Step 2: The Venting Mod
This is the most extreme mod of the three and has the greatest effect on the sound. It can also be overdone and be unpleasant, and poses some risks for damage. It is also not reversible. But, if done right, is the most rewarding of the three mods and I found to have the greatest positive effect on the sound quality.
This mod increases the back venting of the driver. This has the effect of increasing the bass output, while also making everything come across more clearly and crisply. I will say, though, that if overdone the driver will no longer be properly dampened and the bass frequencies will begin to muddy up the mids and highs.
In my case, it was more than worth it since I found the bass of the Grados slightly lacking. This mod satisfied my inner 'bass head' and made the music sound much more punchy and lively. Bass reaches lower, louder, but everything remains as clear as it was before the drivers were vented. The openness that Grados are known for also increased, while highs became crisper and cleaner and lost a bit of glare.
What you need:
Phillips screw driver (larger size)
hair dryer or heat gun
Steps are as follows:
1) Unclip the cans from the headband and remove the pads. This is easy enough, since the cans are just riding on the two pins. By pulling the yoke apart, you can get the pins out of their holes and separate the cans from the headband. Make sure to mark the left and right can before doing this since there are no markings on them, and mark the spot where the two halves meet so we can reassemble them correctly.
2) using a hair dryer or a heat gun on a low setting, slowly warm up one of the cans by blowing hot air on the sides. Make sure to keep it moving to prevent over-heating the plastic. The cans are sealed together using hot glue. We are trying to heat up the plastic so the hot glue softens up and the cans can be pulled apart.
3) After some heating, its time to start prying. If the can feels warm in your hand it should be warm enough that the glue is soft. This does require some strength. Make sure not to twist- just wiggle a bit and pull straight out.
4) You should now be looking at the inside of the can. By holding the driver half up to the light you can see the holes I am talking about. For the SR125i and SR80i, I would recommend punching out 5 holes. For the SR60i I would recommend 2 or 3. Space out the holes you are punching- do every 2 or three holes so they are spaced out around the driver.
5) To actually punch the holes, line up the tip of the screw driver with the hole using a light source shining in from the other side and gently twist the screw driver in the hole. This will punch through the thin black cloth covering the hole and leave clean edges. Make sure to use tweezers to then collect all the loose fabric so it doesn't end up in the space behind the driver diaphragm.
That's pretty much it. We are just punching holes. You can now close up the cans if you are not dampening, but if you vent the drivers I recommend dampening. See the next step with guidelines on dampening and properly reassembling your cans.