How Planar Magnetic Headphones Work Page 2

Advantages of Planar Magnetic Drivers There are so many advantages to this type of driver in a headphone that I’m surprised it hasn’t caught on more. Let’s work our way down the list.

Planar Sound Wavefront --- In my opinion, this may be the most important characteristic advantage of Orthodynamic headphones. Standard dynamic drivers are fairly small and essentially operate as a point source of sound radiating a spherical section wavefront. When a spherical wavefront hits your ears it reflects on the outer ear in a geometrically different way than a planar wavefront. This causes the focusing of sound entering your ear to behave somewhat differently than it would normally. It is surmised that this disturbance of the reflective characteristics of your ear may inhibit normal localization of sound, and therefore disturb the audio image heard.

Headphones like the Stax electrostatics, AKG K1000 earspeakers, and Sennheiser HD 800 with it’s large ring-radiator, are known for their excellent audio imaging likely due to the more planar wavefront they present the ear. I find the imaging (such as it is on headphones) to be quite good on the latest crop of planar magnetic headphones, though possibly not quite as good as those mentioned above. My guess is that the high-end planar magnetic headphone makers (Audez’e and HiFiMAN) need to move the drivers a little forward and angle them back towards the ear to make improvements here.

Low Distortion --- Unlike dynamic drivers that are driven from the point at which the voice coil is attached (usually near the center), planar magnetic drivers are forced to move over their entire surface. This means they don’t suffer from modal break-up found on traditional drivers when the cone surface starts wobbling in undesirable ways at higher frequencies.

Large and Powerful Diaphragm --- Getting powerful, tight bass response is difficult for most dynamic headphones as the driver surface area is relatively small and would have to make large excursions to move the volume of air that good bass response requires. The force used in electrostatic drivers (the static force the makes your socks cling together out of the drier) is relatively weak compared to the electro-magnetic force in planar magnetic drivers. Electrostatic drivers have trouble delivering the horsepower needed for big bass notes. The large surface area of the planar magnetic driver coupled with the powerful drive of the electromagnetic force permits large amounts of air to be moved with authority. My experience with planar magnetic cans is that they offer the best bass response of any type of headphone.

Responsiveness --- The diaphragm in an Orthodynamic headphone is very light, and the electromagnetic force is very strong, so the ability for the signal to accelerate the diaphragm is very, very good. Like electrostatic speakers, planar magnetic headphones tend to sound very coherent and spacious.

Easy on the Amplifier --- Unlike the coiled winding of a dynamic driver, which creates inductive peaks in the impedance characteristics of the headphone, current planar magnetic headphones use a serpentine pattern for their voice coil, which makes their impedance characteristics almost purely resistive. Though they sometimes need quite a bit of voltage to drive them, they are not difficult loads to drive at all.

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COMMENTS
JIGF's picture

Very informative, thanks Tyll.

I took the liberty and posted a link to this article over here (http://www.head-fi.org/forum/thread/493214/hifiman-he-6-planar-magnetic-...). Hope you don't mind.

Tyll Hertsens's picture
Not. One. Bit! In fact, I love it. I think this site should be a gateway for people to find out about headphones; see that there's more than meets the eye; and develop (if it feels like something they might be interested in) a desire to find out more. Readers providing links to further information is a service to folks not familiar with the community of enthusiasts. So thank you very much for the link, JIGF!
LFF's picture

Very informative and loved how you broke them down in the video. Pun intended. Thanks!

kwkarth's picture

Good show Gov!

svyr's picture

so um, he-500 = 1/2 a sandwich = still ortho?

PMM's picture

"My guess is that the high-end planar magnetic headphone makers (Audez’e and HiFiMAN) need to move the drivers a little forward and angle them back towards the ear to make improvements here."

It saddens me a little bit that so few headphone manufacturers understand that. It's something that a number of Sony's headphones have been doing for a long time now (I enjoy this chaotic writeup by the inimitable Leonard Lombardo: http://www.sonicstudios.com/mdr-f1.htm ), and obviously the Senn HD800 and AKG K1000 benefit greatly from the angling.

If by any chance at all some folks from Audez'e and/or HiFiMAN are reading: Please do your best to implement this! You guys are AWESOME for reviving planar magnetics while all of the old dog companies rested on their laurels, but you can still bring 'em closer to the promised land.

Tyll Hertsens's picture
... I just got a new pair of LCD2s and it does look like the padding creates more of an angle to the ear (and is somewhat softer) than my previous one. I'll take pix and go into more detail in my upcoming review.
PMM's picture

That's great news. Looking forward to it.

jrkong's picture

Now if my 11th grade education is correct, the conductive trace would be attracted to the top field and repelled by the bottom field unless the motor principle I learned was wrong.

Pappabetalar's picture

Was at a hifi-store listening to the LCD 2's while I was reading this informative article. Thank you for taking the time to write it!

Insatiable's picture

This article mentions the high end of HiFiMAN's product line. What about the HE-400? It is lower on their product line. I was wondering what you think about it, if you have heard it before. Would you say it would fit the general description of the higher end models, just a little less so? I am looking to buy these as an upgrade from my old ATH-M50.

cindrella's picture

Most of the high end headphones use neodymium magnets and I have always seen this written in the spec column. I did not find it here thought. Could anyone explain me the difference? And what exactly makes it so worthy. Beverly Diamonds Reviews

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