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materials to understand headphones better?

nyxnyxnyx

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First of all, I apologize if similar threads were created prior to this, I used the search function but did not see any.

I am a headphones enthusiast. I have tried many, from some people would laugh at (dt990, grados...) to widely appreciated models (hd650, arya, hd800s....). It's easy to read and exchange subjective opinion nowadays thanks to dedicated audio forums, but what I am missing here is technical insights to broaden my knowledge.

There are so many technical things I like to know better but don't know where to start, like how do different designs of planar work and what they each bring to the table (f.e let's say Audeze LCD2 versus Hifiman HE400), how many ways are there to physically damp the transducer, pros and cons of coating beryllium versus other types of coating, etc....

This forum is probably one of the most objective audio communities so I hope you folks will share what you know about headphones as a whole to help me gain a better understanding. Any articles, books or webinars are greatly appreciated!
 

DVDdoug

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I really don't know the details, but like everything else there are design & engineering trade-offs & compromises and one solution isn't always better than another. Is a ported speaker better than a sealed speaker? Is a smaller engine with a turbo, better than a larger engine without one?

And of course, cost and economics are one of the considerations. At least until you get into the "audiophile world" where normal-logical economics gets flipped-around and a higher price make a product more desirable. ;)

And, every manufacturer is going to tout their design choices as an advantage or benefit.

Some people prefer open headphones and some people prefer closed/sealed headphones. And that's just a preference. There are good headphones designed both ways. Or, there are some uses where closed headphones are required, like a singer listening to a backing-track while recording vocals, or a dance DJ cuing the next track while blocking the sound from the speakers.

So here's what I do know... You can make a good performing headphone with a traditional dynamic driver (magnet, voice coil, and cone or diaphragm). The best example is the affordable AKG K371.

You don't need exotic materials or construction to make a good headphone. And you can have an exotic design with exotic materials, and a high price, without good performance. If you sort the ASR reviews by "recommend" you'll see there is almost no correlation between price & performance.

Planar headphones have a reputation for low distortion and low efficiency/sensitivity.

Electrostatic headphones also have a reputation for low distortion, but I'm not sure if that's true. I think they may be inefficient too, but that's not a big deal since they need to be "energized" with high voltage so you need special amplifier anyway.
 
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nyxnyxnyx

nyxnyxnyx

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I really don't know the details, but like everything else there are design & engineering trade-offs & compromises and one solution isn't always better than another. Is a ported speaker better than a sealed speaker? Is a smaller engine with a turbo, better than a larger engine without one?

And of course, cost and economics are one of the considerations. At least until you get into the "audiophile world" where normal-logical economics gets flipped-around and a higher price make a product more desirable. ;)

And, every manufacturer is going to tout their design choices as an advantage or benefit.

Some people prefer open headphones and some people prefer closed/sealed headphones. And that's just a preference. There are good headphones designed both ways. Or, there are some uses where closed headphones are required, like a singer listening to a backing-track while recording vocals, or a dance DJ cuing the next track while blocking the sound from the speakers.

So here's what I do know... You can make a good performing headphone with a traditional dynamic driver (magnet, voice coil, and cone or diaphragm). The best example is the affordable AKG K371.

You don't need exotic materials or construction to make a good headphone. And you can have an exotic design with exotic materials, and a high price, without good performance. If you sort the ASR reviews by "recommend" you'll see there is almost no correlation between price & performance.

Planar headphones have a reputation for low distortion and low efficiency/sensitivity.

Electrostatic headphones also have a reputation for low distortion, but I'm not sure if that's true. I think they may be inefficient too, but that's not a big deal since they need to be "energized" with high voltage so you need special amplifier anyway.
Thank you for sharing your point of view and I think I am aware and agreeing with it. I do not think higher price equal higher performance and do not suggest it. What I want to know is probably *how* those headphones are created (especially the massively successful models). There must have been considerable R&D poured into the progress, with trials and errors until the prototype is finalized. I want to understand the components and characteristics of different designs or materials better. For example I want to understand why transducers made by Focal are considered great and special by many (not by subjective, flowery descriptions but by understanding how it works properly), etc....

I would have considered to go to a local headphones factory to learn more or even pay for a class or touring trip, but sadly there is no place like that in my city and I don't know any headphones/speakers engineers in real life to talk about it :).
 
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nyxnyxnyx

nyxnyxnyx

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FWIW I used to mod some headphones following some popular mods (dt990 mod, sony z7 mod, he400 mod....) anyone can find on Head-Fi, SBAF, Reddit or other places. I do not have a headphones measurement kit so I cannot confirm what changed for better or worse but it was fun to do it but most mods I've seen only focus on 2 things: The mass-loading and/or cup damping. I understand that if it works then there's no need to change it or question why it is so simple but I can't stop but think that there's no way there are only a few ways to modify and tune a pair of headphones. That's when my curiosity started.
 

asrUser

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Well, you could buy/lend a miniDSP EARS to measure the changes you made. I think it would help you greatly to understand the mods.
 

ADU

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Thank you for sharing your point of view and I think I am aware and agreeing with it. I do not think higher price equal higher performance and do not suggest it. What I want to know is probably *how* those headphones are created (especially the massively successful models). There must have been considerable R&D poured into the progress, with trials and errors until the prototype is finalized. I want to understand the components and characteristics of different designs or materials better. For example I want to understand why transducers made by Focal are considered great and special by many (not by subjective, flowery descriptions but by understanding how it works properly), etc....

I would have considered to go to a local headphones factory to learn more or even pay for a class or touring trip, but sadly there is no place like that in my city and I don't know any headphones/speakers engineers in real life to talk about it :).

You might want to check out Tyll Hertsens videos and articles for Inner Fidelity. He set the standard early on for doing in depth reviews and measurements of headphones. Tyll retired from the audio industry a few years ago. But you can find most of his old articles here on the Stereophile site...


His videos for Inner Fidelity can also be found here...


Alot of headphone developers start out like you, making their own designs by modding and adjusting existing headphones. It's been awhile, but I seem to recall one particular model (made by Fostex, I think?) that was a favorite of the modders back in the day. Not sure what the popular models are now though for that kind of thing.
 

ADU

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There are so many technical things I like to know better but don't know where to start, like how do different designs of planar work and what they each bring to the table (f.e let's say Audeze LCD2 versus Hifiman HE400), how many ways are there to physically damp the transducer, pros and cons of coating beryllium versus other types of coating, etc....

Differences in driver design, materials, damping and so forth were precisely the sort of things that Tyll would often explore in his reviews in some detail.

This is goin back several years, but since you mentioned the beryllium drivers, here is Tyll's review and video for the Focal Utopia, which uses beryllium drivers...



And here is also Jude Mansilla's (of head-fi.org) interview with Focal on the same headphone...

 
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ADU

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I think the headphone I was trying to think of before that was popular with modders was the Fostex T50RP. Here's a 2019 article on it from Headphonesty...


Another Headphonesty article from 2017 on different driver types....

 
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nyxnyxnyx

nyxnyxnyx

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That Fostex mod is probably called "Mad Dogg" mod or something. It used to be popular and IIRC it was not too difficult to execute the mod even if a person is not skilled in DIY.

Thanks for providing additional materials for me to read. I like to be able to separate and distinguish what is marketed as good by companies and what is actually good, to do that I need better insight to not misunderstand or grasp the technique used wrongly. Beryllium seems like it's becoming more popular now thanks to certain IEMs models adopted to use it as a part of the driver.

I wish headphones companies would host talk show or AMA more often. I've only seen a few and the last one was from Dan Clark a while ago.
 

Soandso

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nyx^3, - I like planars very much for listening at night and being enticed song after song. Their notes have such negligible decay I bear superb musical details.

They don't have a circular wire winding type of voice coil. Instead the wire is arrayed somewhat in the shape of the letter "S". The expanse of a driver's diameter which can accommodate that array may account for some of the differences among designs.

Not having a wound voice coil gives planars relatively low impedance irregardless of changing frequency; their signature is "flat". Which makes damping factor of little import. The driver's broad shape gives it surface with the air which dampens them and designs having different expanse of that large surface area (along with the relatively lower mass of a planar driver) introduces degrees of dampening.

If you put a tiny seed on the planar driver and played bass frequencies there would be one frequency where the seed did not bounce. That equates to their bass resonance frequency and planar drivers' excursion is below that resonance frequency. This arrangement is what allows planars to have flat bass and among different designs they may be tuned to different bass resonance frequencies.

Planars incorporate wiring of voltage division. It is part of why their sound pressure level is relatively lower (than dynamic drivers) and different design for voltage division plays out in inherent SPL. Which is why different designs may need more, or less, watts of power to match their volumes and in use get as loud as you want.
 
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nyxnyxnyx

nyxnyxnyx

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nyx^3, - I like planars very much for listening at night and being enticed song after song. Their notes have such negligible decay I bear superb musical details.

They don't have a circular wire winding type of voice coil. Instead the wire is arrayed somewhat in the shape of the letter "S". The expanse of a driver's diameter which can accommodate that array may account for some of the differences among designs.

Not having a wound voice coil gives planars relatively low impedance irregardless of changing frequency; their signature is "flat". Which makes damping factor of little import. The driver's broad shape gives it surface with the air which dampens them and designs having different expanse of that large surface area (along with the relatively lower mass of a planar driver) introduces degrees of dampening.

If you put a tiny seed on the planar driver and played bass frequencies there would be one frequency where the seed did not bounce. That equates to their bass resonance frequency and planar drivers' excursion is below that resonance frequency. This arrangement is what allows planars to have flat bass and among different designs they may be tuned to different bass resonance frequencies.

Planars incorporate wiring of voltage division. It is part of why their sound pressure level is relatively lower (than dynamic drivers) and different design for voltage division plays out in inherent SPL. Which is why different designs may need more, or less, watts of power to match their volumes and in use get as loud as you want.
Thank you for sharing your insight. I love the sound of certain planar headphones as well. I notice that in recent year there is a shift in planar transducer design, if we take Hifiman as an example, I think their older headphones (HE6, HE400, HE500....) all seem to have thicker or weightier transducer than what we have now with newer design (Arya, XS, Ananda....). Do you happen to know or have a theory on why they switched? Last time I tried to get deeper into this it was something about "lighter membrane, faster magnet therefore better CSD, better detail reproduction" but I forgot where I read it from and I don't know how accurate that conclusion is.

Also another characteristic I see of lighter planar design is they seem to need less power than before. If we take the specs of those headphones I mentioned and apply a single calculation on websites such as Digizoid the newer ones are more sensitive, but I don't know exactly why so it is just my observation.
 
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nyxnyxnyx

nyxnyxnyx

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If you put a tiny seed on the planar driver and played bass frequencies there would be one frequency where the seed did not bounce. That equates to their bass resonance frequency and planar drivers' excursion is below that resonance frequency. This arrangement is what allows planars to have flat bass and among different designs they may be tuned to different bass resonance frequencies.
So is this also the part where people define why planar headphones are capable of slamming harder, punchier bass? I apologize I am not so fluent in English so I don't fully understand this part.
 
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