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1) And, frankly, the 830 looks like it oughta just kill, but it doesn't. It's the sound that's uninspiring.
2) The diaphragms heat-ripple because the magnets are weak and a lot of current has to flow in the voice coil to get much diaphragm movement. This doesn't affect sound quality until you blow the voice coil and/or delaminate it and/or melt a hole in the diaphragm.
3) But yeah, if you were going to try the supplemental-magnet gambit, this would be the 'phone to do it on. That's assuming your 830 is like mine. It may not be.
4) If you were going to start from scratch, the bar-magnet route sounds easiest. Your big problem would be getting the magnet array perfectly flat to keep the flux even everywhere in the gap. Well, that and keeping the magnets from making the headphone fly apart, a problem the 830 never had.
This could get interesting!
1) I know! The diaphragm is beautiful. Not on par with the T50, or your beloved T30, but still very nice to look at, imo.
2) Let's hope my EAH-820 owner never used his pair, or was a jazz enthusiast in that case. I wasn't worried about it much, but it does make you cringe a bit.
3) You're saying if magnet strength is comparable between your 830 and my 820? As in the possibility Technics changed their magnet material/source/some other variable sometime during the EAH-8x0 production lifespan (unlikely, I'd guess and hope, for simplicity's sake), your magnets are abnormally weak for an unknown reason (also unlikely I'd guess), or something else specific to one of our pairs?
4) Yea I figured I'd replace the magnets altogether if I were to do anything in that department. In theme with your "field-replaceable" diaphragm statement, should be easy enough to find a block neodymium with the right specs and drill holes to match. In this scenario I don't imagine it being too hard to get both plates parallel.
Random hypothetical. You could even get away tapering the inside magnet faces by .1-.2mm? once, or twice with the added magnet strength. This could possibly replace the felt bumper allowing some extra room for the diaphragm to "stretch out" in. Thoughts?
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1. No, because this is an ortho driver and, theoretically at least, the uniform magnetic field applies force equally over the active surface of the diaphragm: iso-dynamic. For a similar reason a flat passive radiator on a speaker can be a simple disc of foamcore or even plain styrofoam-- the pressure inside the speaker box is the same over every point of the passive diaphragm, so there's no force trying to make the disc flip or ripple.
2. Speakers use lightweight foam formed into half-roll shapes. Take a look at the socalled re-foaming kits for woofers and passives being sold online. Ideally the material would be acoustically dead plus have some appreciable vibration absorbing properties. I'm not claiming this would be easy to design or make or that it wouldn't create twice as many problems as it was meant to solve. It's just a thought experiment to explore ways we might, without resorting to rigidity, let a driver move as a flat plate, which is what it wants to do and what we want it to do.
3. Yeah, come on, you new crowd-- get out there and find the Missing Orthos. There aren't that many left, so it shouldn't take you more than a few minutes. Har. Seriously, see if you can find the mythical HP-1a.
Remember, we want to avoid extra stiffness and rigidity in our diaphragms-- the metal traces stiffen them up enough to require "dummy" traces in some cases to prevent sudden changes in diaphragm stiffness over the surface. Extra material means more mass, less air damping, lower efficiency. But the Russians did a variation of your thinking on I believe the TDS 15: the magnets and voicecoil traces only cover the center area of the diaphragm. I don't know if this helped or hurt.
'Nother random. Why not "just" add an intermediate/periphery to the diaphragm like
AKG on a much smaller scale. Dynamic manufacturers do this every day to achieve piston-like motion. I have to be missing something... What something am I missing?
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Walk around with orthos literally strapped to your head. Y'know, it might work...
And if anybody gives you grief, you just headbutt 'em...
Been there done that using SFI's mounted in MDR-CD380 baffles and a Scott headband stolen from old snowboarding goggles. It was so unimaginably easy to change felt damping schemes w/o having to deal with a single screw. Done right you can achieve realistic results compared to the fully assembled version. As originally posited, though, Idk about its vibrational damping...
