Know Audio: A Loudspeaker Primer

June 25, 2021 by Jenny List 27 Comments

As we’ve started out on our journey through the world of Hi-Fi audio from a strictly practical and engineering viewpoint without being misled by any audiophile woo, we’ve already taken a look at the most important component in any audio system: the listener’s ear. It’s time to move down the chain to the next link; the loudspeaker.

Sound is pressure waves in the air, and the purpose of a loudspeaker is to move the air to create those waves. There are a variety of “exotic” loudspeaker technologies including piezoelectric and electrostatic designs, here we’ll be considering the garden variety moving-coil speaker. It’s most usually used for the large bass or smaller mid-range drivers in a typical speaker system. Continue reading “Know Audio: A Loudspeaker Primer” →

IPod HiFi Gains New High Notes

June 19, 2021 by Jenny List 1 Comment

The iPod HiFi was a stereo speaker add-on produced by Apple in the mid-2000s for their iPod range, a $300-plus speaker cabinet with twin drivers per channel, an iPod dock, aux, and TOSLINK interfaces. It’s caught the eye of [Jake], in particular one posted on Reddit that had an extra set of tweeters to improve the HiFi’s lackluster treble. The question was that it might have been an Apple prototype, but lacking his own [Jake] set out to replicate it.

The job he’s done is to a high quality. The baffle has first 3D scanned, and then recesses were milled out of it so the tweeters could be press-fit in. He’s driving them through a simple LC crossover circuit taken from the speaker drive, and reports himself happy with the result.

Unfortunately, we still don’t know whether or not the Reddit original was an Apple prototype or not. We’d be inclined to say it isn’t and praise the skills of the modder who put the tweeters in, but in case it might be we’d point to something that could deliver some clues. The iPod HiFi didn’t use a passive crossover, instead it had a DSP and active crossover, driving four class D amplifiers. If you find one with tweeters and they’re driven from the DSP through an extra pair of amplifiers then put it on eBay as a “RARE BARN FIND APPLE PROTOTYPE!” and make a fortune, otherwise simply sit back and enjoy the extra treble a previous owner gave it.

Of course, some people baulked at the price tag of the Apple speaker, and made their own.

Using Ikea Guts To Add Sonos Compatibility To A Vintage Speaker

May 15, 2021 by Jenny List 8 Comments

We’re in a fortunate position when it comes to audio gear, because advances in amplifier and signal processing technology have delivered us budget devices that produce a sound that’s excellent in comparison to those of a few years ago. That said, a decent quality device is good whichever decade it was manufactured in, and a speaker from the 1960s can be coaxed into life and sound excellent with a modern amplifier. It’s something [Sebastius] has explored, as he picked up an attractive-looking set of Swedish speakers from the 1960s. Wanting to bring them into the 21st century, he’s upgraded them for Sonos compatibility by hacking in the guts of an IKEA Symfonisk bookshelf speaker.

The speakers themselves looked good enough, but on closer examination they proved to bear the scars of many decades. After testing new wiring and drivers they still had a good sound to them. Their passive crossover meant that hooking them up to a single amplifier is as straightforward as it was decades ago, but a Symfonisk has an active crossover and two amplifiers. Fortunately there’s a neat hack by which those two amplifiers can be combined as one, and this is what he’s done with the resulting Symfonisk electronic package mounted on the reverse of the speaker.

The fate of the original speaker’s broken mid-range and tweeter drivers was a common enough one back in the day as speakers were ill-matched to amplifiers. Too small an amp would need turning up in volume to get a good sound resulting in distortion that would burn out the top end drivers, while too much power would result in the bass drivers being overloaded and failing. It’s unclear whether the drivers in a vintage speaker would be well-matched to an amplifier such as the Symfonisk, but we’re guessing they are safe while run at sensible volumes. Perhaps of more interest is whatever on-board DSP a Symfonisk contains, because while vintage speakers were designed for as flat a response as possible, modern compact speakers use DSP to equalise the frequency and phase responses of otherwise not-very-good-sounding enclosures. If the Symfonisk does this then those adjustments will appear as distortion in the sound of a different cabinet, but the question remains whether that distortion will be significant enough to be detectable by ear.

If the Symfonisk catches your attention, we’ve covered a teardown of it in the past.

Lamps Double As Secret Surround Sound Speakers

April 28, 2021 by Tom Nardi 23 Comments

Combined with today’s massive flat panel displays, a nice surround sound system can provide an extremely immersive environment for watching movies or gaming. But a stumbling block many run into is speaker placement. The front speakers generally just go on either side of the TV, but finding a spot for the rear speakers that’s both visually and acoustically pleasing can be tricky.

Which is why [Peter Waldraff] decided to take a rather unconventional approach and hide his rear surround sound speakers in a pair of functioning table lamps. This not only looks better than leaving the speakers out, but raises them up off the floor and into a better listening position. The whole thing looks very sleek thanks to some clever wiring, to the point that you’d never suspect they were anything other than ordinary lamps.

The trick here is the wooden box located at the apex of the three copper pipes that make up the body of the lamp. [Peter] mounted rows of LEDs to the sides of the box that can be controlled with a switch on the bottom, which provides light in the absence of a traditional light bulb. The unmodified speaker goes inside the box, and connects to the audio wires that were run up one of the pipes.

In the base, the speaker and power wires are bundled together so it appears to be one cable. Since running the power and audio wires together like this could potentially have resulted in an audible hum, [Peter] only ran 12 VDC up through the lamp to the LEDs and used an external “wall wart” transformer. For convenience, he also put a USB charging port in the center of the base.

When speakers or surround sound systems pass our way, it’s usually because some hacker has either made a set from scratch, or has added some new and improved capabilities to their existing gear. This project may be a bit low-tech compared to some that have graced these pages, but it’s undoubtedly a clever and unexpected solution to the problem, and that’s a hack in our book.

Continue reading “Lamps Double As Secret Surround Sound Speakers” →

Ferrofluid Dances In Custom Bluetooth Speaker

April 21, 2021 by Bryan Cockfield 12 Comments

Ferrofluids, as the name implies, are liquids that respond to magnetic fields. They were originally developed for use by NASA as rocket fuel but are available to the general public now for anyone who wants to enjoy their unique properties. For [Dakd Jung], that meant building a special chamber into a Bluetooth speaker that causes the ferrofluid inside to dance along with the rhythm of the music.

This project isn’t quite as simple as pushing the ferrofluid container against a speaker, though. A special electromagnetic device similar to a speaker was used specifically to manipulate the fluid, using a MSGEQ7 equalizer to provide the device with only a specific range of frequencies best tailored for the fluid’s movement. The project includes two speakers for playing the actual music that point upward, and everything is housed inside of a 3D-printed case. There were some additional hurdles to overcome as well, like learning that the glass needed a special treatment to keep the ferrofluid from sticking to it.

All in all it’s a unique project that not only brings sound to a room but a pleasing physical visualization as well. Being able to listen to music or podcasts on a portable speaker, rather than the tinny internal speakers of a phone or laptop, is the sort of thing you think you can live without until you get used to having higher quality sound easily and in every place you go. And, if there’s a way to improve on that small but crucial foundation with something like a dancing ferrofluid that moves with the music the speaker is playing, then we’re going to embrace that as well.

Speaker Is Fully 3D Printed

March 25, 2021 by Al Williams 11 Comments

[Thomas] is always up to some kind of 3D printing project. His latest? A fully 3D printed speaker. This is possible because of designs by [Paul Ellis] that use 3D printed materials for nearly all parts of the speaker. You can see and hear the speaker in the video below.

You might expect different parts of the speaker use different filaments. There are also different techniques such as the use of single-wall printing that makes the speaker possible.

Continue reading “Speaker Is Fully 3D Printed” →

A Hi-Fi Speaker From Some Foil And Magnets

March 22, 2021 by Stephen Ogier 44 Comments

In the world of speakers, mass is the enemy of high frequency response. In order to get the crispest highs, some audiophiles swear by speakers in which the moving element is just a thin ribbon of metal foil. As the first step towards building a set of ribbon headphones, [JGJMatt] has designed a compact ribbon speaker made from aluminum foil.

A 3D-printed body holds six permanent magnets, which produce the static magnetic field necessary for the speaker to work. The sound itself is produced by a corrugated aluminum diaphragm made by taking a strip of foil and creasing it with a gear. Aluminum is difficult to solder, so electrical contact is made with a couple of short segments of copper tape. A little Blu Tack and glue hold it all together, and the result is stunning in its simplicity.

Check out the video after the break to hear how it sounds. If you want to try this yourself, it’s important to remember that ribbon speakers have very low input impedances (0.1 Ω for this design), so in order to prevent damage to your amplifier, a transformer or series resistor must be used to bring the impedance up to the 4-8 Ω your amplifier expects.

[JGJMatt] is no newcomer to exotic speaker technology—check out these thin distributed-mode loudspeakers they made! If you’re more interested in recording music than playing it, you might want to read about how a metal ribbon suspended in a magnetic field is used to make incredible microphones. Shout out to [Itay] for the tip. Continue reading “A Hi-Fi Speaker From Some Foil And Magnets” →