing weddings and corporate videos. I'm new to videography but i'm getting busy fast. I'm discovering sound is crucial and i'm tired of renting lav mics. Is Canon's M-300 as good as the beachtek dxa-4p? As for mics how about the azden sgm-2x? I would like to buy asap. I just don't want to get the wrong stuff.
Thanks again for the info...

For the about the same money I think the DXA-4p is a better deal than the MA-300 for the GL2 camcorder. The MA-300 doesn't have gain control knobs, and the XLR connectors are not swithchable between line level and mic level.

But the MA-300 does have a built in shock mount for a shotgun mic. You might want to go to the GL2 message board and ask "Toogy" why he chose the MA-300 and if he's happy with it. He's a good guy who posts frequently. He also tried either the SGM-1X or 2X, I forget which, and didn't like it. He now uses the very popular Sennheiser ME66. I opted for an Audio Technica AT897.

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Fred

hey man good post, I'd like to add some info if thats cool:


“Where did XLR come from?”

so ITT/CANNON (not canon) developed this audio connector type (XLR) that had an integrated push button locking sytem. The plug type (same size, same push button lock) is produced in not only 3 connector “mic cable”, but 4-pin, 5-pin, up to 7-pin XLR is available.

Obviously the XLR connector type has had a wide range of applications and I believe (although I might be wrong) that the name XLR comes from the stereo pin-out of a 3-pin plug : pin 1- common (X) pin 2- Left (L) pin 3 – Right (R)

“So XLR is stereo?”

No no no. XLR isn’t stereo. And XLR isn’t mono. It’s just the name of that type of plug. You can wire a desk lamp to your wall outlet via XLR plugs if you use the right cable… I mean.. it might melt the plug, but you get my point- the plug does not dictate the signal going through it.


“Ok.. so can an XLR plug conduct a stereo sound signal?”

Yes. It can and sometimes does. Anyone whose ever owned a pair a headphones knows that you can get two discrete audio signals from 3 conductors. The problem is, the signal won’t be balanced. A cable with three conductors (like a mic cable) can only carry one balanced audio signal.

“Balanced?? What??”

Like Fred said, don’t worry about it unless you’re running a mic cable longer than 10 feet. The simple answer is two conductors means you have sound, 3 conductors protects it from getting noise over long distances. I urge you all to read up on balanced audio signals, but some of you won’t need to.

“So I should call it a 3-pin XLR cable?”

although 3-pin XLR cables can carry line (and even speaker) level signals, they are generally referred to as "mic cables." In the audio world, a 3-pin XLR cable is a microphone cable and a microphone cable is almost always 3-pin XLR. The only time you need to specify that you want 3-pin XLR is when you’re buying cable adaptors. The only time “mic cable” is unacceptable is when it’s either not used for audio at all (lighting control, etc.). So please don’t waste people’s time- just say mic cable and they’ll know what you mean.
it’s important to remember that although we call almost all cables by their plug type, simply saying 3-pin XLR doesn’t tell us anything more than what the ends look like and nothing about the cable between them. Nowadays, Mic or XLR generally means a standard mic cable (two insulated wires wrapped in a spiral surrounded by insulation, a metal conductive shield and a rubber outer insulation all of which is rated for a mic level application), but there were and still are devices that use 3 pin XLR for any 3 conductor application (speakers, line level signals, digital lighting control, intercom systems, my melting desk lamp and more). So it is important to know that there are 3-pin XLR cables out there that are not intended for microphones and might have undesirable wire gauges. This shouldn’t be a problem if you ask for a mic cable.

“Why are some cables more expensive than others?”

you can pay anywhere from about $10 to $100 for 20 feet of mic cable. Differences obviously lie in the workmanship:
Strain relief : inside every XLR plug, there is a strain relief of some sort. Basically, the plug is engineered to keep strain off of the soldered connections between the wire and the pins when you yank on the cable. You pay more for better strain relief
Sheild : the shield or ground conductor can be engineered in different ways and of different materials to better protect long cable runs from noise
Gold connectors: yeah they cost more, I think they’re crap. but some people think that I’m crap for thinking that they’re crap.. eh.. its your money.
Cable guarantees/ handmade cables: some manufacturers are so confident in their products that they’ll guarantee against poor workmanship for 1 or 2 years. Some companies make hand soldered cables and will guarantee the cable against defects for life.
Most of these premiums are sought after by audio professionals for cables longer than 20 feet that must endure daily abuse. I think a gentle filmmaker should pay at least $20 but no more than $50 for 20 feet of cable. Whirlwind is a great cable company if you can afford it. www.whirlwindusa.com

“Do I need phantom power?”

That’s a question of what kind of microphone you’re using most likely, you’ll probably want a condenser mic, which means yes. (fred did a great job outlining your options)



Addition to “Balanced lines”: the term balanced does stem from the fact that noise penetrating the shield will be induced on both conductors, but it should be noted that the noise is cancelled due to the twisting of the inner conductors. The constant spiraling insures that any charge affecting the cable directs both conductors equally. This is yet another reason to coil your cables properly, to insure against untwisting the conductors.

Nice addition, calacain.

I especially appreciate the correction of a careless statement I made about the XLR cable only being able to carry a mono signal. I should have said that it can only carry a mono signal if it is going to operate as a balanced cable (you can't balance a left stereo signal with a right stereo signal--they're different from each other).

And what you add about the twisting of the conductors is correct. But for people who like strict definitions I'd like to emphasize that the term "balanced" comes from the fact that the signals in the two conductors are equal in amplitude and opposite in polarity. Such conductors would be balanced even if they were two feet apart. However, balance won't lead to much noise cancellation unless we make sure that it is hard for outside interference to attack just one wire and not the other, and twisting ensures that.

By the way, twisting any wire pair that carries current in opposite directions also helps to keep them from *generating* interference.

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Fred

Thanks for the post. Now I feel a little more educated on the subject. This is my first time posting. So please forgive if I have broken any of your posting etiquettes.

I am a student in the multimedia and design field. I have a GL2, and I would like to purchase a pair of wireless lav mics for future projects. There are so many on the market to choose from with a wide range of pricing it is so confusing on which one to buy.

Can anyone suggest a good brand and model without breaking the bank? Ideally I would like to spend between $125 to $150. I am also interested in getting a shotgun mic if anyone has suggestions there I would really appriciate it.

Thanks!

Pono

X = Ground (earth, ground, neutral)
L = Live (the strand that carries the signal relative to X)
R = Return (the strand that helps cancel out any noise on the line)

To convert XLR to a microphone jack:
Connect X and R together ---> Ground on mic jack
L ---> tip of mic jack (or the L and R signals on the mic jack, if stereo)

Worley

I hae a question. I'm looking at the Rode VXLR as a possible way to use my XLR cable with the Rode VM I just ordered. To adapt back to a minijack connection I have a XLR to minijack cable adapter that came with my Nady CM-2S.

According to the info on the Rode VXLR the tip and ring of the 3.5mm are combined to the #2 pin of the xlr. I'm not getting exactly what they mean here. Will this adapter result in the signal from the Rode VM coming through like a balanced mono signal? And if so will my XLR to minijack adapter provide a mono signal to my camera? Will I have a single channel (I assume the left channel) of sound getting to my camera?

The adapter looks like a good way to avoid the need to use a 1/8 cable that isn't going to be shielded as well as an XLR cable. I'm hoping this will work for me. Would I be better off buying the Rode extension cable? My main problem with it is that it's only 10 feet long.

Any help anyone could give me would be appreciated.

King, you'll get a mono signal applied to both channels, but that will be an unbalanced run, subject to interference like a two wire run.

The RVM applies the same signal in a parallel fashion between its tip and sleeve and between its ring and sleeve. So when that adapter takes the tip and and ring voltage and applies it to pin 2 of the XLR that's fine. Although it doesn say so, the adapter connects the sleeve of the RVM mini plug to both pins 1 and 3. So 1 and 3 are both grounded.

Your adapter at the camera end will do the reverse, applying the pin 2 voltage to tip and ring, with its sleeve connected to 1 and 3.

A balanced run requires that the signal be applied between 2 and 3 with 1 grounded. The only way to connect an unbalanced output like the RVM to an unbalanced input with a balanced XLR run is to use transformer adapters at both ends. Like two of these:
http://www.bhphotovideo.com/bnh/con...oughType=search
At the RVM end you'd use a female/female stereo mini coupler.

Fred

Thanks fretread. I knew it wouldn't be a balanced signal but the better shielding of an XLR seems to allow a lot less interference or at least it has worked that way with my cables. If I try to use a long 1/8 cable I get interference every time with my Nady mic. But I bought an XLR cable and it is completely quiet even though the Nady is a stereo mic which of course means it isn't balanced either.

I went ahead and ordered the adapter so I guess I'll see if I get less interference using it with my XLR cables. I thought about ordering the cable Rode sells but it isn't really long enough to suit my needs.

If you are going to use XLR connections, then I would suggest that you use Canare cable. I've used it for many, many years because not only is it very well made, but it is very flexible and not too heavy. Cables I used prior to finding out about the Canare were a hassle to use in on location (audio) recording (which is what I do) because they were stiff and also could not handle the frequent winding and unwinding that occurred. On top of everything, the Canare cables are reasonably priced.

One place where is can get Canare cable assemblies is Have Inc. The link is

http://store.haveinc.com/Ebus30/Par...rrentPartPage=2

Bob
http://www.dtrmusic.com