In which I once again try to solve all of my problems with knitting. This project changed a lot as it progressed; I learned a whole lot and think I made some big steps forward in researching soft circuits for my own practice. the goal of this piece was to make not a garment with electronics IN it, but a garment that IS the electronic, i.e. the full integration of wearable&electronic. It’s also supposed to be very snuggly and cozy, so I tried to maximize soft&fluffiness, and was very successful in that.
Soft Speaker Sweater ft. Brown Party Liquor (battery pack in front pocket powers speakers, liquor powers model, she wouldn’t come upstairs unless I let her drink)
Above right, the controller is hidden under the folded turtleneck collar and the buttons to toggle the 2 audio files on and off are easily pressed with the right hand.
You can see the amplifier under the speaker in the above left pic; components are connected with conductive thread sewn into the knit fabric using duplicate stitch. The chenille texture allows the thread to be pulled tight against the core thread of the yarn. The yarn is very bulky as well, and this combined with the “shag carpet” texture hides thread and wires.
9V battery slips inside the front pants pocket; I drafted some designs with a little knit pocket for the power source in the sweater itself, but that ruined the fit and line of the garment. What I like about this solution is that the power source can be switched on separately from the audio toggle; so the circuit can be all ready to go and the wearer just needs to press the button at the collar when they feel like surrounding themselves&their cuddle buddy with some ambient fuzz noises.
Materials
CPX controller
Mono audio amp (1.4W 8ohm)
Conductive thread
26 AWG copper magnet wire
Royal Velvet Yarn by Loops and Threads
Knitting needles
Battery pack with switch (I tested with a 9V pack and a 4 AA pack before I decided on the 9V)
Neodymium magnets (I tested 1/2″ and 1/4″ before deciding to just sew both into each speak for max range)
My roommate (age 28)
Ideation & Planning:
I wanted to make an “intuitive makeout soundtrack sweater.” My early ideation was for a cozy sweater with hidden small speakers sewn into it, that each played an audio track mapped to a pin of the CPX controller. The plan was to break the circuit for each speaker with a contact sensor that would connect when someone placed a hand (i.e. hugging/cuddling the wearer and placing pressure on the sensor) on the location of that speaker.
I am left-handed, so I consulted with a few right-handed people to choose the locations of my audio output areas and settled on these areas, from which I chose four for the final piece:
In researching the audio capabilities of the CPX controller, I came to the conclusion that there were not enough pins or memory in the controller for my original plan to be feasible. The controller can also only send audio to powered speakers, and so wiring a power source for all my tiny store-bought speakers would use up more pins than were available (I still have the little speakers from creatron though, and they are still really fun to add to other stuff).
This led me to instead begin designing a sweater with speakers integrated into the fabric itself. The locations of the audio outputs, power source, and controller remained the same as in my original proposal. The path of the conductive thread I sewed throughout the knit fabric of the sweater to connect all the circuits stayed the same as well.
Process:
Obviously the first step was to knit a sweater, so here it is with my needles still stuck in it before it was finished (there’s no pattern to cite, I just measure the person and knit from the top down):
And here it is all grown up with finished, constructed speakers and controller sewn in.
To create the speakers, I knitted coils (1 for each speaker) from copper wire. These function as the front of a speaker; to hold the magnet to the back, I knitted little pouches out of conductive steel thread. The magnet sticks to this square of fabric, and the outer edges are sewn to the copper swatch with more conductive thread.
At this point I set up some little test circuits before sewing in the amplifiers and controller; I had made a separate fabric swatch and speaker coil for this.
Here I found out that 9V was necessary to power all my soft speakers, and that an mp3 in stereo that was above a certain file size could not be played through a mono amplifier, or sent to a single speaker, even if I clipped the stereo audio jack so that left, right, and ground ran through a single wire. I also learned that this is the wrong way to clip it, the clip should go vertically and contact all 3 rings:
Below: Audio coming from controller connects to speakers via conductive threads in fabric of sweater; amps and power not sewn into the final product yet.
Reflections & Next Steps:
Part of the charm of the ambient-noise-cuddle-sweater is that the audio was crappy; but for next time, larger, stronger magnets will be a must. The area of the speaker coil that vibrates depends on the range of the magnet, which depends on its strength. The next size up from the largest magnet I used is almost 20x more expensive, so I may research other aspects of speaker construction that I could alter in my design to increase volume.
Another option could be to add volume controllers or a different type of amplifier into the garment, but this would affect the softness of the circuit, which is my priority in all my pieces for this class.
Although the final piece ended up just having audio turned on/off from the CPX, I kept the speaker placements from my original sensor-triggered circuit so I can develop this idea further. The major obstacle to my original vision was that there just aren’t enough pins! In the future, I would redesign the sweater to omit the CPX completely; since the controller can only play audio through powered speakers, my thinking is that once I have to build soft speakers AND their power source, I might as well make that the focus of the wearable. Doing this also cuts down on some wires/connectors, which leaves room to bring back the pressure sensors I originally wanted.
If I did this project again, I would basically take the ipod test circuit from my process above and sew that into the sweater, but increase the voltage of the power source and get stronger magnets as well as amplifiers.
This project ended up being more of a prototype, but I really enjoyed learning about and researching the construction of fabric speakers (of all types), as well as of speakers in general. I plan to continue working on pieces similar to this moving forward.
Sources:
Wirtz, P. Spiluttini, C. betaKnit Research–V2 Lab for the Unstable Media. V2. Retrieved 04/11/2021 from https://v2.nl/lab/projects/betaknit-research
Woodford, Chris. (2006/2020) Loudspeakers. Retrieved from https://www.explainthatstuff.com/loudspeakers.html. Accessed 2021/04/09
Adafruit. (2021/04/15). CircuitPython Audio Out. Adafruit Learning System. https://learn.adafruit.com/adafruit-circuit-playground-express/circuitpython-audio-out
Kobakant DIY Wearable Technology Documentation. (2013). Fabric Speaker Swatch Example. HOW TO GET WHAT YOU WANT. https://www.kobakant.at/DIY/?p=5935
Kobakant DIY Wearable Technology Documentation. (2013). Knit Speakers. HOW TO GET WHAT YOU WANT. https://www.kobakant.at/DIY/?p=4465