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PSI Audio A21

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2-way reference active studio monitor


The A21-M high power near / mid-field precision monitor covers a broad frequency spectrum, allowing the user to be in full control of their audio production. Its unique and highly optimised assets make it perfect for near, mid-field and surround sound applications where ultimate precision is required.

The powerful bi-amplified output stages features the unique “AOI” output stages and has a protection circuit, which can be monitored via the red LED on the front panel.

The active crossover, with integrated “CPR”, gives the A21-M unprecedented impulse behavior – with excellent stereo imaging. The crossover is also optimized for maximum phase coherence, projecting a wide horizontal and vertical ideal listening area.

The electronics are housed in a unit mechanically isolated from the speaker cabinet to avoid resonance at high sound pressure levels.

Designed to work in harmony with the full range of A series monitors the A21-M also makes ideal front speakers in a surround sound setup, or can be developed in to a more powerful system by adding the A225-M sub – thus protecting your investment.



-Very high SPL in a compact cabinet.

-Flat frequency response.

-Optimised directivity by phase coherency.

-Class G low temperature amplifier stage.

-Compatible with industry standard mouting systems.

-Amplifier unit acoustically uncoupled from speaker cabinet.

-Protection circuits with overload indicator.

-Real balanced input.

-Designed for stereo and multichannel monitoring.

-Magnetically shielded for use close to video monitors.

-AOI Technology.

-ALG Technology.

-CPR Technology.

-PSC Technology.

*Price per unit 


Power RMS:

120 + 50W

Program Power: 


Input Impedance: 

Sym, 10k Ohms

Sensivity for 100 dB @ 1m: 

0.775 V

Signal to Noise Ratio: 

96 dBA

Continuous Max SPL@1m: 

108 dB (single)

Input Overload: 

24 Vpp

Program Max SPL@1m: 

119 dB (pair)

Response at -6dB: 

38 - 23000 Hz


±2 dB (44Hz - 20kHz)

Distortion THD: 

less than 1.4% (90Hz-12kHz)

Phase tolerances: 

±45° (190Hz - 20kHz)

Dispersion (P.N. 4 - 16 kHz) at -6 dB: 

90° x 90° (H x V)


2 Way(s)

Crossover frequency: 

2.4 kHz

Woofer's dim. Ext. / Diaphragm: 

Ø217 mm / Ø170 mm

Tweeter's dim. Ext. / Diaphragm: 

Ø100 mm / Ø25 mm


1 x XLR F / 3P

Signal input: 

1=GND, 2=(+), 3=(-)



Dimensions W x H x D mm: 

250 x 400 x 300

Gross / Net Weight: 

14.8 / 13.4 kg


115/230V (50-60Hz)

Consumption Standby-Quiescent-Max: 

1.2 - 5 - 150 W

Mean / Max Humidity: 

less than 75% / less than 90%

External Temperature: 

5 - 40°C

I can count those models I have reviewed that I would suggest fall into the 'outstanding' category on the fingers of one hand… However, the time has now come to introduce my second hand to the count…

In short, these speakers are extraordinary and deliver a level of performance and accuracy that vanishingly few two‑way designs can match, and which would shame a great many three‑way offerings.

Sound On Sound

Read the complete review here

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