Here is something that anyone who can play the guitar and just happens to be a fan of the Back To The Future movie series, especially the first film! It is a massive speaker that can blast out up to 50 Hz, which is quite loud, so we are told.
According to the team of PhD students who built this speaker here are the details;
Testing the speaker was a FUN time. Electrically, the speaker was driven with a 20kW PWM voltage sourced inverter (intended for motor drives and microgrids) which was powered by a 400V DC power supply. At low frequencies (~10 Hz) peak coil currents were 100A. We connected the amplifier to a number of audio sources including iPods, bass guitars, and Matlab audio scripts. The mechanical sweet spot of operation was 5Hz to 50Hz, that’s where the speaker put out appreciable audio power.
The total cost for this build has been put at just $600 (£374) so there might be some night clubs interested in it.