quick update on simple easy reversible mods I've tried:
ok so i had a go at changing the sound of my LINDY versions to reduce the bass and speed it up a bit. my first plan was to open them up, so off came the backs. i tried them as completely open 'phones for an hour or so, and noticed some strange changes to the noise. first off they sounded more closed with the backs off. they sounded slightly less crisp and sightly more muddy, and the sound stage shrunk. one positive i did note was the complete removal of the 300Hz dip. it did also remove quite a lot of bass below 300Hz, too much in fact, so it might have just lined up the roll off with the notch.
they sounded better with the backs on, so then i noticed 2 small slot holes either side of the headphone cups, right next to where the headband attaches to the cups. i stole a picture from the for sale forum because i cant find my camera, here it is.
here i have circled the slots. i decided to listen to see what sound frequencies were leaving the headphones through these holes, so i ran a sine wave with my ear pressed to these holes. what i noticed was there was no 300hz peak or notch coming from these holes. interesting. so i put some electrical tape over both of these holes on both cups (so all four slots are covered) and the bass has dropped significantly. whats more interesting is the 300Hz dip has also gone, to be replaced by a bass roll off from 300hz down, with quite a sharp drop at 200hz. its like the covering of the ports has moved the notch from 300Hz down to 200Hz. it also shrunk the soundstage a bit, and muddied the mids a bit. stock sounded better.
so ive just removed 2 bits of tape of the front ports so the back two remain covered. now it gets really interesting. with no tape, the notch was at 300Hz, with 4 bits of tape, it was at 200Hz. now with 2 bits of tape, the notch centres at 225hz, but the notch isnt as pronounced or as strong as stock or 4 taped. the bass depth has returned as well, meaning theres no real downside to this mod. it reduces the notch, removes a touch of the mid-bass hump, and keeps the sound fairly open and clean.
its pretty subtle, but ive been playing with EQ since i got these because i found the bass too strong, overpowering and fatiguing, this seems to have helped. not solved, i think a bit more modding will be needed to solve the issue, but its certainly changed the sound a bit.
anyway, thought i would share. enjoy!