Camera trick lets you see sound waves in falling water

24hz-water-camera-trick

From this still image you’d think the hose dispensing the water is being moved back and forth. But watch the video after the break and you’ll see the hose is quite steady, as is the standing wave of water. It’s bizarre to be sure. Knowing how it works makes cognitive sense, but doesn’t really diminish the novelty of the demonstration.

This is the second time [Brasspup] has posted a video of this phenomenon. The newest version does a great job of showing several different patterns. But even the first segment from a year ago, which has over 4 million hits, shows the water moving against gravity. We also saw a similar rig in a links post a year ago.

We’d call it an optical illusion but it’s really more of a technological illusion. The water is falling past a sub-woofer speaker which is tuned to 24 Hz. At the same time, the camera filming the demonstration is capturing 24 frames per second. As was mentioned then, it’s much like flashing a light to freeze the water in mid-air. But the flashing of the frames is what causes this effect.

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A folded horn enclosure to make the most out of a subwoofer

To make the most out of his home theater sound system [Baccula] built this folded horn enclosure for as much bass sound as possible. The design was conceived by [Bill Fitzmaurice] who thought there needed to be a better way to use the subwoofers which are typically used in home systems. His design is called the Tuba HT and it is aimed at a 15″ speaker. [Bill] charges for the building plans, but we don’t mind living vicariously through [Baccula's] construction album.

As you can see, there are a lot of wood parts that went into the cabinet. It starts with a base of 2×4 framing. From there the plywood sawdust really starts to fly as each component is produced. During assembly [Baccula] is careful to fully glue each joint — you don’t want to find out that your sub cabinet vibrates after you get everything installed. All together the new piece of living room furniture stands three feet tall and deep and two feet wide.

The album has no captions but you can read a bit more about the project in the Reddit comments.

The weighted companion cube will never threaten to stab you and, in fact, is a subwoofer

From the techPowerUp! forums comes an awesome weighted companion cube subwoofer built by the metonymical user named [Cube].

This build started off as a coffee table that was to have an oval glass top (no word if the edges were going to be blue or orange). The guts of the cube are taken from a 400 Watt sub. As any good sub builder would, [Cube] kept the air volume and port tuning of the donor box.

We’ve seen a companion cube sub before that featured EL wire for a ‘glowing cube’ effect, but [Cube] may have taken things a little too far by including glowing rings on each side of the cube. The rings lit by 2,500 LEDs mounted on pieces of perspex and wired point-to-point. While [Cube] claims he’s ‘not a electronics guru,’ he certainly has a lot of patience to assemble those lights.

Check out [Cube]‘s YouTube build video after the link. Credit to [Todd] for sending this one in.

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Doorway subwoofer

doorway

We’ve seen some crazy speaker builds in the past (massive folded horns for example). [DiscoJones] wanted to build a set of speakers that could reach very low frequencies and be very efficient. Instead of constructing a large box, he built a baffle that could be placed in a doorway and use the blocked off room as an enclosure. It has eight 12inch subwoofers, eight midrange drivers, and four tweeters. The speakers are fairly cheap and he built a simple crossover to help them work a little better together. The goal was always deep bass though, so don’t expect very high fidelity from a setup like this.

iPod loaded horn boosts your tunes

Waveguide IPod dock

The Griffin AirCurve Dock is a nifty gadget that uses a coiled horn to increase the volume of your iPhone’s speaker. Griffin’s marketing claims that their passive device delivers “amazing amplification” and “you’ll swear there are full-sized speakers in there.” Meh. It does look like an interesting project for someone with a 3D printer. You could experiment with different passage and dock shapes. At least it gives us an excuse to post two massive DIY horns.

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Subwoofer makes cornstarch dance


People tend not to think about the non-Newtonian properties of foodstuffs, but we’re glad at least one person did. When it comes to cornstarch, it’s indeterminate viscosity when mixed with water made it the perfect solution for a pretty neat trick: making a liquid move in reaction to a subwoofer. The unique motion can be attributed to the physical properties of the solution: when enough force is applied quickly, it acts as a solid. Otherwise, it flows like a liquid. The erratic bouncing of the sound waves combined with a little tactile manipulation create varying degrees and speeds of applied pressure, which in turn create a mass of flowing shapes that almost appear to be alive.

We’ve covered weird fluids before, but this is perhaps most similar to SnOil, a game that uses ferrofluids to achieve a similar result. SnOil, however, does not depend of vibrations to create shapes in the fluid, it uses small electromagnets and magnetically charges liquid instead. We love the ordered appearance of the SnOil unit, but the chaotic motion of the cornstarch and it’s non-Newtonian properties make it appear almost otherworldly. We wonder how ferrofluids would react in a situation similar to the cornstarch above, since it would respond to both the vibration and the voice coil’s magnetic field.

[via Neatorama]