I found the results were exactly what I was after- depending on personal tastes, what I am going to mention here can be changed and certain steps skipped. The modifications are going to be broken down into 3 different parts: The quarter mod, dampening mod, and venting mod. I did a combination of all three and found the results to be superb. I rediscovered my music listening through my Gados for the first time, and had a second rediscovery listening to my Grados after the modification. A more specific review of the results is going to be highlighted at the end of the Instructable.
So why are these mods so good? It is because the changes we are making are similar to the design changes you see on the more expensive (and better sounding) Grados. We are effectively turning the entry-level model into the more expensive model. But of course, the more expensive models also have better head bands and construction. That's where the real price difference lies.
So, first go buy some Grados and then mentally prepare yourself to disassemble them. Just a couple of warnings: Doing these modifications will violate your warranty. Also, some of the modifications cannot be easily reversed. And finally, as will all mods, there is a risk you might accidentally damage something during the process. All responsibility for damage falls on the one performing the mods. I cannot be found responsible for damages, so consider yourself warned.
Well, lets get started.
Step 1: The Quarter Mod
The same basic results of this mod can be achieved by purchasing Grado 'bowl' pads, which have a hole in the center anyway and offer more of an around-ear fit. But that costs money. The point of these mods are to use what we have to make the Grados even better.
And on another note- Don't cut too large of a hole in the pad. Too large and there won't be enough cushion between your ear and can, and the headphone will be uncomfortable.
The steps are pretty simple. You will need:
3/4" socket or quarter (This is why its called the quarter mod)
1)Remove the pads from your headphone
2) Place the socket or quarter in the center of the back of the pad and press down hard
3) Cut around the circumference of the socket
And that's it....
Remove the circle you just cut from the pad and save it. It is going to be used later on for the dampening mod.
Now just reinstall the pad on your Grados and enjoy!
Step 2: The Venting Mod
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.
Step 3: Dampening Mod
This mod accomplishes some moderate dampening of the headphone by adding absorbent material to the inside of the can. it specifically is designed to not interfere with the venting of the can, but still prevent any reverberation and internal reflections of high frequencies inside the headphone. This reduces apparent harshness and cleans up the treble slightly. It is a worthwhile modification assuming you are already disassembling the headphone can to accomplish the venting mod.
This mod, as is the quarter mod, relatively benign in that this won't change the sound much and is easily undoable.
For this, you will need:
Hot glue gun
Some felt padding (Optional)
Steps are as follows:
1) Cut out a felt pad the size of the button on the back of the headphone can. This is a spacer of sorts and is optional, but I would recommend it because it adds some increased absorption over the foam circle from the quarter mod alone.
2) Place a small dab of hot glue on the back of the button, and then press on the felt circle. Then, a second small dab of glue and then press on the foam circle from the quarter mod.
3) Using a small dab of hot glue, glue the headphone cable to the back of the driver magnet cover. I don't know how much this actually accomplishes, I would think that the extra mass might provide some dampening to the driver. How noticeable this is in not known to me, since I don't have an a-to-b comparison for this. But it can't hurt.
And there you go. Now its time to reassemble the cans. While you are in the cans, it is worth cleaning out the old bead of hot glue. When you reassemble the can, you can use more hot glue or just friction fit them together. The remaining hot glue residue on the inside of the can is enough that a friction fit won't come apart easily without heating. What you can also do is after friction fitting, reheat the can so the hot glue will re-set and make a stronger bond. Not using more hot glue during reassembly will make the cans easier to pull apart for further modification work.
This is also where the marks we made earlier are handy. We have to make sure the two halves are straight (one is half is not crooked inside the other) and that the half that is pressed in is pressed in to the correct depth. Since the cable limits how car the cans can be pressed together, it's really just important to make sure they are straight. The marks we made earlier help accomplish this.
Step 4: Final Impressions and Taking This Further
But I found no sacrifice in terms of mid-range detail. The Grados, before the mods, sounded very lifelike. Now they sound even more so. The openness of the sound from a vented headphone is increased, where the sound stage is a little more present and less confined then a closed headphone. The mids are smoother but not smothered and are so intoxicating its easy to get sucked into the music. Everything sounds clear with the quietest background vocals or instruments being detectable. The highs follow in the path of the mids, sounding crisper and clearer and more open than before the mods, but any harshness or glare that was detectable before has vanished.
Any down sides? The sound could be little too 'forward'. This is kind of hard to explain without hearing it. This is more of an artifact of the sound stage presentation. Also, The headphones don't do too well at low listening levels. Transients come across too loud or even exaggerated in comparison to the rest of the music. But this can be solved by turning it up. Finally, not much of a problem to the user, because of the increased back venting more sound leaks into the environment. This means your roommates are listening to your music too.
The moral of the story? Grados are great. But for no money and an hour or two they can be made even greater.
So whats next? Here are some other ideas for Grado mods that I have seen and might consider later on down the road:
-Putting a nicer cable on (more of an SR60i or SR80i thing since the SR125i already has a nice cable)
-Lock screws on the posts that allow height adjustment of the cans
-Can mods including making the backs out of mahogany or machined aluminum
A quick Google search can lead to some really informative articles and pictures of (heavily) modified Grados- Grados have become one of the most modified headphone because of their simple construction and easy modification. So feel free to let your imagination run wild.
Enjoy the music.