[voja]

All three of these terms have been used simultaneously for the past several decades. It's been a true nightmare, because they do not have the same meaning and don't relate to the same concept.

I am calling all Head-Fiers to help me out to define each one of these.

Orthodynamic is a term that was first used by YAMAHA back in the 1970s, when they introduced their first orthodynamic headphone, the HP-1. Perhaps the term makes more sense when we separate it with a hyphen, ortho-dynamic. Like a standard planar-magnetic driver, there was a diaphragm in the middle with an embedded voice coil, and a set of stators (a magnet on either side). However, unlike standard planar-magnetic drivers, it didn't use a flat diaphragm. Instead, like dynamic drivers, it used a diaphragm with curves/ridges.

We already know that the term planar-magnetic has been well-defined, but what about isodynamic? Does it refer to the same concept of orthodynamic?

The term "orthodynamic" has been thrown around and used incorrectly ever since it was introduced to the industry, so I am trying to get the facts straight and make sure that we can start, or at least try, using the terms correctly.

 

[Davesrose]

Literature seems to indicate that Yamaha's "orthodynamic" does fundamentally work like other brand's planar magnetic drivers (etymology of "ortho" meaning straight). The diaphragm is a flat thin film, with voice coil traces being radial, along with the surrounding magnetic arrays (so the layout of those designs are different than other planar brands).

https://spectrum.ieee.org/the-consumer-electronics-hall-of-fame-yamaha-hp1-headphones

 

[voja]

Literature seems to indicate that Yamaha's "orthodynamic" does fundamentally work like other brand's planar magnetic drivers (etymology of "ortho" meaning straight). The diaphragm is a flat thin film, with voice coil traces being radial, along with the surrounding magnetic arrays (so the layout of those designs are different than other planar brands).

https://spectrum.ieee.org/the-consumer-electronics-hall-of-fame-yamaha-hp1-headphones

Thank you for contributing! That's a very interesting article.

Based on my research, YAMAHA did use drivers with ridges, i.e. not flat diaphragm. I think ortho indicates "upright", instead of straight. For example, iso (isodynamic) means "even". If that's how we view both terms, we can draw a conclusion that isodynamic drivers use a flat diaphragm, while orthodynamic drivers use an "upright" diaphragm. If this is the case, then it would mean that planar-magnetic and isodynamic refers to the same concept.

Take a look at some of the following pictures, where you can see the raised parts in YAMAHA's drivers (the best example is the company's newest YH-5000SE):

anyways, here's the inside of a dead yamaha driver. Lots of grossness got inside over the years...

There are more pictures to support this, but Google search is not of much help...

 

[castleofargh]

Ortho, iso, planar, Zeus or Jupiter, We get what is being discussed (not your usual driver and not an electrostat). If we wish to get into details, then we'll inevitably specify a certain brand and model so we can get into all the little details of a particular design that helps do this or that (like get around patented designs).
Personally, I tend to call everything planar. If someone says Ortho I understand planar because over time everybody has been using both interchangeably, and if someone brings up isodynamic I think he's trying to brag that he knows a special word. I remember using that in math(isogonal, isocline, isodynamique, I learn them in French but with their etymology, the English words must be similar).

Like just about anything in language, once most people start calling something a certain name, it de facto becomes the right name for it. We can fight that for a while if we catch it early and explain:

But in practice, wrong and stubborn usually prevail to create the new correct expressions. That's how the audiophile lingo has pages of terms that have been robbed of their original meaning by people who didn't know better but kept saying it to sound smart, and that's also how the American language ended up needing its own dictionary.
For example, in this section there has been a long going battle to have soundstage used for the impact a room has on sound(sound, stage!!!!), instead of anything vaguely related to perceived localization of sound or 3D feeling. A battle that shows no sign of standing a chance. Every reviewer and their sisters talk about IEM soundstage.
Back in the days, I was going crazy over people calling the sound propagating to their ears while rubbing a headphone cable "microphonics". In this hobby, just about everybody knows the word meaning just that, while only few know that it's technically about converting vibrations into electricity (like a microphone does, it's the damn name for the tool that does it!). Everybody(in this hobby!!!!!) has adopted another meaning, it's now the proper meaning for the hobby and the one I use... It's that or spending your time on the forum facepalming.

 

[Davesrose]

Thank you for contributing! That's a very interesting article.

Based on my research, YAMAHA did use drivers with ridges, i.e. not flat diaphragm. I think ortho indicates "upright", instead of straight. For example, iso (isodynamic) means "even". If that's how we view both terms, we can draw a conclusion that isodynamic drivers use a flat diaphragm, while orthodynamic drivers use an "upright" diaphragm. If this is the case, then it would mean that planar-magnetic and isodynamic refers to the same concept.

Take a look at some of the following pictures, where you can see the raised parts in YAMAHA's drivers (the best example is the company's newest YH-5000SE):

There are more pictures to support this, but Google search is not of much help...

From what I've read, those ridges are the radial traces and not the actual diaphragm (which is underneath).

https://en.wiktionary.org/wiki/ortho-