RDL HR-MP2 Dual Microphone Preamplifier

Radio Desgn Labs' HR-MP2 is a dual-channel microphone preamplifier with line-level outputs. Each section provides identical rear-panel signal connections and front-panel controls.

Each preamplifier is equipped with a front-panel FILTER switch to enable or disable a 6 dB/octave low-cut filter with a -3 dB cutoff at 80 Hz. Two additional switches on each input select 24 V or 48 V phantom if the master PHANTOM power selector is ON. The INPUT PAD switch allows the operator to attenuate the input signal by 15 dB prior to the preamplifier input stage, increasing the maximum input level from +5 dBu (attenuator out) to greater than +20 dBu. A POLARITY switch provides signal polarity reversal if needed. The GAIN control provides continuous adjustment between 20 dB and 60 dB. An RDL Dual-LED VU meter is provided adjacent to each gain control. The meters are calibrated to indicate +4 dBu at the associated balanced output. A separate CLIP LED flashes if a signal peak is within 3 dB of clipping. The trigger threshold of the CLIP LED is 17 dB above a normal +4 dBu output.

The HR-MP2 offers exceptional input headroom, wide flat frequency response and extremely low noise with very high common-mode signal rejection. Total harmonic distortion and crosstalk are below the noise floor, allowing the HR-MP2 to be operated as a stereo preamplifier or as two separate mono preamplifiers.

Each preamplifier provides three balanced line-level output formats: XLR male, detachable terminal block and 1/4" TRS. A separate summing amplifier provides a combined mono output on a line-level detachable terminal block. Balanced outputs may be wired unbalanced. The rear panel also provides a detachable terminal block and a power input jack to connect 24 Vdc power.

Features:

• Two Independent Microphone Preamplifiers
• Balanced XLR Microphone Inputs
• Independent Controls for Each Preamplifier
• Switch-Selectable Low-Cut Filter
• Front-Panel 20 to 60 dB Gain Control
• Switch-Selectable 24 or 48 Volt Phantom
• Switch-Selectable 15 dB Input Pad
• Switch-Selectable Polarity Reversal
• Dual-LED VU Meter for Each Preamplifier
• CLIP Indicators for Peaks 3 dB Below Clipping
• Balanced Line-Level Outputs
• Each Output Allows Balanced or Unbalanced Connection
• Each Preamp Output on XLR, 1/4" TRS or Detachable Terminal Block
• Separate Summed Output 1 + 2 on Detachable Terminal Block

Specifications

• Typical Performance:
  • Inputs (2): XLR (3 pin, rear panel,1=GND, 2+, 3-)
  • Input level (for +4 dBu output): -56 dBu to 0 dBu (maximum gain without pad, minimum gain with pad)
  • Maximum Input Level: >+5 dBu (input pad disabled), +22 dBu (input pad enabled)
  • Input Impedance: < 1 kOhm balanced
  • Phantom power: Switchable 24 V or 48 V phantom (IEC 1938: 1996-12)
  • Input pad (2): 15 dB nominal (1 per preamplifier)
  • Outputs (7): Each preamplifier (rear-panel): XLR (3 pin,1=GND, 2+, 3-), detachable terminal block, 1/4" TRS
  • Mono sum (rear-panel): detachable terminal block
  • Output level: +4 dBu balanced, -4 dBV unbalanced; +24 dBu maximum balanced
  • Output Impedance: 150 ohms balanced
  • Channels: 2 (1 and 2; may be used for stereo or as two separate mono preamplifiers)
  • Gain Trim (2): 20 dB to 60 dB (front panel adjustable; one for each preamplifier)
  • Frequency Response: 10 Hz to 70 kHz (+/- 0.5 dB, FLAT); -3 dB @ 80 Hz (LOW-CUT FILTER enabled)
  • THD: Below noise floor
  • CMRR: > 80 dB (50 Hz to 5 kHz)
  • Residual Noise (below +4 dBu output):
  • Crosstalk: Below noise floor
  • Indicators (7): POWER LED (blue), Dual-LED VU meter (2, green/red), CLIP (2, red)
  • Power Requirement: 24 Vdc @ 175 mA (200 mA with phantom), Ground-referenced
  • Mounting: Rack-mount using optional rack adapters such as HR-RA2; or operate free-standing (feet included)
  • Dimensions: 1.7" H x 8.6" L x 4.59" (4.3 x 20.6 x 11.66 cm)