Orthodynamic Roundup

[vid]

Some more EQ experiments. I found that the foo_dsp_xgeq plugin for foobar does separate left/right equalizing, and since it seemed to produce a smooth curve (unlike the curiously angular default foobar EQ), I tried it as a replacement for physical mods on the trusty HP-50S.
 
Left picture is for the left channel, right for right. The volume was adjusted so that both channels measured as having about equal amplitude.

 
The resulting curves. Blue and red are the equalized channels, grey is what I used as the target curve - the physically modded left channel. I toned down the 3 kHz peak a little. These graphs show ear canal resonances only; raw data; not to be taken as full-fledged frequency measurements.

 
The idea was to get rid of all mods and instead use EQ to push away the ortho bass hump (by making use of the real-world frequency graph from physical hump-moddings); as putting anything inside the -50S cups seems to turn into a horribly compressed pile its decent soundstage unmodded.
 
The results... Hmm. Hard to say. It sounds good with this EQ, but I'm not sure if it's not a little bit harsher-sounding than the physically modded version. I'm not sure, but not by much in any case. The soundstage is much better in this unmodded way. The ~12 kHz hump needs to go though - it was in the original modded version as well, and it's too loud.

 

[nick n]

Technics810's and their MCS counterpart the 8710 also use a 38mm SFI style driver but at 64 ohms ( or was it 63 i forget ).  I wonder can you somehow measure their resistance if you remove them from the cabling ever. Something to keep in mind for down the road.
 
Also is there a center hole on the magnets also?  Maybe I am blind at the moment.
 
VID:  a 100-110 mm driver now. intense, and they are also single ended/sided driven also ( unipolar )?
 
At least they weren't screwy with their build like the 4 different TRS'd Philips ( 6321,6325, 6326, EM-6721 )or were they?

 

[vid]

Quote:

VID:  a 100-110 mm driver now. intense, and they are also single ended/sided driven also ( unipolar )?

 
Not sure, but Sennheiser seemed confident that they were. Also not sure why they wanted to make the driver so big, but you get a decent planar wave off it anyway.

 

[Kabeer]

Yamaha HP-50M: http://www.ebay.com.au/itm/YAMAHA-Orthodynamic-Headphones-HP-50M-Vintage-Yamaha-Headset-Rare-Collectable-/110954800507#ht_744wt_1271
Dont see many of these about, good at least for someone to grab the photos.

 

[wualta]

Quote:

 
Not sure [they were single-ended], but Sennheiser seemed confident that they were. Also not sure why they wanted to make the driver so big, but you get a decent planar wave off it anyway.

Ideally, you make a single-ended driver big because you can't let the diaphragm get too far away from the stator, because the controlling magnetic/electrostatic field is very shallow with only one stator. A good analogy is the thin film of atmosphere clinging to the planet. Once you're out of that, you're in space, and in space, no one can hear you vibrate. More seriously, once outside what you might call the control field, the diaphragm is, well, uncontrolled, which in practice means distortion in the bass. Make the diaphragm big, and it won't have to move very much to move a lot of air, so it never leaves the control field. Again, the bass panels on Magneplanar speakers are made this way. Works for them.
 
Quote:

Yamaha HP-50M: http://www.ebay.com.au/itm/YAMAHA-Orthodynamic-Headphones-HP-50M-Vintage-Yamaha-Headset-Rare-Collectable-/110954800507#ht_744wt_1271
Dont see many of these about, good at least for someone to grab the photos.

Got 'em.  With the microphone,  you can speak encouraging words to your amplifier. Hyah! Giddap! More current, Scotty!

 

[vid]

Thanks for the space-age explanation, that's pretty cool. I've got a feeling the Unipolars might be capable of decent bass extension (hopefully undistorted) with the help of an EQ, but I've not tried it yet. I keep imagining a sad driver flapping against its casing and getting hurt.

 

[wualta]

Did Senn apply any acoustic resistance (ie, damping) to help control the diaphragm? 

 

[nick n]

Thanks for the link Kabeer.
 
I saw a set last month for sale  but couldn't find where again.
 
These would make possibly the ultimate gamer can, if i did that.
 
VID/Wualta funny you should mention that
The Philips 80mm single ended stator had tiny green dots made from the same stuff as the bonded outer spacer ring, these small dots of green stuff were between each stator hole to keep the diaphragm from getting mangled on the charged stator. Can provide pics if you wish, if the camera's resolution will show them.  I did notice a pile of tiny dots on the diaphragm after dismantling it corresponding to the dots so it must have constantly been hitting that as part of their design, or when pushed too hard.

 

[wualta]

Yep, those greenies are undoubtedly little bumpers. 

 

[vid]

Sennheiser pulled an AKG on the baffle. It's covered by three or four different-looking (and feeling) materials arranged in concentric circles. The transparent middle part is covered by a plastic film. Not sure if there's damping at the back.

 

[wualta]

Aha! Small opening, big diaphragm = "bass lens". But that cloth looks like it's covering a lot of baffle holes. So you think Senn tried something like the Sextett? Weeeirrd.

 

[fe2cruz]

Heat control/dissipation in closed t40v2 project. 
I was wondering how much heat energy most orthodynamic drivers create. It seems like most of the heat would radiate
from my ears and body getting trapped in the headphone pads. Tight sealed deep pleather pads are great for isolation
bass and soundstage but get really hot. I'm wondering if strategically placed aluminum throughout the foam inside the 
pads would help reduce the heat? Would the drivers need some heat dissipation in the closed sealed cups too? Are
there any other materials that would work better to control trapped heat and environmental noise?

 

[Armaegis]

Aluminum in the foam won't do anything. Yes aluminum is a good heat conductor, but if there's nowhere for that heat to actually conduct to... then all you've succeeded in doing is warming up some aluminum.

 

[kalbee]

Aluminum in the foam won't do anything. Yes aluminum is a good heat conductor, but if there's nowhere for that heat to actually conduct to... then all you've succeeded in doing is warming up some aluminum.

Unless you make antennas sticking out of the earpads. In which case is only effective realistically in winter.

Perhaps velours are a better solution?

 

[Armaegis]

Quote:

Unless you make antennas sticking out of the earpads. In which case is only effective realistically in winter.
Perhaps velours are a better solution?

 
At that point you might as well start crafting cups out of aluminum. Either way, still not a great solution unless it's cold outside, in which case it might just have the opposite effect and make your ears too cold. 
 
The best solution still remains the simplest. Air out your ears for a few seconds every couple songs.