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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!

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closed as too broad by RoyC, Dmitry Grigoryev, awjlogan, Elliot Alderson, Finbarr Oct 18 '18 at 9:39

Please edit the question to limit it to a specific problem with enough detail to identify an adequate answer. Avoid asking multiple distinct questions at once. See the How to Ask page for help clarifying this question. If this question can be reworded to fit the rules in the help center, please edit the question.

  • \$\begingroup\$ Low pass filter (analog, not arduino or something) whose output will feed an amplifier input connected to a DC vibration motor... But you have already outlined that. Not much more than that. \$\endgroup\$ – Eugene Sh. Oct 12 '18 at 19:52
  • \$\begingroup\$ @EugeneSh. Thank you for the comment. Since I don't know how the vibration actuator will work and what types of input it might accept, I might have to use a microcontroller, or so I thought. In that case, do I just put the output of the analog low-pass filter to analog input pins on an Arduino? \$\endgroup\$ – You Speak So Well Oct 12 '18 at 20:04
  • \$\begingroup\$ If you want to control the motor wit Arduino? Yeah.. but I would expect some noticeable latency. \$\endgroup\$ – Eugene Sh. Oct 12 '18 at 20:06
  • \$\begingroup\$ Welcome to EE.SE! Find out everything you need to get started by taking a 2-minute tour (electronics.stackexchange.com/tour). \$\endgroup\$ – F.Ahmed Oct 12 '18 at 20:33
  • \$\begingroup\$ Think in terms of a frequency divider. All bass inputs are divided by 2 and 4, to stay an 1 or 2 octaves down from the dominate bass note. Of course this results in a digital output that needs a heavy filter to get it back to a sine wave. These "sub-bass" notes will lag behind the original so it cal have a muddy sound. An Arduino or fast Raspberry Pi 3B could do this as a DSP effect, but cost and programming time may overwhelm you. The best approach is the most expensive such as synthesizers. \$\endgroup\$ – Sparky256 Oct 12 '18 at 20:57
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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.

enter image description here

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.

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    \$\begingroup\$ A rational low cost solution. Other solutions have high price tags.+1 \$\endgroup\$ – Sparky256 Oct 12 '18 at 21:18
  • \$\begingroup\$ Thank you for the incisive and clear answer! I know very little about subwoofers and did some reading. Very cool idea! So you're suggesting basically a little sealed box with 1 subwoofer driver and 1 passive radiator? I'm a noob but where do I find the right components? any links would be awesome! \$\endgroup\$ – You Speak So Well Oct 16 '18 at 16:29
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  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
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  • \$\begingroup\$ If the OP can actually program a complex DSP engine, that would be a somewhat cheap solution. \$\endgroup\$ – Sparky256 Oct 12 '18 at 21:00

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