Headphones and Earphones

HiFiMan HE-500 Over-the-Ear Planar Magnetic Headphones and EF-5 Headphone Amplifier

ARTICLE INDEX

In Use and On the Bench

It's been awhile since I have used headphones, although I do have the ubiquitous earbuds for my iPod. Although earbuds sound good, if you have a high quality pair, over-the-ear really does make a difference. For one thing - and especially with the HE-500's because their outside surface is open to the room - there is less of the "in your head" soundstage. I could easily mentally project the musicians in front of me with the HE-500's.

I could detect no audible distortion of any kind, even with the volume turned all the way up (the HE-500's are not very sensitive, so "all the way up" was loud, but not anywhere near as loud as I can get my regular audio systems to play).

Well, these are the best headphones I have ever experienced. For one thing, they are planar rather than conventional cones, and planar speakers' claim to fame is based on a large surface area that moves only slightly, compare to cone speakers that have a smaller area (piston diameter), so they have to move back and forth a larger distance to move the same amount of air, with the result being more distortion at loud levels. I have to mention at this point that the comparison is with large floor-standing planar speakers compared to their coned counterparts. With headphones, the cone drivers don't have to move very much either, so headphones of any kind tend to have lower distortion than big box speakers.

Secondly, the "in-my-head" soundstage that I dislike with more conventional headphones, and certainly with earbuds, was significantly reduced with the HE-500's due to their open back. I guess the word I would use is "transparency". It's the same effect I hear with floor-standing planar magnetic or ribbon speakers, where the sound comes out the rear side of the speakers as well as the front.

The overall sound of the HE-500's was more neutral than earbuds (which sometimes tend to be a bit bright), and also the bass was more natural (earbuds use a completely sealed chamber between the driver and your eardrum a few millimeters away, which can make deep bass very intense).

Lastly, I heard much more detail in the music than I do with any of my reference setups. This isn't really a fault with speakers. It is due to the fact that the high frequencies decline in loudness faster than the low frequencies as you sit farther and farther from the speakers. Fortunately, this problem is not quite so bad with speakers that use long thin (thin, in the side-to-side dimension) ribbons for the tweeters (some planar speakers have thin ribbons for the high frequencies).

Nevertheless, the headphones beat all my speakers for clarity, detail, freedom from distortion, and neutrality. It is not just my experience, but most people who compare good headphones with good speakers will say the same thing.

So, why bother with a conventional audio system that (1) costs a lot more than headphones; (2) takes up a lot more room than headphones and a headphone amplifier; and (3) sounds better than the conventional system?

The answer is complicated, but here is the way I see it: (1) a conventional audio system can be enjoyed by everyone in the room, and having friends over to listen to your latest SACDs or have background music for a dinner party, is a lot of fun; (2) although the headphone manufacturers are working on it, surround sound is just not practical with headphone, even with several drivers aiming from different directions in the same ear cup; (3) guys like to have "stuff", and a room full of audio gear satisfies that craving.

The solution? Since a good pair of headphones such as the HE-500 along with a good headphone amplifier like the EF-5 won't set you back even as much as just one pair of the good speakers you have in your surround sound setup, so . . . purchase the headphone/amplifier and call it your "Very Personal Music System".

Although I can bench test earbuds, I don't have a satisfactory setup for bench testing earphones. I tried it once, but it really didn't give me a feeling of confidence. So, you will just have to deal with my subjective evaluation of the HE-500's.

However, the EF-5 headphone amplifier is another thing entirely. Here are the test results:

All measurements were made with a 300 ohm load and an 80 kHz bandwidth.

At 1 kHz and 1.4 volts output, THD+N approached clipping (1% THD+N).

 

Using the same test frequency, at 0.5 volts output, distortion was 0.28%. At first glance, this seems high, but remember, this amplifier is a hybrid. The distortion is primarily second order, with only the third and fourth harmonics added. I really could not hear any distortion at all.

 

Using 19 kHz and 20 kHz sine waves, the B-A peak at 1 kHz was 51 dB below the fundamentals.

19 kHz 20 kHz

 

IMD was high, at 1.1% even with only 0.5 volts output.

IMD

 

THD+N vs. Frequency Response was different between the two channels. I would suppose this to be an indicator that one of the triode bias settings needs to be adjusted.

THD+N vs Frequency Response

 

THD+N vs. Output Voltage showed the lowest distortion at 100mv and then a rise to clipping at 1.7 volts output.

THD+N vs. Output Voltage

 

The measured Frequency Response was down 0.5 dB at 20 kHz and down 2 dB at 50 kHz.

Frequency Response