[vid]

What exactly does a "seventies" sound sound like? To me, it's a muffled, veiled kind of sound, but I'm a product of the early 80s and so I can't appreciate the concept from first-hand experience.

 

[wualta]

RE: the Pro 50: No bass, no kidding. No measurements, either. But it's a sample size of one. I don't doubt for a moment that your Pro 50 sounds completely different. So do mine. Interesting that the K250 doesn't have the diaphragms. The Pro 50 is starting to look like some sort of weird buyout of old stock AKG wanted to unload.
 
Seventies sound (in the US, at least) is a colored, midrange-centric sound with humps in the high bass and low treble to make it appear that there's more extension than there is. This drove some of us to electrostatics despite the then-outrageous cost. EDIT: In northern Europe, say Germany, another kind of sound entirely was developing in the '70s, and it eventually became very popular in the US. Many of us started on the road to electrostatics by buying the Sennheiser HD 414 and breaking free of the whomp-and-tizz of mainstream US headphone and speaker sound.
 
Vid, I look forward to your finally getting and measuring a pair of orthos so we can compare the before and after.

 

[DefectiveAudioComponent]

Speaking of bass. I'm done with my latest tweak of the Grundig, to maximize bass extension. It's now got a warm intimate sound 

 
(It always has an intimate sound of course - but air damping gives a better headstage, as well as more bass, than when adding junk on the driver, IMHO. The trick that PMB/Grundig (almost) pulled off here is to get enough bass without damping down the driver, and using an open-back design. They should just have spent a few more hours damping the cups and trying different ear pads.)

 

[wualta]

DAC, refresh my memory, please: what's the Grundig's stock sound? Was the driver tuned low (ie, a natural free-air resonance around 100-200 Hz) to begin with?

 

[citrus]

I want to purchase a YH-2 ortho, does anyone have any recommendations for modding one?

 

[wualta]

 
Quote:

I want to purchase a YH-2 ortho, does anyone have any recommendations for modding one?

Nah.
 
 
Okay, just kidding. If you look through the archives here, I know you'll come across at least two very different mods. And it could be that someone is working on one right now and is dying to share it with you.
 
On the subject of another old Yama ortho, do we have a consensus on the cause for the corrosion of the copper voice coil traces on the YH-1000? Do we agree that it was caused by the breakdown products of the YH-1000's special earpad pleather, and that if they were kept in their box, they're especially doomed? 
 
 

 

[Kabeer]

Quote:

 
Nah.
 
 
Okay, just kidding. If you look through the archives here, I know you'll come across at least two very different mods. And it could be that someone is working on one right now and is dying to share it with you.
 
On the subject of another old Yama ortho, do we have a consensus on the cause for the corrosion of the copper voice coil traces on the YH-1000? Do we agree that it was caused by the breakdown products of the YH-1000's special earpad pleather, and that if they were kept in their box, they're especially doomed? 
 
 

Im not convinced it was caused by the breakdown in earpad pleather...I mean it IS possible....but then why would pairs that were not stored in the box corrode too? And it would have to be some pretty strong products...
The whole issue could have very easily been solved had yamaha just made the bare copper face the cup side of the driver, rather than the ear-side.
 
Also there are photos of a recent pair which seemed to have the pleather fully intact (Also i have a pair which the photos seemingly showed intact pads, but when I wore it they started to flake, showing that the pleather breaks down no matter what (same with wharfedale iso earpads)
 
One thing is for sure, it definately is something entering the driver from the baffle side, maybe its a combo of sweat/dirt mixed with the earpad pleather breaking down?
 

 

[rhythmdevils]

Quote:

Originally Posted by Kabeer /img/forum/go_quote.gif
 
maybe its a combo of sweat/dirt mixed with the earpad pleather breaking down?
 

That sounds like it would make a great smoothie!  Yum!

 

[Armaegis]

While I haven't seen the corrosion myself, sweat seems like a more plausible explanation since it contains trace amounts of sulphur. Homes heated by natural gas will also have slightly higher levels of sulpfur in the air. 

 

[wualta]

The corrosion always  forms a definite pattern corresponding to the magnet holes. It's as if you shone a light on the earcup and the light made the copper corrode wherever it hit, but nowhere else. But not evenly!  Which for me tosses out the atmospheric pollution hypothesis. At first I too went with the sweaty-owner hypothesis, but salt (potassium or sodium) by itself doesn't corrode copper. Copper sulfate's a possibility, but it's a distinctive blue-green, and the corrosion spots in the photos we have aren't green. And that would take a LOT of sweat by someone who loves mustard and garlic. And then there's the unevenness of it:
 
Why do I think it's the earpads, despite what Kabeer says? Because he also said  "Also strangely the corrosion is always on the more OUTER holes rather than the more exposed inner ones." 
 
Plus we don't know the storage history of these headphones. I'm trying to find whether PVC plasticizers (usually a class of chemicals called phthalates) will corrode copper, but having a sticky time of it. I also found that I kept none of the famous gallery of YH-1000 corrosion photos taken by dbel84, which have themselves poofed off this thread. Don, do you still have those photos?
 
 
 
 

 

[liamstrain]

If the pads has natural latex foam in them, that contains a good amount of sulfur in the processing. As that foam breaks down, it would release a lot of localized sulfur to react with copper. 

 

[wualta]

I believe the stuffing in YH-1000 earpads is cotton cloth.

 

[dBel84]

The corrosion is a mystery as most all of the drivers look very similar. 
 

 

 

 
 
These are more images on my pc  -  will upload them to my photobucket account 
 
..dB

 

[wualta]

Ah. Thanks. Well, I guess the answer to my question was no, we don't have a consensus. It's like one of those British murder mysteries... Where's that nosy Felicity Kendal when you need her?

 

[Armaegis]

If anyone has a fried driver they'd be willing to lend me, I could stick one under an electron microscope and see what the composition is...