Headphones

It's not often that reading headphone promotional literature makes me laugh out loud. But Quad's twin proclamations that in the ERA-1 it has combined high sensitivity with low impedance and created a diaphragm lighter than the air it displaces both caused me amusement. High sensitivity with high impedance would have been an achievement; high sensitivity with low impedance anybody can do. And a planar magnetic plastic/metal diaphragm with a density of less than 1.2kg/m³?! That's credible only if you don't understand the difference between solids and gases... In fact – particularly in the context of planar magnetic headphones – the ERA-1 has good rather than exceptional sensitivity but requires lower impedance to achieve it than competitors have needed.

Quad claims a sensitivity of 92dB SPL for 1mW at 1kHz, which for the nominal impedance of 20ohm corresponds to a low-ish voltage sensitivity of 108dB per volt (albeit with ±3dB tolerance specified). In fact the ERA-1 achieves much better than that: we recorded 114.5dB for 1V at 1kHz, averaged for the two capsules. Compare this with the 115.2dB we measured from the Audeze EL-8 open-back [HFN Oct '15]. But the Audeze achieved this with an impedance of about 31ohm – about 50% higher – so Quad has yet to match the current sensitivity of the best planar magnetics we've measured thus far.

The uncorrected frequency responses [Graph 1] are essentially flat below 700Hz, above which output shelves up by about 2dB and becomes more uneven but without the clear peak we'd expect to see at 3kHz for a flat perceived response. This is reflected in the corrected responses [Graph 2], all of which show a deep hole in the lower treble. While this is not exacerbated by excessive bass output, it suggests that the ERA-1 will follow other planar magnetics in having an essentially warm tonal balance. KH

Sensitivity (SPL at 1kHz for 1Vrms input): 114.5dB
Impedance modulus min/max (20Hz-20kHz): 20.0ohm @ 8.2kHz
20.4ohm @ 838Hz
Capsule matching (40Hz-10kHz): ±3.9dB
LF extension (–6dB ref. 200Hz): <12Hz
Distortion 100Hz/1kHz (for 90dB SPL): 1.5% / <0.1%
Weight (inc cable and 0.25in adapter): 472g
Price: £599