background image

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.

Summary of Contents for VMS 5 U

Page 1: ...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...

Page 2: ...ts 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...

Page 3: ...3 15 16 19 17 18 8 9 10 11 12 13 14 1 2 3 6 7 4 5...

Page 4: ...tweight 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 inser...

Page 5: ...echarge 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...

Page 6: ...neath 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...

Page 7: ...ble 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 b...

Page 8: ...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...

Page 9: ...ed 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...

Page 10: ...ible 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...

Page 11: ...cording 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 a...

Page 12: ...ll 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 opti...

Page 13: ...eard 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...

Page 14: ...1 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 0 1 2 3 4 5 6...

Page 15: ...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...

Page 16: ...alanced 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 Recommen...

Page 17: ...ll 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 dis...

Page 18: ...18 16 Block diagram...

Page 19: ...19 Frequency response curves above without low cut filter below with low cut filter...

Page 20: ...0 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...

Page 21: ...to misuse e g incorrect operation mechanical damage abuse or acts of God This guarantee is nullified in the event of tampering by unauthorized persons or agencies To secure your rights under this guar...

Page 22: ...22...

Page 23: ...23...

Page 24: ...24 Subject to change without notice 010102...

Reviews: