Напольная акустика — ProAc Response Four

The Response Four, also written Response 4, is a large three-way floorstander that ProAc of Brackley, Northamptonshire announced in mid-1993. It was designed by Stewart Tyler, who spent a year developing and fine-tuning it and personally tested every pair. The US price was USD 18,000 per pair in 1994 and USD 19,000 in the standard yew finish by 1998, with other veneers adding USD 2,000, and the model was no longer available by 2004.

Key specs that matter

The ported, plinth-mounted cabinet holds five drivers. Two 9 inch bass units from ATC have coated cones, 75 mm ribbon-wound voice coils and die-cast chassis. Two 3 inch ATC soft dome midrange units also use 75 mm ribbon-wound coils and have double-mounted suspensions. The 1 inch coated soft dome tweeter from Scan-Speak is rear loaded, with a damped voice coil cooled by ferrofluid. The response is 20 Hz to 25 kHz within 3 dB, 89 dB for 1 W at 1 m and an 8 ohm nominal impedance. On its plinth with spikes the speaker is about 1600 mm tall, 356 mm wide and 432 mm deep, and it weighs about 136 kg.

Engineering and use context

Electrically this is a three-way crossover with 12 dB per octave slopes, but the bass section works as a four-way mechanical system. The upper woofer has a smaller chamber than the lower one, so the two cover slightly different ranges, and both chambers load into a central chamber ported out of the rear. The tweeter is a special version of the unit in the Response 3 and 3 Signature, with a lighter diaphragm and a different coating, crossed over at a higher frequency. The cabinets are mirror imaged, and the higher-range drivers are progressively offset toward the inner edge, so the array is not strictly vertical. The mass comes from the heavy drivers and the cabinet itself, with no sand or lead filling. The veneer is mirror matched on all sides except the black rear panel, and the grille cloth is acoustically transparent Crimplene. Plinths bolt on, and each speaker stands on four spikes.

Pairing

Two sets of Michell rhodium-plated binding posts at the back accept bi-wiring or two amplifiers, and rhodium-plated strapping pins join them when a single run of cable is used. With its sensitivity and easy nominal load, the Response Four does not call for unusual amplification despite its size.

Alternatives

The ProAc K10 is the current large floorstander of the brand, with two 200 mm Kevlar bass drivers, a 75 mm midrange dome and a ribbon tweeter.