CHANGSTAR: Audiophile Headphone Reviews and Early 90s Style BBS
Main Deck => Discussion for Registered Members Only => Topic started by: dBel84 on December 03, 2012, 07:41:08 PM
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I thought I would do some sleuthing and perhaps start collecting some information on various diaphragm materials to possibly correlate to some of the measurement characteristics that we see.
I have not cataloged much data and it was really only a thought that solidified after seeing the unique material used in the Beyer T50p
(http://i246.photobucket.com/albums/gg104/dBel84/IMG_0595.jpg)
(http://i246.photobucket.com/albums/gg104/dBel84/IMG_0594.jpg)
I am not sure it shows clearly, but the material is similar to a slightly stiffened gel. It remains soft and maleable but retains it's form. I have opened my fair share of drivers and this is the most unique (dynamic) driver I have ever come across. Most other drivers are some type of mylar or metal. Without getting into the numerous variations of planar and others such as the HD800, I wonder if some of the ringing and interesting CSD patterns can be correlated to the diaphragm material itself.
Just a thought, feel free to shoot the thought down.
..dB
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Like conventional speakers, there will definitely be some correlation between diaphragm material across drivers. However, the Voice coil diameter, qts and bl parameters for the driver will determine the differences between the drivers assuming material , size remain the same.
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Wow, so the diaphragm isn't stiff? I imagine it's the same diaphragm as is used on the DT1350, which is pretty darn clean and flat. (or at least can be if you get the right one...)
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OMG, Beyer is using scrotum for drivers?! :P
Driver material absolutely impacts its sonic signature so there should be correlations. Silk domes don't sound like titanium which sounds different than ceramic, aluminum, bio cellulose or paper and bamboo.
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I don't have much to add on the material front other than to say it was obvious with a little modding that there was a whole lot of potential in those drivers.
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Yes I suspect that the 1350 and the 50p are pretty much the same except that the T50p has no damping and sounds like garbage until you give it a little TLC and then it sounds incredible.
I get the whole speaker world cone material effect , it is just that 90% of headphone drivers I have seen look amazingly similar. I know that there are multitudes of driver images on headfi , I will do some mining and see if I compile ( or at least start a compilation ) of drivers.
these are AKG k141 - 501 drivers
(http://www.xmission.com/~alhaz/img_0954-crop-shrink.jpg)
but later k701 look very different
(http://i142.photobucket.com/albums/r96/superkuato/K701_3.jpg)
Feel free to join in and post drivers
- I can always edit the first post and keep all images contained if that makes sense
edit - I see that there are in fact MANY variations on the theme, I have lived a sheltered life - too much planar obsession.
Here is an early DT770 Beyer driver - looks remarkably similar
(http://www.xmission.com/~alhaz/img_0990-crop-shrink.jpg)
..dB
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Sony Vectran, Liquid Cystal Polymer, Bio Cellulose
(https://encrypted-tbn2.gstatic.com/images?q=tbn:ANd9GcQkNbZtw0NItAEh9ruAvO9Ub8u-MVjiybzoo43miQ5lvv-RKMH7iw)(https://encrypted-tbn1.gstatic.com/images?q=tbn:ANd9GcTXrYgAG3Hj87-ET90S_ikqkeQOASirFvltMjRnGk-KLP0aW0xV)(http://t0.gstatic.com/images?q=tbn:ANd9GcRQ8f9dIDzsohmfsrwIeNS_nGhEYosJlGl2s4YgGn1NrFJWNc7ZtM3psYutwg)
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Foster's thin microfiber + (what looks like a) mylar flexure drivers:
(http://cdn.head-fi.org/9/90/900x900px-LL-903a82be_Aurvana20Live_Driver.jpeg) (Creative Live Aurvana!)
(http://cdn.head-fi.org/5/5b/900x900px-LL-5be15d75_098e039c_Denondriver200050007000.png) (Denon AH-D2000)
(http://www.head-fi.org/image/id/3000545/width/900/height/900/flags/LL) (Denon AH-D7100)
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Diaphragm material and coating is certainly going to affect its structural damping, a key parameter if there happens to be mechanical resonances over the audio range.
Furthermore, diaphragm material, thickness, geometry and driving method (e.g large or small voice coil) is going to determine the presence and frequency of mechanical resonances.
I suspect the variations in tonality between tweeter materials lies in the variations in frequency and damping of its mechanical resonances. And the same likely occurs with headphone diaphragms.
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In general (from speaker world):
- More rigid materials = more peaky breakup/resonance modes, faster decaying CSD (outside of the resonance peak), more articulate sound
- Less rigid materials = breakup more evenly distributed, less ringing, but overall slower decaying, less defined sound
- Better quality/design magnet/voice coil/motor = less mid/high distortion
- Larger driver = less bass distortion
- Smaller driver = more bass distortion
- Larger driver = breakup modes/peak(s) at lower frequency
- Smaller driver = breakup modes at higher frequency (ideally out of audio band)
Weird ridges / bumps = trying to get the best of both worlds - adding more rigidity while getting the faster decay
Here's one of my favorite small woofers. Very resolving, articulate, and fast: http://www.seas.no/index.php?option=com_content&task=view&id=63&Itemid=87 (http://www.seas.no/index.php?option=com_content&task=view&id=63&Itemid=87)
Horrible ringing at 8kHz. Good thing it's a woofer where we can cross over at 2kHz.
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Also, mass:
Lighter material = more high end extension, higher resonant mode frequency, less dependence on spider dampening
Heavier material = less high end extension, lower resonant mode frequency, more dependence on spider dampening
Here's the reason 'stats have great high end extension and why balanced armatures have high resonant frequency.
(BAs don't have the extension, because they're highly dampened - otherwise they'd ring like hell.)
For example, mylar is a comparably heavy, stiff material, while cellulose is very light and flexible. Most microfibres are inbetween.
Carbon nanotubes are an interesting rare material, stiff and pretty light. Metal film is comparable to mylar, but usually slightly lighter.
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Mylar is heavier than cellulose? Maybe we are thinking of different versions of mylar and cellulose. Are you ruling paper cones out as cellulose?
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Actually yes. Paper cones are more dense, thicker and softer, also sensitive to moisture. Really low grade material compared to cellulose.
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It's probably better to think in terms of stiffness / mass than what's heavier or lighter. Cones tend to be targeted for a certain application tend to be of a similar mass (regardless of material, even exotic) that suits that application.
Materials like magnesium and aluminum requires a smaller amount of mass to achieve a certain targeted stiffness. Treated / doped / impregnated paper / cellulose is about the same as poly. From what I've seen, for equiv. pairs in a driver line, the paper and poly cones tend to weigh the same +/- a 0.5 grams. They do sound different. I think "paper" just sounds "faster" but has decay issues in comparison to poly. No one (at least no one respectable) uses non-treated "paper" these days.
End it end, it really doesn't matter if it's tuned to sound like shit, i.e. new Denon flagships.