The Royer dBooster (model R-DB20) is an in-line signal booster for passive ribbon and dynamic microphones. It sits between the mic and your preamp or audio interface, runs on the 48 V phantom power already at that input, and adds 12 dB or 20 dB of clean gain from a front-panel switch. Royer first built it to give its R-10 ribbon extra gain on vocals and acoustic instruments, and it lifts any passive low-output mic the same way.

How It Works

The input stage uses paralleled PNP transistors running in pure Class A, and its high 3.6k ohm input impedance keeps the ribbon from being loaded down, which holds coloration and distortion low. A pair of op-amp line drivers feeds a 300 ohm output that drives long cable runs, mic splitters and vintage-style preamps without losing gain. The circuit draws regulated power from phantom and shields the ribbon from it, so the dBooster is safe with any ribbon mic.

Setting It Up

Connect the mic to the dBooster input with a standard XLR cable and the output to a phantom-powered preamp or interface, then turn phantom on and bring the gain up slowly. The 12 dB setting suits most sources, and 20 dB is for very quiet sources, very low-output mics or low-gain preamps. The output is a boosted mic-level signal meant for a mic input.

Features

• 12 dB or 20 dB of gain, set by a front-panel switch
• Class A input stage with paralleled PNP transistors for low noise
• High input impedance that keeps loading off the microphone
• Low output impedance for long cable runs, splitters and vintage-style preamps
• Regulated internal power from 48 V phantom with true electrical isolation
• Safe with all ribbon microphones and shields them from phantom power
• Assembled in the USA

Specifications

• Model: R-DB20
• Gain: 12 dB or 20 dB, switchable
• Frequency response: 20 Hz to 20 kHz, ±0.25 dB
• THD+N: 0.0015% at 20 dB gain (-25 dBu input), 0.001% at 12 dB gain (-6 dBu input)
• IM distortion: Below 0.002% at 20 dB (800 mV output), below 0.005% at 12 dB (2.6 V output)
• Self-noise: Below 11 dBA at 20 dB, below 15 dBA at 12 dB (referred to -48 dB re 1 V/Pa)
• Headroom: 127 dB at 20 dB, 120 dB at 12 dB
• Input impedance: 3.6k ohms
• Output impedance: 300 ohms (20 dB setting)
• Connectors: Balanced XLR input and output (pin 2 hot)
• Power: 48 V phantom, about 5 mA idle and 7.5 mA at full output
• Dimensions: 92 x 51 x 41.3 mm (3.62 x 2.0 x 1.62 in)
• Weight: 170 g (6 oz)
• Warranty: 1 year, parts and labor