Lightspeed PFX Headset: Acoustic-Mapping ANR

Lightspeed’s new aviation headset is clearly the most advanced model to hit the market, but we give the Bose A20 a slight edge in ANR performance.

The market for high-end noise-cancelling aviation headsets has become crowded over the last few years. At $1100, high-end aviation headsets are expensive, but in inflation-adjusted dollars, they’re half what they cost when Bose introduced them in 1988.

Near the top of the ANR headset food chain has been Lightspeed’s Zulu.2, a model that’s stolen plenty of sales from the market-dominant, but aging Bose A20.

After almost a year of delays, Lightspeed released its new $1100 flagship Zulu PFX. Here are our first impressions, based on several days of evaluation. 

What you get
Lightspeed offers three versions of the PFX at the same price point: The common dual-plug configuration, a U-174 plug for helicopters and a panel power plug with LEMO or Redel connectors. We reviewed the dual-plug model.

The unit comes standard with a hard-shell carrying case, a quick-start guide and full user’s guide. That’s refreshing in a world where you have to go hunting online for them. There’s a coupon for a free pair of earseals and a micro-USB cable is included for firmware upgrades. More on that in a minute. You get two audio input cables, one for iOS with an inline button and one with a standard 2.5mm audio jack, a single cable clip, a screw-on belt clip and four AA batteries.

The size of the PFX’s control module, which Lightspeed calls a CPU, immediately jumps out. It is over twice the size of its Zulu.2’s svelte box, rectangular design and both cords feed into the top of the module. The PFX uses four AA batteries and the micro USB connection is built into the battery compartment. The back of the CPU has holes for attaching the belt clip, which is handy given the size of the CPU.
The cords received a nice makeover. They’re dressed in a rope-like sheathing, have a tactile feel and are extremely flexible. The dual plugs feed into a hard rubber “Y” junction that seems engineered to endure many years of abuse.

The headset itself has nearly unchanged ergonomics from the Zulu.2. There are minor aesthetic changes to the egg-shaped earcups, which are now smooth and rounded compared to the more angular predecessor. The removable ear cushions are identical to the Zulu.2, and the earcups still swivel flat. The padding inside the earcup is almost unchanged, with a slightly different and thicker fabric covering the much different internal electronics.

The top headband still sports a removable cushion, while the microphone and boom are anchored off the left ear cup. All in all, it appears that Lightspeed didn’t want to change an aesthetic formula that has worked well on the Zulu.2. Ergonomics, fit and finish is what we would expect from a headset in this price range.

Tuned anr
The standout, bold new feature is Lightspeed’s acoustic response mapping, which seeks to optimize the headset’s noise-cancelling signature to the shape of your head and ear. This is analogous to a home receiver’s room audio mapping technology such as Audyssey. When activated, the headset plays a number of tones into the earcup and uses a microphone to determine how the shape of your ear modifies and reflects the sound.

Using this acoustic map, the PFX calculates a digital filter that attempts to provide the absolute best possible sound quality and noise-cancelling result. This sort of signal manipulation takes a lot of processing power, but once the capability for signal manipulation is there, many other possibilities open up and are used to good effect by the accompanying Flightlink iOS app. PFX stands for Personal Flight Experience, which we think is fitting.

To start the noise mapping, tap the action button, located under the power button. The tones will play and the headset will remember the most recent mapping until it is overwritten again. There is a switch on the side of the CPU that disables the mappings and other customizations that can be done with the companion app, perhaps in case someone reconfigured a shared headset or if it was used in an unusual operating situation. Tapping the action button twice toggles ComPriority, which is a fancy term for auto-muting Bluetooth (and wired) audio when the aircraft radio audio is coming in. Lightspeed recommends remapping after any significant changes, such as putting on thick sunglasses.

So, with all this technology, how does the headset stand up to cockpit use? We evaluated the set in both a G1000 Cessna 172 and a Cessna 310 twin, which is equipped with a PS Engineering PM8000C audio system. We wore the headset with and without eyeglasses and ballcaps, put the set on both male and female heads and we evaluated the performance of its Bluetooth connectivity using an Apple iPhone 5S and two later-gen iPads.

We took the PFX flying with the Zulu.2 predecessor (a product that will remain in the Lightspeed lineup), in addition to a Bose A20 for comparison. We also brought along the AKG AV100 (reviewed in the June 2014 issue of Aviation Consumer), which we think sets a new bar in entertainment audio quality. To compare headsets, we would wear one pair, close our eyes and get used to its sound quality, and then use the next pair to slide the previous pair back off the ears and get an immediate comparison. This was repeated many times.

When first turning on the PFX in flight, the headset goes through three distinct phases, which initialize the ANR circuitry. The system boots up for about four seconds before the noise cancelling comes on. About 15 seconds later, the ANR quality markedly improves. The PFX is continuously adapting and adapting its ANR through a process called Streaming Quiet, although not all the refinements will be apparent to the user. This takes a lot of computing power and hence the latencies in startup.

We reran the acoustic mapping algorithm every time we changed a hat or eyeglass configuration. This didn’t make a particularly noticeable difference, but since there is a delay between the old and new ANR profiles, it would be difficult to detect such a subtle improvement.

Compared with the Zulu.2, we think the ANR quality of the PFX is greatly improved. This headset is noticeably quieter, with much less hiss and a marked reduction in low-pitch engine sounds. Even in the unit’s Home mode, which disables some of the newer mapped ANR algorithms, the PFX sounds a little better. Turn on all the features in Favorites mode and we think the PFX is a hands-down winner over the Zulu.2. Even with Voice Clarity turned off, the aircraft radio quality was improved and with it on, the PFX was better.

The PFX’s comfort was good and seemed identical to the Zulu.2, probably because of the similar earcup cushions and headband design.

On the ground, we noticed an occasional rumble would sneak through the ANR circuitry at low RPM. In flight at around 2200-2300 RPM, there was also an occasional low-pitched fluttering sound—perhaps some sort of ANR resonance— that was apparent at perhaps 5-20 Hz. In flight, we found that the ANR performance was quite impaired by turning the head (or whole body) 30-60 degrees to either side; this was especially pronounced with the left earcup toward the front of the airplane.

With power off (passive mode), the noise reduction was decent and radio volume was good; the panel volume didn’t need immediate adjustment. Better yet, the volume sliders continue to work.

Switching between Home and Favorites mode (Home disables some of the ANR effects and can be used as a failsafe) caused a reduction in the ANR quality. However, Favorites came with a lag of about six seconds. We believe this is because the headset is calculating its ANR response curves and filters, requiring sizable calculation to achieve.

We removed eyeglasses and ballcaps several times to see how the ANR was affected, with acoustic remapping after each change. In the general case, acoustic mapping seemed to improve the ANR and sound quality over the factory default, but again, there was a delay between running the mapping and when the ANR quality adjustments kick in. However, remapping didn’t seem to improve the ANR noticeably when switching glasses/hat configurations. With a ballcap and glasses, ANR was noticeably impaired as compared to glasses alone, even with acoustic re-mapping. Glasses alone seemed to cause only minor impairment in noise-cancelling quality, but glasses with thick temples have a greater negative effect. On a few occasions when taking the headset off to put on a hat, the headset would allow more low-pitch noise to sneak through for a short period of time.

Our evaluators unanimously felt the Bose A20 was quieter than the PFX, even with all the PFX’s ANR options enabled and acoustic mapping completed. One evaluator—an experienced pianist—felt that the Bose was better at blocking the lowest frequencies of noise, which seem to be the most fatiguing during a long journey. High-frequency hiss seemed identical between the two.

For sure, the PFX excels at radio clarity and volume, even with Voice Clarity disabled. With ANR off, the noise reduction is similar, although the PFX may have a slight edge at muffling the low frequencies. The PFX again has crisper and louder radio volume with the ANR off. Two evaluators affirmed that the Bose was more comfortable, with less clamping pressure.

Bluetooth connectivity
The Bluetooth music stream worked well in flight. However, we occasionally experienced periods of pairing difficulty while switching devices in flight—something we’ve also experienced with the Zulu.2. There’s plenty of gain when piping in music—with volume levels capable of exceeding a reasonable comfort level.

Enabling the Front Row Center mode really adds to music quality and makes the music “pop.” The ability to adjust the bass and treble using the Flightlink app was fantastic in finding a setting that appealed.

With music playing via Bluetooth, enabling ComPriority causes the music to recede in volume when any panel audio is present. The music is not entirely muted and can be faintly heard in the background, which is a nice touch, in our view. The performance of the muting and unmuting is responsive; the music would even come back to full volume for a few moments in the gap between loops of a human-recorded ATIS broadcast.

In the twin, ComPriority was a little too sensitive and sometimes played back during quieter parts of a radio call. ComPriority is easily toggled using a double-tap of the action button on the CPU. Unfortunately, there is no audible notification of the new status of ComPriority, just a flashing (or not flashing) pair of red LEDs on the CPU. We think the set can benefit from voice prompts.

It’s prudent to compare the PFX’s Bluetooth music quality to that of the Harmon AKG AV100, which in our estimation still has better music quality, with a pleasing response curve and better bass compared to the slightly hollow PFX. However, enabling Voice Clarity and Front Row Center, while tweaking the bass and treble controls drastically changes the sound. Now the PFX sounds to our ear clearly better than the AKG. Even radio calls come through with better clarity and music has a much better feel, with a surround sound effect and enhanced low and high-end response.

To a true audiophile, the AKG will likely have better sound due to its uniform response rate and good native bass and treble reproduction. We also think the AKG has a slight edge in comfort, with less clamping pressure and softer ear cushions. However, for customized in-flight music listening, the PFX has a clear advantage thanks to the Flightlink app.

With the engine at typical ground RPMs, the Bluetooth phone interface works as expected and the called parties had no complaints about voice quality. Tapping the Bluetooth button once brings up the iPhone’s voice control menu.

We think the PFX should be hardwired for ship’s power whenever possible. The four AA batteries (rechargeable aren’t recommended) last only a claimed 20 hours, and using Bluetooth will reduce that even further. Lightspeed has clearly put a lot of digital signal processing power into this headset, explaining why it burns four batteries in half the time the Zulu.2 uses two.

The supplied cords are too short, especially since placing or mounting that big CPU will be a challenge.Bluetooth phone calls don’t work properly when ComPriority is enabled, which pilots will likely leave enabled. This seems like a common use case for getting last-minute briefings or clearances at uncontrolled fields. Having to toggle it is inconvenient. Hopefully, Lightspeed will address this issue in a future update.
Finally, given the confluence of devices in a modern cockpit, the inability to pair to multiple Bluetooth devices is a curious oversight. The Jawbone line of Bluetooth devices, for example, offer the ability to connect to two devices simultaneously.

At the $1100 price point, we suspect some buyers may opt to wait for Lightspeed to address the quirks our evaluation uncovered.

Existing Zulu.2 headset owners that upgrade will appreciate that the ergonomics carry on in the history of the well-received Zulu.2.

In our view, the PFX’s overall ANR performance doesn’t best the Bose A20, but compensates with more features and configurability. Worth mentioning is that the Bose A20 doesn’t stream Bluetooth music (it requires a patch cable), proof that the model is aging.

The bottom line is that we found enough to like to recommend the Zulu PFX as an investment that, given the technology that’s behind it, can only improve with time.

Contact, 800-332-2421.

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