Sony MDR-CD900ST Detachable Cable Mod - Photo-heavy
Jan 11, 2023 at 6:28 AM Thread Starter Post #1 of 1


Headphoneus Supremus
Oct 11, 2009
I documented a detachable cable mod on the Sony MDR-CD900ST for @digitalreferee

The goals for this mod:
• Looks good
• Minimal destruction
• Single-sided stereo socket
• Reterminate original cable with 3.5mm plug

End of reterminated cable mod is not included because there are enough retermination tutorials already.

_DSC0942.jpgPrepped and ready
_DSC0943.jpgOpen the headphone:

Do not worry about the screws falling into the driver - the screw heads are bigger than the acoustic-lens holes, so there is no risk of them entering and damaging the driver
_DSC0944.jpgUnsolder all the wires.

Take notes or a photograph of all wire solder points.

White = Left
Red/Red = Right
Black/Copper = Ground
_DSC0945.jpgTake note of original cable strain-relief pattern if needed.
_DSC0946.jpgEnd of cable has too much memory of strain relief coil - this will be cut off and used for the modification from the new socket to the left channel driver.
_DSC0948.jpgRemove the strain relief grommet - pull it out from the inside of the cup.
_DSC0949.jpgPull out the frame from the cup starting with the side without wires.
_DSC0950.jpgNow the cup is clear of all other parts and is ready for modifying.

Keep driver and other sensitive parts away or under cover in case of plastic dust from drilling/dremelling.
_DSC0951.jpg6mm drill bit is used to increase the size of the hole for the threaded part of the socket.
_DSC0953.jpgIt doesn't look much bigger.
Original hole was about 5.5mm.
_DSC0956.jpgThe thread is not long enough to thread through this hole and reach the other side.

The main body of the socket needs to be recessed into the body of the cup slightly.

Use a rotary-tool to carve out a recess at a depth of about 2mm.
_DSC0957.jpgNow the thread pokes out just enough for the screw-nut.
_DSC0959.jpgNow is a good time to check that your plugs of choice are not too big and clear the cup edges.
_DSC0960.jpgCut the cable here to remove angled/curved parts.

Keep this cable, it will be needed later.
_DSC0963.jpgDo not strip the cable more than needed
_DSC0964.jpgCut three cables from the off-cut from 2-steps above.
Also shown: the cable is prepared with socket housing and heat-shrink tube.

No more info about original cable - there are enough mod tutorials about this elsewhere.
_DSC0965.jpgSolder the three off-cut cables to the socket.
Make sure the colours correspond to the correct channel.

I already soldered the new plug onto the original cable and plugged it into the new socket - then I used a multimeter to determine which terminals correspond to which channel.
_DSC0966.jpgSolder new socket to left channel driver.
_DSC0967.jpgSolder right channel cables to left channel driver.
_DSC0968.jpgAttach the socket to the headphone, and screw it on tightly.
_DSC0969.jpgPut the damping material back in the correct orientation and over the cables.
It should make direct contact with the driver with no cables between them.
_DSC0970.jpgCables should be folded around the damping material.

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