The PSI Audio A21-M Studio Metal Black is a Swiss-made, fully analogue two-way active monitor for demanding nearfield and midfield work. Its powerful 210 mm woofer, handmade tweeter, Class G/H amplification, AOI driver control and CPR phase-response technology deliver deep bass extension, high headroom and stable stereo imaging without DSP in the audio path.
 
The PSI Audio A21-M Studio Metal Black is a reference-grade active monitor for engineers who need more headroom, bass authority and room coverage than a compact nearfield speaker can provide, while retaining the focused imaging and practical placement flexibility of a two-way design. Handmade and individually calibrated in Switzerland, it is designed for professional recording, mixing, mastering, post-production and critical listening in small to medium control rooms.
The A21-M follows PSI Audio’s fully analogue monitor philosophy. No DSP or digital crossover processing is used in the audio path. Instead, PSI Audio combines purpose-built drivers, analogue crossover electronics, dedicated amplification and individual anechoic calibration. This supports direct transient response, minimal system latency and a coherent presentation for reliable decisions about tonal balance, dynamics, stereo placement, depth and low-frequency control.
 
The two-way system combines a 210 mm woofer with a 25 mm handmade dome tweeter. PSI Audio’s current data specifies a 172 mm woofer diaphragm and a 27 mm tweeter diaphragm within their driver assemblies. A carefully designed waveguide helps control high-frequency dispersion and supports consistent integration at the 2.4 kHz crossover point. The bass-reflex cabinet provides meaningful low-frequency extension while retaining a compact footprint for a monitor capable of both nearfield and midfield use.
 
With a frequency range from 38 Hz to 23 kHz at −6 dB and a tolerance of ±2 dB from 44 Hz to 20 kHz, the A21-M provides reliable information about kick drum fundamentals, bass guitar, low-frequency buildup and the relationship between bass weight and midrange clarity. In many rooms, it can operate as a complete main reference without requiring a subwoofer. For deeper extension, additional bass headroom or immersive-system support, it can be combined with PSI Audio subwoofers and AvAA acoustic-treatment solutions.
 
PSI Audio’s CPR, or Compensated Phase Response, is designed to control phase behaviour through the crossover region. This supports focused stereo imaging, accurate transients and stable depth perception. In practical work, it helps engineers assess panning, vocal placement, reverb tails, time-based effects and mono compatibility with greater confidence.
 
The A21-M also uses PSI Audio’s AOI, or Active Output Impedance, technology. AOI is designed to control driver behaviour and reduce resonance-related effects. Together with the high-power amplification and controlled waveguide, it supports tighter low-frequency response, clearer bass decay and a stable presentation when monitoring complex material at low or high playback levels.
The monitor uses Class G/H amplification for the woofer and Class A/B amplification for the tweeter. It provides 280 W of potential peak power to the low-frequency driver and 45 W to the high-frequency driver. PSI Audio specifies 106 dB continuous SPL, 110 dB short-term SPL and 121 dB peak SPL at one metre. The 80° horizontal by 30° vertical dispersion provides a broad listening zone while limiting excessive energy toward the desk, ceiling and floor.
 
The A21-M is designed for typical listening distances of approximately 1 to 3 metres. This makes it a strong option for high-end nearfield monitoring, compact midfield work and main-monitor duties in smaller professional control rooms. Rear-panel input-sensitivity and room-adaptation controls support integration with professional monitor controllers, converters and analogue signal chains.
The Studio Metal Black finish gives the A21-M a discreet, professional appearance. Each monitor is individually measured and calibrated in an anechoic environment, supporting consistent stereo matching and dependable use in stereo, surround and immersive monitoring systems.
 
The A21-M belongs first in Studio Monitors. Its fully analogue two-way architecture, substantial bass extension, controlled phase behaviour and high output capability make it an excellent primary reference for mix rooms where precision and translation are more important than artificial enhancement.
 
Key features
Swiss-made active 2-way analogue nearfield and midfield reference monitor
Studio Metal Black finish
Fully analogue signal path with no DSP
Handmade and individually calibrated in Switzerland
210 mm woofer with 172 mm diaphragm
25 mm handmade dome tweeter with 27 mm diaphragm
Bass-reflex enclosure
Controlled waveguide for accurate high-frequency dispersion
Class G/H amplification for woofer
Class A/B amplification for tweeter
280 W LF + 45 W HF potential peak amplifier power
Frequency range: 38 Hz–23 kHz at −6 dB
Frequency tolerance: ±2 dB from 44 Hz–20 kHz
Crossover frequency: 2.4 kHz
CPR compensated phase-response technology
AOI active output-impedance technology
ALG overload protection
Dispersion: 80° horizontal × 30° vertical
Continuous maximum SPL: 106 dB at 1 m
Short-term maximum SPL: 110 dB at 1 m
Peak maximum SPL: 121 dB at 1 m
Typical listening distance: 1–3 m
Balanced 3-pin XLR input
Rear-panel input-sensitivity and room-adaptation controls
Suitable for stereo, surround and immersive-monitoring systems
Compatible with PSI Audio subwoofers and AvAA acoustic-treatment solutions
5-year warranty, extendable by one year after registration
 
Applications
Nearfield and midfield mixing
Main-monitor duties in compact control rooms
Mastering, critical listening and professional music production
Editing, post-production and broadcast suites
Accurate assessment of kick, bass and low-frequency balance
Stereo-image, depth, reverb-tail and transient evaluation
Drum, bass, electronic, orchestral and acoustic production
Stereo, surround and immersive-monitoring systems
High-resolution active stereo listening
Professional workflows requiring a fully analogue monitor signal path