The Luxman runs the lamps from 20v dc rails, negative supply if I'm correct. Even if it were ac you could still use the led since regardless of its orientation it will conduct on either the positive or negative half of the ac pulse just like any diode. You however will need to observe the voltage from the rail and use a current limiting resistor. I just refurbished an l235 but changed to amp circuit to incorporate nested feedback and a better power supply. It's a good little amp, but miles away from my Current Feedback open loop design.
Colin
Colin
If you reverse Bias an LED, failure is eminent. The Avago HLMP series is
rated for 5V@100uA (some brands rated at 10uA) maximum reverse voltage. Reverse it at 20V and you will probably will soon have a Blown diode.
That's why you implement a dropper resistor, this will knock down the voltage, all you need to do is measure the rails and adjust accordingly for a decent bias, 4ma is sufficient or lower if you want a duller brightness. It's crude but it will work, however yes on the reliability factor dc will function better. A simple low power 1n4148 is sufficient for such low power.
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