Copper wire has a positive temperature coefficient of resistance (~0.39%/°C). With a current-regulated source, no matter how much the coil resistance changes due to heat, the current is always held constant → flux density remains stable → the sound stays consistent from cold start through warm-up.
Onken SC-500 Horn + OS-500MT Titanium Driver Pair 8 ohms Japan Tested w/Box #10H
Includes original Onken boxes. Rare opportunity: original matched Onken OS-500MT drivers with SC-500 wood horns in preserved condition. This is a rare matched pair of Onken OS-500MT titanium drivers with SC-500 wooden horns, complete with original boxes.