I learned from experimenting with other headphones that if you increase the air volume behind the driver, you extend the low end, both in presence and weight, what you hear gains a lot of body. It's not hard to realise that the drivers are cramped in the HTF560/600s, so... let's mod them! Mine have at least 50hs of music and 15hs of pink noise on them.
First I removed the thin brushed aluminium plate with the panasonic logo, then I dremeled the back of the cups.. leaving the headphones completely open. These drivers LOVE to breathe! What's more amazing, is the fact that if you leave the drivers open air, they lose little bass. Nice big soundstage, at last! Lots of sparkle.. maybe too much highs in comparison with the bass level we're used to. A beautiful signature, nonetheless. They DO leak a lot when completely open, I can hear them from a room or two away...
After enjoying them open air a few days, I decided to go on with the mod. I took epoxy putty and built a longer cup, 2cm long from where the stock cups end. Then added the thin brushed aluminium cover with the oval hole in the middle and the panasonic logo. Epoxy putty dries in 10 minutes so there's not much time to do everything, if you're careful and plan it all then the result will be excellent.
Finally I added the damping cloth to the back of the new cups, and left the hole in the middle completely open (remember, those drivers have to breathe! sound quality gets worse if they don't), assembled everything back and...
OMG!
I'm floored. Bass level is back to out of factory, unmodded, bass heaven these are! With the added benefit of it going LOW, while being in balance with the rest of the frequency range. No muddiness, no low end mess, nothing! Beautiful! Damn, some songs' bass make them rumble and move a lot of air, with the mids and highs clear (not as laser-clear as the superluxes and samson SR850, these fatigue you in no time). Soundstage isn't compressed at all anymore. It's not as defined as the luxes, but it doesn't suck anymore. If only panasonic had added those 2cm to the back of the cups out of the factory, or designed a larger chamber for the driver instead of wasting a lot of room on the decorative rim... :/ The stock headphones are no comparison to what they've become now.
Throw metal, rock, prog metal, indie, dubstep, whatever you want at these, they break no sweat... Hell, even classical doesn't sound weird or bad! (Mozart's violin concerto in G major from a pack of 5 songs HDtracks was offering as a free download to try out their records).
Nightwish's "nemo" gave me chills down my spine, it never sounded so real.. I swear I had the band playing in the same room! I couldn't stop headbanging... DT is just out of this world now.
I'll keep playing with the damping materials now that I have room behind the drivers to do so, and after I'm done I'll sand the epoxy a bit (it'll be as hard as a rock by then), then paint it satin black or something like that.
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Pictures! Sorry for the quality on some of them, when I get a real camera I'll take better ones.
http://www.imagebam.com/image/9460fb163152329
http://www.imagebam.com/image/ffdcf9163152366
http://www.imagebam.com/image/4917c5163152390
http://www.imagebam.com/image/6eef20163152481
http://www.imagebam.com/image/bedfc3163152550