PMC ACTIVE Twenty5 21i Bookshelf Speakers

Another feature is the PMC-designed Advanced Transmission Line Bass System. This provides the bass output of a much larger speaker in a small space. In fact, it goes down as low as 46Hz.

Key Features

• 2 x 100-watt active amplification
• Class D Amplifiers
• Balanced XLR Input
• Unbalanced RCA Input
• Greater detail & more natural
• A full, rich sound at any volume level
• Deeper bass from a smaller cabinet
• 5 Year warranty

Powerful Class D amplification

With the PMC Twenty5.21i Active Speakers, the audio signal is split into high and low-frequency bands, straight after arriving via the RCA or XLR connector. The signal is then fed to two 100 Watt Class D amplifiers giving 200 Watts per channel. Class D works in the digital domain by using a series of high-frequency pulses.

This is known as Pulse width modulation. Additionally, Class D is up to 90% efficient and is often used for active speakers where space is at a premium. Moreover, there is less heat generation and less power is needed for a given output.

Deep bass response with ATL bass loading

To provide a good bass response in compact speakers PMC developed an Advanced Transmission Line Bass Loading System. This uses a tunnel that redirects the sound from behind the bass driver to the outside world. The tunnel is lined with acoustically absorbent materials that remove all but the low frequencies.

On the front of the speaker baffle there is a Laminair port. This redirects the bass sound and smooths the airflow. As a result, the bass is enhanced without booming.

Great musicality

The PMC Twenty5.21i Active Speakers feature accurate and powerful bass along with a clear and realistic mid-range. The highs are sweet and clear due to the tweeters surround. To create a full system just connect the right and left preamp outputs to each speaker. This can be done via standard RCA leads or Balanced 3 pin XLR leads.

Precision made cabinet

The cabinets of the PMC Twenty5.21i Active Speakers are made of precisely machined panels. These tight-fitting panels are made of highly specified HDF material. Some of which are up to 40mm thick. The ATL tunnel also has to be a good fit to prevent leakage and resonance.

This is done by using modern bonding materials that make the whole assembly into a homogenous structure. As a result, the audio is clean and uncoloured. Lastly, the fine veneers are finished in a deep and lustrous sheen.

Computers don’t tell the full story. As well as full frequency analysis, we listen to each speaker we make and run a benchmark BBC speech and music test on every single one.

Who is PMC?

Founded in 1991 by Peter Thomas of the BBC and Adrian Loader of FWO Bauch. The combination of knowledge and a life-long passion for music led to the production of PMC’s first product, the BB5-A, an active main studio monitor. This design was snapped up by the BBC Maida Vale and Metropolis Mastering and remains the world’s reference, used by Prince, Stevie Wonder’s Wonderland Studio, Hospital HDTV Broadcast London and renowned classical labels such as Decca and Harmonia Mundi. Many of today’s movie themes have been crafted using PMC, by such eminent composers as Henry Jackman, Thomas Newman, Tyler Bates and John Debney.