Build Your Own Anechoic Chamber

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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High-End Headphones Get Flexible Boom Upgrade

It seems a reasonable assumption that anyone who’d be willing to spend a few hundred dollars on a pair of headphones is probably the type of person who has a passion for high quality audio. That, or they work for the government. We’re fairly sure [Daniel Harari] falls into that former category though, given how much thought he gave to adding a decent microphone to his Sennheiser HD650 headphones.

Not happy with the results he got from microphones clipped to his shirt or mounted on a stand, [Daniel] realized what he really wanted was a sensitive boom microphone. This would be close enough to his mouth that it wouldn’t pick up stray noises, but at the same time not obstruct his field of view or otherwise get in the way.

He found a few options on the market which would allow him to mount a boom microphone to his HD650’s, but he didn’t want to stick anything to them and risk scratching the finish so those weren’t really an option. [Daniel] decided to go the DIY route, and eventually settled on a microphone that would mount to the headphone’s existing connector which plugs in at the bottom of the cup.

To make his mount, he 3D printed a two piece clamp that could be screwed together and securely attach to the connector without making any permanent changes. Once he had that base component printed, he salvaged the flexible metallic neck from a cheap USB light and used that to hold the female 3.5mm connector. Into that he’s plugged in a small commercially available microphone that is usually used on voice recorders, which [Daniel] said sounds much better than even the larger mics he had tested.

Finally, he used Sugru to encapsulate the wires and create a flexible strain relief. The whole assembly is very light, easily movable, and perhaps most importantly, didn’t require any modifications or damage to a pair of headphones which have a retail price that could double as a car payment.

It’s been a few years since we’ve seen anyone brave enough to hack their pricey Sennheiser headphones. But in the past we covered a modification which gave them an infusion of Bluetooth and even one that reversed a sneaky manufacturer hardware limitation.

“Yell to Press B” Mod Makes N64 Controller Worse

There’s probably no reason anyone would actually desire a mod like this. Well, no good reason. But [William Osman] had been pondering what it would be like to play some classic games with inputs other than buttons, and decided to make an audio sensor responsible for pressing the B button on an old N64 controller. This “Yell To Press B” mod was also something unique to show his hosts when he visited the YouTube video game aficionados, [Game Grumps].

[William] acknowledges that the build is a bit of a hack job, but the project page does a good job of documenting his build process and covering the kinds of decisions involved in interfacing to a separate piece of hardware. After all, most budding hackers have sooner or later asked themselves “how do I make my gadget press a button on this other thing?” [William] ends up using a small relay to close the connection between the traces for the B button when triggered by a microphone module, but he points out that it should be possible to do a non-destructive version of the mod. Examples exist of reading the N64 controller’s state with an Arduino, which could form the basis of a man-in-the-middle approach of “Yell To Press B” (or anything else) instead of soldering to the button contacts. A video is embedded below, in which you can watch people struggle to cope with the bizarre mod.

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The Hot and Cold of Balanced Audio

A few summers of my misspent youth found me working at an outdoor concert venue on the local crew. The local crew helps the show’s technicians — don’t call them roadies; they hate that — put up the show. You unpack the trucks, put up the lights, fly the sound system, help run the show, and put it all back in the trucks at the end. It was grueling work, but a lot of fun, and I got to meet people with names like “Mister Dog Vomit.”

One of the things I most remember about the load-in process was running the snakes. The snakes are fat bundles of cables, one for audio and one for lighting, that run from the stage to the consoles out in the house. The bigger the snakes, the bigger the show. It always impressed me that the audio snake, something like 50 yards long, was able to carry all those low-level signals without picking up interference from the AC thrumming through the lighting snake running right alongside it, while my stereo at home would pick up hum from the three-foot long RCA cable between the turntable and the preamp.

I asked one of the audio techs about that during one show, and he held up the end of the snake where all the cables break out into separate connectors. The chunky silver plugs clinked together as he gave his two-word answer before going back to patching in the console: “Balanced audio.”

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Juggling Machine Listens to the Bounce to Keep Ball in the Air

It’s a seemingly simple task: bounce a ping-pong ball on a wooden paddle. So simple that almost anyone can pick up a ball and a paddle and make a reasonable job of it. Now, close your eyes and try to do it just by the sound the ball makes when it hits the paddle. That’s a little tougher, but this stepper-driven platform juggler manages it with aplomb.

That’s not to say that the path to the finished product in the video below was a smooth one for [tkuhn]. He went through multiple iterations over the last two years, including a version that surrounded the juggling platform with a fence of phototransistors to track where the ball was at any time. That drove four stepper motors through a cross-linkage that popped the platform up at just the right moment to keep the ball moving, and at just the right angle to nudge it back toward the center of the platform. The current version of the platform does away with the optical sensors in favor of four small microphones. The mics pick up the sharp, well-defined sound of the ball hitting the platform, process the signal through an analog circuit, and use that signal to trigger a flip-flop if the signal exceeds a setpoint. An Arduino then measures the time delay between arriving signals, calculates the ball’s position on the platform, and drives the steppers through a PID loop to issue the corrective bounce.

The video below is entrancing, but we found ourselves wishing for a side view of the action too. It’s an impressive build nonetheless, one that reminds us of the many maze-runner and Stewart platform robots we’ve seen.

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Give the Clapper a Hand

While “The Clapper” probably first conjures images of low-budget commercials, it was still a useful way to remotely switch lights and other things around the house. But if the lights you want to switch weren’t plugged into the wall, like a ceiling fan, for example, The Clapper was not going to help you. To add some functionality to this infamous device, [Robin] built one from scratch that has all the extra features built in that you could ever want.

First, the new Clapper attaches to the light switch directly, favoring mechanical action of the switch itself rather than an electromechanical relay which requires wiring. With this setup, it would be easy to install even if you rent an apartment and can’t do things like rewire outlets and it has the advantage of being able to switch any device, even if it doesn’t plug into the wall. There’s also a built-in microphone to listen for claps, but since it’s open-source you could program it to actuate the switch when it hears any sound. It also includes the ability to be wired in to a home automation system as well.

If the reason you’ve stayed out of the home automation game is that you live in a rental and can’t make the necessary modifications to your home, [Robin]’s Clapper might be just the thing you need to finally automate your living space. All the files are available on the project site, including the 3D printing plans and the project code. Once you get started in home automation, though, there’s a lot more you can do with it.

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Test Ideas Now With Sensors Already In Your Pocket

When project inspiration strikes, we’d love to do some quick tests immediately to investigate feasibility. Sadly we’re usually far from our workbench and its collection of sensor modules. This is especially frustrating when the desired sensor is in the smartphone we’re holding, standing near whatever triggered the inspiration. We could download a compass app, or a bubble level app, or something similar to glimpse sensor activity. But if we’re going to download an app, consider Google’s Science Journal app.

It was designed to be an educational resource, turning a smartphone’s sensor array into a pocket laboratory instrument and notebook for students. Fortunately it will work just as well for makers experimenting with project ideas. The exact list of sensors will depend on the specific iOS/Android device, but we can select a sensor and see its output graphed in real-time. This graph can also be recorded into the journal for later analysis.

Science Journal was recently given a promotional push by the band OK Go, as part of their OK Go Sandbox project encouraging students to explore, experiment, and learn. This is right up the alley for OK Go, who has a track record of making music videos that score high on maker appeal. Fans would enjoy their videos explaining behind-the-scene details in the context of math, science, and music.

An interesting side note. Anyone who’s been to Hackaday Superconference or one of the monthly Hackaday LA meetups will likely recognized the venue used in many of the OK Go Sandbox videos. Many of them were filmed at the Supplyframe Design Lab in Pasadena. It’s also nice to see AnnMarie Thomas (Hackaday Prize Judge from 2016 and 2017) collaborated with OK Go for the Sandbox project.

While the Science Journal app has provisions for add-on external sensors, carrying them around would reduce its handy always-available appeal. Not that we’re against pairing smartphones with clever accessories to boost their sensing capabilities: we love them! From trying to turn a smartphone into a Tricorder, to an inexpensive microscope, to exploring serious medical diagnosis, our pocket computers can do it all.

[via Engadget]