A Retro Car Stereo With Arduino Inside

For some car enthusiasts whose passions run towards older vehicles, only originality will do. [RetroJDM] for instance has an RA28 Toyota Celica from the mid 1970s for which he has gone to great lengths to source a pristine center console to replace a damaged original.

There is only one problem with the center console on a 1970s Toyota, it doesn’t have a DIN cut-out for the standard-sized car radios that have become universal in the decades since its manufacture. Instead it has a cut-out for a Toyota-specific radio in the old style with holes for volume and tuning knobs to either side of a protruding center unit that would have contained a tuning dial and a slot for cassettes or maybe 8-track cartridges.

His solution is an interesting one, he’s put together his own car stereo in an enclosure suitable for the Toyota cut-out. Inside the radio there is an Arduino Mega controlling the breakout boards for an Si4703 FM tuner and a VMusic3 MP3/USB music player, and a PT2314 audio processor. For display there is a set of retro LED seven-segment modules, and an MSGEQ7 spectrum analyser. The result is a modern radio with FM, line-input, and MP3 player, with all the functions you’d expect. There is no onboard amplifier though, but this function is fulfilled by an external unit.

The finished unit is topped off with a very professional front panel, which you can see in his demo video below the break.

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Better Car Audio With Guitar Effects

Automotive sound is a huge deal; for many people, it’s the place to listen to music. Back in the 80s, you were lucky to get anything more than two door speakers in the front of the car. Fast forward to today, and you can expect a 10-speaker system in an up-spec’d family sedan.

[Josh] has a car, and wanted to improve the sound. In particular, the aim was to improve the sense of space felt when listening. A car is a relatively small space, and the driver sits in close proximity to the front speakers, so it’s difficult to get a good soundstage.

[Josh]’s approach was to create a “surround” effect for the car stereo, by feeding a left/right difference signal to the rear speakers. This was achieved by the use of a series of op-amps that buffer and then generate a mono signal that represents the difference between the left and right channel. For optimum results, [Josh] wanted to delay the signal being sent to the rear speakers, with a longer delay making the soundstage feel bigger, as if reflections are coming from farther away in a bigger room. To do this, [Josh] simply hooked up the signal to a Boss DD-3 Digital Delay guitar pedal – an off-the-shelf solution to an otherwise sticky problem. The DD-3 gives [Josh] a variable delay time with reasonably high fidelity, so it’s a perfect way to get the project done quickly.

The final piece of the puzzle is a filter. The difference signal doesn’t actually sound all that pleasant to the ears by itself, especially when it comes to transient high-pitched sounds like cymbals, so a lowpass filter is implemented to cut these higher frequencies down.

[Josh] made everything adjustable, from the filter to the delay, so it’s simple to dial things in until they’re just right, rather than relying on calculation or guesswork. The general idea is to feed the difference signal into the rear speakers at a low enough volume and with a subtle delay so that it adds to a general feeling of being in a larger room with the sound coming from all around, as opposed to listening to very loud point sources of audio.

It’s a cool project that we imagine would be very satisfying to dial in and enjoy on the road. What’s more, it’s a fairly straightforward build if you want to experiment with it yourself on your own car. Perhaps your problem is that you need an auxiliary input to your head unit, though – in that case, check out this Subaru project.

Upgrading a Rockford Fosgate Punch 601s to an 801s with just a handful of parts

[Simon] had a Rockford Fosgate Punch 601s amplifier in his car, and while it was a great piece of equipment, he wanted a little more power behind his stereo system. It turns out that with just a handful of parts and a bit of soldering work, he was able to increase his amplifier’s output by 200 watts, putting it on par with a Punch 801s.

The main board in each amp is laid out identically, making the conversion a relatively easy process. A handful of MOSFETs need to be added, along with some resistors and capacitors. Most of the work can be done with a decent soldering iron, though you might want a hot air reflow station to handle the smaller resistors – it all depends on your skill set.

We’re really not sure how big the price difference is between the two amps, but we’re pretty certain that the conversion would be worth it. [Simon] sells conversion kits on his web site for under $60, but you may be able to find the parts for a bit less if you hunt around.

The Rube-Goldberg of car audio

[Anthony Pray] had his car stereo stolen. When thinking about replacing it he realized the he and his wife never used it for anything other than an Auxiliary connection to play songs from their cellphones. So instead of buying a head unit he pulled an unused home audio amplifier out of a dark corner of his house and wired it to the car speakers. Problem solved, except that the under-dash installation meant the only volume control is on the phone playing the audio. He decided to build a wireless audio controller that would let him send commands to the phone without quite as much distraction from the road.

The device you see above is his creation. What a beauty. But seriously, it’s so random and hacked together how can you not love it? And, it works!

The frame is made from plastic coat hangers, and the wheel is an old RC control knob. There’s even a play/pause feature built from the clicking properties of a retractable ball-point pen. A Cypress PSoC board reads the knob and pen positions, then pushes commands via a Bluetooth module in order to control the phone. He recorded a testing video (after the break) which gives you a better look at the functionality of this setup. Continue reading “The Rube-Goldberg of car audio”

2005 Subaru aux-in hacking

2005_subaru_outback_aux_in

The CD player in [mukmuk’s] 2005 Subaru Outback gave up the ghost, and faced with a long road trip ahead of him, he was desperate to find a way to listen to something other than static-filled radio. He considered a 3rd party auxiliary input solution, but after seeing a similar aux-in hack here, he figured he could give it a go himself.

The stereo head unit design was changed between the 2004 and 2005 model years, so while he had a good idea of what to look for, he had to find the proper components on his own. Once he identified the radio module, he was able to locate the left an right input pins through trial and error. He carefully soldered a 3.5” audio jack to the head unit’s input lines, wiring it to cut off the audio signal from the radio whenever his Zune was plugged in.

Everything was reassembled, and the input jack was inconspicuously mounted in a cubby hole just above the stereo. [mukmuk] is quite happy with his modification, and we’re guessing his road trip was far more pleasurable as a result of his work.

Aux-in Hacking an ’04 Subaru Radio

[Jordan] writes in to show us his hacked up car stereo. [Jordan]’s 2004 Subaru, like many of our cars, does not offer any kind of auxiliary input, and aux-in/mp3 adapters tend to run on the not so cheap side of the price scale. Even a replacement head unit was too rich for his blood. So it was time to wire something to the old head unit.

On inspecting the radio’s PCB [Jordan] managed to locate the traces that carry audio from the FM receiver to the stereo’s amplifier.  Most aux input hacks we have seen involve fooling the stereo into thinking some media is inserted, even if interfacing with the audio lines on the PCB. These require that the tape/CD functionality be altered, perhaps permanently. Even worse you may have to shlep around a blank CDR with a bunch of tracks on it! All just to fool the stereo into enabling audio output.

Instead [Jordan] targets the audio lines from the FM stereo, since radio is always enabled when active. Once the audio traces are located they are severed  and bypassed with a 1/8″ stereo plug. This setup allows the FM audio signal to pass through the connector when disconnected, and cuts off any radio audio once your mp3 player is. We have seen this same method used on a vintage stereo hack as well. Nice work!

Hacking the MINI Cooper

cooper_power

[war6763] sent us this hack to power an amplifier in a MINI Cooper. Apparently, aside from being unconventionally handsome, they’re also unconventionally wired. Amplifiers are generally wired to the ignition or stereo and turned on when the car is turned on. Due to some strange wiring, this just isn’t possible in the MINI Cooper. Some people use the cigarette lighter to power on their amplifier, but [war6763] wanted something that left his cigarette lighter free for other things. He built a circuit that monitors the cars built in USB input line and turns his amp on and off accordingly. The entire unit cost around $10.00. You can see the video demonstration after the break.

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