Полочная акустика — Acora Acoustics QRB

The QRB is the compact two-way stand-mount of the QR Series from Acora Acoustics, the Toronto speaker maker founded by Valerio Cora, whose family ran a stonework business. Each QR model copies its SR sibling in layout and drivers but swaps black granite for engineered quartz, and the quartz versions sell for about 20 percent less. In the United States the QRB lists at USD 15,000 per pair, or CAD 20,000 in Canada, with stands priced separately.

Key specs that matter

A 1 inch beryllium dome tweeter sits above a 5.5 inch sandwich paper cone that covers bass and midrange, loaded by a bass reflex port. Acora rates the response at 43 Hz to 35 kHz, the efficiency at 86.5 dB for 1 W at 1 m and the nominal impedance at 8 ohm. The cabinet measures 23 cm wide, 33 cm tall and 28 cm deep, and each speaker is about 17.7 kg, a figure the maker says shifts slightly with the stone chosen. Standard colours are Nardo Quartz, a grey, and Thasos Quartz, a white, and custom colours can be ordered.

Engineering and use context

Walls are cut from quartz slabs 2 cm thick with a high-polish surface and precision machining. Acora picked stone for three reasons it lists itself - rigidity, high mass and low interaction with the energy the drivers put into the box. Because the slabs are stiff on their own, the enclosure has no internal bracing, which the company says also removes surfaces that would reflect energy back inside. The tweeter is custom voiced for Acora and wired without any resistor in its signal path, and the crossover is built around phase alignment between the two drivers, helped by a sloped front baffle that Acora uses to bring the outputs of both units into phase, a feature shared across its stone two-way range. Compared with the granite SRB, the quartz box is roughly 8.6 kg lighter per side, which makes the QRB easier to move and to place on a stand while keeping the same driver set and electrical figures.

Pairing

An easy nominal load and a stated amplifier window of 10 to 150 W mean the QRB does not ask for a high-current design, and modest tube or solid-state amplifiers fall inside the rating. With moderate efficiency, owners of bigger rooms will want to use the top end of that power range. Acora offers its SRS stands for the model, and a pair of BedRock bass modules can take the place of stands to turn it into a three-way system.

Alternatives

The Acora SRB uses the same beryllium tweeter and mid-bass cone in a heavier black granite cabinet.