Sixty years ago this month, the August 1960 issue of Popular Electronics showed how to make the holy grail of crystal sets: a crystal set capable of loudspeaker operation.

The author, Walter B. Ford, reported good reception, including loudspeaker volume on strong local stations. The set relied upon two secrets. First of all, it had two tuned circuits in the front end for maximum selectivity. It also used two 1N34A diodes in a voltage-doubling circuit. For weaker stations, headphones could be used, or it could be used as an excellent AM tuner for an external amplifier. But for the strong stations, it would drive the speaker, with no power source other than the received signal.

The ferrite loopsticks might be hard to find these days, although with a ferrite rod, you should be able to make your own.  More information can be found at this link.  More hints on sourcing the parts can be found at my crystal set parts page.