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- What
microphone should I use with my minidisc? - Which
Pick-up pattern? - Dynamic
or Condenser? - Handheld
or Lavalier? - Mono
or Stereo? - Why
Can’t I Get Enough Volume Fom My Mic? - What’s
plug-in-power, and is
it creating noise on my mic? - Do
I need one cable or two for stereo audio?
What microphone should
I use with my minidisc?
There is no one answer
for everyone. For more details, check out the transom tools What
Microphone Do I Get? column, but the main decisions are these: omni or directional,
dynamic or condenser, handheld or lavalier, mono
or stereo? There are a few additional challenges when using a small
consumer minidisc recorder, as the mic input is a high-impedence 1/8 ”
mini connector, while most pro microphones are low-impedence with XLR connectors.
Get a high-quality converter cable, wired for this purpose, with an 1/8 ”
mono connector on the minidisc end if you are using a single mono microphone.
It may be worthwhile to get a cable that adapts from XLR to mini and also
adjusts the impedence and shunts the plug-in power. The Shure A96F
does all of these things.
Omnidirectional
mics pick-up sound from all directions equally, while directional mics pick-up
best in a limited zone, usually in front of where you aim the mic. An omni
mic is more forgiving of imperfect placement, and will sound more natural
if the source is not directly in front of the mic. Omnis are also less succeptible
to handling noise, wind and p-pops.
Directional mics
give a tighter, more focused sound, and will record less of the surrounding
ambience, which can be good or bad depending on your intent. There are degrees
of directionality, from the cardioid, a fairly wide pattern that is
very practical for close-up interviews, to the shotgun, which has a
very narrow angle of sensitivity, best suited for more distant applications.
In-between are hypercardioids and short-shotguns. As directionality
increases, handling, wind and breath noise become more of a problem, and off-axis
sounds seem increasingly unnatural.
For field recording and
ENG (electronic news gathering) the most popular omni mics are the
and the Beyer M-58.
The most-used cardioid mic is the Shure
SM-58. Shotgun mics by Audio Technica and Sennheiser are frequent choices.
Dynamic mics are more
durable, can handle higher sound pressure levels, and require no additional
power. Condenser mics have a louder output and can pick-up more subtle details,
but require phantom power. That power can be provided by some recorders, a
mixer, an external device, or sometimes an internal battery. Many of the small
consumer minidiscs have something called “plug-in power ” which is
similar to phantom power, but cannot power professional mics. It provides
power for electret mics designed to be used with these recorders.
In most cases you will
get better sound quality with a handheld microphone. Lavaliers are not placed
in an ideal position and often pick up clothes-rustle. But there are circumstances,
such as an intimate conversation where an obvious mic would interfere with
the feel of the interview, or a subject moving in such a way that keeping
him or her “on-mic ” would be impossible, where a lav can save the
day. But with the up-close feel of current radio styles, lavs can often sound
distant or muddy.
Stereo sound can add a
lot to the vividness of your location recordings, but can be quite distracting
during interviews. So you may want a stereo mic for ambience and demos and
a mono mic for interviews. See the transom stereotypes column for details
on techniques and two-mic arrays. The inexpensive stereo mics that are sold
to go with consumer minidisc recorders can get decent sound, and may be more
than sufficient to get some backgrounds for your piece, but they are not particularly
durable, often made of plastic, and have limited bandwidth, reducing high-frequency
detail. Better choices are the relatively inexpensive AudioTechnica [Discontinued], the Rode NT4, or the Sure
822
VP-88.
Why
Can’t I Get Enough Volume From My Mic?
Some users have reported
problems getting enough level into their minidisc recorders or small DAT recorders.
Make sure you are manually setting the record level, the automatic gain control
rarely sounds good. Many of the little Sony minidiscs have the irritating
feature of only allowing level adjustments while the deck is in pause, so
you have to pick a level and stick with it. If you have the record input level
turned up all the way (this adjustment may be a few levels down in menus,
it is NOT the volume + and – on the top of the deck: that’s the headphone
volume) and you still aren’t getting enough level, you have a few options.
Make sure you have a good quality cable, not a pieced-together series of adapters
and mis-matched connectors. If you’re using a dynamic mic, you may want to
try a condenser instead, they almost always have a louder output. Condenser
mics require phantom power, so be sure to pick one that can use an internal
battery, unless you have an external source. A consumer minidisc recorder’s
“plug-in power ” will not power a pro mic. Another volume-increasing
tactic is to use an impedance transformer. The 1/8 ” connectors on small
minidisc machines are high impedence, while pro mics with XLR connectors are
almost always low impedance. You actually don’t want the impedences to match
exactly, but raising the impedance a bit can give you a few more dB of volume.
A cable like the
things: convert your XLR to a mini and raise the impedance enough to give
a bit more volume.
What’s
plug-in-power, and is it creating noise on my mic?
Plug-in-power is a small
voltage delivered from the recorder to certain electret microphones, it’s
similar to phantom power, but the two are not interchangeable. You can’t
power a standard condenser mic with plug-in-power, nor can you run a plug-in-power
mic from the standard phantom power often delivered by pro recorders or mixers.
So the deal is that if
you buy a small consumer level mic, some of which are pretty good, like the
Sony stereo mics, or the discontinued little Radio Shack lavaliers, you can
plug them straight into your minidisc and they’ll get the required power from
the deck. Otherwise you’d need to use an adapter with a battery.
If you want to use a dynamic
mic, such as the EV RE50, or the Beyer M-58, don’t worry about the plug-in
power, you can ignore it, although the Shure a96f will give you better volume,
convert the connector types and shunt the plug-in-power .
If you use a pro condenser
mic that needs phantom power, you’ll need to get one that can use an internal
battery, or get an external phantom power supply, the plug-in-power will NOT
power a pro condenser mic.
There have been occasional
reports about “plug-in power” (a small voltage carried on the mic cable, provided
by many consumer minidiscs and DAT machines that can supply a needed charge
to some electret microphones) creating clicks or noise when using a dynamic
microphone. I’ve never found the plug-in power to create any problem,
dynamic mics generally don’t react to it. If you get hiss from your mic, it’s
most likely just from the relatively weak preamps that were designed to work
with high-impedance electret mics that do make use of the plug-in power. Crackles
are more likely due to a bad cable or dirty or worn jacks.
So, as we’ve discussed
a few times on this site, the Shure a96f will raise the impedance a
bit, which will give some more gain, it also shunts-off plug-in power if you’re
concerned about it, and it’s a nice simple XLR-to-mini cable with the transformer
built-into the XLR jack, so it’s not a kludgey pile of connectors.
I have
one mic, am I recording in stereo?
It depends on your mic
and cable. Most conventional interview mics are mono, in that they only produce
one channel of sound. Often one connects a cable from that mic to the recorder
that is wired to send that same signal to both the left and right channels
of the tape or disc. This is often preferable to only hearing the microphone
in one ear while monitoring the recording, but it doesn’t make it “stereo,”
there’s just an exact copy of the signal on both channels. It’s easy enough
to record just one channel and pan it to the center during your mix, or copy
one signal to both left and right if that’s easier. In fact, when transferring
audio to the computer, it will save disc space to only record one channel
onto your hard disc if the sound is not stereo.
“Stereo ” is
most commonly used to describe two tracks of audio, a left channel and a right
channel, which are meant to represent a spacial orientation analogous to how
our ears hear. Stereo recordings can be made with two microphones, or with
a stereo mic that has two mic elements in one housing. Depending on the recorder’s
input, the signals from the two mics or mic elements can be carried on two
cables, or a single cable.
A similar recording technique
using two mics (or other inputs) which is not truly “stereo ” is
“two-track ” recording, basically using your stereo recorder as a
small multitrack machine. One can record two completely separate sounds, one
on each channel, to be manipulated later in the production process. One could
have one mic for an interviewer and another for the interviewee, each routed
to its own track. One could use both a lavalier and a hand-held mic to record
the same source, routing each mic to its own channel, so one could choose
between the sounds, or combine them, later. If recording interviews or other
sources that can be in mono, even complex multi-mic recordings are often
more useable later in production if half the mics are routed fully left and
the other half fully right, just to reduce the number of “live ”
mics on any one channel.
I
only have one cable, how can it be carrying stereo sound?
Cabling can be very confusing,
because the same types of wires and connectors can be used in very different
ways.
In the analog realm, one
usually needs one cable for each channel of audio, so connecting most gear
will require a cable for the right channel and a cable for the left. RCA cables
and 1/4-inch “TS” cables that have a single ring on the jack, handle
only one channel of audio.
But for the sake of saving
space, small portable recorders, laptops and a few other devices use stereo
inputs or outputs on a single jack.
In that case, one can
use one cable to transfer stereo audio, as long as it is a three-conductor
cable with the correct “TRS” connectors on the ends. TRS stands for
“Tip-Ring-Sleeve” for the three conductors on the plugs. You’ll see
two black bands on the plugs, one near the tip, another ring about midway
down, and the long sleeve of the shaft is a conductor as well. 1/8-inch or
“mini” TRS cables are commonly used for connecting the stereo headphone output
of a small minidisc recorder to the stereo mic input on a computer.
Some stereo mics use a mini TRS (often just called a “stereo mini”) plug to
connect to the mic inputs of a minidisc or a small portable DAT recorder.
One may need adapter cables
to interface a device that uses a stereo input or output with a mixer, or
audio interface. For instance, to connect a portable minidisc to an
audio interface like the M-Box, one needs a cable with a mini TRS on one end,
and two 1/4-inch cables on the other. Plug the mini TRS into the headphone
out of the minidisc, and the 1/4-inch cables into separate left and right
inputs of the interface.
Even professional mono
mics often use an adapter cable that terminates in a mini TRS plug, in
this case because there’s only one channel of audio coming from the mic, the
cable should bee wired to send the audio to both the tip and ring.
There are 1/4″ TRS cables
which are more often used for carrying mono “balanced” audio. A headphones
cable is of the few wires that uses 1/4″ TRS to send stereo audio, more often
those three connectors are used to “balance” a mono signal. The one common
exception is an “insert” cable that uses a 1/4″ TRS to move two channels of
audio, a “send” and “receive” channel to an external processor. These cables
usually have a 1/4″ TRS connector on one end and two (mono) 1/4″ TS connectors
on the other.
In the digital realm,
a single digital connector cable usually transmits two channels of audio.
It’s confusing because the cables look the same as ones you’d use for analog
audio (although you should try to use cables designated for digital audio,
they have specific impedance ratings that are optimized for transmitting digital
signals.)
The S/PDIF standard uses
one RCA cable to send stereo audio along with other info between devices.
AES/EBU uses a single XLR cable to send stereo audio. The two
standards are similar, but one cannot just use adapters to connect an RCA
S/PDIF output to an AES/EBU XLR input. (Some have reported success doing
that, but it’s unreliable). One can buy converter boxes that will maintain
proper cable impedance if one needs to interface S/PDIF and AES/EBU devices.
There’s also an optical
S/PDIF standard that sends stereo signal down an optical cable with small
square-ish plugs on each end. Consumer minidisc recorders often use
an optical digital connection, but in most cases that connection is just an
input, and might require a special cable to attack to the special small optical
input on the minidisc.
Devices using RCA, or
“coax,” S/PDIF can’t be connected to devices using the optical S/PDIF standard
without a special converter box.
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