One of the things I never liked about the HP1000s was a certain shoutyness that they had in the midrange. I came up with an idea a long time ago after measuring the liberated drivers of the SR80:
http://www.head-fi.org/t/566929/headphone-csd-waterfall-plots/105#post_7735041I realized this shoutyness was caused by the cups and not the driver. In CSDs, we can see the shout as a ridge around 2-3kHz. For the HP1000 cups, it's 3kHz.
http://www.changstar.com/index.php/topic,24.msg196.html#msg196The way I reduced the shout on the SR-80 was to line the inside of the cup with good ol' Creatology Foam Sheet material. So I did the same to the HP1000. In addition, I also applied a small circular piece on the back of the metal button. I wanted to eliminate, as much as possible, the sound waves bouncing inside of the HP1000 cup.
The resulting changes were rather impressive. Even more neutral than before. No more mid shout. In addition, this mod brought out some details which were masked by the midrange shout. Everything sounds super smooth and much more refined than before. In other words, I've sort of re-discovered the HP1000 and am listening to them a lot again.
Before mod:
After mod:
