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Author Topic: False paradigm of "open" and "closed" headphones.  (Read 1213 times)

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Marvey

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False paradigm of "open" and "closed" headphones.
« on: August 11, 2015, 08:51:48 PM »
Attached here for future reference. Thanks Claritas for finding this. I have no idea this was deleted from the PM-1 discussion thread on HF. It was relevant within the context of the discussion.

CORRECTION: the example of closed-back sealed ortho should be LCD-XC, not LCD-X.
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Deep Funk

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Re: False paradigm of "open" and "closed" headphones.
« Reply #1 on: August 11, 2015, 09:06:21 PM »
Add the AKG Diffuse Field and Sextett experiments.

Interesting topic indeed.
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Xen

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Re: False paradigm of "open" and "closed" headphones.
« Reply #2 on: August 11, 2015, 09:07:30 PM »
Learning!
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Marvey

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Re: False paradigm of "open" and "closed" headphones.
« Reply #3 on: August 11, 2015, 09:12:37 PM »
Quote from: Deep Funk on August 11, 2015, 09:06:21 PM
AKG Diffuse Field

Sextett =  box with passive radiators. Effectively monopole / closed-back. The "sealed" term above includes "ported" cup designs. (T50RP mods with open ports, Denon D2/5/7000 [yes, they are ported], Darth Beyers, etc.)

...

FUN FACTS:
  • Dipole radiators don't need a seal or as strong a seal to maintain bass extension. In fact, most or not all dipole radiators types tend to have some bass roll-off, e.g. Grado, HD600/650, AD2000, etc.
  • Monopole radiators like most orthos, stats, and some closed cup headphones will require a good seal to get good bass extension.
I came to understand this after taking measurements with simulated open air coupler (foam) and solid-plate couplers. I had always wondered why "open" (or more precisely open-backed) headphones like orthos acted more like closed-cup monopole headphones during the measurement process.
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Kunlun

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Re: False paradigm of "open" and "closed" headphones.
« Reply #4 on: August 11, 2015, 11:34:59 PM »
Thanks for reposting this! I thought it was on here somewhere? Anyway, it's great, thanks again.
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takato14

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Re: False paradigm of "open" and "closed" headphones.
« Reply #5 on: August 12, 2015, 02:52:03 AM »
Quote from: marvey on August 11, 2015, 09:12:37 PM
FUN FACTS:
Most or not all dipole radiators types tend to have some bass roll-off, e.g. Grado, HD600/650, AD2000, etc.
Monopole radiators like most orthos, stats, and some closed cup headphones will require a good seal to get good bass extension.

Uh, Marv, I think you have this backwards. Electrostatic and isodynamic transducers are inherently dipoles, both acoustically and electrically, simply by design. If made closed or having weird enclosure tricks done (airflow control in stats or single-sided/asymmetrical magnet structures in non-isodynamic planars) they can be monopoles as far as acoustics go. I've seen exactly one monopole orthodynamic transducer, and that was an Aiwa ribbon tweeter for DIY speakers.

Dynamics are conversely usually acoustic monopoles if I'm not mistaken, since the back of the diaphragm is (usually) dampened.

If I'm being dense, someone please correct me. Might've misinterpreted some shit in HF's ortho thread a few months back.

EDIT: I'm definitely being dense. As you were.
« Last Edit: August 12, 2015, 03:14:34 AM by takato14 »
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Drakkard

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Re: False paradigm of "open" and "closed" headphones.
« Reply #6 on: August 12, 2015, 12:39:51 PM »
Inner filter material used in HD-800 and audio-technicas does not make them truly Dipole in my opinion. It is a filter. If you remove it, leaving just an open space, measurements and sound will change noticebly. From my expirience, this filter can be very dense. To a point, where difference between using openings with filters in front baffle and just a solid baffle are very minor. This makes me think that usually the reason behind this is not to make headphone act like a dipole, but rather just to reduce structure resonances and reflections. Modders are covering housing with fibre or foam materials for the same reason. In mass production, paper filters is just more simple and cheap way of doing same thing. Also reduce weight.
Also, HD-800 and AD2000 have leaky pads, and it's not shown here.

Moreover, a lot of cheap headphones which looks like a closed-type, isnt such in reality. Many have inner leaks and openings. Thats why many "closed" headphones doesnt isolate well.
Also 90% of headpohnes have ports. Like, our FA-003 isnt really a closed headphone either, as there are two ports.
« Last Edit: August 12, 2015, 01:59:27 PM by Drakkard »
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Xen

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Re: False paradigm of "open" and "closed" headphones.
« Reply #7 on: August 12, 2015, 01:00:30 PM »
Quote from: Drakkard on August 12, 2015, 12:39:51 PM
Also, HD-800 and AD2000 have leaky pads, and it's not shown here.
What are some differences in pad considered "leaky" vs "sealed"? My AD700 pads seem to fit very well around my head. The pads are really not that thick and definitely not so plushy after 5 years of service.
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Drakkard

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Re: False paradigm of "open" and "closed" headphones.
« Reply #8 on: August 12, 2015, 01:03:47 PM »
Quote from: takato14 on August 12, 2015, 02:52:03 AM
Dynamics are conversely usually acoustic monopoles if I'm not mistaken, since the back of the diaphragm is (usually) dampened.
Iso's are dampened too. Its just not hard-glued to the driver assembly.
I know only one Iso witout dampening at all - Myst offerengs.
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Drakkard

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Re: False paradigm of "open" and "closed" headphones.
« Reply #9 on: August 12, 2015, 01:09:34 PM »
Quote from: Xen on August 12, 2015, 01:00:30 PM
What are some differences in pad considered "leaky" vs "sealed"? My AD700 pads seem to fit very well around my head. The pads are really not that thick and definitely not so plushy after 5 years of service.
Well, in my opinion, if you can blow the air through them - they leak.
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