Crown CM-700 User Manual

Mic Memo

Mic Memo

Crown’s Quarterly Microphone Newsletter

Fall 2002 Bruce Bartlett, Editor

CM-700 Chosen for “Dream” Studios

if the room acoustics are very
dead. Otherwise the mics pick
up a lot of room reverb which
muddies the sound. Also, ceil­ing mics work poorly for sound
reinforcement. The distance
from mic to source is just too
great to allow much gain-before-

CM-700

In the July, 2002 issue of Elec­tronic Musician, in the article

"Build a Personal Studio on Any
Budget," the Crown CM-700
cardioid condenser microphone
was chosen to be part of three
proposed "dream" studios.

Those studios were the $6000
portable digital studio, the
$15,000 Windows studio, and
the $30,000 studio without com­puter.

Ceiling-Mounted Conference Mics

Mics are commonly used in con­ference rooms for recording,
teleconferencing, and sound
reinforcement. Many customers
do not want to see the micro­phones, so they specify ceiling­mounted mics. In this case,
appearance is a higher value
than sonic performance.

Ceiling-mounted mics are feasi­ble for audio recording, but only

feedback. If at all possible, use
table-mounted mics for best
gain and clearest sound.

If you want to use an omni ceil­ing-mounted mic, try a Crown
PZM-11 in an electrical box. It
costs little, and its high frequen­cies are boosted for extra clarity.

For less reverb pickup, try four
Crown MB-4 mics on the ceiling
angled 90 degrees from each
other. Feed the four XLR out­puts to an automatic mixer.
Recommended settings on the
mixer are: release time very
long, and automatic gain control
on. Again, this setup is not rec­ommended for sound reinforce­ment.

Crown MB-4 boundary mic

CM-700 for Stage Vocals

Although the CM-700 was not
designed to be a stage-vocal
mic, it can be made to work
quite well in that application.
Singer/guitarist Bob Lichty used
the CM-700 for vocal pickup at a
recent concert. He had this to
say about its use:

"I used the double low-cut filter
on the CM-700 for vocals. For
guitar, I left the low-cut switch
flat and rolled out a bit of the
lows at the board. I learned how
to "mask" my p's and t's with
singing technique, so they are
rarely an issue for me. I love the
sound of the 700, and even my
wife can't believe how different I
sound 'all miked up' versus just
singing at home in the bed­room."

What’s Inside

• CM-700 Chosen for "Dream"
Studios

• Ceiling-mounted Conference
Mics

• CM-700 for Stage Vocals

• Harp Miking

• Lavalier Mic EQ

• Miking an Electronic Organ

• PZM Piano Miking

• CM-311AE Fan

• What’s a PXT?

For more information, call 800-342-6939

1

Mic

Memo

Harp Miking

Here's an unusal miking applica­tion for sound reinforcement.
How do you mike a folk harp? It
is a small instrument about 4
feet tall.

Try a Crown GLM-200, a mini
mic with a hypercardioid polar
pattern.

GLM-200 hypercardioid mic

Mount the mic inside the harp
near one of the sound holes.
You can attach the mic by taping
its cable to the harp, or by using
the supplied GLM-UM Universal
Mount.

the handheld mics. What sort of
equalization is needed to do
this?

First, note that nearly all hand­held vocal mics are directional,
so they have proximity effect
(bass boost when used close to
the mouth). Omnidirectional
lavalier mics have no proximity
effect. To simulate that, you
might boost 4 to 6 dB around
100 Hz. (Be careful with feed­back whenever you apply an EQ
boost.)

Lavalier mics have a built-in
high end rise to compensate for
being off axis to the mouth. You
might need to do more high-fre­quency tweaking by ear. Also,
most lavs exhibit a peak around
630 Hz (about 3 or 4 dB, less
than 1 octave wide) due to body
diffraction and chest reso­nance. Cutting that frequency
by the same amount can
remove the "puffy" sounding
midrange peak, making the lav
sound more like the handheld
mic.

• Ground loops can create hum.

• You might be held liable for
messing with the organ electron­ics.

• The organ technician might
remove the connection.

• Many organs don't have a
composite or full-range feed,
meaning that the electrical sig­nals to the various loudspeaker
drivers are bandpassed. If you
tap off a loudspeaker you may
not get the full spectrum of the
organ. If you combine the band­passed outputs to get a full­range feed, you might be held
liable for tampering.

• A lightning strike that gets into
the organ electronics might get
into the audio system, or vice­versa.

Using a mic instead of a direct
connection avoids all the prob­lems mentioned above. A close­up omni mic, strategically
placed, will pick up very little of
the room and other sounds. We
suggest the Crown GLM-100
mini omni mic. It's very small
and picks up down to 20 Hz.

Ask the harpist to play as you
monitor the sound. Adjust the
angle and position of the GLM­200 until you hear a tonal bal­ance you like.

Lavalier Mic EQ

Many theater sound systems
employ handheld mics for sing­ers and lavalier (clip-on) mics for
actors. Sometimes the sound
operator is asked to make the
lavalier mics sound the same as

For more information, call 800-342-6939

2

Miking an Electric Organ

Some houses of worship feature
an electronic organ. Often it's
necessary to feed the sound of
this organ into the sound sys­tem. It seems reasonable to find
a line-level signal within the
electronics and connect to it, or
connect to the organ’s speaker
terminals. Unfortunately, these
connections can cause several
problems:

Note: This close mic placement
is for sound reinforcement, not
recording. If you want to record
the electronic organ, place a pair
of mics several feet away (about
12 to 20 feet) to pick up the
room reverb as well as the
sound of the organ.

The GLM-100 looks the same
as the GLM-200 pictured on this
page.

Thanks to Pat Brown of Syn Aud
Con for this idea.

Mic

Memo

Letters From Crown Mic Users

PZM Piano Miking

I am a pianist, but totally new to
the recording process; my
unique situation is that I need a
very portable solution because I
have to record from a piano at a
local music school. I have a
Minidisc recorder and I wonder if
it would be possible to make a
decent recording directly into the
Minidisc using the kind of micro­phones you've described. Could
I input two microphones into the
Minidisc player itself, or do I
need to invest in some kind of
pre-amp also?

Please offer some input if you
would about how I could mic a
piano decently (not professional
by any means) while under­standing I am not in position to
haul around a lot of equipment.
I'd appreciate it very much.

Thank you,
Gerard Cox

Reply:

You should be able to make a
very good piano recording using
one or two PZM-185 micro­phones and a MiniDisc recorder.
The PZM-185 is an inexpensive
Pressure Zone Microphone that
is powered by an internal battery
or phantom power. Since you
want a very portable system,

we'd recommend using the bat­tery rather than phantom.

Figure 1 shows some suggested
places to tape a PZM mic to the
underside of the raised piano lid.
For a mono recording with one
mic, tape it in the middle of the
lid, a few inches horizontally
from the hammers. Raise the lid
on the long stick. For a stereo
recording with two mics, tape
one over the treble strings near
the hammers, and one over the
bass strings near the tail, as
shown.

Figure 1. Some suggested mic

placements for PZMs on a piano lid.

The kind of sound you will get
with this miking is up-close and
clear, with little or no room
acoustics. It might be suitable
for pop, jazz, ragtime, or folk
music. If you are recording clas­sical music and you want to
include the room acoustics
(such as in a recital hall), you
should place the mics several
feet from the piano. Either place
them on the floor about 4 feet
apart, or mount them back-to­back on a mic stand, aiming the
edge of the plates at the piano.

The PZM-185 has a high-fre­quency rise for speech clarity. If
you want to flatten the response
to get a more natural sound,
obtain a microphone foam wind­screen. Cut off a 1/4" square
about 1/8" thick and insert it into
the gap between the mic and the
plate. The thicker the foam
piece, the less high frequencies
(treble) you'll hear.

How do you connect the mics to
your MiniDisc recorder? Check
the manual that came with your
recorder. It describes the input
connectors. The recorder
should have a mic input, so you
won't need a mic preamp. Prob­ably the mic input is a single
mini phone jack that is wired for
stereo. If so, you or an electron­ics-savvy friend would need to
make an adapter cable (Figure
2, next page). On the mic end of
the adapter cable is a 3-pin
female XLR connector(two for
stereo). On the recorder end of
the adapter cable is a mini ste­reo phone plug.

The mini stereo phone plug has
three terminals to connect to:
tip, ring, and sleeve. The tip ter­minal is the small one that goes
to the tip of the phone plug. The
ring terminal is a little longer,
and goes to the ring of the
phone plug (the metal cylinder
just behind the tip). The sleeve
terminal is the longest, and it
goes to the sleeve or long cylin­der part of the phone plug.

(continued on next page)

For more information, call 800-342-6939

3

Mic

Memo

PZM Piano Miking
(Continued from page 3)

Inside the female XLR connec­tor, connect pin 1 to the cable
shield, connect pin 2 to the
cable center conductor, and
connect pin 3 to pin 1. Inside
the stereo mini phone plug, con­nect the cable shield to the long
sleeve terminal, and connect the
center conductor to the tip and
ring terminals. (That's assuming
you're using only one micro­phone).

If you're using two microphones
for stereo, you need two adapter
cables that connect to a single

stereo mini phone plug (Figure

3). On the mic end of both
cables, wire a female XLR con­nector as described above. At
the other end of both cables,
connect both shields to the
phone-jack sleeve, connect one
cable's center conductor to the
phone-plug tip terminal, and
connect the other cable's center
conductor to the phone-plug ring
terminal.

If you hear distortion when
recording the piano, set the
MiniDisc recorder’s gain switch
to lower gain. If you’re using a
DAT recorder, switch in the input
pad.

CM-311AE Fan

I just purchased the CM-311AE
and I am so pleased with the
headset, that I have placed a
link to your site on our band's
site.

I would like to spread the word
to the folks that visit our site,
that this is the best headset mic
I've ever used! I've used two
other headsets and they don't
even come close to reproducing
my voice the way I need it to be
done, the clarity is incredible.

Sincerely,
Jay Tucker
www.HeartsonFireband.com

Figure 2. Female XLR to stereo mini phone adapter cable.

What's a PXT?

I came across an older PZM that
doesn't work. Someone told me
that it needs a PXT to operate.
What is that?

Phil Burns
Seattle, WA

Reply: A PXT, which looks like a
short chrome-plated tube, is a
discontinued Crown product. It

For more information, call 800-342-6939

4

is used with older PZM mics like
the PZM-30GPG and PZM-31S.
Those mics have an unbalanced
high-Z output and are powered
with a unipolar DC voltage. You
connect each mic to a PXT
using regular 2-conductor
shielded mic cable. The PXT
converts the mic output to a low­Z balanced signal, and converts
phantom power to a unipolar DC
voltage that powers the mic.

Figure 3. Dual female XLR to stereo mini phone adapter.

A PX-18 is the same but works
off two internal 9V batteries and
has a 1:1 internal transformer to
balance the signal. A PA-18 is
the same but works off two inter­nal 9V batteries and has an
active circuit to balance the sig­nal.

Newer Crown mics have the
electronics built into the mic or
its connector. They have a low­impedance balanced output.