My Washtub P-bass
I’m going to try to document the building of my 4 string washtub bass.
I’m starting from where I am and attempting to rewind to where it started.
The latest modifications were to apply a finish to the wood, and modify the sound chamber, the washtub, to remove some of the “metallic” overtones.
Acoustically I noticed that an “A note” is louder than other notes, and about 2 weeks ago I miked her up for Saturday night and noticed that an “A note” wanted to feed back even at fairly low volumes, so I need to get rid of the “A” resonance.
To mute the overtones of the washtub bottom I used a piece of 1/8″ tempered hardboard ( a 2′ x 2′ piece is $1 at Home Depot). I cut it to about 20″ diameter and glued on 8 pieces of medium density packing foam that were cut to about 3/8″ thick. I mounted the dampener by cutting scraps of wood so they would compress the foam and then wedged and glued the pieces of wood in place between the 4 wooden support blocks and the hardboard. For the center of the dampener I used a wooden “T” mounted between the internal cross brace and the center of the dampener.
The effect on the sound was amazing, no more “boingy” overtones. Now the sound is deep and much more well defined. What now?
My Washtub Bass site 
rockmumbles said
Well with every change comes a new issue, after mounting the tub damper and changing the mounting of the leg I now have a buzz. The buzz is not real noticable acoustically but the piezo pickup amplifies it very nicely?
So today I get to take it apart and epoxy the main support members to the tub.
Keep you posted on the outcome…
rockmumbles said
I finally got a neck of my own for the p-tub bass. I bought an AXS neck with tuners on ebay for $75, it is not as flexible as the “borrowed” ’93 Squire neck, I also like the shape better, the AXS neck is slightly beefier. There still is a problem with neck shape, a standup neck is more comfortable when it is “square” not square shaped but almost as thick as it is wide, similar to the shape of my old vintage Kay bass guitar, a “modern” bass guitar neck is much thinner than the width of the neck.
I’ve also been experimenting with the piezo pickup, I have put a RLC filter on the disk to filter out the high frequencies. I have also built a “mint box buffer” to allow the ultra high impedence piezo pickup to interface with a normal high impedence input. The word is still out, as I really haven’t tested things. I did just receive some piezo film that I want to try instead of the piezo disks.
Two more changes are in the works, one is a new adjustable bridge, the other is a new back for the tub, the dampened tub sound full and has good tone, but the bass lost quite a bit of volume by dampening the tin back, so I’m thinking about cutting out the tin and putting in a plywood back. With the plywood back I may try a sound post also…
More info coming …
rockmumbles said
Well it’s Jan 25 and I haven’t done much for quite a long time with my bass. It has been sitting in the cold and the top has colapsed a bit. I’m going to switch out the neck, and I’m going to have to rebuild the bridge. The last time Rich was in town and we played with the pickup I noticed how much resonance the bridge had through the piezo pickup it had an echo effect. So a new bridge is necessary, I really need to make an adjustable bridge so I have some adjustment as far as the action goes…
My First Washtub Project « My Washtub Bass site said
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Steve said
Great design. I’m going to give it try!