Reviewed on: SoundStage! Solo, September 2021

I measured the Focal Celestee headphones using laboratory-grade equipment: a GRAS Model 43AG ear/cheek simulator/RA0402 ear simulator with KB5000/KB5001 simulated pinnae, and an Audiomatica Clio 12 QC audio analyzer. For isolation measurements, I used a laptop computer running TrueRTA software with an M-Audio MobilePre USB audio interface. For most measurements, the headphones were amplified using a Musical Fidelity V-CAN amplifier; I used a Schiit Magnius amplifier for distortion measurements. These are “flat” measurements; no diffuse-field or free-field compensation curve was employed. If you’d like to learn more about what our measurements mean, click here.

Frequency response

This chart shows the Celestees’ frequency response. While this is a little flatter than normal—which, with headphones, means they have a little more midrange energy relative to the bass and treble—I see no red flags here.

Frequency response

This chart shows how the Celestees’ tonal balance changes when they’re used with a high-impedance source, such as a cheap laptop, some tube amps, or some professional headphone amps. It’s a significant change, with the high-impedance source increasing bass by 2 to 2.5dB between about 40 and 200Hz. This is due to the impedance swing you can see in the impedance chart below.

Frequency response

This chart shows the Celestees’ right-channel response compared with three other audiophile headphones: two closed-back, one open-back. Clearly, this response isn’t out of the ordinary for this product category. The Dan Clark Audio Æon 2 Closed headphones’ response is pretty close to that of the Celestees’, and both are not far off from the Harman curve.


The Celestees’ right-channel spectral-decay plot shows a strong resonance at about 3kHz, but it’s well-damped and likely below the noise floor within about 7ms.


Here’s the THD vs. frequency chart, measured at 90dBA and 100dBA (both levels set with pink noise). The distortion is low, maxing out at about 2% in the bass.


In this chart, the external noise level is 85dB SPL, and numbers below that indicate the degree of attenuation of outside sounds. The lower the lines, the better the isolation. I compared them with several high-end closed-back models, and as you can see, the Celestees’ isolation is typical for their product category.


The Celestees impedance magnitude curve has the bass resonance hump (in this case centered at about 90Hz) we usually see with dynamic drivers; phase is nearly flat.

Sensitivity, measured between 300Hz and 3kHz, using a 1mW signal calculated for 35 ohms rated impedance, is 104.1dB. Thus, the Celestees can deliver loud volume from almost any mobile devices that have headphone jacks.

Bottom line: The Celestees measure fine, and are well-suited for use with portable (and non-portable) devices. They’ll sound bassier with a tube amp.

. . . Brent Butterworth