Project Loud Monkey–need your help

I need your help with a project I’m doing for the upcoming Toronto Mini Maker Faire coming up May 7-8.  Looking for small toys that make simple noise (rhyme!) + that old and enormous stereo gear you have collecting dust in your basement (just need the amp and speakers).  Ping me if you can help.

My good friends Seth Hardy and Alex Leitch from the truly awesome Site 3 coLaboratory are two of the dedicated organizers of this Mini Maker Faire (which is a gathering of all sorts of makers of all sorts of things).  They invited makebright to contribute a project and come out to the event (hope you will too!)

Concept: noise-making [keychains, dollar store toys, talking greeting cards, corporate swag, etc] abound, but we only hear their audio through a tiny 1” speaker at a tiny volume.  Lo-fi.  I’m pretty sure they are capable of much higher-fidelity sound, so I propose to modify them (see example mod below) to allow playback through a big giant stereo amplifier and speakers.  Then we’ll play freakishly loud noises experiment.

Toys like these, amp like this, speakers like… the speakers were too enormous to fit in the picture (think: 80’s stereo gear).  More toys like…

Pretty much any small toy that has these magic sound holes.  Not looking for toy musical instruments, but rather simple sound makers.

Universally, these toys contain the following bits: sound-producing circuit board (upper left), a tiny 1” speaker (right), and some sort of actuator or trigger (pushbutton switch bottom left).

Let me show you an example modification with this flying swag monkey from a trade show that I got from Storz.

We’ll add this RCA connector that I got for $1.25 at A Buck or Two.

He won’t feel a thing.  Just need to cut a few stitches at the seam.

On plush toys, you just feel around for the hard bits inside.

The noise…

maker, removed.

Pop it open and we find…

the usual parts.  These are manufactured to the absolute rock-bottom cost, so instead of discrete chips on the circuit board, you’ll find a chip-on-board construction where the silicon die is bonded directly to the board and then covered with a gob of black epoxy for mechanical stability.

Instead of a push-button switch, this toy is triggered by the classic spring inside a metal barrel (round thingie below the red wires).  When the metal spring is jolted against the metal barrel, the switch is closed.  Useful in this application because the monkey has elastic arms so you can stretch him like a slingshot and let him fly, triggering delightful monkey noise.

Drilled 2 holes in the case and desoldered the wires between the sound circuit board and the speaker.  Then added in the female RCA connector (white plug here) to the speaker, and the male connector to the…

circuit board.  Now to get the original play-through-the-tiny-speaker effect we can just plug these together.  Or…

plug the male connector (remember: from the sound circuit board) straight into…

a big audio amplifier.

Back into the case she goes.

Back into the monkey.

Rock on!

For easier bench testing, I played the sound through this much smaller boombox.

My smart friend, Turi (*not* pictured above), suggested I record the sound from the small lo-fi speaker and the big hi-fi speaker, and compare the two sound samples by frequency analysis.  I used my TASCAM DP-008 and a Shure 57 mic to record the samples from about 12” away.

From processing in Audacity, we’ve got graphs of the sound played through the small integrated speaker, and…

here, we’ve got the sound as played through the boombox speaker.  My expectation was that I would see more bass with the boombox due to the larger speaker, but the real surprise was the midrange around 10kHz.  Much fatter from the boombox.   Ok, this isn’t science, and I probably should have recorded a sample directly from the monkey sound source to the DP-008 for comparison, but…

(1.) the monkey sound is spectacularly loud from a big amp and (2.) qualitatively, it sounds “better”.

If you have any relevant gear you can contribute please give me a shout.  Phase 2, time permitting, is to build and add some intermediate sound manipulators like a wah-wah pedal, a cut-off filter, etc.  Phase 3 of Project Loud Monkey is a sequencer + looper to orchestrate the input sounds into some funky beats.

Happy making,

DW