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These look really interesting! I own an original AKG K1000 from 1989 and they definitely have a better sense of "solidity" and "presence" than ordinary headphon

These look really interesting! I own an original AKG K1000 from 1989 and they definitely have a better sense of "solidity" and "presence" than ordinary headphones with drivers that seal against your head, due to the natural crossfeed. Other than the K1000 successor that got released a year or two ago (mysphere 3) there has been very little development since then in the field of open-air driver headphones. Hopefully these can sound good without breaking the bank! Also this is the first headphone that uses a driver based on the BMR principle that I am aware of

falcolas 7y ago
HiFiMan has a series of open air planar magnetic drivers, and they're absolutely awesome to listen to. I've yet to find other headphones that can stack up. Their only downside is the weight.
- voldacar 7y ago
  Which Hifimans are you referring to? Just to clarify, I'm talking not about open-back headphones, but headphones that don't have pads and consequently don't form a seal between the ear and the driver.
  - falcolas 7y ago
    There is no seal. A seal implies a lack of air movement and sound isolation associated with closed back headphones. Open back headphones have no sound isolation in or out. The parts that contact around your ears with HiFiMan's simply set the distance from the driver to your ear, in a comfortable way.
    - voldacar 7y ago
      That is incorrect. When I say "seal", I am referring to the sealed cavity between ear and driver, not to anything behind the driver. This is actually quite important for planars in particular, as a broken seal between the ear and driver leads to rapid bass rolloff, due to the lack of excursion found in most planar drivers (ime this is most noticeable with audezes since their excursion is especially low but I notice it with my HE-6 when I don't have the pads on my head quite right and there's a tiny gap between my head and the pads somewhere)
      - p1esk 7y ago
        What would be the sound difference between such open-air headphones (no seal between ear and driver), and placing my head in between regular speakers (few inches distance, ignoring comfort concerns)?
        voldacar 7y ago
        Well for one, most speaker drivers aren't designed to cover the full range of 20hz-20khz, something headphone drivers are explicitly designed to do (historically there have been a couple of multi-driver headphones, but they were horrible without exception). Even a high quality midrange driver for a speaker will probably only have a good response between 300hz-5000hz and past the upper frequency limit you will get major treble spikes and rolloff due to the cone entering its breakup mode resonances, so it will sound predictably awful. Now there are fullrange speaker drivers, but these do not generally have flat response characteristics as they tend to roll off early on both ends of the spectrum, and fullrange drivers with multiple cones (aka "whizzer" cones) tend to have a breakup spike in the upper mids at around 3-5khz. I am a little less sure about the physics of this part, but I believe that even if you had a theoretically optimum speaker driver, you would run into Q-factor related issues because speaker drivers are meant to be listened to in the far field rather than being placed right up against your head, so if you had the driver right next to your head, your eardrums would see a huge FR spike in the midrange, due to a resonance/standing wave forming in the cavity between your ear and the surface of the driver. Headphone drivers, since they are designed to be placed up against the ear, are usually damped, mechanically or electrically, specifically to avoid this. The K1000 in particular is damped electrically (there's a small notch filter (?) on a tiny pcb that feeds the driver) since its sensitivity is already very low with the little amount of mechanical damping it has. One common issue between something like a K1000 and a headphone made with open air speaker drivers (no baffle or box behind the driver) is that they both experience rear wave phase cancellation at very low frequencies, which causes a 12db/octave rolloff below the primary resonance of the driver. This is due to the negative wave from behind the driver wrapping around to the front of the driver and decreasing the amplitude of the positive wave. TLDR speaker drivers, compared to purpose-built headphone drivers, are highly sub-optimal due to limited FR range, breakup modes, and Q factor / improper damping for the application. Directivity and near-field effects (both of which would further distort FR) would probably also be an issue with speaker drivers but I don't know of anyone really trying to build a high quality headphone from speaker drivers so I can't comment on that.

falcolas 7y ago

HiFiMan has a series of open air planar magnetic drivers, and they're absolutely awesome to listen to. I've yet to find other headphones that can stack up. Their only downside is the weight.

voldacar 7y ago
Which Hifimans are you referring to? Just to clarify, I'm talking not about open-back headphones, but headphones that don't have pads and consequently don't form a seal between the ear and the driver.
- falcolas 7y ago
  There is no seal. A seal implies a lack of air movement and sound isolation associated with closed back headphones. Open back headphones have no sound isolation in or out. The parts that contact around your ears with HiFiMan's simply set the distance from the driver to your ear, in a comfortable way.
  - voldacar 7y ago
    That is incorrect. When I say "seal", I am referring to the sealed cavity between ear and driver, not to anything behind the driver. This is actually quite important for planars in particular, as a broken seal between the ear and driver leads to rapid bass rolloff, due to the lack of excursion found in most planar drivers (ime this is most noticeable with audezes since their excursion is especially low but I notice it with my HE-6 when I don't have the pads on my head quite right and there's a tiny gap between my head and the pads somewhere)
    - p1esk 7y ago
      What would be the sound difference between such open-air headphones (no seal between ear and driver), and placing my head in between regular speakers (few inches distance, ignoring comfort concerns)?
      - voldacar 7y ago
        Well for one, most speaker drivers aren't designed to cover the full range of 20hz-20khz, something headphone drivers are explicitly designed to do (historically there have been a couple of multi-driver headphones, but they were horrible without exception). Even a high quality midrange driver for a speaker will probably only have a good response between 300hz-5000hz and past the upper frequency limit you will get major treble spikes and rolloff due to the cone entering its breakup mode resonances, so it will sound predictably awful. Now there are fullrange speaker drivers, but these do not generally have flat response characteristics as they tend to roll off early on both ends of the spectrum, and fullrange drivers with multiple cones (aka "whizzer" cones) tend to have a breakup spike in the upper mids at around 3-5khz. I am a little less sure about the physics of this part, but I believe that even if you had a theoretically optimum speaker driver, you would run into Q-factor related issues because speaker drivers are meant to be listened to in the far field rather than being placed right up against your head, so if you had the driver right next to your head, your eardrums would see a huge FR spike in the midrange, due to a resonance/standing wave forming in the cavity between your ear and the surface of the driver. Headphone drivers, since they are designed to be placed up against the ear, are usually damped, mechanically or electrically, specifically to avoid this. The K1000 in particular is damped electrically (there's a small notch filter (?) on a tiny pcb that feeds the driver) since its sensitivity is already very low with the little amount of mechanical damping it has. One common issue between something like a K1000 and a headphone made with open air speaker drivers (no baffle or box behind the driver) is that they both experience rear wave phase cancellation at very low frequencies, which causes a 12db/octave rolloff below the primary resonance of the driver. This is due to the negative wave from behind the driver wrapping around to the front of the driver and decreasing the amplitude of the positive wave. TLDR speaker drivers, compared to purpose-built headphone drivers, are highly sub-optimal due to limited FR range, breakup modes, and Q factor / improper damping for the application. Directivity and near-field effects (both of which would further distort FR) would probably also be an issue with speaker drivers but I don't know of anyone really trying to build a high quality headphone from speaker drivers so I can't comment on that.