Warwick Acoustics Aperio Headphone System Lab Report

Lab Report

The two capsules of the Aperio behaved somewhat differently on our artificial ear, as the two overlaid uncorrected responses show [see Graph 1]. In particular, the left capsule had a lower output below 1kHz and a distinct notch at around 500Hz. Both capsules evince a dip at about 60Hz and a nearby peak at 70Hz, suggesting a common structural resonance there – which was confirmed by the acoustic crosstalk test (result not shown) which showed a large crosstalk peak at 72Hz, almost certainly caused by a poorly damped headband resonance.

Warwick Acoustics has its own response target function but from the third-octave corrected responses this appears to be pretty close to the classic diffuse-field (DF) target [green trace, Graph 2]. The averaged response of the two capsules is pretty flat with DF correction applied, albeit with some shelving down above 1kHz. The Harman-corrected response [red trace] is pretty flat too, without the lower midrange and bass prominence, but bear in mind we are using Harman's earliest (2013) correction. Later iterations of the Harman target response from 2015 and 2017 have significantly boosted bass output, so applying their inverses would indicate that the Aperio is lacking bass output. This despite its fine bass extension, which is in marked contrast to the Stax Lambda Signature [HFN Nov '13], which had a response peak at 80Hz and rolled off rapidly below that.

Both the corrected and uncorrected responses were obtained with good earpad sealing, but the Aperio is sensitive to this so if the seal is compromised, either by thick spectacle frames or hair, bass output can drop by up to 20dB at 20Hz. So the Aperio's perceived tonal balance may change if you wear chunky specs and/or have a thick barnet! You might suppose from the small ripples in the uncorrected frequency responses that the measurements were corrupted by noise but this feature – seen also in planar magnetic designs – is caused by closely packed diaphragm resonances. Cumulative spectral decay waterfalls for both capsules show that the Aperio – just like the Sonoma Model One – has a series of high-Q diaphragm resonances reaching up to around 6kHz. KH


Unequalised responses (L/R, grey/red; ave. 3rd-octave, black) show differences below 1kHz but are otherwise reasonably flat [see responses, below]


Third-octave freq. resp. (red = Harman corrected; cyan = FF corrected; green = DF corrected)

Capsule matching (40Hz-10kHz) ±11.0dB
LF extension (–6dB ref. 200Hz) <20Hz
Distortion 100Hz/1kHz (for 90dB SPL) 0.1% / 0.2%
Weight (headset only) 406g
Price £20,000
Warwick Acoustics Ltd
Nuneaton, UK
Supplied by: Warwick Acoustics Ltd
01247 722 0377