[ujamerstand]

Quote:

I've wondered the same thing for years. AKG certainly wasn't afraid of new and interesting ideas that pushed the edge. 
Maybe they got burned with some spectacular failures in the market place and just got shy.

 

a low-end consumer grade product that got too costly perhaps? Anyways, I've tried out the idea in the patent, I lined the insides of the enclosure with weatherstrips, and suspended the driver within. This decoupled the driver from the enclosure. (No more cheap grado plastic resonance!) What resulted is perhaps the most satisfying open-back scheme I've heard so far. The best part: the weatherstrips creates air gaps that allow air to escape, thus you'd think there would be a lack of bass. However in reality, the bass is present, and it's tighter than the bass from all the other schemes I've tried so far. (Edit: actually, a tight seal between the pads and the driver is still needed to get good bass, I had a good seal to start with because I lined the edge of the drivers with tack. The weatherstrips simply isolates the driver from the crappy plastic enclosure, damping the resonance that muffles up the mids, a problem that hunted my open-back designs.) I'd encourage people to try it in their open-back designs. 

 

[wualta]

Quote:

As I understand it, having a closed back creates a reflective surface for the backwave, and will introduce non-linearities into the midrange and treble, on top of what's already there. An open-back, however, lets all that out, and so presents a cleaner soundscape. Unfortunately, if you don't have a perfect seal on the pads, this will reduce the level of bass, due to phase cancellation -- which occurs in an inversely proportional relationship to the frequency.

Well put. That's always been my understanding. A reflective surface behind the driver will create a hump in the treble that's hard to get rid of, and which many people can't stand, and I don't blame them. Even with absorptive stuffing, this treble buildup can hang around like a bad smell. For very dark headphones like some NADs, this effect might actually be helpful, but it has to be carefully controlled to avoid the comb-filter effects and other nasties that random uncontrolled reflections cause.


 
Quote:

I've tried out the idea in the [AKG] patent, I lined the insides of the enclosure with weatherstrips, and suspended the driver within. This decoupled the driver from the enclosure. (No more cheap grado plastic resonance!) What resulted is perhaps the most satisfying open-back scheme I've heard so far. 

I'm happy to see someone willing to defy accepted HF "wisdom" on this and decouple the driver from the enclosure. The best revenge is the unimpeachably good result.
 
The downside of making this a commercial product might have been, as has been pointed out, the necessity of getting a better-than-good backwave seal, plus the durability of what amounts to a foam driver mounting. 
 
The late Dr. Rudolf Goerike (a cofounder of AKG) was one whose mind seemed to push out new designs the way an air popper pushes out popcorn. Not all the ideas could be turned into commercial products, some that did couldn't survive in the marketplace, and some could be done much more simply than his original conception. But the thing was to keep the ideas coming, which he certainly did. We can learn a lot by studying his work.

 

[rhythmdevils]

Very interesting about the open back ideas.  What makes an open back headphone any different than the sound of just holding drivers connected to baffles and pads against your ears? 
 
I've read Wualta post about grado using the tube shaped cups behind the driver to control the backwave. 
 
I also wonder if drivers that are tuned for closed back designs have much chance in open back setups, that aren't reflecting certain frequencies back in more than others (which the drivers are likely tuned to sound good with).  Like the NAD's mentioned. 
 
I have a pair of KOA woody MS1.  I was thinking tonight about attaching the Fostex T10 driver/baffle/pads to the woody cups with grado earpad assembly.  And adding some damping to the inside of the wood cup's screen to keep it from being too open.  Seems like that's been tried a fair amount though.  Any success? 

 

[DefectiveAudioComponent]

I noticed the similarity with the drawings and the K41 too, but I assumed they were just similarities... I would guess it's a regular dynamic headphone, but if anyone has a K41 to open up....
 
Quote:

Good idea ujmamerstand, but I dont picture AKG developing a whole new ortho line and then releasing it as a one off $19 headphone without any fanfare and then dissapearing... Id love it if it is true though...

 

 

[LFF]

Well guys. I had a chance to listen to the HE-6.
 
In short....they are very, very impressive.
 
I listened to a few songs with them and everything I heard was awesome. I felt they had a nice flat frequency response and the bass was all there. You can definitely tell or should I say...feel...the low bass registers.
 
Although the model I heard was a pre-production pair, if the actual run sounds anything like the one I heard today....I want one!!!!

 

[jageur272]

Quote:

Well guys. I had a chance to listen to the HE-6.
 
In short....they are very, very impressive.
 
I listened to a few songs with them and everything I heard was awesome. I felt they had a nice flat frequency response and the bass was all there. You can definitely tell or should I say...feel...the low bass registers.
 
Although the model I heard was a pre-production pair, if the actual run sounds anything like the one I heard today....I want one!!!!

I really need to raise the funds to get either an HE-6 or an LCD2 (or both...)

 

[Sambones]

I've heard how the SFI 120ohm's require a lot of juice, but they appear to be much easier to drive than my Concept CE-H's (Fostex T20 oem). I don't think damping is the issue, either.

 

[wualta]

I think it could very well be due to their original intended use-- the SFI was a tweeter in an large elaborate, not to say eccentric, dipole speaker. The T20 driver was a headphone driver from the ground up.

 

[LFF]

Quote:

I really need to raise the funds to get either an HE-6 or an LCD2 (or both...)

Me too!
 
I really loved the HE-6. It looks good and it's really, really comfortable. The bass is awesome yet it doesn't overpower any of the other frequencies. It's a very impressive headphone. Too bad it's so pricey.

 

[HeadphoneAddict]

Quote:

Me too!
 
I really loved the HE-6. It looks good and it's really, really comfortable. The bass is awesome yet it doesn't overpower any of the other frequencies. It's a very impressive headphone. Too bad it's so pricey.

What amps did you try, and how did they stack up against each other with HE-6?

 

[Sambones]

Hey, check it out: another pair of Quadraflex Q45's http://cgi.ebay.com/Vintage-Quadraflex-High-Velocity-Headphones-Japan-/270600138016?cmd=ViewItem&pt=LH_DefaultDomain_0&hash=item3f01066d20
 
Every time I see them, my heart gives a little skip. Someone needs to invent a time-machine and murder the person who decided to make such a horrible headphone look so good.

 

[dBel84]

but it would make an ideal frame for the likes of Kabeer - gotta look at the bright side..dB

 

[LFF]

Quote:

What amps did you try, and how did they stack up against each other with HE-6?

The Equilibrato from Eddie Current and I can't remember the name of the other one.
 
The HE-6 are very power hungry.

 

[Kabeer]

Quote:

but it would make an ideal frame for the likes of Kabeer - gotta look at the bright side..dB

Thanks, Iv put it on watch. Getting it down from USA might be a bit pricey for a headband...but looks like it should do the job I want. Ill see how it goes.
 
Does anyone else have an equally useless dynamic I can take a large headband from?
 
 
PS, if someone is REALLY interested in a vintage Fostex T50 and isnt afraid to pull out the green for one, send me a pm...

 

[BoilermakerFan]

Quote:

Thanks, Iv put it on watch. Getting it down from USA might be a bit pricey for a headband...but looks like it should do the job I want. Ill see how it goes.
 
Does anyone else have an equally useless dynamic I can take a large headband from?
 
 
PS, if someone is REALLY interested in a vintage Fostex T50 and isnt afraid to pull out the green for one, send me a pm...

Don't you dare butcher that frame!  It deserves to hold my electret drivers! 
 
It would be much easier to use a modded Grado frame.  I have the first KH-33 frame, but it mounts in the center of the cup back like the T20/T50s.
 
 
What's really wild is the Q45s look like T50/RP18 frames/cups with Kenwood style front baffles.  All of my KH-*3 series cans have that slightly extended, chamfered front baffle, only the inserts in the back center for mounting the drivers changes.  Pretty ingenious tooling for injection molding so many different headphones off one basic set of dies.