Well, curious is a splendid quality to have.
I have never asked myself such question about that black part that sticks out a lot from the rest of the driver's aspect. And me that took for granted that I knew the HP 1000 driver good!
Quote:
what an incredible journey i had!! i would have killed my own hp2!!
Rofl! Actually I do think headphone drivers in general can survive music
this loud, but I'm way too conservative to recommend anyone trying it with discontinued HP 1000 drivers! even for the sake of curiosity... but I'm quite happy you did it, I find it VERY INTERESTING too! so thank you
It is a " "known fact" " on Head-Fi that the drivers for the HP 1000 were manufactured by microphone Japanese company
Primo, as commissioned by Joseph Grado to make them to his own specs. Apparently it is written Primo right on top of the driver (source: Rhydon [http://www.head-fi.org/t/269488/grado-drivers/15#post_3431274]).
http://www.primomic.com/products/ is a list of many of their products/schematics/patents? including their headphone drivers code named "DH-XX" (with XX as numbers), some of which quite intricate and complex in design. The HP 1000 driver looks based off the DH-57, but the dimensions do not match, the HP-1000 drivers (named "DH-40", according to the same source) have a 46.2 ± 0.3 mm outer diameter (my own measure), and not 48.4 mm.
What you're telling me you saw implies that this joint (in between two
red lines) would be some kind of living hinge/edge, as opposed to a cement or glue, that lets the black back body vibrate along...
(I'm a visual)
Vibrate along with what, in reaction to what? I see three possibilities here, either (1/3), like you said, the black body vibrates held "in the air" only by the "living edge", as a reaction to higher volumes of air being pumped by the diaphragm... personally I think it would confuse/mess up the sound more than it would serve any positive stabilizing(?) function.
Either (2/3) the black body is attached to the actual diaphragm by those "Mysterious layers" (as shown in the above picture) serving as a solid bridge, bonding together the two parts, unifying together the front and the back of the driver. Though I wouldn't know more about the advantages of such configuration/feature, compared to previous scenario, this time the diaphragm-black body ensemble would vibrate in a more unified/"coherent" way.
And (3/3), the magnet, instead of being attached to the white capsule, resides in the black body, and floats with it... but that would make no sense at all, so let's forget about 3/3.
if my assumption is right and the black part is actually a part of the driver
If your assumption is right, the black body is actually an important part of the HP 1000's sound!
I should report your discovery in the "Headphones' drivers" thread and ask if they would know why it's like that, serving which purpose, and if they know of other drivers doing that.
*edit: I think I recall reading an old thread on Head-Fi where people in it made allusions to the fact that this black part could be mobile. The context was that Larry@headphile.com (Xanadu something on Head-Fi) had received a seemingly never disassembled HP 3 in which the drivers had some kind of sponge cemented on their back (actual image of one of the drivers in question, next to a normal HP 1000 driver):
At the time, not knowing exactly what a HP-3 were, the people believed that this mod was done at Grado Labs and were some kind of failed experiment, giving explanation to both the 100$ reduced MSRP and the fact that HP 3 were made in such limited quantities. Yet, this is not a characteristic of the HP 3 at all, because that model is said in the official documentation to be identical in shape to its better matched drivers HP 2 and HP 1 counterparts, just like this HP3 proves to be:
(left picture, identical in appearance to a HP-2, nothing appended on the back of its drivers)
So it's definitely the job of a modder... Purrin did something similar in his HP 1000 too (http://www.head-fi.org/t/596028/joe-grado-hp1000-modifications/75#post_8322637)
Anyway back to that old thread with Larry in it and how it matters to us: Larry did felt like this added ring of acoustic foam changed the sound a lot, if not dramatically. And I think, though I'm unsure, that it is at that point (that I can't recall precisely) in the thread that someone suggested that the black body was a mobile resonating part, which's movement were being impeded by the spongy thing.
Photos:
we see through the white "podium" a change in color, I wonder why that is... could the magnet be so large?
the ultra-wide bandwidth cable; the strands of copper are twisted around a plastic tube/cylinder... this copper is the same as the copper used for the voice coil of the HP 1000 driver and throughout the HPA-1 and -2, as Joseph wanted them to match perfectly.
. Joseph uses words more simply and literally, and it's quite apparent when he's exaggerating (like the "400% more details" about his upgraded flat pads).