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Originally Posted by wualta /img/forum/go_quote.gif
They're an easy load, but they're not very efficient by today's standards, so you'll need an amp with a decently high rail (aka power-supply) voltage. I find a standard CMoy to be perfectly adequate even with bass boost, but I'm not a headbanger.
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There's a thread on That Other Forum where an ortho enthusiast recommends gluing a disc of felt to the back of the driver to improve bass response. I haven't tried this on my YH-2's yet.
But yes, they do need some voltage gain. A pimeta with two 9v batteries ought to do it, though.
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Wow! Any possibility of your posting photos of this? I've got two HP-1s and two of the later YH-1s, and haven't come across a foam problem yet, but knowing how many foams from the '70s came undone, it's surprising that I haven't seen what you've seen. |
Well, there's nothing to take pictures of anymore, really. I threw away what was left of the foam damping material a week ago.
When i got them off ebay a couple years ago they had some bad distortion and i basically put them in a ziplock bag and forgot about them. I'd only paid about $25 anyway.
When i found the url i mentioned above, I realized that there IS a use for my old pair of MDR-V200's, stole the earpads off them, and started opening up the YH-2's.
What i found was bits of brown foam all through 'em. The foam damping material behind the drivers had just completely broken down.
FWIW the YH-2 and HP-1 construction is identical. They even have the same size drivers. The YH-2 is just a funky maroon color. At least mine are.
Several rounds of softly puffing air at the drivers later, i think i have almost all, if not all of it out. I need to do some more listening tests.
I can only presume that it was a low quality foam, or that the headphones were used in an environment unfriendly to foam rubber.
The pictures in the refurbishment url show a yellow foam in the HP-1, that appears to be in good condition. Probably better foam.
Once I'm satisfied that i've got these as clean as they can be, i'll probably start experimenting with felt and poly-fill as replacement damping material.