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FEL MicBooster MB-1 Technical Specification

The FEL MicBooster MB-1 is a portable phantom powered microphone preamplifier. It passes the phantom power on to its input for microphone powering.

Designed for situations where low level mic signals will benefit from a level boost. It is ideally placed at the microphone end of long cable runs, which can be susceptible to buzzes, hums and noise. This way the microphone signal is lifted relative to any potential noise and before it reaches the mixing desk or recorder.

Audio performance

• 20, 30 or 40 dB of gain adjustable in three discrete click-free steps, for accurate repeatable gain setting.
• 20 Hz to 20 kHz bandwidth.
• High immunity to RF interference due to transformer balanced input and fully screened metal enclosure.
• Low impedance transformer balanced output to drive long cable runs.

Power

• Powered solely from 48 volt phantom power.
• No batteries to change or run down.
• No mains cables to run in.
• No power switch to forget.
• As long as the mixing desk or recorder is supplying phantom power then the preamp is working.
• Ultra low current amplifier; using only a fraction of the available power leaving the remainder to run the microphone as normal.

Transformer balanced input and output

• Custom manufactured Sowter transformers.
• Superb quality and freedom from interference.
• Complete audio isolation between the source and the mixing desk.
• Transformers have mu-metal cores to ensure minimal distortion, and a thick mu-metal can protects the transformer from hum fields. Multiple interleaved windings are used for high bandwidth and clean transient response.

Mechanical construction

• Strong extruded aluminium case.
• Protective nylon bezels either end.
• Aluminium chassis
• Internal circuitry is contained in its own screened can and epoxy encapsulated for maximum moisture resistance and robustness.
• Gain switch is protected from knocks being positioned between the XLR connectors.

Gain 20, 30 or 40 dB, switch selectable

Gain Accuracy ±1 dB (relative to 1kHz level with 150 ohm source)

Frequency response 20 Hz - 20 kHz ± 1 dB, 150 ohm source

Equivalent input noise -120 dB at 20 dB gain, 150 ohm source

THD + Noise Better than 0.08%

Output Clipping Level 0 dBu with 1500 ohm load

Input clipping Level -20 dBu at 20 dB gain to -40 dBu at 40 dB gain

Input Transformer balanced, 1,500 ohm input impedance

Output Transformer balanced 30 ohm output impedance

Power Requirements

48V Phantom Power (DIN 45 596)

Current consumption 850 micro amps

Connectors Neutrik silver plated 3 pin XLR (MB-1S 5 pin).

Dimensions and weight Including switch:

MB-1: 80 mm (l) x 110 mm(w) x 48 mm(h), 520 grams

MB-1S: 120 mm (l) x 110 mm(w) x 48 mm(h), 820 grams

Operational Guidelines

The preamplifier is designed only to boost low level mic signals before they go into the microphone input of a recorder or sound mixer.

It should not be used to amplify a signal to line level as at output levels above 0 dBu distortion will occur. A typical situation may be an effects mic which would normally have 50 dB of gain at the mixer. Instead you could reduce the mixer gain to 30 dB and have 20 dB provided close to the microphone by the MicBooster.

The preamplifier is best positioned as close to the microphone as possible, in this way the maximum signal to noise benefit will be achieved.

It is powered from 48 volt phantom power which is normally switchable on the microphone input of most professional recorders and mixers. It cannot be used with other forms of microphone power.

CE conformity

Conforms to European EMC directive 89/336/EEC: Professional Audio Products Standard EN 55103 (1996); Part 1 (emissions) and Part 2 (immunity). The MicBooster MB-1 and MB-1S are intended for use in environments E1(residential) and E2 (light industrial). It meets the applicable tests and performance criteria found in the standard for these environments. EMC conformance is based on the use of screened connecting cables.