A Legend is born… again.


First introduced in 1992 under the “Studer Professional” brand, the A3, as it was formerly called, was intended to be the most accurate 2-way monitor on the market.
For this purpose, we developed unique analog technology, compensated the phase response and created the best-adapted amplification for each driver.

Over the past 20 years, more than 10’000 A3 and A21 have been sold.

To celebrate this 20th birthday, we wanted to upgrade the A21 even further.
But after 20 years of continuous improvements, what could possibly be left to improve?

The A21 already wins all the serious blind tests, it’s the model most loved by “Tonmeister” (Golden Ears) and by the most demanding sound engineers, it’s the most transparent and accurate monitor of its kind and everybody agrees that it has the most accurate stereo image they’ve ever heard.

As we always seek to maximize SPL max and audible range bandwidth while keeping perfectly natural and dynamic transients we tried to push it slightly further. So we kept the same fully analog technology, introduced a new and more powerful motor, modified and improved the filters as well as the adapted output impedance.

While finalising this new upgrade, as usual we submitted the prototypes to a panel of educate A21-M (V2 and V3) users, as well as people who used other brands and they all tested them in their own environment. They were unanimous and the A21-M V4 exceeds their, already very high expectations.

This development took over a year and the result is astonishing! We are now proud to show you the brand new A21-M V4.

Please come and see it at the forthcoming IBC in Amsterdam and AES in New York or ask your local distributor/reseller for a demonstration.

A3 and A21 history:

1996 – PSI A20/2: creation of the first prototype
1998 – Studer A3: the original monitor was born
2003 – PSI Audio A21/2: the original technology inside a PSI Audio cabinet
2006 – PSI Audio A21-M: introduction of polypropylene membrane for better consistency and durability
2009 – PSI Audio A21-M V2: modification of the filters for a wider dispersion
2010 – PSI Audio A21-M V3: introduction of Class G amplification
2015- PSI Audio A21-M V3: new woofer frame and cabinet design
2017 – PSI Audio A21-M V4: more powerful engine, improved crossover filters and output impedance