From it's humble beginnings as an old replacement tire tube long forgotten on the garage shelf and pieces of scrap lumber collecting dust, make this instrument of mass intonation, The Big Axe Bass. OK, it only has one "string" but it sings in the lower registers.
Add a simple piezo pickup to this and amplify the signal to broadcast to those beyond earshot "Behold the Big Axe Bass of Righteousness, make one to spread the groove, as long as it is not rap...maybe disco too"
WARNING: Do not crank the amp up to 11. May signal Armageddon and/or your nasty neighbor who doesn't appreciate good music at three in the morning. Subsonic booms do carry further in open environments. Has not been used to stun fish. Word.
Step 1: Shoplifting List
One bicycle inner tube - doesn't really matter if you prefer schrader or presta valves or if the tire can hold air or not. Mine was actually sitting on a utility shelf in the garage for about 20 years or more, that's the last time I rode my little red Bottechia road bike. I guess I am not as crazy as I used to be when I was riding around in the streets of Brooklyn...wait...
A long piece of wood 1"x3"x6'. Fancy if you have oak or another exotic wood.
Another scrap of wood, a block 2"x4"x"6" or whatever cutoff you have to act as the bridge of our bass guitar.
A cardboard box big enough to make a reasonable facsimilie of an axe head.
Piezo buzzer pickup - I'll show you how to make one
(piezo buzzer, shielded 2 conductor cable or speaker wire, 1/4" plug to fit instrument input jack on instrument amplifier or female 1/4 jack to fit instrument cord to amplifier)
Soldering iron and solder( Lead and earthquake warning for residents of California, tag not to be removed under penalty of law)
Instrument amplifier - may work plugged into a set of computer speakers, haven't tried to see how well the piezo pickup works on the mic or line input of a computer sound card.
Some black or red construction paper, glue
Aluminum duct sealing tape to mimic the metal edge of the axe
No woodworking skillz or tools necessary, hopefully
CAUTION: Working with sharp tools is only fun when no one gets hurt. Exercise care and know how to use your tools. Wear eye protection.
Step 2: Get the Buzz
Create your own piezo pickup so you can plug this monstrosity into an instrument amplifier.
Piezo buzzers contain an unique crystal wafer that when current is applied across it, will vibrate making a sound. If you vibrate the crystal with sound, it will generate an electronic signal that can be amplified.
I had an old carbon monoxide detector waiting to be recycled so I was able to gut out the piezo buzzer from there. Yeah, yeah, the CO detector module itself is scary to be near but you can always get a spare piezo buzzer from an electronics store. Here are some tidbits and this if you happen to hack a smoke alarm.
I cracked my piezo buzzer open to take a look at the piezo element. The case was pried open with just a screwdriver. Some may be glued or fused together.
Just solder leads to the ground and hot, marked on the case with the corresponding wire to your instrument plug or jack.
The plug outside or "ring", the bigger part will be the ground. The tip or core is the hot.
If you are using shielded coax type cable, the outer braided sheath will be ground and the inner filament will be hot. Paired speaker wire will have one wire marked or a different color so you can reference what you are using as ground or hot.
I used a bit of heat shrink tubing to insulate the solder joints so they will not contact when compressed inside the plug shell and act as a strain relief on the piezo pickup. Use the big part of the soldering iron and hold it close to heat up the shrink tubing or use a heat gun. Heat guns are cheaper than hair dryers and do a great job of blasting intense heat. Worth getting as a tool.
I tried to use the pickup with the case intact but the buzzer case was not transmitting enough sound. I removed the front shell of the case and just taped the piezo assembly together. The wires were already soldered to the case pins and just needed to be pressed up to the piezo disk element to make electrical contact.
Step 3: Assembly Required
This might be the most dangerous step of the instructable.
If you do not have a good grip on your wood, you essentially turn it into a projectile causing bodily harm. You will end up with a serious harpoon gun.
Hardwood is preferable to soft woods.
Using one hand, hold on to your stick firmly.
At the far end of the stick, put the rubber on top so as to hook the end of the tire.
The valve can be sticking up at one end.
Pull down and hook the tire on the other end. You will need to stretch the tube so that it will fit. Once it is on, if there is a lot of slack, the rubber tire may be too big and the length of the wood too small. Conversely, if your wood is too big and the rubber tire too small, then you may need a bigger size. I think mine was average and fit just right *sigh*.
You might want to sand the ends of the wood stick a little bit to keep it from abrading the rubber tire.
Take your wood block and place it about 2/3rds down from whatever you pick as the top of the instrument. Put it under the rubber tire to lift it off the surface of the stick. This is the bridge of your bass guitar. The bridge is held in place by the compression of the rubber tire. It also alows you to adjust it if necessary or lets you move it to experiment with the instrument.
Place the piezo pickup right under the tire and on top of the bridge. I found it best that the tire contact the pickup for best sound.
Step 4: Put an Edge on It
Here is the axe
Make a faux axe head to place as a decorative element to your fine instrument.
Take a piece of cardboard and just freehand something that looks like the shape of an axe head. Go with the standard ACME axe head design or medieval double-headed axe, adze, etc.
Cut the axe head shape out.
Glue about 4 or five layers of cardboard to build up the thickness.
Trim off the excess cardboard using your original cutout as a guide.
Alternate the direction of the cardboard grain of each layer for additional strength. You can also piece together small pieces of cardboard since the layers are laminated.
Rip off the skin of one side of the cardboard to cover the raw edges of your cardboard stack.
Cover with construction paper glued on.
Cover the grinded part of the blade with aluminum duct sealing tape. I ripped one edge of the tape so it would look more feathered in where the edge is ground.
Step 5: Rock On
Place the axe head under one end of the instrument.
You can glue or tape it on if you are worried about it falling out when you're heavily rocking a steady beat.
Plug it into your amplifier of choice.
Experiment with processing the sound if you have some effects pedals.
The rubber tire can be thumped, picked, plucked, slapped, played with mallets, drumsticks, sharpies, pencils, played on both sides of the bridge, has multiple "stretch" tunings.
Can be played upright or make a guitar strap with another bicycle tube.
Discover the possibilities with this simple instrument.
So, there you go, the Big Axe Bass, that's how we rock and roll.