These studio headphones provides excellent monitoring resolution at a surprisingly affordable price.
Equation Audio is a subsidiary of the American Trans Dominion Corporation, based in Nashville. The subject of this review is one of the company's three headphone models, the closed-backed RP20.
Weighing a relatively lightweight 350g, these headphones feature full circumaural earcups with user-replaceable cushions. The cable is a ludicrously long 3m (10 feet), which quickly tied my legs together without any outside assistance! Although terminated in a 3.5mm jack plug, there is a 6.3mm (quarter-inch) screw-on adaptor provided. The cable is permanently fixed to the left earcup, with wires to the right earcup being hidden inside the headband assembly.
Each earcup is supported by yolk-type suspension arms from an adjustable padded headband. It is not clear which — if any — parts are replaceable other than the cushions themselves, and the construction of the headphones does not appear to lend itself to field servicing. Each earcup can be rotated about a vertical axis up to 90 degrees towards the front and up to 45 degrees to the rear, and there is twisting freedom in the headband to allow one earpiece to be pushed back behind the ear if required. The headband itself allows up to 4cm of adjustment on each side to accommodate different head (or hairdo) sizes. The adjustment is not automatic — you have to physically slide each earpiece arm to the required position — but once set as required the headband seems to retain its configuration quite well.
The published specifications are contained on a single side of glossy paper. The sensitivity is 100dB ±3dB for 1mW at 1kHz with a lowish impedance of 32Ω, and the frequency response is given as 10Hz-22kHz ±3dB. The actual drivers are described as 50mm dynamic devices with Neodymium magnets. The headphones come with a two-year warranty.
Like most circumaural, closed-backed headphones, the RP20 offers a useful degree of sound isolation from the outside world. The headphones are fairly comfortable to wear, with a sufficient side pressure to ensure the headphones remain firmly in place when looking down or moving the head quickly, but without being too oppressive.
The headphones are certainly quite efficient, producing only slightly less volume than my preferred (and rather more expensive) Sony MDR7509 headphones. They also share the same size drivers, and the overall bandwidth seemed similar. The bass response was not quite as smooth and weighty as the Sony model, but there wasn't that much in it. The high end is smooth and airy when the source material warrants it, and the mid-range resolution delivers plenty of detail and clarity even in complex mixes. The RP20 doesn't sound unduly boxy and constrained, despite being a closed-back design, although it isn't quite as open and spacious as a good open-backed headphone. Provided that the earcups are resting against the head (either on or off the ear), sound leakage is minimal, so these headphones are well suited to studio tracking duties.
In terms of UK price, the RP20 sits amongst such reliable headphones as AKG's K271 Studio, Beyer's DT150, Sony's MDR7506, and Sennheiser's HD280 Pro, and on sonic quality it compares very favourably in this company. I remain a little unconvinced about the long-term maintainability of the RP20, compared with models such as the Beyer DT150 or Sony MDR7506 in which every part can be replaced by the user. However, the two-year warranty can be extended to three years, which is a good sign. Well worth a personal audition if you are in the market for good-value closed-backed headphones.