Floorstanding loudspeakers — German Physiks Borderland MK IV

The Borderland MK IV is a floorstanding omnidirectional loudspeaker from German Physiks, placed above the HRS-130 in the brand's catalogue of DDD-based designs. One DDD driver in carbon fibre is mounted above a slim cabinet of octagonal cross-section, and a 12-inch woofer fires downward from the base. The fourth version brought a new crossover intended to improve bass extension and the blend between woofer and DDD driver. A carbon fibre sister model is sold as the Carbon Mk IV.

Key specs that matter

Rated bandwidth is 28 Hz to 24,000 Hz, a sensitivity of 86.1 dB for 1 W at 1 m and an impedance of 4 ohm. The crossover point is 190 Hz, with 12 dB per octave electrical and 18 dB per octave acoustic slopes on both the DDD and woofer sections. Power handling is 300 W nominal and 600 W short term. The footprint is 404 mm square, height is 1,229 mm and each speaker weighs 54 kg. German Physiks suggests rooms of 15 to 90 m2. Dual pairs of WBT nextgen terminals are fitted, and jumpers come in the box for owners running one cable per side. The standard finishes are black or white high-polish polyester and carbon fibre, while satin or high-polish veneers and paints are special orders. Warranty cover lasts 5 years.

Engineering and use context

The DDD cone is carbon fibre only 0.15 mm thick, and its moving mass stays under 3 grams. It works pistonically at low frequencies and relies on bending-wave and modal radiation across most of its range from the crossover point upward, close to seven octaves, so no crossover interrupts the midrange. Each driver takes about 6 hours to build by hand in Germany and is then tested, pre-aged for 96 hours with music, measured again and matched into a pair. The 12-inch woofer is shared with the larger Loreley model. It sits in a sealed lower enclosure linked by a small opening to a cavity at the top that forms a Helmholtz resonator tuned to the main enclosure resonance. Smaller octagonal panels of heavy MDF are stiffer than large flat ones, Hawaphon damping sheet filled with steel shot lines each panel, and thick felt damps the internal air. Support pillars, terminal plates and screws are V4 stainless steel, chosen for a design life of at least 25 years. Rear jumpers alter treble output by -2, 0, +2 or +4 dB around 8,000 Hz.

Pairing

The maker specifies an amplifier of at least 160 W into the nominal load, so a low-powered valve amplifier is not a suitable partner. Thanks to the dual terminals, one stereo amplifier can drive the woofers while a second feeds the DDD drivers.

Alternatives

The German Physiks HRS-130 is a smaller and lighter floorstander from the same catalogue, also built around a single carbon fibre DDD driver.