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
Table of contents Control layouts: 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 . . . . .
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The VMS 5 U is designed for indoor and outdoor professional recording applications.
When the unit is first turned on, there will be a four- to five-second delay before it is ready for use. This is necessary so that the unit can function reliably 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.
not, the batteries need to be changed, or recharged if they are NiCd/NiMH types. When running on internal batteries, 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 automatically.
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 protective diode will prevent current from flowing.
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.
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" (figure8) capsule in M/S recording. 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. 6. Setting the preamp gain 8.
. Connecting the outputs VMS 5 U For A/B, X/Y or ORTF recordings the task of the VMS 5 U is to amplify and 1 2 filter the signals presented to its inputs, 3 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.
. Connecting headphones stereo recording techniques (A/B, X/Y, Any stereo headphones with an impedance of 32 to 2,000 Ohms can be connected to the headphone output 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).
red dot 0° S→channel II M→channel I The MK 8 as viewed from the front, when the microphone is used horizontally as shown. One possible way to set up an M/S microphone arrangement: top: cardioid as M microphone bottom: S microphone (figure-8) range of settings will depend on the type of microphone used for the M channel; the broader its directional pattern, the farther the "WIDTH" control can be turned up.
main stereo axis Increasing ratio of S signal to M signal mono “Virtual microphones” in an M/S recording, showing the left channel result (M+S) when a cardioid is used for the M-channel microphone (unusable) ϕ = one-half the recording angle, α = one-half the angle between the two “virtual microphones” Extreme settings of the WIDTH control can lead to unexpected and possibly undesirable results.
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. The BALANCE control is calibrated to the sensitivity of Schoeps microphones, with a cardioid as the “M” channel microphone of reference.
13. M/S dematrixing in post-production 14. M/S side inversion switch 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 rightchannel 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 control. Typically the GAIN knob <2> would be set to the 4 dB or 10 dB position.
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 microphones 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.
ca. 7 hours (1600 mAh NiMH) ca. 12 hours (3400 mAh gelled lead acid battery (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.
16.
Frequency response curves: above: without low-cut filter; below: with low-cut filter 19
17. Important information The VMS 5 U was designed for professional applications in indoor and outdoor 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 overheating internal batteries.
18. Warranty We guarantee our products for a period of twenty-four months, except for cables, batteries and cells (including rechargeable batteries and cells) and any other products of other manufacturers for which SCHOEPS is only the reseller; for these products the period of guarantee is six months. The guarantee period begins on the date of purchase. Please provide your bill of sale in all cases as proof of guarantee; without it, repairs will be undertaken only at the owner’s expense.
Subject to change without notice 010102 24
