Schoeps UNIVERSAL-OMNI-H-ST, UNIVERSAL-OMNI-S-ST, WIDE-CARDIOID-ST, SWITCHABLE-PATTRN-ST, SUPERCARDIOID-ST Users Manual

MK --

Microphone Capsules

CMC --

Microphone Amplifiers

User Guide

Colette
Modular System

Colette
Modular System

Table of Contents

page
System Overview 2
CMC -- Microphone Amplifiers 3

Phantom Powering 5
Technical Specifications 7
Notes on Electromagnetic Compatibility 7
Block Diagram 8

MK -- Microphone Capsules 9

Capsule Selection 9
Attaching a Capsule 9
Basic Characteristics of Transducers 10
Suggested Capsules for Specific Applications 11
Pressure Transducers 12
Boundary Layer Microphones 13

Pressure Gradient Transducers 14
Specifications for Complete Microphones 21
Care and Maintenance 22
Possible Problems 22
Warranty 24

SCHOEPS GmbH · Spitalstr. 20 · D-76227 Karlsruhe (Durlach) · Tel: [phone] · Fax: [phone]

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System Overview (Extract)

Colette Modular System

2

inline filters

inline

attenuator

microphone

capsules

attenuator

swivel

low-cut

filter

microphone

amplifiers

.
.
.

20 capsules
in all

RC KC

Active Tube

(special
version)

MK DZC GVC

KC

Active Cable

CUT

Signal:

balanced
unbalanced

TR 200 KCg Active
Table Stand

RC

Active Tube

LP 40 U

low-pass filter

Active Accessories

CMC 6, P12 / P48

CMC 3, P12

CMC 5, P48

LC 60, LC 120

low-cut filters

OSIX CI

elastic suspension
with Active Cable

e.g. VMS 5 U

microphone preamplifier
with M/S matrix

MDZ 10,
MDZ 20

CMC 4, T12

SCHOEPS GmbH · Spitalstr. 20 · D-76227 Karlsruhe (Durlach) · Tel: [phone] · Fax: [phone]

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CMC -- Microphone Amplifiers

Microphone Amplifiers

3

Dear customer:

Thank you for choosing SCHOEPS CMC
(”Colette”) Series microphones. This is the most
extensive and diverse modular microphone
system in the world, offering the highest pos­sible professional sound quality in an extremely
wide range of practical configurations. A system
overview is shown on page 2.

Colette Modular System

A condenser microphone is formed by the
combination of two main components: a cap­sule and a microphone amplifier:

The capsule is the component which converts
sound waves into a varying electrical voltage.
It determines the directionality and, for the
most part, the sound quality of the microphone.
The amplifier is the other main component,
with the circuitry needed to accept external
powering, polarize (charge) the capacitive
capsule, obtain the audio signal from it, and
convert that signal to one which is balanced
and low-impedance.

Microphones of the Colette Series are mod­ular: Any type of CMC microphone amplifier
can be used with any type of Colette capsule.
Approximately 20 different capsule types (MK --)
are available for wide-ranging applications,
and several types of amplifier (CMC --) are
available for various powering and connection
schemes.

In addition, the practical value of a Colette
Series microphone is greatly enhanced by
Colette ”Active Accessories” – special goose­necks, ultra-thin cables or narrow extension
tubes which allow the capsule to be separated
some distance from its amplifier and placed
unobtrusively, as if it were a miniature micro­phone. Colette Active Cables are often used
to help conceal microphones for film and video
production, while Colette Active Extension
Tubes have become a mainstay of concert

amplification, recording and broadcasting.
The active circuitry in these accessories converts
the audio signal to lower impedance directly
at the capsule, so that there is no loss of sound
quality:

In the following pages you will find technical
information, application hints and advice con­cerning the care and maintenance of these
microphones. We begin by considering the
CMC amplifier and how to power and connect
SCHOEPS condenser microphones; the second
part of this manual concerns the capsules of
the Colette Series. For information on acces­sories (including Active Accessories), please see
our main catalog or visit www.schoeps.de.

CMC -- Microphone Amplifiers

...are distinguished by:
– flat frequency response
– low noise and distortion
– balanced, symmetrical, very low-impedance

output

– ability to be used with very long cables

(e.g. several hundred meters)

– versions for various powering schemes

Several standard versions are available. All
feature a symmetrical, class-A output stage
which uses neither coupling conden sers nor an
output transformer. This leads to a low output
impedance, insensitivity to electrical interfer­ence, low distortion and light weight.

CMC amplifiers are electrically active com ­po nents which require operating current. This
will most often be supplied by the inputs of a
mixer, preamplifier (such as the SCHOEPS
VMS 5U shown on page 2) or recorder that
has suitable microphone powering built in.
Otherwise, a stand-alone microphone power
supply of proper type can be used.

Standard Versions

Four standard models of CMC amplifier are
offered to fit the specific type(s) of microphone

MK-- CMC--

+

++

Active Accessories

powering which the user expects to encounter.
Variants of these types are also available, offer­ing different output levels and/or extended
frequency range. Each amplifier works only with
the specific type and voltage(s) of power ing
for which it is designed.

Please note: The two amplifiers in a stereo pair

of CMC microphones should be of the same
type. For critical applications, pairs of capsules
can be selected at the factory for pre cisely
matched sensitivity and frequency response.
(A small extra fee is charged for this service.)

Most modern, solid-state professional micro ­phones use a standardized powering scheme
known as ”phantom powering,” and most
recording equipment offers a 48-Volt supply
for such microphones. Some equipment, how­ever, provides a 12-Volt supply for phantom
powering, or can be readily modified to provide
such a supply. The SCHOEPS CMC 6 amplifier
series can work with either voltage, switching
its circuitry automatically to the corresponding
mode of operation. It maintains the same level
of performance in either mode, while drawing
only the necessary amount of current from the
phantom supply.

Note that the CMC 6 is designed to work
with standard 12-Volt or standard 48-Volt
phantom powering, but it is not a ”12-to-48
Volt” microphone. Any input to which it is
connected must implement one of those two
standard phantom powering methods. Not
only must the supply voltage meet the stan­dard; the resistors must be correct as well.

For applications in which it is certain that only
48-Volt or only 12-Volt phantom powering
will be used, the CMC 5 and CMC 3 (respec ­tively) remain available at slightly lower cost.
The CMC 6 offers greater flexibility in powering
as well as superior immunity to radio-frequency
interference; it is also the only amplifier model
which can be delivered in the special ”xt” ver­sion (see description under ”Special Versions”
below).

From an audio standpoint, the most signifi­cant difference between the CMC 6 and the
CMC 3 or 5 is the response at the very lowest
audio frequencies: The standard version of the

CMC 6 has a 12 dB/octave rolloff below 20 Hz
as a protection against infrasonics, while the
stan dard version of the CMC 3 or 5 has a 6 dB/
octave rolloff below 30 Hz. Any CMC amplifier
can be specially ordered, or modified after
delivery, for any desired rolloff frequency within
reason; please see the description of the CMC
”linear” version for further details.

In general if a 48-Volt microphone is con­nected to 12-Volt phantom powering, no dam­age will occur but the microphone will not work
properly. On the other hand a CMC 3 could
be powered safely and effectively by a 48-Volt
phantom supply if it can provide 11 mA per
microphone. But that current exceeds what is
required for standard 48-Volt phantom power­ing, and unfortunately many existing supplies
do not even meet the standard. Therefore this
mode of operation should not normally be
relied upon.

In the realm of film and video sound an
older system called ”parallel powering” or ”T”
powering (”Ton ader spei sung”) at 12 ± 1 Volts
is sometimes still used, particularly with Nagra
tape recorders; the CMC 4 amplifier model
works with that system. See Fig. 3, p. 6 for a
schematic diagram; since this method of pow­ering has been in decline for some time now,
it is not described in detail in this manual.
Please contact your SCHOEPS dealer or SCHOEPS
GmbH with any questions concerning its use.

Special Versions

CMC 6 U”xt” – the 40 kHz version

This variant is indicated by the letters ”xt”
engraved on the output socket. When an ”xt”
amplifier is used with any axially-addressed
Colette capsule, the response range of the
microphone will extend beyond 40 kHz. The
response above 10 kHz will also be elevated
slightly. Specific frequency response curves
can be seen in our main catalog or on our
Web site, www.schoeps.de .

CMC “+5 dB”

The sensitivity of a microphone with this ampli ­fier variant is 5 dB above the normal type,
while the equivalent noise level is somewhat

GmbH · Spitalstr. 20 · D-76227 Karlsruhe (Durlach) · Tel: [phone] · Fax: [phone]

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Types of Microphone Amplifiers

Microphone Amplifiers

4

greater. The increased output levels can help
to raise a microphone's signal above the input
noise level of the equipment to which it is
connected, especially when sound levels are
low to moderate. However, the overload limit
of that equipment, and of the microphone
itself, will also be reached 5 dB sooner.

CMC ”linear”

CMC microphone amplifiers normally have a
rolloff in response below 30 Hz (20 Hz in the
CMC 6) to guard against infrasonic distur­bances from various sources such as vibration
and air motion. However, when using pressure
(omnidirectional) transducers, particularly with
digital recording, it can be desirable to pick up
frequencies even lower than 20 - 30 Hz. The
special technology of the CMC microphone
amplifiers makes this possible; on request we
can deliver microphone amplifiers with response
extending as low as 3 Hz.

For live recording, however, some caution
is advised with respect to infrasonics. Since
pressure transducers can pick up very low fre­quencies, ventilation systems in large spaces
(churches, concert halls) or traffic rumble can
create a problem. With pressure gradient trans ­ducers the risk is even greater. They are far
less sensitive to very low frequency sound, but
respond much more strongly to low-frequency
mechanical stimuli such as air currents and
solid-borne noise. Such signals may be below
the audible range, but they can overload pre­amp inputs, particularly those that have
undersized input transformers.

Phantom Powering (DIN EN 61938)

(formerly DIN 45 596)

”Phantom” powering is a standard method of
providing the operating current for a micro­phone's circuitry through ordinary two-conduc­tor shielded cable. Precisely equal DC flows in
both modulation leads, making it ”invisible”
and harmless to most balanced microphones
that don't require such powering (e.g. most
dynamic microphones, including ribbons).
Exceptions are quite rare. The only likely cases
in which standard phantom powering will en -

danger a balanced microphone (e.g. a ribbon)
are if a microphone cable, con nector or adapter
is defective or wired in a non-standard way,
such that one modulation lead of the micro­phone is shorted to ground at DC while the
powering is on. If a microphone is connected
to such a cable with the powering turned on,
impulse current will flow through its coil or
ribbon, possibly causing damage.

Fig. 1 shows the only valid 48 V and 12 V
phan tom powering circuit (abbreviations: P48
and P12) that can be realized with resistors as
opposed to a center-tapped input transformer.
This illustration is based on the international
standard document EN 61938, ratified in

1997. Our microphones are developed and
tested with power supplies that con form to
the requirements of this standard. Proper oper­ation with non-standard power supplies can­not be guaranteed. Circuit arrangements that
deviate from the standard can cause opera­tional problems (i.e. distortion or even gaps in
the signal), particularly at high sound pressure
levels or in the presence of strong wind noise.
Such problems may often seem to defy analysis
until their real cause is discovered.

The permissible tolerance of the feed resistor
values as such is ±20%. However, the differ­ence between the resistors of any one pair
should be less than 0.4% (i.e. 27 Ohms for
48-Volt phantom powering with 6.8 kOhm).
This close matching is necessary to maintain
adequate common mode rejection. It will also
prevent significant DC from flowing through
the primary of the input transformer (if one is
present) and causing distortion or reduced
dynamic range.

A microphone designed for 48-Volt phan­tom powering could draw as much as 10 mA
according to the standard. A SCHOEPS CMC 5
or CMC 6 will draw about 4 mA even when
Active Accessories are used; this falls well
within the limit set by the prevailing standard.
There are certain commercially available power
supplies, preamplifiers, and mixing desks –
mostly older, but some more recent – which
fail to meet this standard and hence may not
be able to power SCHOEPS microphones ade­quately. Where doubt exists, equipment should

SCHOEPS GmbH · Spitalstr. 20 · D-76227 Karlsruhe (Durlach) · Tel: [phone] · Fax: [phone]

www.schoeps.de · [e-mail]

Phantom Powering

Microphone Amplifiers

5

SCHOEPS GmbH · Spitalstr. 20 · D-76227 Karlsruhe (Durlach) · Tel: [phone] · Fax: [phone]

www.schoeps.de · [e-mail]

Phantom Powering

Microphone Amplifiers

6

If possible, an unbalanced input should be bal­anced with a high-quality microphone input
transformer. That will also allow the signal leads
from the microphone to be balanced, for best
rejection of interference.

If such an arrangement is not possible, how­ever, a CMC microphone may be operated in
unbalanced mode by taking the signal from
pin 2 via a coupling condenser with a value as
shown in Figure 2 above. The signal from pin 3
must be left unconnected; do not short it to
ground. This ”unbalancing act” must occur
between the power supply and the preamplifier
input, however, since naturally all three pins
of the microphone must still connect to its
phantom or parallel power supply.

+ phase

- phase

2 (4)

3 (5)

microphone

1

screen

cable

powering

R

S

U

S

input

R

S

P48: US= 48 V ± 4 V; RS= 6,8 kW*, I

max.

= 10 mA

P12: U

S

= 12V ± 1V; RS= 680 W*, I

max.

= 15 mA

I/2

I/2

I

+ phase

- phase

2 (4)

3 (5)

microphone

1

screen

cable

powering

R

S

U

S

input

R

S

R

R

C

C

* see note in the text concerning tolerances

with XLR-5
(stereo microphones)

Fig. 2

To add phantom powering
to a balanced, grounded,
transformerless input, capa ­citors must be inserted into
the signal lines and polariza­tion resistors provided as
shown.

*

*

*

Fig. 1

Input with transformer
(or balanced, floating trans­formerless input)

XLR-3­connector

XLR-3
connector

XLR-3­connector

cable

Ohms

Ohms

* recommended values:

C: 100

μ

F, 63V; R: 22kΩ, 1%

** Tolerance ca. 5%; precise

matching is not critical.

Fig. 3

Parallel powering;
with parallel powering there is low-impedance
DC across pins 2 and 3. This can damage
dynamic microphones, especially ribbons.

z.B.
10 kOhm

**

**

R

*

be checked to verify its suitability for profes­sional work with SCHOEPS microphones. On
page 8 a method is described for checking a
phantom supply quickly and easily.

For P12 the standard allows a current of
15 mA. A SCHOEPS CMC 3 will draw 11 mA
while a CMC 6 needs 8 mA at 12 Volts.

Fig. 2 shows a bal an ced but groun ded am ­pli fier in put. In this case eit her a trans for mer
(see fig. 1) or ad di tio nal ca pa ci tors ha ve to be
in ser ted in the au dio li ne.

Unbalanced Operation

Unbalanced operation of CMC microphone
amplifiers is not recommended; both noise and
vulnerability to interference will be increased.

shield

shield

shield

SCHOEPS GmbH · Spitalstr. 20 · D-76227 Karlsruhe (Durlach) · Tel: [phone] · Fax: [phone]

www.schoeps.de · [e-mail]

Technical Specifications, Electromagnetic Compatibility

Microphone Amplifiers

Amplifier type Powering Current Impedance Low-cut

consumption frequency (-3 dB)

CMC 6U / 6Uxt: 12 V phantom 8 mA 25 Ohms 20 Hz

48 V phantom 4 mA 35 Ohms 20 Hz

(automatic switchover)
CMC 5U: 48 V phantom 4 mA 35 Ohms 30 Hz
CMC 3U: 12 V phantom 11 mA 20 Ohms 30 Hz
CMC 4U: 12 V parallel 9 mA 13 Ohms 30 Hz

Polarity: Increasing sound pressure on the microphone's 0° axis produces a positive-going voltage

at pin 2.
Maximum output voltage: 1 V (at 1 kHz and 1 kOhm load resistance)
Minimum recommended load resistance: 600 Ohms (A load resistance below this value will par-

ticularly reduce the maximum output level.)
The other technical specifications depend on the choice of capsule – see page 12 ff.
Length: 116 mm (incl. 3 mm capsule thread)
Diameter: 20 mm
Weight: 65 – 68 g, depending on type
Surface finish: matte gray (g) or nickel (ni)

electromagnetic fields. This is particularly true
for CMC 6 amplifiers made since 2004; they
can be recognized by the gold-colored shield
plate in their output connector.

Due to the wide dynamic range of studio
microphones, the smallest signal amplitudes
are in the microvolt (1/1,000,000 Volt) range.
Cable shielding and the grounding scheme of
the preamp or mixer input are also crucial.
Thus no microphone can ever be immune to
all possible disturbances under all circumstances.
But the following suggestions can help to
reduce the likelihood of picking up noise:

1) Keep both the microphone and the cable

away from sources of interference such as

monitors, digital equipment (computers),

RF emitters (mobile phones), power trans-

formers, power lines, SCR dimmers, switch-

ing power supplies etc.

2) Use only high-quality cables with a high

degree of shield coverage.

3) Keep all cables as short as possible.

4) Dress audio cables away from power cables.

If they must cross, it should be at right angles.

5) At the preamp or mixer input, the shield of

the microphone cable should connect to

chassis ground in the shortest way possible.

If necessary, this coupling can be capacitive.

Simultaneous Connection to Multiple Inputs

If one microphone must be connected to mul­tiple inputs simultaneously, an active micro phone
splitter should be used in order to preserve
the loading and powering conditions for the
microphone, and to prevent interference.

Maximum Cable Length

Cable lengths of several hundred meters are
possible; Colette Series microphones are some ­times used with cables as long as 500 m (over
1/4 mile!). But the practical limit depends on
the electrical capacitance of the cable, which
is sometimes an unknown quantity. The lower
this capacitance is per unit length, the longer
the cable can be. All SCHOEPS cables have
very low capacitance (100 pF/m between the
conductors).

The main risks with excessively long micro­phone cables are losses at high frequencies
due to cable capacitance, reduced ability to
handle very high sound pressure levels, and
increased likelihood of picking up interference.

No tes on Electromagnetic Compatibility

SCHOEPS CMC microphone amplifiers are
virtually immune to magnetic, electric and

7

SCHOEPS GmbH · Spitalstr. 20 · D-76227 Karlsruhe (Durlach) · Tel: [phone] · Fax: [phone]

www.schoeps.de · [e-mail]

Block Diagram of the CMC 3, 5, 6 Microphone Amplifiers

Microphone Amplifiers

8

Capsule

MK --

Capsule

MK --

Impedance

converter

Output

stage

DC/DC

converter

Regulator

EMI filter

e.g. cable KC -- or

tube RC --

Active Accessories:

3

1

4

2

3

1

3

1

3

1

4

2

3

1

Screen

-Phase

+Phase

XLR-3

Connector

2

3

1

2

3

1

2

Center contact ( )

Inner ring (0 V)

Middle ring (+60 V)

Outer ring (+6,2 V)

Microphone

cable

Microphone Amplifier

CMC --

Phantom

powering

U

s

= +48 V

R

s

= 6.8 kΩ

R

s

= 6.8 kΩ

∼

∼

Preampli -

fier,

recorder

or mixing

desk

4

1

2

3

*

*

**

∼

∼

3

1

Impedance

converter

+Phase: An excursion of the diaphragm towards the back electrode (posi-

tive pressure phase) leads to a positive signal at this pin.

*matched pair; see page 5

** Here are three simple methods for verifying correct phantom powering.

These measurements should be made at an unused input. Reduce the

channel gain to protect loudspeakers, etc. If microphones are connected

to other inputs at the same time, no substantial difference should occur

in the results.

1. Measure the open-circuit voltage between ground (pin 1) and either

pin 2 or pin 3 of the XLR input. Given the permitted tolerances, this

voltage should be between 44 and 52 VDC for P48, and between 11

and 13 VDC for P12. Then, measure the short-circuit current between

ground (pin 1) and either pin 2 or pin 3 of the XLR input. Given the per-

mitted tolerances, this current should be between 5.9 and 8.5 mA DC

for P48, and between 15 and 21 mA DC for P12.

screen

-phase

+phase

XLR-3

connector

XLR-3

connector

Pin 1: screen (GND)

Pin 2: +phase

Pin 3: –phase

Bottom view

(as the pins are seen)

1

2

3

Note: Well-designed phantom power supplies must tolerate at least a

temporary short circuit without damage; an unbalanced connection

(which is occasionally necessary) would cause the same current to be

drawn. To be safe, however, don't leave the short circuit in place longer

than necessary.

2) Measure the DC voltages on the modulation leads with a microphone

connected, e.g. by opening the connector shell of the cable. The two

voltages (from pin 2 and pin 3 to pin 1) must be identical. With a CMC 5

or CMC 6 and a 48-Volt supply, they should be about 34 Volts (mini-

mum = 30 Volts). For P12 this is 8.3 Volts (minimum 7.3 Volts) with a

CMC 3, and 9 Volts (minimum 8 Volts) with a CMC 6.

3) For P48, use a SCHOEPS PHS 48 tester. Plug it in to the XLR input socket;

if the LED glows and stays lit, all is well.

Nominal voltage gain: stan-

dard CMC amplifier: -2 dB,

”+5 dB” version: +3 dB.