How good are Dynamic drivers?

I’m curious, I know that your average planar magnetic or electrostatic drivers are more capable than your average dynamic driver but what about the most advanced dynamic drivers? How do they fare against planar and electrostats and what are the strengths and weaknesses of each technology?

BTW I’m focusing about how technically capable these technologies are, I understand that sound is subjective and that people hearing varies but this conversation is not about that.

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How so? What is your definition of “more capable”?

I’m under the impression that, for example, your typical planar has better bass extension than a typical dynamic and they tend to be a faster and more precise.

They are usually less sensitive (requiring more power) and limited in excursion compared to dynamics so they require a much larger surface area to produce higher SPL (slam).

Every driver has pluses and minuses. To call one technology “better” than another you have to specify in which area. A blanket statement cannot be made.

I will say it’s a mistake to believe that core technology dictates a sound, this goes as much for Dynamic vs Planar as it does for R2R vs DSD or anything else, it’s kind of true at the entry level that DSD sounds more analytical, but in more expensive components you get analytic R2R DAC’s and softer sounding DSD ones.

Some of us with TOTL headphones were discussing which entry level < $400 headphones we still used and the list was exclusively dynamic headphones.

Planars tend to sound faster (though not always), Bass is actually hard to manage in a planar driver, Audeze planars have a lot of bass, but it’s less true of hifimans outside of the very high end.
Biodynamics are competitive in bass quantity with planars and IMO have better bass control at the lower price points.
Having said that the best presented Bass I’ve heard is from a planar (D8000 Pro) but they claim a unique design to do that.

Some of the tricks used in planar’s to resolve FR issues tend to affect others, the addition phasors in the LCD line is considered to be a negative impact on other aspects by some.

Manufacturing variation is a problem is planars, because fields strength and membrane tension impact things, you’ll here talk of Unicorn LCD-2’s etc.

Everything in Audio is trade-off’s nothings “best”.
If Dynamic’s were at a fundamental disadvantage, you wouldn’t see them in TOTL designs.
D8000 Pro, Susvara, LCD4, Empyrium - Planar
Utopia, Verite - Dynamic

And of course you have Electrostatics, with a completely different set of tradeoffs.

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That’s exactly what I’m trying to learn actually, maybe I phrased it wrong but I don’t think that any technology is better in all departments although I am under the impression that planar and electrostatic seem to win in more areas sound wise over dynamic.

What you say is all correct. But IF we were to attempt to establish a baseline, we should remove things like cost, manufacturing hurdles, etc. So, if we said “which technology at its absolute best currently available” is superior, we would still end up with the same answers. But it would be a more appropriate comparison. Just splitting hairs, I know.

Sure you can optimize for a metric, and simple metrics it’s likely one technology would be dominant.
But you have to define best in that statement and it’s not a metric there is likely to be agreement on and it’s not likely to be simple.

TOTL designs are closest thing we have cost no object/manufacturing difficulty no object and how that relates to the real world.
Each of the TOTL headphones I listed have their proponents who’ll claim they are the “best”, which implies that there is a place for Dynamics.

Yup, in total agreement with you. That’s why in my original post I asked for a definition of “most capable”. Because there are different attributes that each technology tends to excel at. Of course we’d have to throw out subjective opinions and focus strictly on measurements like distortion, decay, etc.

If that’s the case, What tend to be the strengths and weaknesses of each technology?

Not being a tech guy like we’re lucky to have a number of on this forum, I’m always looking for the real deal behind questions such as this one from AcquiredTrack7. There seem to be a lot of memes out there about the typical properties of these technologies. I’ve encountered that dynamics have the most natural timbre, while planars and even electrostats are often reported to have a plasticky or metallic edge. Fast/speed plus good bass but not always sufficient treble are memes I keep encountering for planars. Likewise, poor bass but super amounts of detail seem to be common memes for electrostats. Somewhat sloppy bass but over-all natural timbre and of course good dynamics are memes for dynamics.

Many of these memes seem to have been around for a very long time and persist despite real technical evolution over the past decade. For example, the whole point of Focal’s M-dome + metal (deposition?) diaphragm drivers is apparently to produce a tight and especially punchy sound. Audeze typically uses two-sided magnet structures that trade off extra weight for increased punchiness, precision, etc. Yet Audeze has persistent trouble achieving an adequate ear amplification hump, while HifiMan has a strong upper mids hump, but it tends to be too narrow.

And of course the meme that AcquiredTrack7 is partly inquiring about, that planar is simply an all-around newer and better tech than dynamic, is at least working on achieving official meme status. But when you find a tech-focused interview with a headphone engineer, they’re universally quick to state that each of the technologies is a mix of strengths and weakness. Pick your poison. It’s all about juggling a thousand different tricks to minimize problems while maximizing strengths. I’ve come away with the impression that a few of the variables that can be juggled include diaphragm materials, size, shape and surrounds. Magnet materials and topology. Enclosure materials and shape. And of course the degree of enclosure openness or closedness. Plus, a huge and endless labyrinth of ear pad materials, seal, shape, etc.

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The main advantage of planars is the ultra light diaghragm. It also moves more uniformally (less flexing, deformation) than a dynamic cone/dome/etc. This all leads to a “faster” driver with better detail and less distortion.

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This.    

The disadvantage of a planar is mostly in the bass/SPL area. They simply don’t have the excursion that a dynamic driver has. So they don’t move as much air. It’s why planar headphone drivers have to be much bigger in surface area to produce “loud”/“impactful” bass. If you look at 2ch speakers, pretty much all of the designs using planars only use them for tweet and mid frequencies. Only Magnepan uses bass panels and they are HUGE.

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Here is Magnepan’s TOTL speaker. 95% of what you see is for bass reproduction.

Magnepan-30.7-15

I also see >2000€ in room treatment.

Re planar:

Can we parse this out a bit? I’m going to state a bunch of vague ideas I’ve acquired, and I want you tech guys to tear them to shreds. The driver rectangle is suspended like a trampoline in a surrounding frame. The magnetic trace(s) on the surface of the the diaphragm pull it up toward the (flat?) electromagnet suspended above/beside it. The stronger the electromagnet and the thinner/lighter(?) the material of the diaphragm, the greater the potential excursion of the diaphragm. But to achieve that greater excursion the separation of diaphragm and electromagnet would need to be greater (invoking inverse-square-of-distance power loss?). Traces and electromagnets on both sides could potentially roughly double the excursion. The more flexible the attachment of the diaphragm to its frame/surrounds the larger and more linear its movement could be.

More or less, but as the Diaphram becomes lighter and less rigid, you introduce issues with motion introducing waves on the surface of the material.
Dynamic drivers have the same issue, it’s why you selections of materials for the cones, paper vs wood (yes really) vs plastic vs Carbon Fiber vs various metals, all potentially coated with various things.

Caveat this is an area I really have no expertise in.

Fundamentally both use a magnetic field to move something backwards and forwards, that moves the air.

So you’ve got the shape of the thing moving the air cone vs flat panel.
You’ve got the stiffness of the thing moving the air relative to the force acting on it
How the magnets impinge on the air motion
How dense a coil you can create for the magnet to act on to create force
How the magnetic flux changes through the travel of the driver
etc etc.

But those aren’t in isolation for example building a driver with excessive force that’s too fast for the material it’s moving, would cause ringing in the material being moved.

It took a surprisingly long time for Neodymium magnets to be used broadly in dynamic drivers, and I’m sure cost wasn’t the only reason for that.

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Yup.

Yes but not quite. Just like a trampoline can only be stretched so far before it breaks or you run out of strength (in this case the strength of the magnetic force), there is a physical limit to the excursion.

See my previous comment. There is a physical limit. If you use a magnetic field strong enough, the diaphragm will simply break (fail) once past its limit of stretching. There is also the issue of bigger and more magnets in front of the diaphragm impeding the natural flow of air and resulting in distortion.

Planar diaphragms do not have surrounds. They are directly attached to the frame. Therefore, all excursion depends on how much the diaghram material is able to stretch before either breaking or permanently deforming.

Since a planar diaphragm is a very thin sheet of plastic, it must be under tension to hold its flat shape. Therefore a separate flexible surround is not used.

The amount of tension put on it plays a big role as well. The higher the tension, the less opportunity for the diaphragm to deform during movement. This leads to more accurate reproduction of the signal. However, a higher tension raises the resonance frequency which in turn limits its ability to reproduce low frequencies. A higher tension on the diaphragm also lower efficiency (sensitivity) resulting in the requirement of stronger (bigger or more) magnets and/or higher power amplifier.

Then you have issues with diaphragm dampening. These are the same as for dynamic cones. Without adding some sort of absorption material to the surface, it becomes very hard to control resonances internal to the material of the dighragm/cone. Adding material to control internal resonance increases the weight. More weight = a driver that is either slower for the given amount of power (not as resolving) or a driver that requires substantially more power. More power = more problems with dissipating the heat from the coil or risk frying it.

Everything is a trade-off. If there was one optimum way to do things, everyone would be doing it and all drivers would sound the same.

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I think poly mentioned something like this, but I think the confusion also lies in the fact that most people (me included) who have listened to planars, e-stats etc have maybe only been in the lower price ranges. Because i heard the 4xx and sundara i used to think planars would always sound less organic, less impactful, maybe not heavy hitting bass. But then I got the lcd 2 prefazor and it destroyed all my ideas about planars as it ended up being one of the most impactful and visceral headphones i had ever heard in addition to being the most organic sounding audio equipment I have ever heard. Before that I thought that dynamics and biodynamic would be the most organic due to my experience with the hawks and senheiser. Now i think that the three probably can equal each other in most aspects and it just depends on the price. However i haven’t heard the top of the line headphones yet so maybe there they do show different roofs in terms of capabilities and specific things that differentiate the actual drivers

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