Swiss studio monitor manufacturer PSI Audio has updated its A21-M professional studio monitor with a new and more powerful driver, and optimisation of filters and impedance, to become the A21-M V4.

The A21-M dates back 1996 when PSI Audio produced the speaker as the A3 under the Studer Professional brand. The company has continually improved the design and, to date, more than 10,000 A3 and A21 monitors have been sold.

In 2003, the PSI Audio A21/2 incorporated the technology previously sold as Studer A3 in a PSI Audio cabinet for the first time. In 2006, the A21-M equipped the monitor with a polypropylene membrane to improve consistency and durability. The following iterations saw modifications to the filters for wider dispersion (A21-M V2, 2009), the use of class0G amplification (V3, 2010) and a new woofer frame and cabinet design (V3, 2015). Since all PSI products are developed and built by hand in the company’s facility in Yverdon-les-Bains in Switzerland, small improvements and optimisations can be made without a new model launch. A PSI Audio monitor is always up to date when leaving the workshop.

As much as the PSI Audio team relies on its expertise and vision, it also appreciates external feedback. In the final development stages of the new upgrade, a group of users was brought in to test prototypes in their own working environments. These testers were chosen to include both users of earlier A21-M versions (V2 and V3) and users of other brands of monitors.

The main aim for the A21-M V4 revision was to increase the maximum sound pressure level and frequency range, while retaining the natural sound reproduction the speaker is known for.

The PSI Audio A21-M is shipping now in burgundy red, white and black, with an MSRP of £2,642 (inc VAT).