Alternatives to the vacuum tube and transistor?

[Enzo]

Maybe add a small gasoline engine as a tweeter?

 

[benb]

Now I'm imagining how an electric car horn works, basically an electromagnetic buzzer with a diaphragm and horn attached, vibrating at the resonant frequency of the horn, and they're remarkably efficient at turning electricity into sound. Air horns used by trucks and trains have similar efficiency.

Imagine a rocket engine with the combustion turned on and off at the desired frequency ...

 

[RJM1]

"Imagine a rocket engine with the combustion turned on and off at the desired frequency ..."
Argus engine, German V1.
V1 Pulsejet AS 014 Test - YouTube

 

[pelanj]

There were some trials to build PWM control for HV motors in locomotives - based on contactors. The result was heavy and the contacts were burned out in a short while. Then, high power thyristors were ivented and this idea was forgotten.

 

[Ozark HiFi Doctor]

~ s i l e n c e ~ as alternative to anything that is real.

 

[jan.didden]

Now I'm imagining how an electric car horn works, basically an electromagnetic buzzer with a diaphragm and horn attached, vibrating at the resonant frequency of the horn, and they're remarkably efficient at turning electricity into sound. Air horns used by trucks and trains have similar efficiency.

The reason that they are so efficient is because they are used at a single frequency (or narrow band) and everything is optimized for that frequency.

Try to cover a frequency band and there goes your efficiency.

Jan