The Sony WM-7 only work with original headphone. If connect sony WM-7 unit headphone port to external speaker/other headphone will cause the unit start to switch tape direction continously between FWD and RV. Does anyone have solution for using an external adaptor (or any mod) to use other headphone/external speaker?
The WM-7 needs a minimum load in order to work correctly. Internally it has 33 ohm resistors on the output connected when the jack is not inserted. It will work with a majority of headphones out there; I tested it with 16 ohm and 50 ohms impedance headphones and works perfectly without triggering the remote control circuit. The problem appears when you try to connect it to an external amp, which has a high input impedance and will trigger the remote control circut. Same applies with active headphones, that have built-in amplifiers or with high impedance ones (I don't have headphones with higher impedance than 50ohms, so I cannot say where the threshold is). What you can do in this case is build an adaptor which has 2 load resistors to ground. You can start with 33 ohms and increase the value if you want more voltage swing.
