KSC75’s on sporta pro headband. Sounds completely different then on any other headband I’ve tried even the porta pro band. Got some kick and a bit of mid bass… stock pads that I used my wife’s conditioner on because the stock pads feel like sandpaper to me..
I picked up these Grado SR60e headphones on eBay over a decade ago. They were not what I was expecting—this was my first experience with Grado, and I had no idea at the time they were so bright and had no bass at all.
Having worked live rock shows back in the 90s, my ears took a beating, leaving me with tinnitus. Because of that sensitivity, the stock treble presentation was completely shrill and unbearable for me to listen to for more than a few minutes at a time.
I could have just swapped third-party drivers into them at any point, but where’s the fun in that? Instead, I have been tinkering with these off and on for more than a decade to see if by tuning alone, I could alter the tonality to be the exact opposite of a Grado. Although I didn’t exactly achieve the exact opposite, these sound nothing like stock. Yesterday, I finally hit the breakthrough that put them over the top: layering Koss stock foam pads underneath Geekria L-Cush bowl pads.
Modifications & Build Notes
Driver Port Venting: Punched out every acoustic port around the perimeter of the driver housing to open up the low end, allowing bass extension to come through naturally.
Rear Magnet Damping: Applied a thick, dense self-adhesive felt furniture pad directly over the back center mass of the driver to reduce unwanted enclosure resonances.
Mesh Reflection Damping: Placed a smaller circular felt disc onto the inside of the rear mesh (under the plastic logo button) to absorb rearward acoustic reflections within the cup housing.
Hybrid Front Pad Assembly:
Layered a flat, porous Koss stock foam pad directly over the front driver housing to serve as an acoustic filter that tames the direct 2kHz–5kHz high-frequency spike.
Installed a Geekria L-Cush bowl pad over the top of the Koss foam layer to lock it in place, increase ear distance, and widen the soundstage.
Custom Paracord Recable:
Stripped four conductors from a 4-pin shielded microphone cable, soldering the negative leads together at the ground sleeve.
Sleeved the wiring in two different diameters of black paracord to build a flexible cable.
Terminated the cable with an Amphenol gold-contact 3.5mm TRS stereo plug.
Fabricated the Y-split using a repurposed plastic jump rope bead sealed with heat shrink tubing, with internal zip-tie strain reliefs placed inside the earcup housings.
Sound Profile & Koss Comparison
Tonality & Bass: The tonality is similar to the KTXPro1, with bass response comparable to Koss 60-ohm models.
Larger 40mm Driver: Moves more air than Koss's 30mm drivers, providing a tactile physical impact that smaller drivers can't replicate.
Bowl Pad Chamber: Keeps the driver positioned slightly off the ear, producing a wider soundstage than on-ear Koss designs.
Controlled Enclosure: The Grado earcup functions as an acoustic chamber, giving instruments more body compared to open-backed on-ears.
Transient Speed: Retains Grado's fast driver speed on instruments, but without the fatiguing high-frequency spike.
Although these probably won’t be my go-to headphones—it’s hard for me to not want to just slap on my KPH40s—they are a lot of fun to listen to now, and they are certainly one of my favorites that I own.
Got a couple of free 128 GB iPhone 6s pluses the other and set them up as music players. I just use Apple Music as I’m already paying for Apple TV and all that. I was really surprised how well the headphone out on these work with the Koss 60 ohm headphones. They hit way harder then just using an apple Dongle, make using my Fiio KA1 not necessary all the time. I have an old iPad 6 with a headphone out and the 6s plus sounds about as good. I’ve had the iPod 5.5 and it doesn’t sound nearly as good I think as this. Built in Bluetooth so I can use almost all of my headphones with them. Also… free so there’s that.
I paired my Fiio EH11s and these Greekria pads. They just slip right on top of the Fiio pads and really improve the comfort and open them up a bit without really compromising the sound. I’ve been a Koss fan since the mid 80s, and this setup really gives me everything I like about Koss with Bluetooth.
Fun little convenience mod. KTXpro drivers on a porta pro. Bought some $5.00 USBC headphones from 5below. Cut the buds off of those and soldered those onto the drivers,and added some Yaxi pads. Sounds OK. Not as good as the KPH 40s, but not bad. Don’t need to worry about a DAC and can make phonecalls Ect.
In 1976, Casio released the S-14 (Square) and R-17 (Round) models. These are frequently identified by the X-1 branding found on the case back cover. Much like modern tech buzzwords, the "X-1" moniker was a marketing and technical designation used to signal a new generation of functionality—specifically, the first to integrate five functions (Time, Calendar, World Time, Stopwatch, and Counter) into a single module. These watches are found both with and without this specific branding on the case back, likely due to variations in production runs.
The Engineering Leap: Ceramic vs. Green PCBs
While the 02 and 03 series used "green" or brown organic resin boards, those watches often required two physically stacked PCBs to handle their logic, making the cases thicker. For the X-1, R-11, and R-15, Casio moved to Alumina Ceramic (Porcelain) substrates.
The choice between these materials in 1976 came down to a few specific limitations:
• Why Green Boards (FR-4) Couldn't Do It Then: In the mid-70s, the "green" boards we use today were much more primitive. They could only support relatively wide, simple copper traces. To get the complexity of a 5-function "computer" watch onto one of these boards, it would have had to be massive—too large for a wrist.
• Multilayer Architecture: Unlike the stacked boards of the 02 series, ceramic allowed for multilayer technology. When held up to a strong light source, you can see internal traces "baked" into the layers of the substrate. This 3D routing allowed signals to "tunnel" under each other within a single thin board, saving significant space.
• Precision Mounting: Ceramic is perfectly flat and rigid. This was necessary because the high-density LSI chips used in these watches had dozens of microscopic gold wire bonds. In 1976, plastic boards tended to warp or expand with body heat; if the board flexed even slightly, it would snap those gold wires. Ceramic’s thermal expansion matches the silicon chip, keeping the connections stable.
Why We Use Green Boards Today
Today, the "green" board has caught up. Modern manufacturing allows us to stack 10+ layers of copper into a single thin epoxy board—doing exactly what the porcelain did in 1976, but with the added benefit of being flexible and impact-resistant.
Because these vintage porcelain boards are ceramic, they are brittle and cannot be flexed. While surface corrosion from old batteries can often be bypassed with conductive silver epoxy pens, a break in the internal "baked-in" traces is generally unrepairable. These watches stand as a specific example of high-precision Japanese microelectronics from the era when Casio was perfecting the "computer" watch.