Orthodynamic Roundup - Page 6

This upsurge of isodynamic brotherhood is amazing. Where to begin?

First, here's a photo of an EAH-830's diaphragm, still in its frame.

As you can see, it will probably be more trouble to repair such diaphragms than to simply buy another set of headphones via online auction. You could probe along the aluminum trace with an ohmmeter and a low-power microscope and try to aim a tiny dab of silver paint when and if you find the break (which could be a microscopic hairline crack), but it's not the method I'd recommend if you aspire to sanity. This is especially true of the original Orthodynamic and PMB100 diaphragms, which are corrugated and thus harder to inspect.

Having said that, some of us are artists. We don't think in practical terms. If we see something that strikes us as elegant and beautiful (in both Apollonian and Dionysian senses), we must have it in its pristine state, no matter the cost. So don't let me talk you out of trying to make the diaphragm from scratch using the photolithography techniques originally used by Matsush'ta/Technics. Just don't expect it to be easy, cheap or successful at the first or even third go.

The EAH-830 thread is here, by the way. I took the liberty of PhotoShopping Icsaszar's scan of the 820 diaphragm and posting it to that thread.



Damping the Pro 30 is just like what we might call Stage One damping of the Yamahas: stick one or two discs of cheap fabric-store felt behind the driver and cut rings of felt to damp the circumferential vents (the Yamahas already have felt for the vents). The stiff foam pad in the Pro 30 presses the felt against the drivers very nicely, or at least it did when the headphone was new— you might want to add some fresh foam. The Yamahas could use something like that. I'll try to take apart my Pro 30s this weekend and shoot some photos. And you're right, they'll sound kinda sorta okay, not bad for 1984, right out of the box. Audio-Technica, who made them for R.Shack, did try to damp them, but left the job only half done. Sneak over to JoAnn Fabrics (a national chain with an online presence), get a 25-cent 12" square of felt, borrow your mom's scissors, practice good scissors safety, and practice cutting until your felt discs are perfect circles-- doesn't help the damping but does wonders for the feng shui-- and report back.

To answer an earlier and very important question put forward by brewdog, the way to tell if a headphone (or speaker or any transducer) needs damping is to see if it has difficulty handling transients-- sharp clicks and tics. With a headphone, the easiest test would be to quickly brush the heaphone's connector across a voltage source, like a small battery. Some inexpensive clip leads from, yes, Radio Shack come in handy for many things, and this is one of them. You should hear perfectly sharp little tik-tik sounds, almost like the ripping of a fine fabric where you can hear individual tiny filaments breaking. If you hear anything else, there's a problem. Yamaha proved with the Orthodynamics that a headphone could have an absolutely lousy transient response and still sound halfway decent. I've always maintained that the reason the Orthos could get away with this was that their natural resonance was fairly smooth and linear and distributed evenly over a large area of the audio spectrum rather than concentrated in one spot, but that's another story. Try the DC-flick test on the YH-1000 and report back.

To all of you embarking on this "finishing the job the manufacturers started" adventure, welcome. These things are as rewarding to work on as bicycles.

Edited by wualta - 12/22/11 at 5:46pm

It's glued on, and you're quite correct-- it's not a problem; in fact it's a help, and though it may look "aggressive", in practice it's not aggressive enough, but you'd still be setting yourself back if you removed it (simple enough to do with a blowtorch, but why bother with headphones when there are cats to frighten?).

The rule with damping these things is that if it looks like too much, it's probably only half of what's needed. Having said that, too much damping is, well, too much. It gives you fantastic transient response but a bloodless trebly sound that only certain people will like. If you do a damping mod and all the bass goes away and won't come back even with a bass EQ boost of seismic proportions, you've overdamped.

It's also worth noting that two layers of insufficiently-dense damping material doesn't double the amount of damping, at least not in my experience. Sounds weird, I know. I have no good explanation for this. Damp properly in one layer (and/or tweak this one layer with a reflex disc), but if that doesn't do it, find a denser material for your damping disc.

I strongly suspect you'll find that Yamaha placed no more damping in the YH-1000 than it did in any of the other Orthodynamics. I'd be pleased to be proven wrong. Eagerly awaiting the photos.

UPDATE: Not that I want to break the suspense, but the photos never arrived. However, Yamaha DID use damping of a sort (the fake fiberglass cookies used in Stax electret and Audio-Technica and Fostex 'phones) in the YH-1000. 

 

Yes, don't take them outside. There's a structural weak point, the short plastic strut that connects the headband to the earcup and ends in a ball joint. If that breaks, you're done for. You'll like the KSC-75. Watch HF for excited postings indicating they're on sale somewhere.

 

Yes, definitely, or even deafanatley. Start with a simple inexpensive CMoy amp. Tons of 'em available on eBay.
 

Be aware that the amps (and thus the headphone output) in midrange Sony home theater receivers tend to sound terrible.

Edited by wualta - 12/22/11 at 5:48pm

I wish. Turns out the metal cup has a flange that sits in a cutaway just the right size with keyways to make sure it's oriented correctly, then a ring of plastic is sonic-welded (looks too neat to be solvent) down on top of it, locking it in place. You basically have to destroy the cup to get the thing apart.


Hee hee. I was thinking epoxy the heck out of the broken strut, then a steel ferrule (like a butt connector) clamped gently over the still-curing joint for reinforcement. The strut's hollow, as it turns out. Thick walls but still hollow. Couldn't believe it. The whole assembly seems needlessly complex for something that ends up being so vulnerable. Want to see a photo?


You can see the chewed-up fixing ring that holds down the metal cup. The front half of the ring has been broken off. ...Does this seem needlessly complex to you?

Good idea, but nah. Checked it both with a NdFeB magnet and by near-total destruction.

Brewdog, the difference in efficiency between the two 'phones will make it difficult to compare. But if the YH-1000 really does go tic instead of chickhhh (and I'm exaggerating here for clarity), no hollowness, no rubbery echo, just a quick start and stop, then it may have some damping goin' on. That I'd like to see. Do see if you can get hold of a KSC-75, though. It'll give you something known-good (not great, but good) to compare to.

UPDATE: Listening to the mp3 and accounting for compression artifacts and microphone quality, it doesn't sound too bad. Thanks for doing the test and recording it! That was going above the call of orthodynamic duty. Loaded quickly for me, by the way.

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