Heathkit Tuner Saved From Junk Pile

April 4, 2026 by Al Williams 4 Comments

We miss the old Heathkit. You could build equipment that rivaled or even surpassed commercial devices. The cost was usually reasonable and, even if you could get by with less, the satisfaction of using gear you built yourself was worth a lot. Not to mention the knowledge you’d gain and your confidence in troubleshooting should the need arise. So we were jealous of [RCD66] when he found a Heathkit AJ-43C stereo tuner in the recycle bin.

As you can see in the video below, it needed a lot of love to get back to its former self. The device dates from around 1965, when the kit cost $130. In 1965, that was a lot of money. Back then, that would have bought you about four ounces of gold and would have been a great down payment on a $1,500 VW bug.

Things were a bit of a mess, so he removed all the parts and replaced most of them. Unsurprisingly, the electrolytic capacitors all tested bad. The transistors were all germanium, but if they tested good, his plan was to reuse them. There were several PCBs inside, and he made some changes, such as replacing the zener diode power supply with something more modern.

How did it sound? Watch the video and see for yourself. We usually like troubleshooting specific problems on gear like this, but in this case, it was probably smart to just do a total rework.

Heathkit had quite an origin story. This isn’t the first time we’ve seen someone strip and rebuild a Heathkit.

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ESPer-CDP Plays CDs And Streams In Style

May 31, 2025 by Tyler August 12 Comments

What do you get when you combine an ESP32, a 16-bit DAC, an antique VFD, and an IDE CD-ROM drive? Not much, unless you put in the work, which [Akasaka Ryuunosuke] did to create ESPer-CDP, a modern addition for your hi-fi rack.

It plays CDs (of course), but also can also scrobb the disks to Last.fm, automatically fetch track names and lyrics for CDs, and of course stream internet radio. It even acts as a Bluetooth speaker, because when you have an ESP32 and a DAC, why not? Of course we cannot help but award extra style points for the use of a VFD, a salvaged Futaba GP1232A02. There’s just something about VFDs and stereo equipment that makes them go together like milk and cookies.

close up of front of machine showing VFD. — Between the panel and the VFD, this could almost pass as vintage Sony.

In terms of CD access, it looks like the IDE interface is being used to issue ATAPI commands to the CD-ROM drive to get audio out via S/PDIF. (Do you remember when you had to hook your CD drive to your sound card to play music CDs?) This goes through a now-discontinued WM8805 receiver — a sign this project has been in the works for a while — that translates S/PDIF into an I2S stream the ESP32 can easily work with.

Work with it it does, with the aforementioned scrobbing, along with track ID and time-sinked lyrics via CDDB or MusicBrainz. The ESP32 should have the computing power to pull data through the IDE bus and decode it, but we have to admit that this hack gets the job done — albeit at the expense of losing the ability to read data CDs, like MP3 or MIDI. [Akasaka Ryuunosuk] has plans to include such functionality into v2, along with the ability to use a more modern SATA CD-ROM drive. We look forward to seeing it, especially if it keeps the VFD and classic styling. It just needs to be paired with a classic amplifier, and maybe a DIY turntable to top off the stack.

Thanks to [Akasaka Ryuunosuke] for the tip. If you also crave our eternal gratitude (which is worth its weight in gold, don’t forget), drop us a tip of your own. We’d love to hear from you.

Trashed Sound System Lives To Rock Another Day

May 22, 2025 by Bryan Cockfield 6 Comments

Plenty of consumer goods, from passenger vehicles to toys to electronics, get tossed out prematurely for all kinds of reasons. Repairable damage, market trends, planned obsolescence, and bad design can all lead to an early sunset on something that might still have some useful life in it. This was certainly the case for a sound system that [Bill] found — despite a set of good speakers, the poor design of the hardware combined with some damage was enough for the owner to toss it. But [Bill] took up the challenge to get it back in working order again.

The main problem with this unit is that of design. It relies on a remote control to turn it on and operate everything, and if that breaks or is lost, the entire unit won’t even power on. Tracing the remote back to the control board reveals a 15-pin connector, and some other audio sleuths online have a few ways of using this port to control the system without the remote.

[Bill] found a few mistakes that needed to be corrected, and was eventually able to get an ESP8266 (and eventually an ESP32) to control the unit thanks largely to the fact that it communicates using a slightly modified I2C protocol.

There were a few pieces of physical damage to correct, too. First, the AC power cable had been cut off which was simple enough to replace, but [Bill] also found that a power connector inside the unit was loose as well. With that taken care of he has a perfectly functional and remarkably inexpensive sound system ready for movies or music. There are some other options available for getting a set of speakers blasting tunes again as well, like building the amplifier for them from scratch from the get-go.

An image showing an original grey and blue Sony Walkman with the text "1970" below it, and an arrow pointing to the right of it at a much smaller blue Walkman with the text "2000" underneath it, and a final arrow pointing to the right to a bright orange cassette player by We Are Rewind in a man's hand with the text "now" beneath it.

Why Are Cassette And CD Players So Big Now?

March 1, 2025 by Navarre Bartz 65 Comments

The early 2000s were the halcyon days of physical media. While not as svelte as MP3 players became, why are those early 2000s machines smaller than all the new models popping up amidst the retro audio craze?

We’ve bemoaned the end of the electromechanical era before, and the Verge recently interviewed the people at We Are Rewind and Filo to get the skinny on just why these newer cassette and CD players aren’t as small as their predecessors. It turns out that all currently produced cassette players use the same mechanism with some small tweaks in materials (like metal flywheels in these higher quality models) because the engineering required to design a smaller and better sounding alternative isn’t warranted by the niche nature of the cassette resurgence.

A similar fate has befallen the laser head of CD mechanisms, which is why we don’t have those smooth, rounded players anymore. Economies of scale in the early 2000s mean that even a cheap player from that era can outperform a lot of the newer ones, although you won’t have newer features like Bluetooth to scandalize your audiophile friends. A new Minidisc player is certainly out of the question, although production of discs only ended this February.

If you’re looking to get back into cassettes, this masterclass is a good place to start. If you don’t fancy any of the players the Verge looked at, how about rolling your own incarnation with the guts from a vintage machine or just going for the aesthetic if cassettes aren’t your jam?

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Parametric Design Process Produces Unique Speakers

February 17, 2025 by Bryan Cockfield 28 Comments

When building one-off projects, it’s common to draw up a plan on a sheet of paper or in CAD, or even wing it and hope for the best outcome without any formal plans. Each of these design philosophies has its ups and downs but both tend to be rigid, offering little flexibility as the project progresses. To solve this, designers often turn to parametric design where changes to any part of the design are automatically reflected throughout the rest, offering far greater flexibility while still maintaining an overall plan. [Cal Bryant] used this parametric method to devise a new set of speakers for an office, with excellent results.

The bulk of the speakers were designed with OpenSCAD, with the parametric design allowing for easy adjustments to accommodate different drivers and enclosure volumes. A number of the panels of the speakers are curved as well, which is more difficult with traditional speaker materials like MDF but much easier with this 3D printed design. There were a few hiccups along the way though; while the plastic used here is much denser than MDF, the amount of infill needed to be experimented with to achieve a good finish. The parametric design paid off here as well as the original didn’t fit exactly within the print bed, so without having to split up the print the speakers’ shape was slightly tweaked instead. In the end he has a finished set of speakers that look and sound like a high-end product.

There are a few other perks to a parametric design like this as well. [Cal] can take his design for smaller desk-based speakers and tweak a few dimensions and get a model designed to stand up on the floor instead. It’s a design process that adds a lot of options and although it takes a bit more up-front effort it can be worth it while prototyping or even for producing different products quickly. If you want to make something much larger than the print bed and slightly changing the design won’t cut it, [Cal] recently showed us how to easily print huge objects like arcade cabinets with fairly standard sized 3D printers.

Cassette Tape Plays MP3s

January 6, 2025 by Bryan Cockfield 66 Comments

Cassette tapes were a major way of listening to (and recording) music througout the 1980s and 1990s and were in every hi-fi stereo, boom box, and passenger vehicle of the era. Their decline was largely as a result of improvements in CD technology and the rise of the MP3 player, and as a result we live in a world largely absent of this once-ubiquitous technology. There are still a few places where these devices crop up, and thanks to some modern technology their capabilities as a music playback device can be greatly enhanced.

The build starts, as one might expect, by disassembling the cassette and removing the magnetic tape from the plastic casing. With the interior of the cassette empty it’s capable of holding a small battery, USB-C battery charger, and a Bluetooth module. The head of an old tape deck can be wired to the audio output of the Bluetooth module and then put back in place in the housing in place of the old tape. With the cassette casing reassembled, there’s nothing left to do but pair it to a smartphone or other music-playing device and push play on the nearest tape deck.

As smartphones continue to lose their 3.5 mm headphone jacks, builds like this can keep lots of older stereos relevant and usable again, including for those of us still driving older vehicles that have functioning tape decks. Of course, if you’re driving a classic antique auto with a tape technology even older than the compact cassette, there are still a few Bluetooth-enabled options for you as well.

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Weird Old Stereo Accessories

May 26, 2024 by Al Williams 25 Comments

Some people trick out their cars. Some, their computers. There are even people who max out their audio systems, although back in 1979, there was more of that going on, probably, than today where you discresionary income is split so many ways. Case in point: [Alan Cross] remembers how excited he was to get the Radio Shack catalog that year. He was working at a grocery store, saved his money, and — over time — picked up a haul ranging from an equalizer to a strobe light.

Who didn’t need a power meter or a “light organ?” These gadgets seem cheap until you realize it was 1979 and [Alan] was a student working at a grocery store. He points out that the $20 power meter is about the same as $80 today.

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