Hi, this is a very simple, free mod that will very noticeably increase the amount of bass, increase bass extension, and give an overall warmer presentation on the Ultrasone HFI-780s. I'm using a set with over 200 hours on them easy.
I shouldn't have to say this, but doing this mod voids your warranty.
1. Remove the earpad (pull it off) to get to the mu-metal shield and remove the three screws holding it down with a small electronics philips screwdriver.
2. Once you remove the 3 screws and take the mu-metal plate out, look behind the drive and you will find a white pacman-shaped sticker with a single hole where the "mouth" is. This sticker is covering 3 more holes. Uncover an extra or all the other holes to to allow the driver to breath more and produce more bass. EDIT 7/17/10: It 's best to leave 1 hole covered, as uncovering all of them causes a slamming/distortion in the drivers. This keeps the bass tight.
It will look like this when you're done if you chose to remove the entire sticker.
That's it!. Just put everything back the way it was (the earpads just snap back on) and enjoy!
Deep, emphasized rumbling bass, and a very warm, welcoming sound to it. Before I was contemplating doing a recable of these myself to try and improve the sound, but now I'm only doing it because the cord length is stupid (1m or 4m with adapter, wtf?) I'm going to use 7-8ft of Gotham GAC-3.
EDIT 7/17/10: It 's best to leave 1 hole covered, as uncovering all of them causes a slamming/distortion in the drivers. This keeps the bass tight.
Edited by shake - 3/22/13 at 7:35am