HUM Audio RP-2 is a two-channel microphone preamplifier with transformer-balanced, fully discrete Class-A circuitry and a dedicated remote controller — HUM Audio's flagship studio preamp, and the direct topological basis for the channel preamps in the N-TROPHY console and N-Closure modules. Built around Jensen JE990 opamps, gain range 20–60 dB. The defining feature is the physical separation of the preamp box from the controller: the two units connect via a single standard XLR cable, allowing the preamp to be positioned close to the microphones — minimizing mic cable run length and associated signal loss — while the controller sits conveniently on the console surface. The gain control circuit uses a four-cell photocell (opto) network — complete electrical separation between the audio path and the control signal, with no mechanical gain-stage influence on the sound at any setting. Hand-assembled in Poland.
Photocell gain circuit and passive M/S matrix
Using photocells (photoelectric cells) for gain control rather than conventional mechanical potentiometers or VCA circuits provides complete electrical isolation between the audio signal and the controller's control circuits — no shared paths that could introduce noise, interference, or sonic degradation at different gain settings. The passive M/S matrix built into the preamp box uses a transformer with a passive matrix network — the signal can be recorded in encoded M/S format (directly to two DAW tracks for later matrixing in the box) or decoded stereo (ready L/R after matrixing inside the preamp), with no active circuits anywhere in the matrix path. Operating modes: Stereo L/R, M/S encoded, M/S decoded, and Dual/Mono. The Air Boost function is a passive, smooth-sounding high-frequency booster modeled on the HF boost circuitry in Pultec-style processors — adds air and openness without digital edge. HPF at 50 Hz: passive filter at 6 dB/oct, switchable.
Signal path architecture and remote controller
The RP-2 signal path is transformer-balanced at both the microphone input and the line output — no electrolytic capacitors in the audio path, extremely short signal route, audiophile-grade selected components throughout, military-spec silver cables. Microphone input impedance of 2 kOhm is optimal for passive ribbon microphones without ribbon damping. Line/instrument input impedance is 100 kOhm. Maximum output level is +27 dBu, output impedance 600 ohms. THD+N is 0.027% at 60 dB gain. All functions in the remote controller are switched by high-quality relays and Alps potentiometers. The controller draws power through the same XLR cable that connects it to the preamp. Included in the set: preamp box, remote controller, external power supply, custom cables, mic head dust covers, and a flight case. Two-year warranty.
KEY FEATURES
- 2-channel microphone preamp — transformer-balanced, fully discrete, Class-A
- Jensen JE990-based — same topology as N-TROPHY console and N-Closure modules
- Physical preamp/controller separation — preamp near microphones, controller on the work surface
- 4-cell photocell (opto) gain circuit — complete electrical isolation of audio path from control signal
- Gain range: +20 dB to +60 dB
- Operating modes: Stereo L/R, M/S encoded, M/S decoded, Dual/Mono
- Passive transformer-based M/S matrix (no active circuits in the matrix path)
- Air Boost: passive Pultec-style HF booster
- HPF 50 Hz, passive, 6 dB/oct
- Pad: -20 dB
- Phase inversion
- Phantom power: +48V
- Mic input impedance: 2 kOhm — optimal for passive ribbon microphones
- Line/Hi-Z input impedance: 100 kOhm
- Maximum output level: +27 dBu; output impedance: 600 ohms
- No electrolytic capacitors in the audio path
- Alps potentiometers and relays in controller; controller powered via XLR cable
- Included: preamp box, remote controller, external PSU, custom cables, mic head covers, flight case
- Hand-assembled in Poland; 2-year warranty
TECHNICAL SPECIFICATIONS
- Type: 2-channel mic preamp, transformer-balanced, discrete, Class-A
- Base opamp: Jensen JE990
- Gain control: 4-cell photocell (opto) circuit
- Gain range: +20 dB to +60 dB
- Input impedance XLR Mic: 2 kOhm
- Input impedance TRS Line/Hi-Z: 100 kOhm
- Maximum output level: +27 dBu
- Output impedance: 600 ohms
- Frequency response: 20 Hz – 50 kHz +/- 0.4 dB
- THD+N: 0.027% @ 60 dB gain
- Phantom power: +48V
- Pad: -20 dB
- HPF: 50 Hz, 6 dB/oct, passive
- M/S matrix: passive, transformer-based
- Preamp–controller connection: 1x standard 3-pin XLR cable
- Preamp connectors: 2x TRS in (gold-plated), 2x XLR Mic in (Neutrik, gold-plated), 2x XLR Line out (Neutrik, gold-plated), 1x XLR Control out
- Preamp dimensions: 355 mm (L incl. sockets) x 144.5 mm (W) x 118 mm (H)
- Controller dimensions: 123.5 mm (L) x 154 mm (W) x 55–59 mm (H)
- Weight: preamp box 4.4 kg; controller 0.5 kg; full set in flight case 9.9 kg
- Warranty: 2 years
