David Clark H10-56HXL ANR Headset

It looks old fashioned, it's painted an unfashionable green and it's not made of carbon fibre. On top of all of that it doesn't have GA style plugs - you know the big one and the little one. This headset's made for helicopters so it has the single plug style. So the question is in these days of super-lightweight headsets made of space-age materials with mobile phone and MP3 interfaces built-in why would you choose a dinosaur? I didn't shell out close to $1,000 dollars without some considerable work and thought. More of that later but first let's learn about the headset.

Delivery, Versions & Installation

Most of us are familiar with the David Clark headsets and probably in particular the H10-13.4. This seems to be the world's most loved headset, at least until the Pilot, Avcom and various other headsets came along. The H10-56HXL comes from the same stable and looks pretty similar. The main thing when buying this headset is that you need an adaptor from the U-174/U single jack helicopter plug to the well known double GA plug. The most logical choice is David Clark part number 18253G-05 - it's a simple helicopter female to a GA double. The headset comes with the David Clark "Satisfaction Guarantee" - basically they say they'll do what's needed to keep you happy. Anecdotal information suggests that they do just that.

Features

• The key features of the H10-56HXL are:
   
   
  
• It provides 27 dB of passive noise attenuation; plus
   
   
  
• 17-22db of active noise attenuation;
   
   
  
• It has individual volume controls for each ear; and
   
   
  
• A super-soft headband pad.
   
   
  

That's it in a nutshell. The headset weighs in at 624 grams compared to DC's X-11 at 343 grams so it's no lightweight. In addition you get a sense of bulk - the earcups are bigger than a standard DC with additional depth. The battery pack is small and compact holding a 9 volt battery with a simple On/Off switch on the outside. A switch inside the battery pack allows you to select "auto-off" so that the ANR turns off when the headset is disconnected from the aircraft or the aircraft master is turned off. Battery life is around 25 hours and there is the option for a panel mounted power supply.

The other noticeable difference are the headset cords. Betraying its helicopter origins each of the cords is coiled like a telephone cord. This is a great feature it keeps the cords out of the road and prevents the kind of tangles that I always seem to create with headset cords.

The Headset

It's probably worth dwelling on ANR and noise attenuation generally for just a moment. All GA style headsets are designed to provide noise attenuation and communication capabilities. Going back to the standard DC H10-13.4 it has 23dB of passive attenuation. Occupational health guidelines suggest that somewhere around 24dB of attenuation is required in GA aircraft. The important thing to remember about the decibel (dB) is that it's a logarithmic measure of sound power and an increase of 3dB is equivalent to a doubling of sound power. In that context the H10-56HXL has over double the sound attenuation of the H10-13.4.

The problem with headsets as with other hearing protection is that they do not attenuate all frequencies equally. They tend to be better at the middle and higher frequencies and pretty lousy at the low frequencies. Low frequency noise exposure causes hearing loss in the mid-high frequency range - just where speech sounds live. The solution is ANR - Active Noise Reduction, sometimes also called ENC (Electronic Noise Cancellation). ANR uses a small microphone that samples low frequency sounds and a small speaker that creates an equivalent sound 180 degrees out of phase. The result is that the sampled sound is entirely blocked.

This is the basis for my choice of the H10-56HXL. A young adulthood with substantial exposure to tractor, bulldozer, power tool, aircraft, helicopter and firearms noise has left me with a small hearing deficit. I am really conscious of not doing anything more to damage my hearing. In addition any reduction in noise leads to a reduction in fatigue. The newer ANR aviation headsets such as the David Clark X-11 have passive attenuation of about 17dB - the Bose and others are not substantially different. The manufacturers are not keen on you knowing this but that is about the level that they offer. That means that they offer passive attenuation that is about 8 times less than the H10-56HXL - and many of those mid-high frequencies are not attenuated by ANR. So the hearing protection is not that great.

Yes a phone and music interface would be great but you need to be able to hear the music and you can't do that if you are deaf. Third party interfaces such as the Flightcell can provide that and more.

Using The H10-56HXL

Enough of the technical discussion, what is the headset like to use? Setting up in the aircraft is simple. I leave the GA adapter permanently fixed to the headset. When I jump in I simply plug in to the two intercom jacks as normal and find a spot for the ANR module. This is a bit of a problem. The module is small and has a belt clip on the back. However clipping it to your belt usually means that it's squashed under your harness - not comfortable. I usually find a spot for it in a pocket or on the centre console or even the parcel shelf behind my seat.

Once I've got my harness on I grab the headset and settle it onto my ears. I wear glasses and the gel seals cope with no trouble. This was one of my worries before I bought the headset after hearing horror stories about ANR gone mad because the arm of the glasses broke the seal. But I worried needlessly.

I normally leave the ANR turned off during start up. Even without ANR this is simply the quietest headset that you are ever likely to wear. If you switch from a run of the mill headset to a H10-56HXL you will be pretty amazed at the difference in passive sound protection. That's great if the batteries run out and you can also rest easy knowing that the mid-high frequencies are well blocked.

The headset also has individual volume controls for each ear. With the microphone boom on the right side the ear controls rotate backward to decrease volume. This is a great feature if the aircraft is noisier on one side or the other or if you have hearing that varies from ear to ear. I find that I use much lower volume settings on this headset than on others because of the massive reduction in background noise.

When the ANR is turned on you get a brief hissing sound and then an eerie silence. Yes you can hear the engine - in almost supernatural detail - but you can't hear any of that repetitive low frequency noise that is so intrusive. In a helicopter the thumping of the blades is gone and you are left hearing what really matters.

The microphone boom is very adaptable. It is made in two parts. The section closest to the headset is wire and the section holding the mic is a flexible boom. That allows you to move the mike further and closer and also position it left/right and up/down. It's very easy to get it just where you want it and to keep it there.

The headband padding is very ample. I don't tend to get hot spots under the band. I do think there's a business opportunity for someone to make aviation caps without a button in the top. No matter what I do I can't stop the button on the cap hurting eventually. The headband is adjustable in the standard DC fashion: put it on your head and push the earcups up whilst holding the top of the band down. Clamping pressure is not noticeably different to any other headset and is certainly not uncomfortable. The extra bulk of the headset is no greater than say the Telex Stratus and I certainly don't notice it in use.

I loved my H01-56HXL headset so much that I searched for a newish second hand set for my wife and our daughter. Both of them are small people and my daughter in particular is very petite. Neither of them finds that the additional weight of the headset is a problem. I've worn the headset for up to 3 hours at a time with no problems and my wife far prefers it to the extra noise she has to suffer with a standard headset.

In summary this is a great headset that gets very little press, unlike it's flashier cousins. Once you have used a headset like this you'll never go back to a standard headset. No it doesn't look flash, no it's not carbon fibre, no it's not black. It does however offer the best hearing protection available in a headset.

Likes

• Fabulous passive sound attenuation coupled with simple, effective ANR;
   
   
  
• Robustness - you just can't kill DC headsets and this one is no different;
   
   
  
• Comfort;
   
   
  
• Simplicity;
   
   
  

Wish List

• A mobile phone/music interface;
   
   
  

Mike

many of the points you make about ANR, especially about the poor passive noise reduction are very valid and when I was researching this space I very much felt that unless you were a very informed consumer that there were many traps for the uninformed. Once again marketers have triumphed over the technical staff to our ultimate detriment.

I chose the Telex Stratus 50D's for exactly the reasons you have identified, for those looking for a true competitor to the headsets youve presented above, here are the technical specs from the 50D's owners handbook:-

"The Telex Stratus 50-D is a medium-weight, active noise-reduction headset with

is 50+dB of noise reduction."

It was the stong passive performance and the more complete specifications, in addition to the more usual reasons for choosing a headset that had me select these. Not saying they are better or worse than the DC's just that they are orders of magnitude better than those other poor performing ANR headsets that you refer to.

Andy