For security reason, now most of the installation require the amplifier would be safe enough for grounding the earth line and signal line, but the Class-D amplifier without transformer, how could that be done?
I heard maybe Crown have done it successfully, but it is high cost for manufacturer, does anyone can help by offer a cost-effective solution?
I heard maybe Crown have done it successfully, but it is high cost for manufacturer, does anyone can help by offer a cost-effective solution?

I don't quite follow you on this but would remind you that any direct mains connected circuitry is highly dangerous and against forum RULES. If that is what you mean 🙂
All amplifier circuitry is to be powered via a transformer as isolation, whether that be a conventional power supply or switching supply.
Really? as far as i know, some Class-D amplifier in the market without both signal and power amplifiers? i means the public address 100 volt or commercial amplifier.
There must be an amplifier of some sort to drive a 100 volt speaker line. The class of amplifier wouldn't matter... but there has to be one.
Most Class D amplifiers are bridged but they don't have to be... you could use a single ended Class D stage and then ground the speaker and signal lines without problem.
Most Class D amplifiers are bridged but they don't have to be... you could use a single ended Class D stage and then ground the speaker and signal lines without problem.
As far as I am aware, there has never been a "live" audio amplifier. One would need at least an optical or transformer coupled input stage with a transformer coupled output termination for the speakers.
There was a design similar to that but it was not adopted by major reputable manufacturers. Class D still requires a smooth ish power supply, not raw mains!
There was a design similar to that but it was not adopted by major reputable manufacturers. Class D still requires a smooth ish power supply, not raw mains!
I'm pretty certain that an amp deriving its output from rectified mains won't pass regulatory requirements in the great majority of countries.
Besides, the only benefit of such an amplifier would be size and cost, due to the lack of a full PSU. And even then, the need to provide isolation between the mains, audio input, control inputs/surfaces, etc... would eat back a significant part of your cost/space savings.
Besides, the only benefit of such an amplifier would be size and cost, due to the lack of a full PSU. And even then, the need to provide isolation between the mains, audio input, control inputs/surfaces, etc... would eat back a significant part of your cost/space savings.
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