Floorstanding loudspeakers — Pbn Audio M3!5

Built by PBN Audio, the company run by Peter Noerbaek, the M3!5 is a passive three-way tower that was added to extend the M!Series to a suite of three models. Spike feet are optional, and the maker describes it as built for rooms dedicated to a full audio system rather than a shared living space.

Key specs that matter

Heading the driver line-up is an 18 inch paper cone woofer, model 2245H, designed by an engineer who has worked closely with Noerbaek on several earlier projects. Above it sits a 12 inch paper cone midrange, model 2206H, and the top octaves are handled by a 6 inch ribbon, model SA8535. PBN quotes a frequency response of 25 Hz to 35 kHz and a nominal impedance of 8 ohm. Sensitivity is rated at 92.5 dB for 2.83 V at 1 m. The cabinet measures roughly 53 cm wide, 69 cm deep and 137 cm high, and each speaker weighs about 156.5 kg.

Engineering and use context

The crossover splits the signal at 200 Hz and 1,300 Hz using steep slopes, so the woofer handles just the deep bass while the midrange cone carries the whole midrange up to the ribbon. Assigning such a wide span to one paper driver avoids a further crossover point in the vocal range. The impedance curve is not flat, and PBN states the extremes openly - a minimum of 4.75 ohm at 350 Hz and a maximum of 32 ohm at 4,500 Hz. The low point falls just above the woofer handover, where the midrange takes over the load. Given the weight of each box, moving and placing the speakers is a two or three person task, and floor strength should be checked before delivery. Cabinets are made to order, and the brand offers a range of hardwood veneers and finishes for its speakers.

Pairing

The rated sensitivity means modest amplifier power reaches useful levels, yet the low impedance minimum still calls for a design that copes calmly once impedance drops under its nominal figure. PBN itself builds the Olympia EB-SA amplifiers, which the brand uses in its own demonstration systems, so a matched set from one maker is possible. Low output tube designs can work, though the impedance peak in the treble region will shift their frequency balance more than it would with a solid state unit of low output impedance.

Alternatives

The PBN Audio M2!5 is the next floorstander in the same series, using twin 15 inch woofers and a dual diaphragm compression driver on a waveguide, crossed at 900 Hz, in a cabinet of about 127 kg standing just under 1.5 m tall.