How can I drive this random speaker at max power, and various frequencies?

Other Hardware General Electronics
1

I have a random speaker out of a cheapo subwoofer, and I want to make some "Cornstarch monsters", which require a low base tone. But after much googling I can't quite figure out how to simply make it work.

I know I have to feed it some ac voltage, at various frequencies, but I have no idea what voltage is required, how much current, and also if it needs to be a sine wave, or if a square wave can work. All I know is when I measure resistance with a multimeter I get 7.3 ohms.

Can anyone help, and suggest the cheapest and easiest way to drive this speaker at up to its max potential, and preferrably variable frequency? I don't really care if I end up blowing it out, its just a junk speaker.

2

The Best/easiest way would be to use an audio amplifier. If you don't have access to an Amplifier the cheapest way would be an h - bridge to drive the speaker and program the arduino to toggle i/o pins at the appropriate frequency.
How many watts is the speaker rated for?

3

Class D amplification is ideal, much more efficient, but for a subwoofer driver you might
be talking anything from 50W to 400W power (whether that's actually necessary is another
question).... A signal generator is needed to generate nice sine wave of varying frequency.

In theory at least an Arduino could generate fast PWM in antiphase (a class D signal) which
then only needs boosting with a MOSFET H-bridge and filtering with LC filter to the speaker.

In practice its quite challenging to roll-your-own like this.

4

carl1864:
Can anyone help, and suggest the cheapest and easiest way to drive this speaker at up to its max potential, and preferrably variable frequency? I don't really care if I end up blowing it out, its just a junk speaker.

Arduinos aren't much good for this - they have no analog outputs.

You can't really just filter an PWM signal when you need variable frequency, you'd have to add an external DAC.

carl1864:
After much googling I can't quite figure out how to simply make it work.

You're probably looking for the wrong sort of solution - one with Arduinos and MOSFETs and things.

Much easier to use your PC sound output (with some sort of "Signal Generator" program) and an audio amplifier.