Orthodynamic Roundup - Page 10

It might be, but the 3:1 loudness ratio sounds about right if you're comparing a YH-2 to something like the HD 600. There's a lot of energy under that hump. Sucking it all out makes a big difference.

It is possible to overdamp. What we're after is the point of critical damping, adding more and more damping until we reach the point where the 'fram starts, and most important, stops when it's told to.

By the way, my profound appreciation to you for your work with the microsuede. Meanwhile I'm also trying some nonwoven polyester, like Tyvek only thicker and fluffed up, that's used to stop drafts over doorsills. Sill seal, threshold tape, something like that. Found a big roll of it at the dollar store.

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Specs from Germany, YH-100 microsuede results

German HiFi Wikipedia has an entry for Yamaha headphones with a focus on the Orthodynamic series. Why this should be so, I don't know. But here it all is, with dates of manufacture and specifications:

Yamaha Kopfhörer - Hifi-Wiki.de - die freie Gerätedatenbank

A couple of interesting things turn up, assuming the source is reliable. The most interesting, to me, are:


There is no listing for the HP-1a.

The uberOrtho, the YH-1000, is older than the YH-100. In fact, the YH-100 appears to have replaced the fancy-dancy YH-1000, despite having 5dB lower efficiency. They do resemble one another physically... perhaps the YH-100 was a cost-reduced version of the YH-1000?

There are links but no entries for the [mythical?] HP-1000 or the nonmythical YH-5M, the world's first and only orthodynamic IEM.

The impedance shown for the YH-1000 is incorrect. Photos of the the YH-1000's box show an impedance of 100 ohms, not 80. So this source isn't entirely reliable.


An interesting little dab of information against the blackness of space even so.

On to other things. The MicroTex microfiber pseudosuede (which we'll call "microsuede" for short) makes an excellent damping layer (see post #106). In fact, I think it's too good, since it's starting to eat into the fatness of the bass. The YH-100 now sounds kinda like (but don't get excited) an SR-X Mk3 or a Fostex T50, which is to say it's startlingly detailed and ultraclear (it's obvious that Radiohead's Kid A sounds like it was recorded on a 1981 multitrack cassette deck, while the producer of Rachael Yamagata's Happenstance went for a very clean sound, very Neumann U87ish), but it verges on brightness. That's what happens when you overdamp-- you've tightly trapped a layer of air next to the diaphragm, and it acts like the air in an acoustic suspension speaker cabinet-- the natural resonant frequency of the driver goes up since the stiffness of the air in the cabinet adds itself to the stiffness of the driver's suspension, or in the case of a first-gen Orthodynamic, the diaphragm's compliance. This moves the resonant hump upward in frequency while still squashing it and spreading it over a large bandwidth. It's the equivalent of putting a woofer in a box that's too small for it. As ericj found, the efficiency of the 'phones takes a huge hit when there's this much damping.

This is with the microsuede disc directly behind the driver, and just behind that a disc of felt, helping to even out the pressure supplied by the orange foam rubber disc which is behind that.

We're not too far off. [UPDATE: The microsuede might be okay for some isodynamics, but it wasn't what the YH-100 needed at all. It ended up unacceptably overdamped.] The search for a material with the perfect porosity will continue.

It would be nice to find a thin fabric with ideal porosity. I can dream, can't I?

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Shock horror! (is there any other kind?) No, seriously, it would make the response graph look great, but the transient response would still be gawdawful, or, if you're PG Wodehouse, gawdelpus. I wish the problem could be solved that easily, but it's really a mechanical problem.


Ericj, that's a good idea, although the magnets on the old A-T drivers (used in the Pro30 and elsewhere) are a tad heavy. But if the backwave is tamed, no reason why it couldn't work, although the bass will be somewhat attenuated.

And I should say that while the Pro 30 driver is just slightly smaller in diameter than Koss', it is probably, I'm guessing off the top of my head, thicker. So the answer to your question is: maybe it will fit. It can certainly be made to fit.

Correct-- Just the opposite, in fact. A big "smiley" would pretty much do it. And the 'phone would sound pretty good. Until, of course, you wanted to hear real bass or your Dynavector Hello Kitty with the boron-sputtered bamboo cantilever came a cropper upside a tiny boulder-- then you'd hear the same bad wobblewobble in the bass-- worse, in fact, because more energy is being fed to a resonant system, which simply stores it and spits it out over a spread of time and frequency like a radio transmitter-- and a chokkhh instead of a tic (largely because the lower mids and upper bass are underdamped and thus aren't in sync with the treble).

You bring up a very important point-- why not simply find the frequency response of the driver, calculate its exact inverse, and filter in the digital domain. The reason this would have limited success is, I suspect, the real reason behind many serious Head-Fiers avoidance of EQ of any kind. It solves one problem but leaves entirely untouched a worse one, and they've heard it in all its... well, shock horror.

Most systems don't have transient response quite as poor as the undamped Orthodynamics have in the bass, so it's usually not a big problem if corrective EQ is applied to those systems. But most systems do have a bete noir somewhere, usually in the bass or mids, and the bete often has a litter of little betelets scattered throughout, and we learn, or not, to live with them, as long as EQ doesn't feed them and make them grow too big to keep. But it might.

So it's not a matter of the characteristics of the filter wrecking the sound-- it's more a matter of the filter revealing problems that can make listening uncomfortable, often on a subliminal level.

I'm not saying your approach is wrong; it's just that the Orthodynamic driver has such a big problem mechanically that it should be solved at least partly mechanically, otherwise things could get ugly. In fact, I've advocated EQ for headphones in general, both as an aid to better listening and to assess transient handling. Further, in fact: I'm still listening to my damped YH-100 with some boost in the low bass and high treble because while I still consider its diaphragm insufficiently under control, it's good enough that EQ makes it better rather than worse.


 

This is so true, it's positively truthful. We trade off. We agree that spaciousness is more important, so we let transient response slip a bit and we have the Stax Lambda. We add mechanical damping and we have the SR-X Mk3 with its blitzen transients but a crippled soundstage.

Edited by wualta - 7/11/10 at 4:13pm

Sure. But that's equivalent to correcting for room response with an ideal loudspeaker. It's not meant to correct a problem with the ribbon itself.

To some extent, yes. But I'd say it's mostly the ability to handle transients and not store energy that makes this type of transducer attractive. If a designer can do it by using nothing but air to damp the nasties (Lambda Signature is the poster 'phone here), more power to him/her. What you want is sail area. Doesn't the Omega II have more diaphragm area than the Lambda? The isodynamic driver doesn't have that option. Not unless someone builds a nice big one with lightweight electromagnets. Imagine how geeky that would look!

Elaborate on this, please. What happens to the uppers?


Now you're starting to think like a cardioid mic designer.



Celestion built a ribbon (detailed in my man Martin Colloms' book High Performance Loudspeakers) which used strings of silicone rubber to counteract this love of gravity you speak of. There may yet be a way to unobtrusively suspend and center. All eyes are on you.

Good thing too. What an enormous effort to achieve psychoacoustic (=fake?) bass! It inspires respect and shock horror at the same time. Makes you want to yell to the designer "Turn on a subwoofer!"

I wonder what would happen if a layer of PVDF were bonded to a thin layer of Mylar? Efficiency would suffer, but maybe bass would improve along with the mechanical properties of this film sandwich.

Those old Pioneer HPM 'phones do reasonably well as they are. My gut says it wouldn't take a whole lot to tip them over to producing "real" bass. Of course, I could be wrong. Can't beat 'em for sheer simplicity, though. Maybe add a KSC-75 driver...

Toward A Damping Strategy

Excellent. Most Ortho earpads turn up intact, unlike the Audio-Technica and Stax pads from the '70s and early '80s, but for those that don't, this is useful information, and it's great to have the velour option.

I too feel I must alert the faithful and reprint here some speculation I tucked away on a thread about the HP-3. It came to me that it isn't enough to suggest that modders try to hit some unspecified optimum amount of damping (the socalled critical amount). What is needed is the basic information that will allow each owner to plan a damping strategy based on his religious beliefs and the abilities of the equipment available. Here's that random thought taking form and shape before your eyes:

Since we now have several imminent mod jobs being done by several people with their differing expectations and preferences and materials, a thought on how much to damp. How far should you go? For some, too far is not far enough, and normally I'd take the engineer's approach and say the point of critical damping, this far and no farther, would be the point to shoot for. But then I thought, no, damping does two things simultaneously: it gets control of the diaphragm, which is good, but it also changes the frequency response-- it makes the 'phone brighter and brighter the dampier it gets. It could very well be that at the point where your ears tell you that transients are now splintered-quartz sharp and that's the way you like it, uh huh, the bass is quite a bit rolled off. This is more likely to happen with "tight" Orthodynamics, eg the HP-1/2/3 and the YH-1/2/3, than it would with "loose" ones like the YH-100 and [probably] the YH-1000.

Where you then find yourself is the same place the guys at Electro-Voice were when they had this idea that you could build a vented speaker with overdamped bass (the sixth-order Butterworth alignment used in the Interface series) and then compensate for the rolled-off bass with an outboard EQ box, and how many crazy audio nuts could they possibly sell it to. In other words, you may want to make a damping-beyond-the-pale choice whereby you now have a pair of what we might call "EQ 'phones", 'phones that must have EQ to sound right. The upside is that these 'phones will have transient handling like you've never heard-- every single jot and tittle in the recording is audible, and bass thwacks become downright dangerous to your hearing at high volume. The downside is that power handling in the bass will be reduced by the amount of bass boost you have to apply, and your amp might clip that much sooner, etc. etc. At this point the 'phone may have a slightly elevated, even rising, treble, which might have to be tamed with more EQ.

The difference between EQing an undamped Ortho and EQing an overdamped Ortho is night and day. One will simply make existing problems worse, the other merely lifts bass of an extraordinary quality up to proper listening level.

And I know some folks have religious objections to EQ. This is not for them.

Anyway, it's just a thought. You might want to explore the Overdamped Side just to hear what it's like. You'll need a good amp and a preamp with enough flexibility to apply bass in the quantities and locations on the FR graph where it's needed.

Now: imagine having this much user control over a typical dynamic headphone's diaphragm and sound. You perhaps begin to see why I've come to call the Orthodynamic line "kits"-- they're damping-optional. You supply the damping you want to get the sound and detail you want.

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