mjhjmtu

First, I'll admit that I haven't done any real electrical engineering in years so I'm quite rusty. But here's a fun project to contemplate:

I'm building a device that "rumbles" with the bass in the audio, to increase immersion. One similar device is this Basslet. It's a "silent haptic subwoofer" if you will.

Current concept:

1. USB or 3.5mm jack audio input from PC


2. Some low pass filtering, ideally configurable. Was hoping to use an Arduino but not sure if it's powerful enough... Google searches didn't help.


3. Output processed signal to a vibration actuator (motor? linear?)

Desired result: a box that vibrates with the lowest thumps in music and movie audio.

Any tips on where to look/start? Should be a fun project!

Deciding on the actuator will precede any decision on the driver.

Philips AmbX many years ago did a rumbler for gaming, and XBox controllers have rumblers built in that consist of nothing more than small motors with eccentrics attached - just a bigger version of the vibrator in cellphones. These can be made to rumble at varying frequencies depending on drive voltage (most are just brushed DC motors), but are pretty crude and not great for syncing to music though acceptable for sound effects.

For a better relationship to the actual bass you need a device that can be made to have a displacement that follows the bass, at last over a limited frequency range. A mass attached to a linear motor or solenoid is an obvious choice - looks like that is what the Basslet does, but probably the cheapest way is to use a speaker. I have at home one small Bluetooth speaker that really thumps a lot more than the larger versions I have of the same, and the trick is the use of an auxiliary bass radiator. This is similar to a speaker, without the voice coil, and with additional mass attached to the cone or plane, which gives it a far lower resonant frequency than a similarly sized speaker could - at the expense of a limited range over which it can resonate. The surprising thing is that it can be driven by the pressure generated in a sealed enclosure by a bass driver only about 60mm in diameter.

This is one I found on Alibaba that is similar. This then becomes more of a mechanical project, with a fairly simple amplifier that would need a low-pass filter. The ABR can be tuned by adding mass to lower the resonance.

1. You can use a dspic to process audio, instead of arduino.


2. For the actuator you can use something similar to the motors used in the game controllers. As this has to be small, you can even use some stepper motor similar to the ones present in old notebook floppy drives. A motor embedded in the pcb might be an idea: https://hackaday.io/project/39494-pcb-motor .
   The idea is that you have some umballanced wheel that turns with a motor.


3. I would look for ideas from game dyiers, like this: https://lifehacker.com/build-a-diy-rumbling-gaming-chair-1765337209