The Springboard (Pt. 9, Finished)

This is the ninth and final of a number of posts pertaining to the progress of my 21M.299 (The Social Lives of Instruments) final project, The Springboard.

The finished instrument.

I have finished the instrument! The polyurethane has dried, the instrument reassembled, and the pickups have been mounted. Near the end of this post is a sound sample.

Reassembling the Instrument

After allowing the polyurethane to dry for 24 hours, I began reassembling the instrument. This was easy enough, though I did split the bridge components while screwing them down. Because they’re not under a lot of force, I loosened the screws a bit and pretended that it never happened. Oh well.

Mounting Piezos

With the instrument reassembled, it was time to mount the piezo sensors. As a reminder these sensors will pick up the vibrations in the wood and convert them to an electrical signal that can then be amplified.

In my last post I remarked that I needed to figure out how to best mount the piezo sensors in order to get a full round tone. My first attempt involved hot-gluing around the sensors edge, as shown in the below picture.

The original single piezo sensor.

This didn’t really work so well- the tone was tinny and quiet unless I applied pressure to the back of the sensor.  Because of this, I believed that pressure was the answer, and devised a new mounting solution that involved a W shaped piece of wood that would screw into the back of the instrument and apply pressure to the center of the sensor.

It didn’t work.

Though the wood held the sensor in place, the sound was even quieter than before. Loosening the wood seemed to make it louder, but then the sensor could move around. I was at a loss. I tried placing paper between the center of the sensor and the board, gluing only parts of the edges, using both the bracket and glue.. but nothing gave me a decent tone.

Then it occurred to me- maybe it wasn’t the pressure, but rather the mass behind the sensor. I grabbed a few pennies I had lying around and hot-glued them together, creating a mass of coins. I then glued the sensor down as I had initially (around the edges) and glued the mass of coins to the back.

The tone was deeper and louder! Except now it was muffled..

I had read online that you could place the sensors in series or parallel in order to increase their loudness and decrease their impedance respectively. I didn’t really want to unsolder everything and wire them up in series, so I tried in parallel. The configuration is shown in the image below.

The two piezo sensors mounted on the instrument.

The un-massed sensor brought back the high frequency content I had lost with the massed sensor, but maintained the fullness of the sound. After spending hours trying to figure out how to mount the sensors I was happy, even if it looked a bit janky.

Tweaks and Playing the Instrument

With the instrument completed, I could begin playing it again.

After readjusting the height of the springs at the screws so that each could be played without playing the surrounding spring, I realized the center spring sounded pretty bad. It had a lot of off harmonics and a weak fundamental compared to the surrounding two. To fix this I increased its tension by cutting off some of the spring and stretching the remaining further. This improved its tone, though it still isn’t as good as the surrounding two.

The smallest spring had been over stretched and was now deformed. I ordered a few replacements for it (two of higher tension, and two of the same). I ended up using the same spring but cut down a bit. (The original small spring I was using had been cut down more).

Here’s a recording of me playing the instrument. My playing is not really good at all.. I’m still trying to learn how to use the bow and play it well. But it gives an idea. A Strymon Big Sky reverb pedal is used throughout.

Closing Thoughts

The instrument doesn’t sound quite like how I hoped it would, but its close. There are a lot of higher off harmonics that make the tone very nasally and screechy. I’m honestly not sure how these could be fixed other than by improving my technique. Even with that, I believe they may just be a part of the nature of the springs. I would have liked to develop custom pickups for the instrument (I think they would have helped reduce the off harmonics and also made the instrument less sensitive to movement and other non-musical noise), however time and resource constraints didn’t allow me to pursue this.

The instrument is also a bit awkward to play, it’s not quite tall enough to play standing up or sitting easily, but it’s too big to play holding. If I ever made another, I’d figure out the ergonomics better.

Despite of this, I think the instrument was a success. Using springs as the resonating body was a complete experiment- it was an off-the-wall thought I had that I decided to stick with. I had a vague notion of what I wanted (something that sounded eerie, haunting, but also musical) and I went straight to building it. Sure, the tone isn’t quite where I wanted, but I’ve ended up with an instrument that can produce something new, unique, and unheard before. Even if its not the most musical, I think there’s something to be said for that.

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