Putting 3D Printed Speaker Drivers To The Test

September 7, 2019 by Tom Nardi 15 Comments

Over the years, we’ve seen numerous projects that attempted to 3D print speaker enclosures that deliver not only a bit of custom flair, but hopefully halfway decent sound. Though as you’d probably expect, the drivers themselves are always standard run-of-the mill hardware mounted into the plastic enclosure. But given the research being conducted by [Paul Ellis], that might not be a safe assumption for much longer.

His quest to develop a full-range 3D speaker has taken him through several design revisions over the last two years, with each one being put through testing procedure that compared its frequency response to “real” speakers from manufacturers like Dayton and Bose. The project is very much ongoing, but a recently completed iteration of the driver design managed to exceed 80 dB at 1 W. In terms of audio quality, [Paul] reports they can hold their own against commercially available drivers. You can hear for yourself in the video after the break.

Ultimately, he hopes to be able to sell his 3D printed speakers in kit form to anyone who’s looking for the last word in bespoke audio hardware. The idea being that the drivers and enclosure will be completely modular, allowing the user to swap out individual components for ones printed (or not) in different materials so they can tune the in-person sound to their exact specifications. To facilitate this rapid reconfiguring of the drivers, the designs use some neat tricks like having the magnets be removable rather than glued in so they could be swapped out non-destructively.

This isn’t the first fully 3D printed speaker driver we’ve ever seen, Formlabs showed one off that was made on their SLA printer back in 2015, and we actually saw a rudimentary take on the same idea earlier this year. But the work that [Paul] has done here is certainly the most thorough, and dare we say practical, take we’ve ever seen on the concept.

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Candy-Colored Synth Sounds Sweet

August 26, 2019 by Kristina Panos 14 Comments

Let’s face it, synthesizers are awesome. But commercial synths are pretty expensive. Even the little toy ones like the KORG Volca and the MicroKORG will run you a few hundred bucks. For the most part, they’re worth the price because they’re packed with features. This is great for experienced synth wizards, but can be intimidating to those who just want to make some bleeps and bloops.

[Kenneth] caught the mini-synth bug, but can’t afford to catch ’em all. After a visit to the Moog factory, he was inspired to engineer his own box based on the Moog Sirin. The result is KELPIE, an extremely portable and capable synth with 12 voices, 16 knobs, and 4 LED buttons. KELPIE is plug and play—power and a MIDI device, like a keyboard, are the only requirements. It has both 1/8″ and 1/4″ jacks in addition to a standard MIDI DIN connection. [Kenneth] rolled his own board based on the Teensy 3.2 chip and the Teensy audio shield.

Part of the reason Kenneth built this synthesizer is to practice designing a product from the ground up. Throughout the process, he has tried to keep both the production line and the DIYer in mind: the prototype is a two-part resin print, but the design could also be injection molded.

We love that KELPIE takes its visual design cues from the translucent candy-colored Game Boys of the late 90s. (We had the purple one, but always lusted after the see-through kind.) Can we talk about those knobs? Those are resin-printed, too. To color the indicators, [Kenneth] used the crayon technique, which amounts to dripping molten crayon into the groove and scraping it off once hardened. Don’t delay; glide past the break to watch a demo.

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When Toothbrushes, Typewriters, And Credit Card Machines Form A Band

August 23, 2019 by Roger Cheng 5 Comments

Many everyday objects make some noise as a side effect of their day job, so some of us would hack them into music instruments that can play a song or two. It’s fun, but it’s been done. YouTube channel [Device Orchestra] goes far beyond a device buzzing out a tune – they are full fledged singing (and dancing!) performers. Watch their cover of Take on Me embedded after the break, and if you liked it head over to the channel for more.

The buzz of a stepper motor, easily commanded for varying speeds, is the easiest entry point into this world of mechanical music. They used to be quite common in computer equipment such as floppy drives, hard drives, and flatbed scanners. As those pieces of equipment become outdated and sold for cheap, it became feasible to assemble a large number of them with the Floppotron being something of a high-water mark.

After one of our more recent mentions in this area, when the mechanical sound of a floppy drive is used in the score of a motion picture, there were definite signs of fatigue in the feedback. “We’re ready for something new” so here we are without any computer peripherals! [Device Orchestra] features percussion by typewriters, vocals by toothbrushes, and choreography by credit card machines with the help of kitchen utensils. Coordinating them all is an impressive pile of wires acting as stage manager.

We love to see creativity with affordable everyday objects like this. But we also see the same concept done with equipment on the opposite end of the price spectrum such as a soothing performance of Bach using the coils of a MRI machine.

[Thanks @Bornach1 for the tip]

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MIDI Controller In A Concertina Looks Sea Shanty-Ready

August 18, 2019 by Dan Maloney 5 Comments

Did you know that the English concertina, that hand-pumped bellows instrument favored by sailors both legitimate and piratical in the Age of Sail, was invented by none other than [Sir Charles Wheatstone]? We didn’t, but [Dave Ehnebuske] knew that the venerable English gentleman was tickling the keys of his instrument nearly two decades before experimenting with the bridge circuit that would bear his name.

This, however, is not the reason [Dave] built a MIDI controller in the form of an English concertina. That has more to do with the fact that he already knows how to play one, they’re relatively easy to build, and it’s a great form factor for a MIDI controller. A real concertina has a series of reeds that vibrate as air from the hand bellows is directed over them by valves controlled by a forest of keys. [Dave]’s controller apes that form, with two wind boxes made from laser-cut plywood connected by a bellows made from cardboard, Tyvek, and nylon fabric. The keys are non-clicky Cherry MX-types that are scanned by a Bluefeather microcontroller. To provide some control over expression, [Dave] included a pressure sensor, which alters the volume of the notes played depending on how hard he pushes the bellows. The controller talks MIDI over Bluetooth, and you can hear it in action below.

We’ve seen MIDI controllers in just about everything, from a pair of skate shoes to a fidget spinner. But this is the first time we’ve seen one done up like this. Great job, [Dave]!

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MIDI Harp Looks Pretty Sharp

August 17, 2019 by Kristina Panos 9 Comments

[Julien] is one of those cool dads who shows his love with time invested rather than money spent. His daughter plays the harp, and you would not believe the price of concert harps. Even the cheap ones are several thousand USD. So naturally, he decided he would build her a MIDI concert harp from the ground up.

This plucky work in progress uses a strain gauge and an AD620 amplifier on every string to detect the tension when plucked. These amplifiers are connected to Arduinos, with an Arduino every nine strings. The Arduinos send MIDI events via USB to a Raspberry Pi, which is running the open synth platform Zynthian along with Pianoteq.

The harp is strung with guitar strings painted with silver, because he wanted capacitive touch support as well. But he scrapped that plan due to speed and reliability issues. Strain past the break to check out a brief demo video.

[Julien] used strings because he wanted to anchor the harpist in tactility. But you’re right; many if not most MIDI harps use lasers.

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Latex Bellows From Scratch

August 12, 2019 by Brian McEvoy 17 Comments

You would be forgiven for thinking that the semi-spherical bulb [Len], from the Bellowphone channel, is holding is a toilet bowl float. It is a bellows of his design that is similar to the squeezable part of a bike horn but is more substantial and less irritating at six in the morning. These rubber squeeze balls are old-school in the best way, and craftsmanship rolls out from every second of his videos. The backdrops to [Len’s] videos are alive with tools, materials, examples, and instruments the same way our offices and maker spaces erupt with soldering irons, LEDs, and passives.

His video walks through all the steps to make latex bellows starting with a rigid stemmed bulb and painting it with latex. This takes a bunch of coats with the associated drying time, so if you need a lot of bellows, you will want multiple bulbs. After coating of latex, we move to the contraption known as the Snout Master 5000. The SM5K looks like a wooden jig held in a table vise, but it is a purpose-built over-engineered chuck with four ball bearings held in a vise. When the latex is thick enough, the form is removed, and the bulb is repaired, then, more coats. Each ball has roughly twenty layers, and with three hours between coats, this is a weekend job at a minimum. Good things come to those who coat. The final steps are boiling the bulbs and adding a silicone preservative. They can last up to a decade with proper maintenance.

We see lots of electronic and automated instruments here, and spherical balls are definitely on the human interface spectrum, but the techniques we see from [Len] would allow anyone to design their own bellows more conducive to mechanization. [Len] says one of his inspiration is [Harry Partch] and his Blo-Boy, an organ powered by fireplace bellows. We think these squeeze balls are even better.

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Acoustic Lenses Show Sound Can Be Focused Like Light

August 10, 2019 by Donald Papp 30 Comments

Acoustic lenses are remarkable devices that just got cooler. A recent presentation at SIGGRAPH 2019 showed that with the help of 3D printing, it is possible to build the acoustic equivalent of optical devices. That is to say, configurations that redirect or focus sound waves. One fascinating demonstration worked like an acoustic prism, able to send different notes from a simple melody in different directions. Another was a device that dynamically varied the distance between two lenses in order to focus sound onto a moving target. In both cases, the sounds originate from an ordinary speaker and are shaped by passing through the acoustic lens or lenses, which are entirely passive devices.

Researchers from the University of Sussex used 3D printing for a modular approach to acoustic lens design. 16 different pre-printed “bricks” (shown here) can be assembled in various combinations to get different results. There are limitations, however. The demonstration lenses only work in a narrow bandwidth, meaning that the sound they work with is limited to about an octave at best. That’s enough for a simple melody, but not nearly enough to cover a human’s full audible range. Download the PDF for a quick read about the details, it’s only two pages but loaded with enough to whet your appetite to know more.