LightSPEED Technologies' K-Series Active Noise Reduction Headsets

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Since Bose first introduced their $1,000 ANR headset to aviation in 1989, we've been waiting for a headset with the same sublime comfort and spectacular noise reduction but at half price. Headset giants David Clark, Peltor and Telex all jumped into the fray, but all came up short in our judgement. Now, some ex-Tektronix audio whizzes in Lake Oswego, Oregon, have come up with a innovative $439 ANR headset that comes within a hair's breadth of the comfort and quiet of the Bose but costs less than half as much. We rate the LightSPEED 20K the clear price-performance winner among ANR aviation headsets. They also have an economy model 15K priced at $299 that compares very favorably with the $600 ANRs we've tested.

  Also see Mike Busch's review of LightSPEED's newest headset, the 25XL.  

LightSPEED 20KWhen Bose introduced the first active noise reduction (ANR) headset to the aviation community at Oshkosh in 1989, pilots who visited Bose's big black trailer and tried the headset had two distinct reactions to it:

Reaction A: "I just can't believe how quiet and comfortable this headset is! I've simply gotta have one!!! I don't care what it costs."

Reaction B: "How much did you say this headset costs? A thousand bucks??? Be serious! They'll never get away with pricing it that high! The price has got to come down! I'll just wait until it does. No way that I'm going to spend a grand on any headset!"

AVweb's publisher Carl Marbach and I make a good case study. He's an "A" and I'm a "B." Carl bought his first Bose headset at that 1989 Oshkosh trailer and has simply refused to use any lesser headset since. I, on the other hand, have lots of hours wearing other peoples' Bose headsets and I agree that they're absolutely marvelous — but I simply have never been able to bring myself to spend a kilobuck on a headset. For eight years, I've been waiting for the price to come down. And for eight years, Bose has stubbornly held it firm. The nerve of those people!

Where's the Competition?

Meanwhile, the other major players in the aviation headset business introduced their own ANR headsets, all at prices somewhat lower than Bose. And I've tried them all. Telex was the first to field a competitive active headset. I flew with it but didn't like it at all, which didn't surprise me because I've never much cared for Telex headsets.

Next, David Clark entered the ANR competition. This time, I really had my hopes up because I've always been a big-time DC fan and my headsets have always been green (as opposed to my wallet). But again I was disappointed: DC's ANR offerings were just DC passives with some ANR circuitry added...and not terribly good ANR circuitry at that. They didn't come close to offering the comfort of the Bose, and I still couldn't wait to get the darned things off toward the end of a long flight. Okay, they're incrementally better than my faithful old DC passive headsets...but they sure aren't worth $700 in my book!

Call me frugal. Call me a cheapskate. I'm guilty as charged ... and I've been called a lot worse.

I tried the Peltors and the Sennheisers and a couple of the off-brand ANRs too. But none of them were comfortable enough or quiet enough or cheap enough to persuade me to forsake my trusty DC green-earcup head-in-a-vise passives.

But that just changed! A small audio company in Oregon that nobody ever heard of is about to stand the aviation headset market right on its proverbial ear. The comfortable, quiet and cheap ANR headset that I've been waiting eight years to purchase is now here! Good things do come to those who wait...but sometimes you've got to be incredibly patient.

So Who the Heck Is LightSPEED?

LightSPEED logoLightSPEED Technologies in Lake Oswego, Oregon, was founded a few years back by some engineering, manufacturing and marketing people who formerly worked for Tektronix, the giant electronics and instrumentation company. LightSPEED manufactures a variety of precision audio products including wireless microphones, hearing aids, and classroom amplification systems. About a year ago, they stuck their corporate toe into the aviation headset market by introducing the LightSPEED model 15K ANR headset at Oshkosh '96, priced at $299. (More about the 15K later in this article.)

Recently, LightSPEED introduced their second-generation 20K aviation headset, priced at $439. That's the one I'm all excited about. They're showing the 20K for the first time at Oshkosh '97, and my guess is that once the word's out they'll have trouble keeping up with the demand. I've already ordered two of the 20K's for my airplane...just to make sure I beat the rush.

Look and Feel

EarcupsThe LightSPEED headset looks, well, different. It appears to be made entirely of gray plastic, and has a sort of extra-terrestrial look (as if designed by aliens from Roswell, NM). It turns out that the headband actually has a metal core, but it's totally sheathed in plastic. The yokes, earcups, and adjusting mechanism are all plastic, too. So I imagine that this headset won't take the kind of physical abuse that a David Clark headset will. But then neither will a Bose.

The earcups have a distinctive triangular shape, and are fitted with ultra-deep (inch-and-a-half thick) earseals that contain three layers of temperature-sensitive foam, each layer having a different density than its neighbor. The earseals remind me of the aftermarket Oregon Aero "Soft-Seal" cushions that I use on my DCs for increased comfort; they use the same sort of temperature-sensitive foam construction. (Hmm, LightSPEED is in Oregon, too.) The foam softens where it touches warm skin, making it capable of accomodating the head shape perfectly with minimal clamping force. It also seals exceptionally well around the temple pieces of eyeglasses or sunglasses. (But don't leave this headset in the plane overnight when it's below freezing outside, or the earseals will be rock-hard when you first try to don the headset.)

HeadbandThe headband is also padded with one-inch-thick soft foam pillows, and is adjustable over a wide range by means of "ratchety" sliding rails that connect the headband to the earcup yokes. Unlike my DCs, there are no tools required to loosen the headband adjustment (which is good) and no way to lock the adjustment in place (which could be a disadvantage if you carry the headset around in a carrying bag rather than leaving it in the airplane like I do). I have a wide head (some say swelled) and the headset fit me fine without going to max extension. LightSPEED claims that the low end of the adjustment range accomodates children, and it certainly looked that way to me although I didn't actually try it out on a kid.

MicrophoneThe microphone uses an electret element (the best kind) with an integral foam blast shield. It mounts on a thin flexible "gooseneck" boom with a ratcheting plastic elevation adjustment where it attaches to the left earcup. It seems like a good arrangement. My only complaint is that the headset is permanently a "lefty." When I'm flying in the right seat, I usually like to turn my headset around so that the mic boom is on the right side. I can do this with my DC, but not with the LightSPEED because its triangular earcups are canted for optimum fit and distinctively left- and right-handed. This is only a minor drawback, though..

Comfort is a very subjective thing, but I found the LightSPEED to be every bit as comfortable as the Bose. In some ways, I liked it better: it weighs less (16 ounces) and the earseals don't have that strange "breast-implant feel" of the Bose gel-filled seals. Certainly, the LightSPEED is as comfortable as any headset I've tried.

ANR Performance

LightSPEED 20K bandpass diagramLet's cut to the chase. The active noise reduction capabilities of the LightSPEED 20K are simply outstanding. Flip on the switch and it "sucks the noise right out of your head" just like the Bose does.

Lab tests indicate that the LightSPEED 20K ANR system provides exactly the same number of decibels of active noise reduction as the Bose Series II ... about 20dB maximum. The LightSPEED's achieves maximum reduction at about 110 Hz while the Bose's notch is centered at about 180 Hz. Is the difference significant? Let's see.

Suppose you fly a propeller-driven airplane with a constant-speed prop, and suppose your normal cruise is at 2400 RPM. Divide by 60 and you get 40 revolutions-per-second. Now, the biggest low-frequency noise source in your cockpit is power pulses from the propeller. If you have a two-bladed prop, your noise peak will occur at about twice engine RPM or 80 Hz; if your prop is three-bladed, it's three times engine RPM or 120 Hz. Either way, the LightSPEED's 110 Hz notch frequency is pretty close to optimum.

Another major noise source is exhaust noise. If you have a four-cylinder engine, your exhaust noise occurs at twice engine RPM (because each cylinder fires once per two crankshaft revolutions) or about 80 Hz. With a six-cylinder powerplant, it's more like 120 Hz. So theoretically, the LightSPEED's 110 Hz notch might be a tad better at eliminating exhaust noise than the Bose's 180 Hz notch.

LightSPEED 20K cockpit noise level graph But subjectively, to be perfectly honest, it's hard to tell the difference. Both headsets do a first-class job of cancelling low-frequency noise characteristic of piston-powered propeller-driven aircraft. As far as I can see, the primary difference is that the Bose costs more than twice as much.

If you're into such stuff, check out the noise graph at right. It shows a spectrum analysis inside the cockpit of a Cessna 172 with a four-cylinder engine and two-bladed prop. You can clearly see the prop- and exhaust-noise peak around 80 Hz, as theory predicts. And you can see that the 20K knocks it down by 20 dB (from slightly over 100 dB to slightly over 80 dB), just as advertised. But you can also see that there's plenty of low-frequency noise throughout the 50-200 Hz spectrum where ANR circuitry does most of its magic.

Audio Quality

The speakers in the LightSPEED 20K earcups offer excellent comm intelligibility, but if you're heavily into listening to CDs in-flight (instead of Rush Limbaugh or ballgames or news), the fidelity of the Bose transducers is somewhat better. However, the LightSPEED is certainly acceptable for music and offers stereo as well as monaural modes (manually switched, not automatic as in the Bose Series II).

Microphone audio quality and noise cancellation is excellent, as you might expect from a company that built its reputation manufacturing high-quality wireless microphones before getting into the aviation headset business.

Hookup

All active headets are at a disadvantage to passives when it comes time to hook them up, because of the need for a power module for the ANR circuitry. Bose offers its Series II headset in two different models: a permanently-installed model in which the power module is mounted behind the instrument panel, and a portable model with an external power module that contains a battery pack.

LightSPEED power moduleThe LightSPEED comes in only one flavor: battery-powered. The headset is connected to a small power module via a four-and-a-half foot cord. The power module contains two AA-size alkaline batteries (which are good for at least 20 hours of use), two slider-type volume controls, a stero/mono switch, an on/off switch, a battery-check switch, and three battery-level LEDs. The power module is also connected to a pair of standard mic and phone plugs via foot-long pigtails.

The question is: what to do with the power module in-flight?

In my airplane, the headset jacks are located at the extreme lower outside corners of the instrument panel, so the LightSPEED power module simply hangs down by the lower cockpit sidewall out of harm's way. On the other hand, if your jacks are located high on the instrument panel or, worse yet, on the cockpit ceiling, the dangling power module could definitely get in the way...in which case, you might have to relocate your jacks, use an extension cord, or secure the power module with Velcro.

Another related hassle is that the on/off switch on the LightSPEED power module is unguarded. This isn't a problem if you normally leave the headset in the airplane as I do...you simply have to remember to turn the thing off when you power down the airplane. But if you carry the headset around with you, it's awfully easy to bump the button accidentally and turn the thing on...resulting in dead batteries next time you try to use the headset. I'd like to see LightSPEED change the switch design to one that's harder to actuate inadvertantly. Meantime, either be careful or pop out the batteries before you store the headset.

The Lower-Priced Spread

LightSPEED 15KAs mentioned earlier, LightSPEED also offers an even-lower-priced ANR headset: the 15K. Physically, it's virtually identical to the 20K except that it uses earseals that aren't quite as deep and contain two layers of thermal foam padding (instead of three).

The big difference is that the 15K uses older and less-effective ANR circuitry, and offers about 5 dB less low-frequency noise reduction. The decibel scale is logarithmic, and 5 dB is a lot! So the 15K is simply not as quiet as the 20K, but it's equally comfortable and sells for $150 less. The 15K also comes with a two-year warranty, compared with three years for the 20K.

The 15K doesn't offer Bose-quality noise reduction, but it's on a par with other ANR sets I've tried in the $600 price range (like the DC and Telex), and it's more comfortable and a whole lot cheaper. It's also a significant improvement in both quiet and comfort compared to passive headsets at a price ($299) that's on a par with what you'd pay for a David Clark passive set.

I'd definitely opt for the 20K for crewmembers of a piston-powered aircraft...its superior noise cancellation is worth the extra $150. But for passengers, or for quieter aircraft (jets, turboprops, and airplanes with geared engines like the Cessna 421), the 15K would do just fine.

Where to Buy Them

LightSPEED logoLightSPEED Technologies has a web site where you can review the features and specifications of LightSPEED ANR models, read answers to frequently-asked questions, learn a great deal about the theory and design of ANR headsets in general (and LightSPEED's in particular), and order the headsets online.

Avionics West, Inc.LightSPEED ANR headsets are also available from a number of dealers, some of whom offer the headsets at small discounts from list. (There's not a lot of dealer margin on these units, so don't expect big discounts.) One of LightSPEED's "preferred dealers" is Avionics West, Inc., who maintains an on-line site and accepts online orders for all LightSPEED headset models (as well as a number of other brands).


WARNING: I've been flying with my LightSPEED 20K for nearly two years now, and it's spoiled me rotten. Wearing my old-faithful David Clark passives now seems like sheer torture. Once you get used to the comfort and quiet of the LightSPEED, there's definitely no going back. You've been warned!


Read what one AVweb reader had to say about his LightSPEED 20K.