Schoeps VMS 5 U User manual

VMS 5 U
User’s Manual
Microphone preamplifier with phantom powering,
M/S matrix and headphone output,
with special input for Schoeps active Y-cable

2
Control layouts:
Front:
<1> Signal level indicators
<2> Preamp gain control
<3> Left/Right balance control
<4> Switch for low-cut filter
<5> Channel assignment switch (for
M/S)
<6> Stereo width control (for M/S)
<7> Main output selector
<8> Headphone jack
<9> Headphone output selector
<10> Headphone level control
<11> Phantom power switch
<12> Battery level meter
<13> External power indicator (yellow);
low-battery warning (red)
<14> On/Off switch
Rear, as seen from above*:
<15> Input for SCHOEPS active Y-cable
<16> Balanced XLR microphone inputs
<17> Balanced XLR line outputs
<18> Input for external power supply
<19> Input selector switch
* The connectors and labels on the rear
of the VMS 5 U are “upside-down”
with respect to the front of the unit.
This simplifies its use, since the unit
does not need to be turned around
sideways to read the labels.
Table of contents
1. Inserting batteries . . . . . . . .4
2. Battery level meter . . . . . . . .5
3. Automatic shutoff . . . . . . . .6
4. External powering . . . . . . . .6
5. Connecting microphones . . .8
6. Setting the preamp gain . . .9
7. Balance setting . . . . . . . . . .9
8. Signal level indicators . . . . .9
9. Low-cut filter . . . . . . . . . . . .9
10. Connecting the outputs . . .10
11. Connecting headphones . .11
12. M/S recording/WIDTH . . . .11
13. M/S dematrixing . . . . . . . .15
14. M/S side inversion switch .15
15 Technical specifications . . . .16
16. Block diagram . . . . . . . . . .18
17. Important information . . . .20
18. Warranty . . . . . . . . . . . . . .21

3
<15> <16>
<19>
<17> <18>
<8> <9> <10> <11> <12> <13> <14>
<1> <2> <3> <6> <7><4> <5>

4
The VMS 5 U is designed for indoor
and outdoor professional recording
applications. Its features include:
– 48 Volt phantom powering
– Special input for SCHOEPS active
Y-cable
– Switchable M/S matrix
– Frequency range: 20 Hz - 80 kHz
(-3 dB)
– Headphone output, switchable
(before or after the M/S matrix)
– Can be operated from internal bat-
teries or external power
– Automatic “glitch-free” switchover
to battery powering if the AC supply
is interrupted
– Rechargeable batteries are automati-
cally protected from extreme dis-
charge
– Durable, high-quality switches and
connectors (gold-plated contacts)
– Lightweight, robust all-metal housing
1. Inserting batteries
The VMS 5 U operates from six AA
(LR 6) cells (included). Primary cells
(preferably alkaline) can be used, or
rechargeables such as NiCd or NiMH.
To insert batteries, turn the unit off
and open the battery compartment on
the underside by turning the slotted
button in the lid (perhaps with the aid
of a coin) one quarter turn in either
direction.
Please note:
The orientation of the batteries is
shown on the battery holders:
All batteries must go in the
same direction!
Make sure that the battery contacts
are kept clean. If necessary, clean the
contacts with a pencil eraser.
After inserting batteries, close the
battery compartment lid and lock it by
turning the slotted button a quarter
turn in either direction until it clicks
into place.

5
When the unit is first turned on, there
will be a four- to five-second delay
before it is ready for use. This is neces-
sary so that the unit can function reli-
ably even with relatively low-powered
AC supplies.
Watch the battery level with special
care when using rechargeable batteries;
as they lose their charge, their voltage
will often drop off quite rapidly.
What happens if …
… a battery is inserted the wrong
way? The resulting voltage will be too
low to operate the unit. If several bat-
teries (cells) are put in backwards, an
internal fuse may burn out and need
replacing. An emergency replacement
is provided within the unit. Both fuses
(designated “2A F”) are accessible
within the battery compartment by
using a pair of regular pliers; see the
diagram on the lid of the battery com-
partment.
We recommend using alkaline bat-
teries because they have the greatest
capacity and the longest shelf life.
Zinc-carbon batteries and rechargeable
batteries (NiCd or NiMH) will not power
the unit for as long a time (see “Speci-
fications” at the end of this manual).
We strongly advise against mixing
different types of batteries or batteries
of differing “ages” together. Recharge-
ables should all be of the same type
and capacity as one another; all batter-
ies should be changed and/or charged
together as a set. This is to avoid the
risk of one or more cells (those of
lower capacity) being too deeply dis-
charged; even “sealed” alkaline cells
can leak corrosive chemicals, while
rechargeable batteries can undergo
voltage reversal and be permanently
damaged. Further, operation time
would be reduced unnecessarily.
Though it may seem obvious that
only new batteries in good condition
should be used, we are obliged to
warn against the use of weak or dam-
aged batteries, to avoid harming the
circuitry of the VMS 5 U.
What should be done if the unit
does not work with a new set of
batteries? Turn the unit off, then wait
half a second and turn it back on.
If the “LOW BAT.” LED lights briefly
but then goes out, the batteries are
simply too weak; the charge is enough
to turn the unit on initially, but then
an automatic shutoff takes effect.
Please note: If the unit is not used
for a prolonged period, the batteries
should be removed to prevent possible
damage by leaking.
2. Battery level meter /
LOW BAT
Powering with internal batteries /
rechargeables
The battery level meter (<12> in the
photo on page 3) shows the state of
the internal batteries. At the start of a
recording the needle should always be
in the green zone of the meter. If it is

6
not, the batteries need to be changed,
or recharged if they are NiCd/NiMH
types. When running on internal bat-
teries, the borderline between the red
and green zones is at about 7 Volts; at
this level the “LOW BAT” LED begins to
flash. With high-capacity rechargeable
batteries (1300 mAh) there should be
approximately a 10-minute interval
before the unit shuts itself off automat-
ically.
External powering
When the unit is externally powered
(and only then!) it is acceptable if the
battery indicator <12> is in the red
zone. It is calibrated for internal battery
powering, and its reading will be offset
slightly when external powering is used:
the boundary between red and green
will be at 7.5 Volts while the far end
of the green region will be at 10 Volts.
When the indicator is near the left end
of the red region the unit will no longer
function.
The “LOW BAT” LED <13> will begin
to blink at around 7,5 Volts, but can
be ignored with external powering.
3. Automatic shutoff
The unit will turn itself off if the volt-
age of the internal batteries falls beneath
the limit of proper functioning. This
avoids overly deep discharge of the
batteries, which could otherwise lead
to chemical leakage or, in the case of
rechargeable batteries, life-shortening
damage and possible cell reversal.
To turn the unit back on after an
automatic shutoff, turn the power
switch off and then on again, and/or
replace the batteries as needed.
When the unit is powered externally,
the automatic shutoff circuit is dis-
abled so that a brief interruption in
external power will not cause a pro-
longed shutdown in the absence of
internal batteries. However, a minimum
of 5.2 Volts (externally) must be sup-
plied for the unit to continue operating.
4. External powering
The VMS 5 U can be powered by
external batteries or AC power adap-
ters through a socket on the back of
the unit. The 5.5 mm/2.1 mm coaxial
power plug is a commonly available
part, and is found on AC power adap-
ters of many kinds.
We generally recommend using the
SCHOEPS mains adapter VMS 5 DC. If
another type or external batteries are
used, please note the following hints:
The voltage at the socket may be
anywhere between 5.5 and 15.5 Volts
DC.
Recommendation: voltage and current
(approximate):
6 V, 500 mA
8 V, 400 mA
9 V, 350 mA
10 V, 300 mA
12 V, 300 mA
15 V, 250 mA

7
0.5 A fast-blow fuse will burn out. It is
accessible through the battery com-
partment; a spare fuse is provided
within the unit. The locations of both
the actual and the spare fuse are shown
in the drawing on the inside of the bat-
tery compartment lid. A pair of regular
pliers (not "needle-nose") can be used
to facilitate changing the fuse.
By maintaining separate grounds for
audio signals and for powering, the
supply regulation circuitry of the
VMS 5 U permits the sharing of a com-
mon power source with other equip-
ment, without the risk of ground loops.
Notes on operation with an AC
power supply
Any AC power supply that will deliver
at least 7 V at 500 mA in actual use
and an open-circuit voltage of no more
than 16 V will be suitable. For exam-
ple, the SCHOEPS AC power supply
VMS 5 DC (input = 230 VAC, equipped
with "Euro plug") delivers a stabilized
12 Volts DC.
Please note: Different countries use
different AC voltages. Always make
sure that your power supply is appro-
priate for the AC voltage where you are.
Notes on operation with exter-
nal batteries
The batteries should have a nominal
voltage of 6 to 12 Volts and a capacity
of at least 500 mAh. A 6-Volt set of
gelled lead-acid rechargeable batteries
Note the polarity of the DC power
connector: the positive pole of the
power supply must be connected to
the center contact of the external
powering socket (<18> on page 3).
The unit will not be harmed by reverse
polarity, but will not operate; a protec-
tive diode will prevent current from
flowing.
If a sufficient external DC voltage is
connected to the external powering
socket of the unit, the "EXT" LED (<13>
on page 3) will light, even if the unit is
turned off; it is strictly an indication of
available powering, not of the unit’s
on/off status. In this mode of opera-
tion, any batteries inside the unit will
neither be charged nor discharged.
If for any reason the external power-
ing should drop below the minimum
required voltage (e.g. loss or reduction
of AC power), the unit will immediately
switch over to battery power, assum-
ing of course that batteries of sufficient
voltage are in the unit; the yellow LED
will then go out. This automatic switch-
over will occur without any disturbance
in the audio signal.
The “LOW BAT” LED <13> will blink
when the input voltage is less than or
equal to about 7.5 Volts, but this can
be ignored unless the battery indicator
is at the low end of the red region.
The meter is calibrated with reference
to internal batteries and will “under-read”
slightly with external power sources.
If too high a voltage is applied to the
external powering socket, the internal

with a capacity of 3.5 Ah can power
the VMS 5 U for about 12 hours.
9-Volt transistor radio-type batteries
have excessive internal resistance and
insufficient capacity; they cannot be
used.
Please note: When running on
external batteries, during any longer
pauses (or at the end of a recording)
the unit should be switched off and
the external batteries disconnected.
Simply turning the unit off would not
prevent draining the external batteries,
since a residual current of about 40
mA is drawn from any external power
source. And disconnecting the external
power connector without switching
the unit off would cause a switchover
to any internal batteries, drawing the
full operating current from them.
5. Connecting microphones
The VMS 5 U can be used with 48
Volt phantom powered microphones
or with microphone capsules and the
active Y-cable of the SCHOEPS
"Colette" series. A switch (<19> on
page 3) on the back of the unit selects
one of these two types of inputs.
If the setting of this switch must be
changed while the unit is in use, please
lower the headphone volume level or
remove your headphones temporarily.
8
Connecting 48-Volt phantom pow-
ered studio condenser microphones
For the highest-quality, lowest-noise
recordings, use condenser microphones
with a sensitivity of at least 8 mV/Pa.
Turn the unit off and connect the
microphones to the inputs (<16> on
page 3) on the back of the unit. The
input selector switch <19> must be in
its downward position (pointing to the
words "Made in Germany"). The "P48"
switch <11> must be in the "ON" posi-
tion for phantom powered microphones.
Then the unit can be powered on.
For ordinary stereo recordings (not
M/S), channel I is usually the left chan-
nel while channel II is usually the right.
For M/S recordings, the "mid" micro-
phone (e.g. a forward-facing cardioid
or supercardioid) should be connected
to channel I, while the "side" (figure-8)
microphone should connected to
channel II.
Connecting SCHOEPS micro-
phones with an active Y cable
If the recording environment is rela-
tively free of interfering signals, it is
also possible to use an unbalanced
cable such as the SCHOEPS
KCY 250/5I. An input for this type of
cable is available on the back of the
unit <15>.
To use this input, turn the unit off,
attach the cable to the VMS 5 U and
attach two SCHOEPS Colette-series
capsules to the cable. The input selec-
tor switch <19> must be in the "KCY"

9
control should normally remain at its
center detent setting.
In M/S recording, the Balance setting
controls the ratio of mid to side signal
and thus will affect the stereo image
width and the maximum recording
angle.
8. Signal level indicators
The two LEDs <1> serve as a rough
indication of signal levels; they always
indicate the higher level of the two
channels. The yellow LED can and
should be lit very frequently, but if the
red LED is lit at all it should be seldom
and only quite briefly.
9. Low-cut filter
A 20 Hz high-pass filter with a slope
of 18 dB/octave is active at all times. It
suppresses infrasonic interference, but
is otherwise nearly inaudible in its
effect.
An additional, "soft" low-cut filter
(150 Hz, 6 dB/octave) can be activated
by switching the "FILTER" toggle
switch to the down position, in order
to reduce wind and solid-borne noise
even further, or to compensate for the
bass boost which directional micro-
phones exhibit when used close to
sound sources ("proximity effect"). But
this filter should be used only when
needed since it has a distinctly audible
effect.
position. Now you can turn the unit on.
For ordinary stereo recordings (not
M/S), the cable marked in red should
carry the right channel signal; it should
carry the signal from the "side" (figure-
8) capsule in M/S recording.
6. Setting the preamp gain
When recording, the GAIN control
<2> should be set as high as possible
for the sake of a good signal-to-noise
ratio. It is set correctly if the red LED of
the signal level indicator <1> lights up
only rarely and very briefly during the
loudest passages to be recorded.
Setting the gain any higher will pose a
danger of overload distortion.
When using the VMS 5 U for dema-
trixing after recording, the GAIN control
should be set to 4 or 10 dB again by
observing the yellow and red LEDs.
Please note: Phantom power should
be turned off when dematrixing after
recording. Please remove headphones
or turn the headphone volume control
to its lowest setting when turning off
phantom powering.
7. Balance setting
To compensate for a possible differ-
ence in the sensitivity of the micro-
phones, the Balance knob <3> can be
used to adjust the relative gain of the
two channels. When microphones of
equal sensitivity are used, the balance

10. Connecting the outputs
For A/B, X/Y or ORTF recordings the
task of the VMS 5 U is to amplify and
filter the signals presented to its inputs,
and to deliver the result to the outputs
<17>. For this purpose the "Output"
switch (<7> on page 3) must be in its
"Preamp" setting.
For M/S recordings there are two
possibilities. The M and S signals can
be sent through the matrix and the
resulting L and R signals recorded
("Output" switch in the "Matrix" posi-
tion), or the M and S signals can be
recorded directly, and dematrixed in
subsequent playback (switch in the
"Preamp" position). Dematrixed L and
R signals can be monitored while the
M and S signals are being recorded.
If possible, the equipment to which
the main outputs of the VMS 5 U are
connected should have balanced inputs
for best possible rejection of hum and
radio-frequency interference. Not all
recorders offer balanced inputs, but
with short cables (less than a few
meters) this is generally not so critical.
If you need to connect the output of
the VMS 5 U to an unbalanced input,
the best way is to connect pin 2 of the
VMS 5 U's output to the "hot" contact
of the input, while the shield of the
cable to the recorder’s inputs should
be connected both to pin 1 and the
housing of the XLR connector at the
VMS 5 U’s outputs.
With equipment whose circuit ground
10
is not directly connected to its chassis
ground, the risk of interference can be
lessened by using shielded, two-con-
ductor cable. As before, pin 2 of the
VMS 5 U's output should be connected
to the "hot" contact of the input,
while the circuit ground will be carried
by pin 3 of the output, and the cable
shield will then merely connect the two
component housings with one another.
Connecting the VMS 5 U to an unbal-
anced input
VMS 5 U
recorder
1
3
2

11
11. Connecting headphones
Any stereo headphones with an
impedance of 32 to 2,000 Ohms can
be connected to the headphone out-
put of the VMS 5 U. Headphones with
a miniature plug can be used with a
commonly available adapter.
The headphone output is used for
monitoring; a switch <9> selects either
the unaltered "PREAMP" signals (e.g.
for A/B, X/Y or ORTF-style recording)
or the "MATRIX" outputs (left and right
signals derived from an M/S recording
setup).
Please note: When turning phan-
tom power on or off, or when setting
the input selector switch, please turn
the headphone volume control to its
minimum setting.
In the interest of hearing conserva-
tion, do not monitor at high sound
levels. Prolonged listening through
headphones at high levels can damage
your hearing more severely than listen-
ing at what may seem like the equiva-
lent level on loudspeakers.
12. M/S recording / WIDTH
M/S is used primarily when recording
sound for film or television, but is also
useful for music recording. Its advan-
tage is that the stereo image can be
adjusted after the recording has been
made, in post-production.
The principle of M/S: As with other
stereo recording techniques (A/B, X/Y,
ORTF, "Blumlein" etc.) two micro-
phones are used, of which one (the
"side" or "S" channel) must have a
figure-8 directional pattern; the other
microphone (the "mid" or "M" chan-
nel) may have any desired pattern. The
two microphones are placed one
directly above the other, but while the
M-channel microphone is aimed at the
sound source, the S-channel micro-
phone is aimed 90º to the left (see
illustration, top of page 12). Thus the
two microphones do not directly pick
up the left and right channel playback
signals; instead, these signals are
derived by means of a sum-and-differ-
ence matrix circuit such as the one in
the VMS 5 U. The left channel play-
back signal is formed by adding M+S,
while the right channel playback signal
is formed by subtracting M-S. This
works because the two lobes of a fig-
ure-8 microphone’s pattern are in
opposite polarity to one another.
The result is as if two "virtual micro-
phones" had been aimed symmetrical-
ly with respect to the main axis of the
actual M-channel microphone. The
directional pattern of these "virtual
microphones" depends on the actual
pattern of the M-channel microphone
as well as on the setting of the "WIDTH"
control <6>, which determines the rel-
ative gain applied to the M and S sig-
nals fed into the matrix.
The "WIDTH" control sets the width
of the stereophonic image. The useful

12
range of settings will depend on the
type of microphone used for the M
channel; the broader its directional
pattern, the farther the "WIDTH" con-
trol can be turned up. This control also
affects the recording angle – the widest
arc, as viewed from the microphones'
position, which may be picked up
without creating ambiguity as to the
location of sound sources. In general,
the greater the directionality of the M-
channel microphone, the narrower the
recording angle will be (see the dia-
grams on the opposite page).
The farther the "WIDTH" control is
turned up, the greater will be the angle
between the "virtual microphones." The
recording angle, on the other hand,
will become narrower. Any sound
sources located beyond that angle
(near the edges) will be picked up out
of phase, and will seem to jump over
to the channel opposite from where
they were in reality.
The optimal WIDTH control setting
depends on the directional pattern of
the microphone being used for the M
channel, the relative sensitivity of the
two microphones, and the recording
environment. Setting "4" would be a
suggested starting point.
In M/S recording, the WIDTH control
and the balance setting both control
the relationship of M to S, thus affect-
ing the stereo image width and the
recording angle as well. When using
One possible way to set up an M/S
microphone arrangement:
top: cardioid as M microphone
bottom: S microphone (figure-8)
The MK 8 as viewed from
the front, when the micro-
phone is used horizontally
as shown.
red dot
0°
S→channel II
M→channel I

13
ϕ = one-half the recording angle,
α = one-half the angle between the two “virtual microphones”
“Virtual microphones” in an M/S recording, showing the left channel
result (M+S) when a cardioid is used for the M-channel microphone
Extreme settings of the WIDTH control
can lead to unexpected and possibly
undesirable results. A sound source
that is moving from left to right, for
example, will normally be heard in a
steadily decreasing degree in the left-
channel output signal. But if that
sound source crosses past the null in
the polar diagram of the left-channel
"virtual microphone" (see above), its
presence in the left-channel output
signal will begin to increase again. This
will cause it to be located incorrectly
within the stereo image. The signal
will also be out of phase, which can
cause further problems: in a Dolby
Surround recording, for example, this
sound source could be audible in the
surround-channel loudspeakers.
main stereo axis
Increasing ratio of S signal to M signal
(unusable)
mono

14
microphones of equal sensitivity, the
BALANCE knob should normally be at
or near its center setting. If microphones
of unequal sensitivity are used, the
BALANCE control should be set so as
to compensate for as much as possible
of the difference; otherwise the
WIDTH control may not offer a useful
range of settings.
M= MK 2, CCM 2
M= MK 21, CCM 21
M= MK41, CCM 41
M= MK4, CCM 4
Effect of the WIDTH control on the recording angle, for various
types of "M"-channel microphones
Effect of the WIDTH control on the gain applied to
"M" and "S" signals
S/M
M
M
S
S
012345678910
012345678910
+10 dB
-10 dB
-20 dB
0 dB
180°
60°
0°
120°
The BALANCE control is calibrated to
the sensitivity of Schoeps microphones,
with a cardioid as the “M” channel
microphone of reference. When using a
Schoeps super-cardioid for the “M”
channel, the default setting of the
BALANCE control would be 2 dB to
the left of the normal center setting.

15
13. M/S dematrixing in
post-production
If the M and S channels of an M/S
recording are recorded directly, they
can be dematrixed afterward by the
VMS 5 U to produce left- and right-
channel signals. The recorded signals
can simply be fed into the inputs (with
phantom power turned off!) and the
OUTPUT switch set to the "MATRIX"
position. The stereo image width can
then be adjusted with the WIDTH con-
trol. Typically the GAIN knob <2>
would be set to the 4 dB or 10 dB
position.
This capability is especially valuable
because monitoring a live recording
over headphones may not allow the
engineer to find an optimal setting for
the stereo image width as it would be
reproduced through loudspeakers.
In addition to experimenting with
various width settings, it can some-
times be very useful to equalize the M
and S channels separately. For exam-
ple, boosting the frequencies below
100 Hz in the M channel prior to
dematrixing can increase the sense of
spaciousness in a recording without
upsetting the accuracy of its overall
stereo imaging (not recommended for
LP recordings, or where there is exces-
sive low-frequency noise or “room
rumble”).
14. M/S side inversion
switch
Whenever a pair of microphones is
suspended overhead, the sense of left
and right can become reversed. In M/S
recording with the “M/S side inversion
switch” <5> the output channel
assignments can be corrected if this
should occur.

16
15. Technical Specifications
Inputs
Switchable between two XLR-3 sockets and a
special input for the SCHOEPS KCY “active
cable.”
XLR inputs are balanced and transformerless;
the 48 Volt phantom powering is switchable
(for subsequent M/S dematrixing).
Input impedance: 20 kOhm
Recommended min imum sensitivity of micro-
phones at XLR inputs: 8 mV/Pa
Maximum input level for <0.5% THD:
at 4 dB gain setting: 14 dBV (5Vrms)
at 20 dB gain setting: -2.2 dBV (780 mVrms)
Preamplifier gain settings: 4, 10, 20, 30 or 40 dB
Overall performance specifications of VMS 5 U
with SCHOEPS CMC 64 (cardioid):
Equivalent noise level: 25,5 dB (CCIR, qps);
15 dB (A-weighted)
Maximum sound pressure level:
(at 4 or 10 dB gain): limited by CMC micro-
phone amplifier to 132 dB
(at 20 dB gain): 130 dB
(at 30 dB gain): 120 dB
(at 40 dB gain): 109 dB
Level indicators: -20 dB, -3 dB
The “Balance” potentiometer permits compen-
sation for differences in microphone sensitivity.
A polarity inversion switch permits rapid change
of channel assignments in M/S recording.
Outputs
The outputs are impedance-balanced, trans-
formerless and are switchable between the
amplified microphone signals and the decoded
M/S stereo signals.
Output impedance: 100 Ohm
Maximum output level for <0.5% THD:
18 dBV (8 Vrms)
Recommended load impedance: 2 kOhm or
greater
Headphone output
Switchable; either the amplified microphone sig-
nals (=left/right for A/B recordings, or mid/side
for M/S) or the decoded M/S stereo signals
can be monitored.
Headphone impedance: 32 - 2,000 Ohms
Headphone socket: ¼” stereo phone jack
Filters
An infrasonic filter (20 Hz, 18 dB/oct.) is perma-
nently active. In addition, a low-cut filter
(150 Hz, 6 dB/oct.) can be switched on.
The upper frequency limit is 80 kHz.
Powering
An internal filter/regulator circuit which gener-
ates and stabilizes the supply voltages permits a
wide range of input voltages (5.5 V to 15.5 V).
Operation with internal batteries (possi-
bly rechargeable)
Number and type of cells: 6 x AA (also called
LR6)
Recommended primary cell type: Alkaline
Recommended rechargeable cell type: NiMH
A user-replaceable fuse protects against revers-
ing the polarity of the batteries.
Battery life with alkaline cells: ca. 8.5 hours
Battery life with rechargeable batteries:
ca. 3 hours (700 mAh NiCd)
ca. 5 hours (1100 mAh NiMH)
ca. 5,5 hours (1300 mAh NiMH)

ca. 7 hours (1600 mAh NiMH)
ca. 12 hours (3400 mAh gelled lead acid bat-
tery (external))
A voltage indicator displays the battery voltage
within the unit.
A warning LED will begin to blink if the voltage
falls beneath a critical value (time remaining
at that point with most higher-capacity
rechargeable batteries: at least 10 minutes).
The unit will shut itself off automatically to help
prevent damage from draining the batteries
completely.
External powering
An appropriate AC power adapter is available
(model VMS 5 DC). Other adapters offering a
regulated output voltage of 6 Volts DC (at
500 mA) to 15 Volts DC (at 250 mA) can also
be used. Under no circumstances should an
open-circuit voltage of 16 V be exceeded;
otherwise a fuse inside the VMS 5 U will
blow. (See page 7.)
Coaxial socket, 5.5/2.1 mm diameter
Reverse polarity will not damage the unit,
though it will not operate.
If external powering is present, any internal bat-
teries are automatically disconnected (indicated
by yellow LED “EXT.”). This protects the bat-
teries from being discharged unintentionally.
The battery voltage indicator displays the level of
any external powering.
External powering with outboard rechargeable
battery: nominal 6 – 12 V; we recommend
gelled lead-acid batteries (6 V, 3400 mAh
type = 12 hours of operation).
Parallel operation of a VMS 5 U along with one
or more other pieces of equipment from a
single power supply is generally possible,
because of the internal voltage regulation.
Robust, black aluminum case.
Overall measurements: (W ×H ×D):
162 mm ×60 mm ×172 mm
(approximately 6-2/3” ×2-1/3” ×6-3/4”)
Weight (with batteries): 1.1 kg (approximately 2
lb. 7 oz.)
These specifications are subject to revision and
correction without notice.
17

18
16. Block diagram

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Frequency response curves: above: without low-cut filter; below: with low-cut filter

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17. Important information
The VMS 5 U was designed for profes-
sional applications in indoor and out-
door recording, but should be used
only in a dry place (e.g. not in the rain,
since that could cause a hazardous
condition for the user as a result of AC
powering). Apart from that potential
hazard there is also the risk of water
damage to the unit itself.
Do not operate the unit in strong, direct
sunlight because of the risk of over-
heating internal batteries. The allowable
temperature range is -20° C to + 50° C.
The headphone volume levels which
can be achieved with this unit can, with
prolonged use, cause lasting damage
to one’s hearing. Please monitor only at
the minimum necessary levels.
Cables: Use only shielded cable with at
least 90% shield coverage. All SCHOEPS
cables fullfill this requirement.
Declaration of conformity
For the VMS 5 U we herewith declare
that it complies with the directive
89/336/EWG on EMC (electromagnetic
compatibility) of the EC council.
This product is not subject to further
directives.
For the judgement of this product in
respect of EMC the following stan-
dards are applicable:
EN 55103–1, EN 55103–2
The manufacturer accepts full respon-
sibility for this declaration.