I measured the E55BT Quincy Editions using a G.R.A.S. Model 43AG ear/cheek 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 headphone amplifier. On the G.R.A.S., I used the original KB0065 simulated pinna for most measurements, as well as the new KB5000 pinna for certain measurements, as noted. For Bluetooth-sourced measurements, I used a Sony HWS-BTA2W Bluetooth transmitter to send signals from the Clio 10 FW to the headphones. These are “flat” measurements; no diffuse-field or free-field compensation curve was employed.
I had trouble getting consistent frequency-response measurements from the E55BT Quincy Editions. Their relatively small earcups (which don’t swivel very freely) and relatively small headband made it difficult to get a consistent fit and seal on the ear/cheek simulator. The measurements you see here are the results of many curves taken to find the best seal (indicated by the level of bass) and the most characteristic average response. Also, measurements using Bluetooth signals had to be gated to compensate for Bluetooth’s latency; this gating can affect the measurement curve.
The E55BT Quincy Editions’ frequency response, taken with a Bluetooth signal, looks basically textbook above 1kHz, with a strong peak at about 2.6kHz and a weaker one at about 6kHz; this is the response generally considered to best mimic the sound of real speakers in a real room. The dip in the lower midrange at around 300Hz is a little unusual.
This chart shows the E55BT Quincy Editions’ 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 for at least the next year before I begin using only the new pinna.
This chart shows the right-channel frequency response of the Quincy Editions, measured using pink noise fed via a Bluetooth signal and using a wired connection from a Samsung Galaxy S8 phone. The wired-connection response is almost identical, with just a couple dB more low-bass output. This is an admirable and, sadly, rare result for active headphones; most show substantially different response when used in passive, wired mode. Although I didn’t include the chart here, the wired connection produced no notable difference in response when I added 70 ohms additional output impedance to the V-CAN amp’s 5-ohm native output impedance.
This chart shows the right-channel frequency response of the E55BT Quincy Editions vs. the standard E55BTs, measured using pink noise fed via Bluetooth. There seem to be slight but consistent differences in the responses of the two models.
This chart shows the E55BT Quincy Editions’ measured right-channel frequency response compared with those of three closed-back headphones: NAD Viso HP50, Bose QC35, and Sony MDR-7506. Except for the Quincy Editions’ deep midrange dip at about 300Hz, their response seems well within the norm.
The spectral-decay (waterfall) chart shows a very clean response free of troublesome resonances.
The total harmonic distortion (THD) of the E55BT Quincy Editions -- measured with a wired connection because the Clio 10 FW’s sine sweeps can’t accommodate Bluetooth’s latency -- is higher than average below 100Hz, rising to maximums of 4.7% at 90dBA and 13.5% at 100dBA. However, these levels, especially 100dBA, are much louder than most listeners will want to -- or should -- use, and I heard no distortion when listening to the headphones.
In this chart, the external noise level is 85dB SPL; the numbers below that indicate the degree of attenuation of outside sounds. (Note that I recently switched to measuring at a level of 85dB instead of 75dB; this doesn’t change the way the isolation curves look, but an 85dB level lets me get better measurements of noise-canceling headphones, which demand a lower noise floor.) In my measurements, the isolation of the E55BT Quincy Editions is relatively poor. This is surely due in part to the difficulty I had in getting a good seal on the ear/cheek simulator, but it also corresponds with my subjective listening impressions.
The E55BT Quincy Editions’ impedance magnitude and phase in wired mode are almost flat, with an average of 36 ohms through most of the audioband, and a low maximum phase shift of about +20°.
The sensitivity of the E55BT Quincy Editions in wired mode, measured between 300Hz and 3kHz with a 1mW signal, is 103.8dB. If the battery runs down and you have to switch to a wired connection, the JBLs will still play plenty loud.
. . . Brent Butterworth