Focal Aria 936 loudspeaker Measurements

Sidebar 4: Measurements

I used DRA Labs' MLSSA system and a calibrated DPA 4006 microphone to measure the Focal Aria 936's frequency response in the farfield, and an Earthworks QTC-40 for the nearfield responses. The Earthworks microphone has a small, ¼" capsule, and so presents minimal obstruction to air flow in the ports. For logistical reasons, I measured a different sample from those auditioned by Robert Deutsch. The speaker was bolted to its plinth for the measurements, so that the downward-firing port was the specified distance from the floor. All measurements were performed with the grille removed.

My estimate of the Focal's voltage sensitivity was 89.5dB(B)/2.83V/m—close to the specified 90dB, and usefully a little higher than average. The Aria 936 is specified as having a nominal impedance of 8 ohms and a minimum impedance of 2.8 ohms; my measurement (fig.1) confirmed the minimum value at 108Hz, but as the impedance stays below 4 ohms from the upper bass though the lower midrange, where music has high levels of energy, I would recommended using a amplifier rated into 4 ohms with this speaker.


Fig.1 Focal Aria 936, electrical impedance (solid) and phase (dashed) (2 ohms/vertical div.).

The small wrinkle at 22.9kHz in the impedance traces indicates that this is the frequency of the metal-diaphragm tweeter's primary breakup mode. The traces are otherwise free from the midrange discontinuities that would suggest the presence of enclosure resonances. Nevertheless, investigating the cabinet walls' vibrational behavior with a plastic-tape accelerometer uncovered modes at 234, 332, and 344Hz. These resonances were lowest in level on the sidewalls (fig.2) and highest on the rear and top panels, where their effects will be less audible.


Fig.2 Focal Aria 936, cumulative spectral-decay plot calculated from output of accelerometer fastened to center of side panel level with top woofer (MLS driving voltage to speaker, 7.55V; measurement bandwidth, 2kHz).

The Focal's impedance-magnitude trace has a clearly defined minimum value at 40Hz, which would be the tuning frequency of the port in a reflex design; however, with its three woofers and two ports, the Aria 936's low-frequency behavior is complicated. Fig.3 shows the nearfield responses of the midrange drive-unit (black trace), top woofer (blue), middle woofer (green), bottom woofer (red), front port (purple), and bottom port (gray), all with their levels plotted in the ratios of their radiating diameters. The midrange crosses over to the three woofers at around 150Hz, though the top woofer rolls off a little slower in the midrange than the lower two woofers. The middle and top woofers appear to be loaded by the front-firing port, with very similar minimum-motion notches in their outputs at around 44Hz. The bottom woofer's minimum-motion notch occurs slightly lower in frequency, at 39Hz. Both port outputs are commendably free from midrange resonant peaks.


Fig.3 Focal Aria 936, nearfield responses of: midrange drive-unit (black), top woofer (blue), middle woofer (green), bottom woofer (red), front port (purple), bottom port (gray).

The complex sum of these nearfield responses, taking into account both acoustic phase and the different distance of each radiator from a nominal farfield microphone position, is shown as the trace below 300Hz in fig.4. A large part of the upper-bass peak apparent in this graph will be due to the inevitable exaggeration of the nearfield measurement technique. But with the overlap between the outputs of the three woofers and the midrange drive-unit in the same region, it is hard to escape the conclusion that the Aria 936 will have too much upper-bass energy in all but very large rooms. I note that Bob Deutsch found that the Focal's bass sounded extended, but without the low frequencies sounding "boomy or bloated," which suggests that the woofer alignment is on the overdamped side. Though the tuning frequencies of the ports bracket 40Hz, close to the frequency of the lowest string of the electric bass and double bass, RD did comment on the Aria 936's excellent low-frequency extension; I suspect that this is actually related to the speaker's exaggerated upper bass.


Fig.4 Focal Aria 936, anechoic response on tweeter axis at 50", averaged across 30° horizontal window and corrected for microphone response, with complex sum of nearfield responses plotted below 300Hz.

Higher in frequency in fig.4, the 936's midrange and treble are extraordinarily smooth and even. The rise in response due to the tweeter's primary diaphragm resonance occurs above 15kHz, and it can be seen that there is a sharply defined antiresonance above 20kHz, but below the frequency of the tweeter resonance. A loudspeaker's perceived tonal balance depends not just on its frequency response but also on how that response changes off axis. Fig.5 shows the Aria 936's horizontal radiation pattern, referenced to the tweeter-axis response. Despite the midrange drive-unit's relatively large radiating diameter, there is only a relatively slight off-axis flare at the base of the tweeter's passband, and the contour lines in this graph are evenly spaced and uniform. As is always the case with a 1" tweeter, the output falls off to the sides above 10kHz, but this will not lead to a lack of top-octave air in rooms of normal size. In the vertical plane (fig.6), a suckout at the upper crossover frequency occurs 10° above the tweeter axis, but as the tweeter is a high 43" above the floor, this will not be a problem. The average ear height for a seated listener is 36" from the floor, so it's just as well that the upper-frequency suckout doesn't start to develop until 10° below the tweeter axis.


Fig.5 Focal Aria 936, lateral response family at 50", normalized to response on tweeter axis, from back to front: differences in response 90–5° off axis, reference response, differences in response 5–90° off axis.


Fig.6 Focal Aria 936, vertical response family at 50", normalized to response on tweeter axis, from back to front: differences in response 10–5° above axis, reference response, differences in response 5–10° below axis.

Turning to the time domain, the Focal Aria 936's step response on the tweeter axis (fig.7) shows that the tweeter and midrange drive-units are connected in positive acoustic polarity, the woofers in inverted polarity. But more important than the individual drive-unit polarities is the fact that the decay of each unit's step smoothly blends with the start of that of the next lower in frequency. This suggests optimal crossover design, given the different distance of each unit's acoustic center from the microphone position. RD commented on the Aria 936's superb transparency, which is what I would have expected from the clean decay seen in the speaker's cumulative spectral-decay plot (fig.8).


Fig.7 Focal Aria 936, step response on tweeter axis at 50" (5ms time window, 30kHz bandwidth).


Fig.8 Focal Aria 936, cumulative spectral-decay plot on tweeter axis at 50" (0.15ms risetime).

The Focal Aria 936's measured performance would not be out of place in an expensive loudspeaker. That it costs just $3999/pair makes it an extraordinary value.—John Atkinson

US distributor: Audio Plus Services
156 Lawrence Paquette Industrial Drive
Champlain, NY 12919
(800) 663-9352

Rick Tomaszewicz's picture

You suggested perusal of Recommended Components for a good matching amp. Perhaps it's time for Stereophile to develop an app which matches recommended or reviewed components based on reviewer-observed synergies? Now that's an app that could save our hobbyists a lot of money and frustration! You could use all the usual criteria such as speaker efficiency v.s. amp output, but also provide guidance on frequency balance matching, i.e.; soft phono preamp with bright cartridge.

remlab's picture

..has that old Focal/Wilson 20khz resonance. Compensates for us old guys hearing.

Allen Fant's picture

This newest series are on my radar to demo. In the past, I really liked the 918/928 models.

I am interested in the new driver material.

eriks's picture

Unfortunately a lot of listeners point the Focal's straight to their ears. This might be good for many speaker's, but not for the Profile's which shared a similar tweeter design and resonance. They have a more neutral tonal balance and image much better with the speaker's toed in as little as possible.

eriks's picture

Hey Robert,

You might have been snookered a little by Focal. While they make good stuff, the al/mg tweeter with a poron surround has been around for about a decade. It's not so new. Still sounds good though. :)



Vlasto's picture

Focals are actually paired very ofter with German T+A...very pleased combination ...


latinaudio's picture

Where did you saw that combination? I have a pair of Focal Electra 926 plus T+A electronics and the highs still sizzle, although the bass performance got better...

growboxguy's picture

On a whim I just purchased a set of Aria 926 for the crazy price of $1799 shipped, brand new from an authorized reseller. I had to take the white color for that price but hey, I will work with it.

My question is will these mate well with my Bryston 3b SST? I listen to mainly rock at high volumes, I use a subwoofer crossing at 60 hz so low end wont be a problem. My system consists of a Bryston BDP-2, Teac UD-301 DA converter, Yamaha CX-A 5000 preamp, Bryston 3b sst for mains and an old school Classe Audio DR-10 on a pair of JL Audio 12w6v3 in a custom sealed enclosure.

Thanks so much!