A Mostly 3D Printed Speaker

April 17, 2019 by Lewin Day 2 Comments

The common magnetic loudspeaker is, fundamentally, a fairly simple machine. A static magnetic field is generated by a permanent magnet, and a membrane is mechanically connected to a coil. When a varying electrical current is passed through the coil, this causes the coil to move due to the magnetic field, vibrating the membrane and producing sound. [Mattosx] put this theory into practice with a simple 3D-printed speaker.

It’s not the first 3D-printed speaker we’ve ever seen, but it’s one of the cutest. The main body of the speaker is rectangular, and has a cavity in which three neodymium magnets are placed. The vibrating membrane is then printed separately, including an integrated spindle upon which the coil is wound. The assembly is held together with some socket-head cap screws which complement the pleasantly modern look.

The device does a good job delivering the bleeps when hooked up to an Arduino, and we could see this basic design serving well in all manner of charming 3D-printed builds. Video after the break.

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Create An Aurora Of Your Own

February 2, 2019 by Bryan Cockfield 14 Comments

Throughout our day-to-day experiences, we come across or make use of many scientific principles which we might not be aware of, even if we immediately recognize them when they’re described. One such curiosity is that of caustics, which refers not only to corrosive substances, but can also refer to a behavior of light that can be observed when it passes through transparent objects. Holding up a glass to a light source will produce the effect, for example, and while this is certainly interesting, there are also ways of manipulating these patterns using lasers, which makes an aurora-like effect.

The first part of this project is finding a light source. LEDs proved to be too broad for good resolution, so [Neuromodulator] pulled the lasers out of some DVD drives for point sources. From there, the surface of the water he was using to generate the caustic patterns needed to be agitated, as the patterns don’t form when passing through a smooth surface. For this he used a small speaker and driver circuit which allows precise control of the ripples on the water.

The final part of the project was fixing the lasers to a special lens scavenged from a projector, and hooking everything up to the driver circuit for the lasers. From there, the caustic patterns can be produced and controlled, although [Neuromodulator] notes that the effects that this device has on film are quite different from the way the human eye and brain perceive them in real life. If you’re fascinated by the effect, even through the lens of the camera, there are other light-based art installations that might catch your eye as well.

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Refurbishing A Classic Electrostatic Speaker PSU

December 22, 2018 by Jenny List 8 Comments

Sometimes a project takes longer than it should to land in the Hackaday in-tray, but when we read about it there’s such gold to be found that it’s worth sharing with you our readers despite its slight lack of freshness. So it is with [Andrew Back]’s refurbishment of his Quad electrostatic speaker system power supply, it may have been published back in August but the glimpse it gives us into these legendary audio components is fascinating.

The inner workings of an electrostatic loudspeaker

An electrostatic speaker is in effect a capacitor with a very large surface area, of which one plate is a flexible membrane suspended between two pieces of acoustically transparent mesh that form the other plates. A very high DC bias voltage in the multiple kilovolts region is applied across the capacitor, and the audio is superimposed upon it at a peak-to-peak voltage of somewhere under a kilovolt through a step-up transformer from the audio amplifier. There are some refinements such as that the audio is fed as a push-pull signal to the opposing mesh plates and that there are bass and treble panels with different thickness membranes, but these speakers are otherwise surprisingly simple devices.

The problem with [Andrew]’s speakers became apparent when he took a high voltage probe to them, one speaker delivered 3 kV from its power supply while the other delivered only 1 kV. Each supply took the form of a mains transformer and a voltage multiplier board, so from there it became a case of replacing the aged diodes and capacitors with modern equivalents before applying an insulating layer for safety.

Electrostatic speakers are no stranger to Hackaday, we’ve taken an in-depth look at them in the past. You may also find some of our colleague [Steven Dufresne]’s writing on the matter to be of interest, on measuring high voltages, and his experience wrangling high voltage.

Build Your Own Anechoic Chamber

December 14, 2018 by Bryan Cockfield 16 Comments

For professional-level sound recording, you’ll need professional-level equipment. Microphones and mixing gear are the obvious necessities, as well as a good computer with the right software on it. But once you have those things covered, you’ll also need a place to record. Without a good acoustic space, you’ll have all kinds of reflections and artefacts in your sound recordings, and if you can’t rent a studio you can always build your anechoic chamber.

While it is possible to carpet the walls of a room or randomly glue egg crate foam to your walls, [Tech Ingredients] tests some homemade panels of various shapes, sizes, and materials against commercially available solutions. To do this he uses a special enclosed speaker pointed at the material, and a microphone to measure the sound reflections. The tests show promising results for the homemade acoustic-absorbing panels, at a fraction of the cost of ready-made panels.

From there, we are shown how to make and assemble these panels in order to get the best performance from them. When dealing with acoustics, even the glue used to hold everything together can change the properties of the materials. We also see a few other cost saving methods in construction that can help when building the panels themselves as well. And, while this build focuses on acoustic anechoic chambers, don’t forget that there are anechoic chambers for electromagnetic radiation that use the same principles as well.

Thanks to [jafinch78] for the tip!

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Simulating A Speaker

November 20, 2018 by Al Williams 21 Comments

Speakers are one of those components that are simple to use, but difficult to simulate. Most of us have used a simple resistor to do the job. But a speaker’s response is much more complex, and while that might be enough for a simple simulation the fidelity is nowhere near close. [Sourav Gupta] recently shared his technique for modeling speakers and it looks as though it does a credible job.

[Sourav] shows how a simple resistor and an inductor can do the job, but for better fidelity you need more components to model some mechanical effects. The final model has six components which keeps it easy enough to construct but the problem lies in finding the values of those six components. [Sourav] shows how to use the Thiele-Small parameters to solve that problem. Speaker makers provide these as a guide to low frequency performance, and they capture things such as Q, mass, displacement, and other factors that affect the model.

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A 3D-Printed Egg-Shaped Speaker Cabinet

November 8, 2018 by Jenny List 21 Comments

There are few limits to the extent audiophiles will go in their quest for the perfect sound. This applies in particular to the loudspeaker, and with that aim [Heine Nielsen] has created an eye-catching set of 3D-printed egg-shaped enclosures.

The theory of a loudspeaker enclosure is that it should simulate an infinite space behind an infinite plane in which the speaker driver is mounted, and the reasoning behind spherical or egg-shaped enclosures goes that they better achieve that aim through presenting a uniform inner surface without the corners of a more conventional rectangular enclosure. [Heine]’s enclosures 3D-printed ported enclosures achieve this more easily than traditional methods of building this shape.

A loudspeaker enclosure is more than just a box though, whatever material it is made from must adequately dampen any resonances and absorb as much energy as possible. Conventional speakers try to achieve this by using high-mass and particulate materials, but 3D-printing does not lend itself to this. Instead, he created a significant air gap between two layers which he hopes will create the same effect.

This is an interesting design and approach to speaker cabinet construction, but we think from an audio perspective its one that will be well served by more development. What would be the effect of filling that air gap with something of higher mass, for example, and should the parameters of the egg shape and the port be derived for a particular driver by calculation from its Thiele-Small parameters. We look forward to more on this theme.

These aren’t the first 3D-printed enclosures we’ve seen, but if you’re after something truly unusual how about an electrostatic?

The Diaphragm Is The Coil In These Flexible PCB Speakers

September 21, 2018 by Dan Maloney 10 Comments

Speakers used to be largish electromechanical affairs, with magnets, moving coils, and paper cones all working together to move air around in a pleasing way. They’ve gotten much smaller, of course, small enough to screw directly into your ears or live inside the slimmest of smartphones and still delivery reasonable sound quality. The basic mechanism hasn’t changed much, but that doesn’t mean there aren’t other ways to make transduce electrical signals into acoustic waves.

Take these speakers made from flexible printed circuit boards, for instance. While working on his flexible PCB soft actuators, [Carl Bugeja] noticed that the PWM signals coursing through the coils on the thin PCB material while they were positioned over a magnet made an audible beeping. He decided to capitalize on that and try to make a decent speaker from the PCBs. An early prototype hooked to a simple amplifier showed promise, so he 3D-printed a ring to support the PCB like a diaphragm over a small neodymium magnet. The sound quality was decent, but the volume was low, so [Carl] experimented with a paper cone attached to the PCB to crank it up a bit. That didn’t help much, but common objects acting as resonators seemed to work fairly well. Check out the results in the video below.

This is very much a work in progress, but given [Carl]’s record with PCB creations from robotic fish to stepper motors built right into the PCB, we’d say he’ll make substantial improvements. Follow his and others’ progress in the Musical Instruments Challenge part of the 2018 Hackaday Prize.

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