PMC Active Twenty5.21i Active Bookshelf Speaker, Oak (Pair)

The PMC Active Twenty5.21i is an active 2-way bookshelf speaker that combines amplifier and active crossover directly in the cabinet, needing only a source with volume control.

Small in volume, anything but small in performance. As the most compact speaker in the Active twenty5i series, the .21i gets the same technology as its larger siblings – two internal 100 W power amps per cabinet and an active crossover that drives each driver directly.

Why the Active Twenty5.21i?

Because it makes the hi-fi tower on the shelf redundant. Instead of speaker, power amp, and cable clutter, you only need a signal source with level control – a preamplifier or a streamer with volume control. The electronics inside the speaker, tuned precisely to the drivers, handle the rest. The heart of it remains PMC's Advanced Transmission Line (ATL): a folded cabinet principle from the studio world that extracts deeper, cleaner bass from a small volume than any comparable bass-reflex cabinet.

What you hear

Detail-rich mids, delicate treble that's never shrill, and bass that reaches down to 46 Hz – remarkable for this cabinet size. The sound is neutral and honest: the .21i doesn't flatter, it shows what's on the recording. With the gain switch (low/high) you match the sensitivity to your source.

Who is the Active Twenty5.21i for – and who isn't it for?

For anyone who wants high-end sound in small to medium-sized rooms without building an electronics rack. It's also a pleasure as a high-quality effects speaker in an active surround setup. Straight talk: if you just run Bluetooth on the side occasionally, you're leaving a lot on the table here – only a good source wakes up its potential. And if you want to fill a large room, you're better off with the .22i or a floorstanding model.

Our verdict

A well-thought-out, honest active speaker that the trade press praises across the board. If you want to reduce the number of boxes without giving up serious hi-fi standards, the .21i is exactly right. Hand on heart: no one has ever regretted two fewer power amps in the rack.

Technical data

• Type: Active 2-way bookshelf speaker with ATL cabinet
• Drivers: 140 mm (5.5") g-weave™ woofer, 19 mm SONOMEX™ soft-dome tweeter (PMC/SEAS)
• Amplification: 2 × 100 W RMS per speaker (tweeter + woofer, internal)
• Crossover: active, analogue – crossover frequency 1.65 kHz
• Frequency response: 46 Hz – 25 kHz
• Effective ATL™ length: 1.72 m
• Gain/sensitivity: 1 Vrms = 96.5 dB SPL @ 1 m (low) / 106.5 dB SPL @ 1 m (high)
• Inputs: balanced XLR + unbalanced RCA
• Input impedance: >14 kΩ
• Dispersion: 100° horizontal / 90° vertical
• Mains voltage: 90–260 V, IEC C14
• Available finishes: walnut, diamond black, oak
• Dimensions (W × H × D): 162 × 340 × 269 mm (+ 9 mm grille)
• Weight: 6 kg per unit

Frequently asked questions

Do I need an amplifier for the PMC Active Twenty5.21i?

No, you don't need a separate power amp. With 2 × 100 W, the amplification is already built into the speaker. You just add a source with volume control – a preamplifier or a streamer with level control, connected via XLR or RCA.

What room size does the Twenty5.21i suit?

Ideal for small to medium-sized rooms. As a compact bookshelf speaker, thanks to its ATL cabinet it delivers bass down to 46 Hz that you wouldn't expect from its size. Placed freely on stands you get the most out of it; on a shelf it works well too.

What is PMC's ATL technology?

ATL stands for Advanced Transmission Line, a folded cabinet principle instead of bass reflex. It uses the woofer's energy more efficiently and produces deeper, more precise bass from a compact cabinet. The technology comes from PMC's studio monitors and shapes the natural, realistic sound.

Why buy the PMC Active Twenty5.21i from HD Zürisee?

Because as an experienced team in Wädenswil, we don't just sell the box – we sell the right system: the right source, preamplifier, and cabling, matched to your room. Mauri takes care of delivery and setup, and we're happy to advise on questions no one answers online.

Pairs well with

More from the same sonic universe: active speakers, bookshelf speakers, streamers & network players, preamplifiers, speaker stands.