On this step I've included some samples of the instrument in use. All three mp3s are the same snippet, recorded three different ways:
"tub_bass_mic" is an acoustic recording using a regular old microphone, as evidenced by the background noise and sounds of people walking around in my studio
"tub_bass_contact_mic" uses the contact microphone - squeaky clean and provides very different tone than a normal acoustic microphone
"tub_bass_mix_with_eq_and_reverb" - a mix of both mics with some EQ and reverb, this is probably how I would use it on a record
Step 1: Overview
Our bass makes use of plastic-coated galvanized steel cable (a.k.a. plastic-coated aircraft cable) for the string - this will be nearly impossible to break and provides far superior tone and playability to parachute/nylon cable. The plastic coating allows you to play the string with bare hands.
Our neck is unattached and pivots on the rim of the tub. Notes are thus created by flexing the neck to change the amount of tension on the string. This makes for a more intuitive playing style than an instrument with a fixed neck and fret board, but it will take some practice for your muscles to learn how to hit and hold specific notes. A used-up wire spool acts as a slide-able capo, allowing us to play in different pitch ranges/keys.
Our instrument also adds an optional pickup for amplification in the form of a contact microphone. I made mine from scratch using the recipe from Nicolas Collins' excellent Handmade Electronic Music (essential reading for instrument makers/hackers), but readymade contact mics are also available on the cheap.
This is the same tub bass that is used by The Asker Brothers to achieve their signature thwonk-a-donk sound. Let's begin!
Step 2: Materials & Tools
One tub, our resonant chamber.
One broom/mop handle, the neck. This should be un-tapered so you can make use of a sliding capo.
One used-up wire spool, the capo. Make sure it's a good fit on the neck - you'll need a little extra space for the string when fitting the capo over the neck. I found that a standard-sized wire spool was the perfect fit for a standard broom/mop handle.
Plastic-coated aircraft cable, the string. This is the only part you're not likely to find in the local hardware store. I ordered mine from webriggingsupply.com, part no. 02C030477. We'll be stripping the coating on the ends of the string to thread it through the neck/tub/hardware, and the width of the interior steel portion of the cable should be 1/16. This width of cable has lovely tone. Get at least six feet of cable.
Ferrules and Stops, cable hardware for 1/16 steel cable. This is the hardware we'll use to attach the string to our neck and tub. I was able to find packages of National item #N283-846 at the local hardware store, two of those put me in business.
One jar lid, the washer we use underneath the tub when attaching the string.
Optional: one contact microphone to act as a pickup for amplication. Make your own or buy one.
Dremel tool. We'll be using the disc sander bit to cut/shape the aircraft cable and to make a notch in the bottom of the neck. The 3/32 drill bit will be used to drill holes for threading in the neck, tub, and jar lid.
Wire stripper. Used to strip plastic coating off the ends of our string and to crimp the cable hardware.
A saw. To cut off the little screwy section of our broom/mop handle.
Step 3: Prep String for Neck
Step 4: Attach String to Neck
Step 5: Prepare Neck
Now to measure and the cut string: Put the notched end of the neck on the lip of the tub, as if you were playing it. Hold the unattached end of the string to the center of the tub with your hand. The string should be taught when the neck is perpendicular to the ground - find this length then make a mark 10 inches further down the cable (we need some slack to pass the string through the tub and loop it through the hardware). Cut the string using the disc sander bit on the dremel tool and strip off 10 inches of coating, similar to what we did to the other end of the string.
Step 6: Prep Tub
Now attach the string to the tub: Thread the cable through the tub, jar lid, and ferrules. Make sure your string is the correct length before securing the ferrules: test it by putting the neck in place and pulling lightly to determine exactly where the hardware should be attached on the stripped end of the cable.
This is the part of the instrument that will be pulled on the hardest, so I used two ferrules to increase the grip on the cable. Once you're confident about the string length, crimp the ferrules to secure a good grip on the cable.
Step 7: Attach Capo and Contact Mic
And that's it! The world is yours to rumble with tubby goodness. ENJOY.