Reviewed on: SoundStage! Solo, December 2018
I measured the R-220s using a G.R.A.S. Model 43AG ear/cheek simulator/RA0402 ear simulator, a Clio 10 FW audio analyzer, a laptop computer running TrueRTA software with an M-Audio MobilePre USB audio interface, and a Musical Fidelity V-CAN amp. On the Model 43AG, I used the new KB5000 and KB5001 anthropomorphic simulated pinnae for most measurements, and the stainless-steel coupler included with the RA0045 for certain other measurements as noted. These are “flat” measurements; no diffuse-field or free-field compensation curve was employed.
The above chart shows the R-220s’ frequency response measured with the KB5000 and KB5001 anthropomorphic simulated pinnae. Above 1kHz, this measurement looks typical for earphones. But below 1kHz, there’s a lot less bass than we usually see.
This chart shows the R-220s’ right-channel frequency response measured with the RA0045 ear simulator’s stainless-steel coupler (which I’ve used for years) and the new KB5000 simulated pinna, which I recently switched to because it more accurately reflects the structure and pliability of the human ear and provides a more realistic simulacrum of what you’ll actually experience with headphones or earphones. This is just for sake of comparison with older measurements of mine.
As usual with earphones incorporating balanced-armature drivers, the R-220s show a tonal balance shift when you go from a low-impedance source device (typically between 0.5 and 5 ohms) to a relatively high-impedance source device (typically 75 to 125 ohms). In this case, the bass and lower midrange will be attenuated by about 1dB, and the treble boosted by 2 to 3dB.
This chart shows the R-220s’ right-channel response compared with two other earphones in the same price range (the Campfire Comets and the Acoustic Research AR-E010s used in wired mode), as well as the AKG N5005s, the earphones that currently best conform to the “Harman curve,” shown in research by Harman International to be the preferred in-ear headphone response for most listeners. Again, the R-220s’ response is much more heavily balanced toward the treble than the other models -- even the AR-E010s, which have only a little more bass but also balance out the sound with a somewhat reduced treble response.
The R-220s’ spectral decay (waterfall) chart shows only an extremely high-Q (i.e., narrow) and weak (-40dB) resonance around 5kHz. There’s no chance this would be audible.
The R-220s’ distortion is modest for balanced-armature earphones, running about 1% at the loud listening level of 90dBA, and 2% at the extremely loud level of 100dBA.
In this chart, the external noise level is 85dB SPL, and numbers below that indicate the degree of attenuation of outside sounds. The R-220s’ isolation (shown with and without its flange) is about average for earphones of this type, maybe a little above average between 500Hz and 1kHz.
Most balanced-armature earphones show some impedance swing, but the R-220s show a little more than most, rising from the rated 29 ohms below 500Hz to a high of about 130 ohms at 20kHz. The phase also swings a lot, from 0 degrees in the bass to +60 degrees at 20kHz. This is why the sound changes with high-impedance sources.
Sensitivity of the R-220s, measured between 300Hz and 3kHz, using a 1mW signal calculated for the rated 29 ohms impedance, is 97.2dB. That’s low for earphones; the reason for the low number is that the response is skewed toward the treble. So the upper mids and treble will be a lot louder than that, but the bass will be lower.
. . . Brent Butterworth
brentb@soundstagenetwork.com