ColetteStereo Microphone Preamplifier VMS 5 U
| VMS 5 U | |
|---|---|
| Frequency response | 20 Hz – 80 kHz (-3 dB) |
| Input impedance | 20 kΩ |
| Input | switchable between two XLR-3F sockets and a special input for the SCHOEPS KCY Active Cable |
| Input | recommended minimum sensitivity of microphones at XLR inputs: 8 mV/Pa |
| Maximum input level for 0.5% THD | at 4 dB gain setting: 14 dBV (5 Vrms) at 20 dB gain setting: -2.2 dBV (780 mVrms) |
| Preamplifier gain | can be set to 4, 10, 20, 30 or 40 dB |
| Maximum sound pressure level at 0.5% THD | with CMC 6 and MK 4 (cardioid) at a gain of 4 dB: 132 dB at 10 dB: 132 dB at 20 dB: 130 dB at 30 dB: 120 dB at 40 dB: 109 dB |
| Equivalent noise level | at a gain of 4 dB: 16.5 dB-A at 10 dB: 16 dB-A at 20 dB: 15.5 dB-A at 30 dB: 15.5 dB-A at 40 dB: 15.5 dB-A |
| Equivalent noise level (CCIR) | at a gain of 4 dB: 27.5 dB-CCIR at 10 dB: 26.5 dB-CCIR at 20 dB: 26 dB-CCIR at 30 dB: 26 dB-CCIR at 40 dB: 25.5dB-CCIR |
| Level indicators | -20 dB, -3 dB |
| Additional comments | The BALANCE potentiometer permits compensation for differences in microphone sensitivity up to 20 dB. |
| Additional comments | The polarity inversion switch permits rapid change of input channel assignments in M/S recording, as when changing between an upright stereo microphone and one that is hanging downwards. |
| Output | The outputs are impedance-balanced and transformerless, and are switchable between the amplified microphone signals and the decoded M/S stereo signals. |
| Output impedance | 100 Ω |
| Maximum output level for 0.5% THD | 18 dBV (8 Veff) |
| Minimum recommended load impedance | 2kΩ |
| Headphone output | Switchable; either the amplified microphone signals (=left / right for A/B recordings, or mid / side for M/S) or the decoded M/S stereo signals can be monitored. |
| Output impedance | 32 – 2,000 Ω |
| Output socket | 1/4'' stereo phone jack |
| Filter(s) | An infrasonic filter (20 Hz, 18 dB/oct.) is permanently 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 generates and stabilizes the supply voltages permits a wide range of input voltages (5.5 V to 15.5 V). |
| Battery powering | Operation with internal batteries (possibly rechargeable) Number and type of cells: 6 × AA (also called LR6) Recommended primary cell type: Alkaline Recommended rechargeable cell type: NiMH A user-replaceable fuse protects against reversing 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 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 1300 mAh rechargeable batteries: at least 10 minutes). The unit will shut itself off automatically to help prevent damage from draining the batteries completely. The unit resumes operation only after the on / off switch is used. |
| External powering | An appropriate AC power adapter is available (model VMS 5 DC-W). Other adapters offering a regulated or unregulated 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. 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 batteries are automatically disconnected (indicated by yellow LED “EXT.”). This protects the batteries 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. |
| Dimensions | Overall measurements: (W × H × D): approximately 6-2/3'' × 2-1/3'' × 6-3/4'' which corresponds to 162 × 60 × 172 mm |
| Weight | with batteries: approximately 2 lb. 7 oz. which corresponds to 1.1 kg |
A special version (VMS 5 U lin.) without the fixed 20 Hz low-cut filter is available for measurement applications.
This version is not recommended for audio applications because of the possibility of infrasonic noise problems.
This version is not recommended for audio applications because of the possibility of infrasonic noise problems.