Musical Chair

by Ham-made in Circuits > Electronics

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Musical Chair

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Musical Chair

Disillusioned by the name of the game ''musical chairs,'' I set off to create an actual musical chair, as in, a chair that can be played as a musical instrument, a rocking chair if you will. My hope is to eventually play a true game of musical chairs. Let’s rock!

A note on chair selection :

While most chairs will work for this application, a wooden chair with arms will give you the most sonic options. After having found a suitable candidate, (I do not recommend using one of your current dining chairs…) I found mine in a skip, (i.e. my dining room ), you can start the preplanning stage.

Tools and Materials

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Materials are separated by utility in the photographs, construction tools and electronic tools. Gather what you need and borrow what you don’t have (unless what you don’t have is the chair… )!

Not included in the photographs are the materials needed for the preplanning step which are: a piece of cardstock (Bristol board ), a pencil, a utility knife, any low-tack tape, and scissors.

Construction Tools:

- Drill

- Appropriately sized twist drill bits and forstner or spade bit (not illustrated )

- File (bastard or triangle )

- Chisel

- Utility knife

- Sandpaper (120-200 grit )

- Hammer

- Writing instrument (that is visible on different surfaces )

- Large or small Phillips screw driver (according to your tuners )

- Socket wrench, Crescent wrench (not illustrated ), or pliers (not illustrated and not recommended ) according again to the size of your tuner, potentiometer, and audio jack nuts

- Coping saw or jigsaw (not illustrated )

- Bandsaw and scroll saw (optional and illustrated in Step 6 )

Electronic Tools:

- Hot melt glue gun

- Soldering iron

- Solder (Rosin core )

- Wire strippers

- Needle nose pliers

- Side cutters

- Hookup wire (two different colours, gauge doesn’t have to be too thick )

- Guitar speed tuning tool (optional )

- Cyanoacrylate glue

- Heat shrink tubing

- Lighter (or heat gun/hot air tool )

- Utility knife

- Writing instrument (able to label wires )

- Low-tack tape

- Scissors (optional…if you’re not into ripping tape )

Electronic components :

- Piezo elements (quantity is up to you )

- 500K potentiometer

- ¼’’ Audio jack (mono )

- Hookup wire

*Where to source the electronic components is covered in a later step!

Musical Components:

- Guitar tuners

- Guitar strings (thicker gauges )

Miscellaneous:

A wooden chair with arms

Preplanning

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In this preplanning step (which is especially important for those wanting to create an acoustic musical chair ) we will make a cardstock and masking tape template of the underside of the chair’s seat.

Depending on the complexity of your future design, this task could be nearly impossible to complete at a later step. Try to make the template as accurate as possible, the cardstock should not surpass the outer dimensions of the chair.

Layout

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Now, time to plan the layout of the strings and tuners! To do this, we will be using yarn, painter’s or masking tape, writing instruments, and a ruler.

I recommend using the flattest parts of the chair to house the tuners and to stay away from placing the tuners on the tops of the arms of the chair as it renders it uncomfortable to play. Try arranging the yarn so that they are inherently different lengths to widen your tuning options.

*Nevertheless, take care to not exceed the total length of the musical strings that you will be using, you’ll want enough slack to get at least a couple of windings around the post of the tuner to maximize tuning stability. I also pulled the yarn around different corners of the chair to act as bridges (akin to the bridges on any stringed instrument ).

After stringing up the chair with yarn to demarcate the desired placement of the eventual musical strings and tuners, I placed painter’s tape on all the surfaces that will be receiving holes. I then proceeded to mark the intersections of the hole placements based on the yarn layout. Being conscious that I could easily mistake a musical string sized hole for a tuner sized hole, I marked the string holes with a different coloured marker (i.e. red dots ).

Drilling Operations

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After planning the placement of the tuners and strings, it’s simply a matter of drilling the appropriate sized holes in the marked locations. Try your best to drill the holes as straight as possible. If you can easily disassemble your chair, I would recommend using a drill press to drill the holes necessary to receive the tuners.

Depending on the thickness of the parts into which you are drilling for the tuners, countersinking larger holes might be necessary to accommodate the thickness required for the proper operation of the tuners. In my case, all the parts receiving the tuners were on the thick side, so I countersunk the holes using a forstner bit from the inside of the chair when possible to reduce the thickness of the wood. If your chair parts are too thick as well, I recommend drilling a small pilot hole where the tuner will go, then using a larger forstner or spade bit, drill to the desired thickness (preferably from the back, i.e. the inside of the chair ), and finally drill the hole that will accommodate the tuner.

*A note on tuner hole placement, be sure to consider the hole’s proximity to the edge of the chair piece into which the tuner is being placed, as you will need enough clearance for the tuner to operate properly. If, for aesthetic purposes, you placed the tuner hole too far away from an edge for it to function properly, scalloping the edge of the chair piece is a simple solution. The best tools to use for that purpose are a spokeshave and cabinet scraper, but you could get away with using a utility knife and some sand paper.

Once all the tuner holes are drilled you can proceed to drill all the smaller string holes (marked in a different colour ). Be sure to drill a hole large enough to accommodate the string that you will be using and small enough to catch the ferrule (or ballend ) of the string, keeping it locked in place. If you decide to use a string without a ferrule (such as a nylon string if making a classical musical chair ), you can tie a knot around a small piece of wire or a bead to keep it in place.

Tuner Installation

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After all drilling operations are completed, proceed by installing the tuners, paying close attention to orientation and straightness. I recommend predrilling the tiny holes that receive the screws that keep the tuner locked in place as they’re often made of soft metals that are very prone to stripping. After installing the first tuner, string it up like you would a guitar by first snaking the string through the necessary holes and tune it not to any pitch, but to a moderate tension.

Celebrate this first step by sitting in the chair whilst plucking the string, being sure to shift the weight of your body around to change the tension on the string in whammy-esque fashion!

Resonance Chamber

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Even if you plan to amplify the chair, I suggest turning the underside of the chair’s seat into a resonance chamber by using the cardstock template of the underside of the chair, that we completed during the preplanning stage, to use as a guide to cut out a corresponding piece of thin plywood (known under different names, often referred to as door skin ). Other materials such as, masonite (hardboard ) or even Plexiglas can also be used. I used a bandsaw to cut out the exterior shape and a scroll saw to cut out the f-holes; if you don't have access to these stationary power tools you could use a jigsaw or even a coping saw to make the cuts. Be sure to drill holes in the interior shapes (f-holes in my case, ) to be able to insert a scroll, jig, or coping saw blade and cut them out.

Depending on the design of your chair and the flexibility of the plywood that you’re using, the plywood plate might have to be cut into halves to enable it to be affixed to the underside of the chair. Small tweaks to the plate will most likely be necessary for a snug fit, accomplished by sanding the areas of concern.

Once the plywood is accurately cut to shape, I suggest cutting a single or many sound holes; placement can vary without much effect on the amplitude or sound of the chair. I chose to cut out a classic f-hole design to increase the chair’s credibility as a musical instrument. I freehanded the design, but if you don’t have a wasted visual arts degree, you can print off a template from the plethora of online templates, cut it out and trace it onto your piece of plywood. If you don’t have access to a printer you can hold up a piece of paper to your computer or tablet screen and use it as a lightbox to trace the design. Be creative with the sound hole design even if most will never see this detail!

Proceed to then affix the plywood to the underside of the chair with screws (predrill pilot holes to avoid splitting ). By using screws, you can easily modify the plywood plate and make multiples to experiment with hole size, shape, and placement.

*I made mine out of masonite and decided to apply a mahogany veneer to enhance its visual appeal.

If you happen to have access to a laser cutter or a CNC, you could also create the plates that way!

Stringing Up the Chair As an Acoustic Instrument

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Once the plywood plate has been installed, proceed to install and tune up the rest of the strings in the same manner that you installed the first. Once the additional strings are installed, you might find that some strings, even under tension, rattle against different parts of the chair. These strings will require additional bridges made from small blocks of hardwood (I used maple ). Using a triangle file or the corner edge of a flat file, file small v-shaped grooves to accommodate the thickness of the different strings.

If the strings are under enough tension, that tension will be enough to hold the bridge in place. If the bridge slides around; however, it can be glued in placed using either regular yellow wood glue (bare wood to bare wood ), or 5-minute epoxy or cyanoacrylate glue if there is a finish. You could also sand the area to be glued to bare wood if you only have access to wood glue or a PVA glue. The holding strength isn’t really all that important, the tension of the strings will take care of that, the glue is to prevent the bridge from sliding around.

As a side note, for those who wish to experiment with bridge placement, I recommend using less permanent methods of affixing the bridge. This will in turn, give you more sonic options as you will be able to modify the lengths of the tensioned strings on both sides of the bridge by changing its placement. Less permanent methods of attachment include blue tac, weak double-sided tape, hot glue, and screws threaded from behind. You could equally let the bridge hang loose under the tension of the strings and use its mobility in a live performance setting.

Once the chair is all strung up, you can enjoy your new musical (acoustic ) chair! Now…for those of you willing to rock, let’s amplify the chair and turn it into a rocking chair!

Amplifying the Chair

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First thing’s first, remove the plywood panel that was just installed as we’ll be hiding most of the wiring on the underside of the chair!

To amplify the chair, I’ll be using a just a handful of electronic components scavenged from children’s toys and a broken electric guitar. We’re on the hunt for: piezo elements, a 500k potentiometer, a ¼’’ jack and some different coloured hookup wire (shielded if possible ) to reduce interference noise.

Hunting for Components

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Piezo Elements:

For the piezo elements, they’re often found in items you would not expect, such as, exercise equipment and microwaves. Basically, anything that beeps, most likely has a piezo element inside of it. Their ubiquity and sensitivity are why they’re my preferred amplification method. I salvaged the piezo elements that I’m using from a children’s interactive drumming toy found beside a dumpster, five drum pads = 5 piezo elements ! The best places to find piezo elements are alarms (especially small handheld alarms ), expired fire and carbon monoxide alarms (change them regularly according to local fire department recommendations! ), ultrasonic insect and rodent deterrents, broken digital alarm clocks, and interactive children’s toys. You can also purchase them from online suppliers and auction sites but…most project materials and tools that you will ever need are most likely being discarded by someone else, ask around and scavenge before purchasing anything!

Potentiometers and 1/4'' jacks:

I salvaged the 500K potentiometer and ¼’’ jack from the aforementioned broken electric guitar (literally snapped in two…future project: non-musical chair made from musical instruments,) but you can salvage the components from old stereos or HIFI equipment, broken amplifiers, radios, or other defunct sound equipment.

Pro Tip: A good place to start is your local music store, they often have a miscellaneous parts bin that you can rifle through, especially if you explain to them what you’ll be using the parts for! Electric guitar volume and tone pots (potentiometers ) are usually around 500K, if you’re unsure of the pot’s value, look for any printed or stamped information on its base to help you determine it (even if it’s a serial number, it will enable you to look up the component’s spec sheet ). The value of the pot is rarely clearly visible; however, especially if you’re salvaging it.

To determine its definitive value, use a multimeter, if you don’t have access to a multimeter simply test the component by: turning it completely counter-clockwise, connecting the circuit to a small amplifier, and if no sound is produced until the pot is turned clockwise, then you should be able to use the pot for this purpose. Nevertheless, try swapping it out for alternatives if you have the option, to see which pot increases the volume most fluidly.

Pickup Installation and Wiring

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To determine the placement of the pickups, identify the areas of the chair where the strings transfer their vibrations. This is typically at the natural bridges of the chair, i.e. corners over which the strings are stretched, or at the additional small bridges used to prevent the strings from rattling. If you are using magnetic pickups try placing them in areas under the strings where there is enough, but not too much clearance. Piezo contact-type pickups should be placed on the underside of the bridges and on the solid parts of the chair that transfer the most vibrations.

Once the placement has been determined, wire positive and negative leads to the pickups before installing them. You can refer to the diagram provided, which illustrates wiring everything in parallel i.e. wire all the positive wires together and then all the negative or ground wires together. I used some masking tape to keep the piezo elements from moving around while I measured out and soldered the wires.

I suggest colour coding the wires, most people use red for positive and black for ground, but any two different colours will fulfill the purpose of reducing confusion when wiring everything up. I also recommend using different colours to distinguish between the positive and negative leads of the magnetic vs. piezo pickups if applicable.

After everything is wired up, test out the circuit before installing everything permanently. This is also when you must decide the final placement of the ¼’’ jack and volume pot as you will need to drill two final holes into the chair.

Due to the thickness of the wood, I recommend hogging out as much material as you can from the inside of the chair where you are planning on placing the electrical components as their installation requires a thickness of only a few millimeters. After drilling a pilot hole to mark the center of the component placement, I used a forstner bit to hog out the material, but a spade bit would also work. After installing the ¼’’ jack and volume pot, I used a few dabs of cyanoacrylate glue to hold the piezo elements in place and additional globs of hot melt glue on their backs to keep them securely fastened long-term.

Finalisation and Additonal Accoutrements

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Once the electronics have been permanently installed, screw the plywood panel back on to the underside of the chair, plug the chair into an amplifier, and rock out by plucking, strumming, or bowing the strings! You can also tap on the different parts of the chair percussively whilst simultaneously plucking the strings! Don't forget the « shifting body weight » trick to manipulate the tension on the strings in whammy-esque fashion!

The thing about creating your own instrument is that you automatically become simultaneously the best and the worst player of said instrument…it will take some practice to figure out the instrument’s intricacies before gigging with it. Good luck and rocking chair on !

Additional Accoutrements and a Note on Tuning:

*Tuning:

You can tune the strings to any pitch, as long as excessive tension is not applied to the strings. If the string pitch becomes inaudibly high (couple notches below dog whistle ) then the tension is excessive. If the pitch of the string is inaudibly low because there is so little tension on the string that it flops around like a car dealership air dancer, increase the tension on the string. Because of the nature of the instrument, each string might have different sections tuned to different pitches, simply make sure that each section is approximately evenly tensioned.

*Additional Accoutrements:

1. As one of the boards of the seat of my chair was loose I decided to turn it into an additional sonic feature by removing it completely, routing out a cavity for a hinge, then installing the hinge to both the back edge of the board and the frame of the chair. This enables me to use the loose board percussively.

2. The feet of the chair also have the potential to become an additional sonic flavour in your arsenal by harnessing the power of friction. You could add different endcaps that screw into the feet of the chair such as textured wooden end caps, or leather end caps to achieve different sonic effects.

3. You can choose to refinish the chair by sanding and staining it or simply by painting it with chalk paint or any other thick paint that adheres well to furniture. You could also cover it in fabric, vinyl stickers, sheet music, etc.