Headphones: More HiFi Than you Think
by henning[Note: this is a post by my friend Ray, who knows a lot about headphones!]
Hello, I’m here again on Henning’s site and I wish to share with you some of my knowledge on another topic near and dear to me. I’ve been a heavy headphone user all my life, and one of the things you can do to complete your HT rig is to think about maximizing your enjoyment of movies (and music) through headphones. For me, headphones are an integral part of my spare time, because quite often, my wife might be asleep already and I’m still in the mood to catch up on my online DVD rentals later at night.
Headphones for Home Theater
What’s there to know you ask? There isn’t much to it, you are thinking. Well, maybe. Most people don’t pay too much attention to headphones. I think you should though, because picking a good headphone rig can really enhance the versatility of your movie watching experience. Have you spent big money buying speakers/subs/amps, but listen through mediocre sounding headphones? One of the things that people don’t realize is that headphones can rival top end speaker systems in resolution. A high grade headphone setup costing say, a few hundred dollars can give a degree of accuracy and detail recovery of, say, a speaker system costing thousands. This is a good thing in movies, because picking up the actor’s dialogue is where headphones can shine. For me, this is great when I’m watching a movie where the audio mix makes it hard to understand what they are saying…without resorting to the subtitles on the DVD.
However, there are some drawbacks. First, one thing wrong with headphones is that they are stereo transducers, not an array of surround sound speakers, because you hear exactly what is coming only out of each channel in each ear alone, so the resulting directional sense of sound (the “soundstage”) you get is quite exaggerated and nothing like a speaker system. With headphones, all the sound is usually perceived as “blobs of sound” in your head, usually one big blob in the middle, one at each ear. Fortunately, Dolby and others know about this and created circuits/processors specifically for surround sound listening. These circuits are called HRTF (Head Related Transfer Function) processors. The research done in this area by Dolby and other engineers take into account the way the sound is affected by the shape of your head, shape of your outer ear, the delays from the sound waves bouncing around and from each channel, the frequency response changes and other parameters etc. They measured what the transfer function of headphone listening should be like to perceive the same 3D image that you get through speakers. Thus the circuit can do an extremely good job of relaying a soundstage using just headphones. Lots of research has been done on this if you want to find out more. Dolby invented the Dolby Headphone processor, and this processing is incorporated in many HT receivers/preamps, and it does a pretty good job for movie listening. You really do get a sense of 3D surround. I find it a bit too exaggerated for music listening but it does work wonders in opening up the sense of 3D.
Headphone Home Theater Solutions
Dolby Headphone is one company’s attempt at enhancing the headphone experience, but there are others too. Yamaha uses their own proprietary Silent Cinema circuit. AKG makes an extremely effective outboard unit called the Hearo 999 which you connect directly to your digital audio output of the DVD, and it is a very flexible unit with ten different general HRTF settings to suit the music or movie material you are playing. JVC makes a small outboard unit that gives you Dolby Headphone capability to any receiver that doesn’t have it already.
The other limitation of headphones is that, well, they can’t provide the visceral impact that a good subwoofer can provide, and there is no way you can circumvent that unless you buy some kind of couch shaker device to give you that rumbling feeling where you are sitting. Suffice it to say that speakers still give you more of the “you are there” feeling in that regard.
Buying Headphones
Now lastly, about the headphones itself. Buying headphones is a wide subject, and can be as varied as picking out speakers. I could spend pages talking about headphones, so I won’t try. You can do your own research at popular enthusiast sites like www.Head-Fi.org, but here are a few tidbits I thought I should mention.
Common sense dictates that wireless headphones are a good solution as you are free from the tangling and logistics of a cord, but I strongly suggest you consider picking up a wired headphone with a good quality extension cable such as the $40 USD one made by Grado Labs. Most wireless headphones really don’t sound all that great. The really good sounding headphones are mostly available only in wired sets meant for serious audiophile music listening.
If you decide to buy a wired headphone, there are lots of choices. Like speakers, there is a sweet spot where you can get a high performance headphone for a hundred bucks, but even if you have a roomier budget, you can get some amazing sounding headphones for a still reasonable sum. That’s the great thing about headphones, the barrier to true hi-fidelity headphones is quite inexpensive. There is no need to spend $14000 on Sennheiser’s electrostatic Orpheus system, the top Beyerdynamic or AKG dynamic model costs no more than $300-400 (USD) if you want one of the best. Like all things, going higher may get you better sound, but the law of diminishing returns applies. So it’s up to you to find that “bang for buck” ratio you are comfortable with. There are standouts in the under $100 range, but moving up buys you more “audiophile” grade improvements that are more appreciated as you develop your ear and critical listening habits.
Buying on Spec?
One thing to note that you cannot buy headphones, unlike speakers, based on specs alone, because manufacturers don’t specify +/- dB frequency response measurement specs like you would find on other audio equipment’s specsheet. There is a reason for this and it is because with headphones, due to the way you perceive sound, and the way they couple with your ears acoustically, and the wide range of ear shapes, you actually do NOT want a headphone that gives a flat response at your eardrum. Again lots of research has been done in psychoacoustics and most headphones are designed so that the target frequency response is tilted down in the treble for the most natural sound. They also design the frequency response so certain frequency ranges have a notch in them to take into account ear pinna reflections, varying acoustic ear cancel impedance, resonances and other technical stuff like that. So publishing the frequency response wouldn’t be useful because almost all people have no idea how to interpret them properly anyway. And every manufacturer has its own “secret target” formula which they aim their design based on their own R&D. Manufacturers like Grado Labs don’t even aim for a neutral curve, they are designed to sound good with music and are tuned by ear.
Comfort and Fit
Comfort is a big issue too, and I find circumaural headphones, the ones that surround your ear instead of resting on your ear (supra-aural), to be most comfortable for the long haul. They can get a bit hot though. Closed air headphones have a sealed enclosure that leak less sound, and are good if you don’t want to hear your roommates, but the best sounding headphones tend to be of the open air variety. There is just a lot more choice for open designs it seems.
Headphone Pre-Amps
Also, one other thing most people don’t realize is that the headphone output circuit in practically all receivers/preamps are basically an afterthought, even very high end brands. So serious listeners insist on an outboard headphone amplifier which connects to your line out and provides a separate headphone jack. This provides a quality high grade circuit for delivering the delicate signal to the headphones. For HT use, the AKG Hearo 999 is such a unit but can process surround sound. For stereo music, there’s lots of great headphone amps nowadays as headphone listening has really taken off and manufacturers are realizing the large market around headphone listening. 
From DIY vendors on ebay selling CMOY circuits in Altoids tins, to $2000 Class A units with dedicated power supplies and top grade quality DAC’s worthy of a home in any money-no-object audiophile setup. I personally use a headphone amp from HeadRoom Corp (www.headphone.com) which incorporate a simple but effective HTRF (crossfeed) circuit, and AKG’s current the top-of-the-line AKG K701 Reference model headphones in my system. For HT movies, I rely on the Dolby Headphone circuit with Beyer Dynamic DT880 headphones, I only use the headphone amp for music listening. For headphones, there are other great brands out there, like Grado, Sony, Audio Technica, Stax that have the whole range of prices covered starting at $40 to thousands of dollars for their limited edition models. There’s a headphone for every taste, budget and shape of head. I suggest finding a store that has several you can try, and take your time like you did shopping for speakers. Like all hobbies involving equipment, half the fun is the thrill of the hunt.
Buy Headphones for Better Listening
So…hopefully the next time you need to use a headphone, think about whether you think you are getting most out of your headphones. It might be worth the upgrading from the Apple iBuds or the cheapo $20 Sony’s you might be using at your computer to get the most out of your system.
One of the things that most people don’t realize is that the acoustics of the typical home theater room plays a huge role in the quality of the bass you get. You can spend tens of thousands on your sound system and have a top of the line subwoofer, but due to the way bass travels in your room, you may still end up with very boomy bass. In some parts of a typical room, the bass waves build up and you end up with huge frequency response peaks and dips, which is heard as very overbearing or weak bass depending on where you are sitting. Try a different seating position, and you may suddenly find your bass quality varying again. Usually smaller and medium sized rooms show most unevenness. A great deal of experimentation in placement of your sub can often help minimize the problem so the sound, and/or spending lots of money on expensive acoustical treatments is also going to help. The third way to solve the problem (for your listening location) is by equalizing your system for flat frequency response. A lot of receivers nowadays, like my current Yamaha, come with fully auto equalizer function using a supplied microphone. But these equalizers don’t do much in the bass region where all the problems occur.
Did you know that you could plug an HDMI cable directly into the wall? Pretty cool. Just one small problem: the wall plate costs $49.95. That’s a little pricey for a plastic-surrounded HDMI connector, but such is life in the custom install world. I have many custom wall plates in my home that house speaker terminals, RG6 connectors, RCA connectors, and Cat5 connectors. When I finish my basement I might have to add one of these for my PS3 to be located near where I sit. No, wait! The PS3 will have wireless controllers. Never mind.
I’m always excited to get something interesting in the mail, and last night that something was the 
Mark Johnson over at Audioholics had a problem - his wife. You see, Mark and his wife bought a new home and Mark got his wife to concede to his wish for a home theater in their living room. Just one catch - no wires could be visible. Now I have to say, if my wife made this request of me I’d be in a lot of trouble. But Mark was game, and found himself a nice HDMI cable at 
