HUM Audio ARM-1L is a phantom-powered active ribbon microphone with a 2-inch (50.8 mm) aluminum ribbon element, 1.8 microns thick, shielded with copper — the longer, more characterful variant of the ARM-1 line, distinguished from the ARM-1S (1-inch ribbon) by blue suspension spider details. Fully discrete active electronics on 48V phantom power deliver -38 dB sensitivity (1 mV/Pa) — 1 dB higher than the ARM-1S — at condenser microphone output levels. The longer ribbon of the ARM-1L produces a more contoured, characterful sound with a fuller low end below 100 Hz and slightly more presence in the upper-mids (6–10 kHz) compared to the more neutral ARM-1S. The ARM-1L is essentially a mono version of HUM Audio's flagship RS-2 recording system, without the stereo and remote control functionality. Hand-built in Poland, reviewed in Sound On Sound.
Long copper-shielded ribbon — full low end and contoured character
The longer ribbon element (2 inches vs 1 inch in the ARM-1S) and copper shielding result in a lower low-frequency boundary (30 Hz vs 40 Hz in the ARM-1S), a fuller low end, and gentle presence in the 6–10 kHz range. Sound On Sound describes the ARM-1L as more contoured and characterful than the ARM-1S — in drum overhead applications it delivered richer low-mids and a more prominent snare due to the upper-midrange lift; on acoustic guitar the subtle mid presence complemented the brightness of a small-diaphragm condenser pair. An internal transducer shockmount isolates the ribbon from mechanically transmitted vibrations; an additional external spider shockmount completes the isolation — a dual anti-vibration system. A three-position HPF switch (OFF / 100 Hz / 50 Hz, 6 dB/oct) at the XLR connector base allows proximity effect control without an external equalizer. Active electronics provide a low 22-ohm output impedance — the microphone works with any preamplifier without impedance matching; at a distance of approximately 1.5 feet only around 30 dB of preamp gain was required in testing.
Applications and comparison with ARM-1S
The ARM-1L excels on electric guitar, brass, drum overheads and room mics, string sections benefiting from warmth and body, acoustic guitar paired with a small-diaphragm condenser, and wherever a contoured, low-end-rich, upper-mid-present ribbon character is the goal. The ARM-1S with its shorter 1-inch ribbon (without copper shielding) is more neutral and tonally balanced — preferred for classical piano, woodwinds, vocals, and sources requiring accurate, flat response. Both models share an identical body (286.5 mm length, 60 mm diameter), the same active electronics, the same HPF circuit, and the same spider mount — the only difference is ribbon length, copper shielding, and tonal character. The microphone ships with an external spider shockmount, a mic head dust protection cover, and a flight case.
KEY FEATURES
- Phantom-powered active ribbon microphone with 2-inch (50.8 mm) 1.8-micron aluminum ribbon, copper-shielded
- Discrete active electronics — -38 dB sensitivity (1 mV/Pa), condenser microphone output level
- Long ribbon = fuller low end, 6–10 kHz presence, contoured character (vs ARM-1S: more neutral)
- Frequency response: 30 Hz – 14 kHz +/- 3 dB
- Maximum SPL: 137 dB
- 22-ohm output impedance — works with any preamp without impedance matching
- Switchable HPF (3 positions): OFF / 100 Hz / 50 Hz, 6 dB/oct — at XLR connector base
- Dual anti-vibration system: internal shockmount + external spider
- Phantom power 48V +/-5V
- Gold-plated XLR connector
- Identical body to ARM-1S — difference only in ribbon length/shielding and detail color (blue vs white)
- Essentially a mono version of HUM Audio's RS-2 without stereo and remote control functions
- Applications: electric guitar, brass, drum overheads and rooms, strings, acoustic guitar
- Included: ARM-1L microphone, external spider shockmount, mic head dust cover, flight case
- Hand-built in Poland; 2-year warranty
TECHNICAL SPECIFICATIONS
- Acoustic operating principle: electrodynamic pressure gradient with active electronics (phantom)
- Polar pattern: figure-8
- Generating element: 2-inch (50.8 mm) aluminum ribbon, 1.8 microns thick, copper-shielded
- Frequency response: 30 Hz – 14 kHz +/- 3 dB
- Sensitivity: -38 dB re. 1V/Pa (1 mV/Pa)
- Maximum SPL: 137 dB
- Output impedance: 22 ohms (electronic)
- Recommended load impedance: 150 ohms or greater
- HPF: 50 Hz and 100 Hz, 6 dB/oct, switchable (OFF/100 Hz/50 Hz)
- Power: phantom +48V +/-5V
- Anti-vibration system: dual (internal + external spider)
- Body length: 286.5 mm
- Body diameter: 60 mm (upper)
- Spider external diameter: 126 mm
- Flight case dimensions: 320 x 230 x 155 mm
- Finish: matte grey with blue details (distinguishes from ARM-1S: white details)
- Included: ARM-1L microphone, spider shockmount, mic head dust cover, flight case
