I measured the ATH-ADX5000s 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, a Musical Fidelity V-CAN amp, and an Audio-gd NFB-1AMP for distortion measurements. On the Model 43AG, I used the original KB0065 simulated pinna for most measurements as well as the new KB5000 pinna for certain measurements, as noted. These are “flat” measurements; no diffuse-field or free-field compensation curve was employed.
Although the ATH-ADX5000s’ frequency response shows that its tonal balance is fairly similar to those of typical competitors, it does reveal some interesting idiosyncrasies. First is the midrange bump at about 1.3kHz. Then there’s the lack of the usual peak between 2 and 3kHz, which is generally considered necessary for headphones to deliver a sound approximating that of speakers in a room. However, there are strong peaks at 3.4 and 6.3kHz. I can’t remember seeing a response quite like this before, so I can’t confidently predict how it will sound, but if someone showed me a response curve like this and asked me to interpret it, I’d guess it would sound fairly flat but just a little bass-shy.
Note that this is the best match I was able to get between the left and right channels, after about 20 minutes of experimentation. Getting these measurements to match is always a challenge because slight changes in headphone position change the measured response, and the left and right simulated pinnae (which are based on averages of molds made from hundreds of human ears) aren’t perfect mirror images of each other (neither are your ears, for that matter). So I’m always reluctant to criticize headphones for channel matching. I didn’t notice a mismatch when listening, but still, this doesn’t impress me.
This chart shows the ATH-ADX5000s’ right-channel frequency response measured with the old KB0065 pinna (which I’ve used for years) and G.R.A.S.’s new KB5000 pinna, which I’ll be switching to because it more accurately reflects the structure and pliability of the human ear. (I include this mostly for future reference rather than as something you should draw conclusions from; I intend to show both measurements in every review until later this year, when I begin using only the new pinna.)
Here you can see how the ATH-ADX5000s’ tonal balance changes when they’re used with a high-impedance source, such as a cheap laptop or some cheap professional headphone amps. It’s not a big difference, largely because the ATH-ADX5000s’ high impedance means that changes in the source impedance don’t have as big an effect. But the headphones’ uneven impedance curve (see below) does result in a bass boost of about 1dB and a reduction of about 1dB in the lower treble, between 2 and 3kHz. Not a huge difference, but still an audible one.
This chart shows how the ATH-ADX5000s compare with several competing open-back headphones: the Audeze LCD-Xes, the HiFiMan HE1000 V2s, and the Sennheiser HD 800 Ses. While the overall balance is similar in all of these models, the ATH-ADX5000s’ competitors clearly have less energy between 1 and 2kHz, and more between 2 and 3kHz -- and that’s right in the “sweet spot” of human hearing, so the Audio-Technicas will certainly sound a little different.
The ATH-ADX5000s’ spectral decay (waterfall) chart shows no high-amplitude resonances, but many high-Q (i.e., narrow), very-low-amplitude (about -40dB) resonances between 1 and 5kHz. This is typical of open-back models; it doesn’t seem to affect their tonal balance, but I speculate that it’s part of what gives them a more spacious sound. Incidentally, I put 4” of denim insulation on top of the headphones when I take this measurement, so the resonances don’t represent room reflections of the sound coming off the back of the headphones.
The measured total harmonic distortion (THD) of the ATH-ADX5000s is low at any sane listening level. At 90dBA, which is quite loud, the THD rises to only about 1.5% at 20Hz. At the extremely loud level of 100dBA, it’s about 1.5% between 100 and 400Hz, and rises to about 4.7% at 20Hz.
In this chart the external noise level is 85dB SPL; the numbers below that indicate the degree of attenuation of outside sounds. Like the other open-back models (the Audeze LCD-Xes and the HiFiMan HE1000 V2s), the ATH-ADX5000s provide no significant isolation. It’s interesting, though, to see how the ATH-ADX5000s and HE1000 V2s -- both of which have very open backs -- deliver less isolation than the LCD-Xes. If you want isolation, you’ll have to go with a closed-back model such as the Audeze LCD-XCs (also shown).
To the best of my memory, all over-ear and on-ear dynamic headphones I’ve tested have an impedance bump at the driver resonance (always in the bass); nonetheless, the ATH-ADX5000s’ is pretty extreme. The nominal impedance is about the same as the rated impedance of 420 ohms, but the impedance breaks 1400 ohms at 90Hz. Fortunately, because the overall impedance is high, this doesn’t cause major changes in tonal balance if a high-impedance source device is used. The phase response is pretty flat, though.
The sensitivity of the ATH-ADX5000s, measured between 300Hz and 3kHz with a 1mW signal calculated for 420 ohms impedance, is 101.8dB, which is 1.8dB higher than specified. This means that even though they weren’t designed for the purpose, the ATH-ADX5000s will work reasonably well with low-quality source devices.
. . . Brent Butterworth