Salvaging Audio Amplifiers From Vintage Volvos

The common automotive scrap yard is a land of plenty for the enterprising hacker., where many items that would be prohibitively expensive elsewhere can often be had for a song. This isn’t just limited to strictly automotive parts either, as the modern vehicle is full of all kinds of hardware. [Nikita] managed to salvage a pair of audio amplifiers from an old Volvo, and put them to good use. It’s a great idea if you’re looking for cheap audio hardware!

The amplifiers are from a Volvo 760 made in 1984. There’s one rated at 40 watts per channel, and a smaller device rated at 25 watts per channel – likely to drive the front and rear speakers from separate amps. The amplifiers take 12 volts nominally, as one would expect. After some initial testing with a car battery and unsticking old relays, things began to crackle into life.

With the hardware now functioning, it was simply a case of bolting the amplifiers into a frame, hooking them up to a converted ATX power supply, and wiring up some connectors for speakers and audio input. With a few bits and pieces invested, [Nikita] now has a good quality amplifier to run audio in the workshop.

There’s plenty of useful hardware you can score down at the wreckers, and we see these parts used in hacks all the time – from peculiar milling machines to automated watering systems.

Quiet Your Car The Cheap And Effective Way

If you’ve been on the Earth for a couple of decades or more, or have just grown up riding around in some older metal, you’d know that cars can be incredibly noisy. If you’re unfamiliar, buy yourself a nice car like a 2000 Honda Civic, strip out all the carpet and interior panels, and go for a drive. Huge amounts of research and development have gone into making modern cars as quiet and comfortable as possible. Through the correct use of sound deadening materials and techniques, a car can be made much quieter and audio quality from the sound system can be improved too. [camerajack21] decided to get to work on their Volkswagen to see what could be done.

The project in question pays special attention to the door panels. These are where the primary speakers are housed, and there were issues with rattles if the speakers were allowed to operate at frequencies below 100 Hz. Weather stripping, foam, and improved fasteners were pressed into service to reduce this issue.

Think of a musical bell. If you touch a small part of the bell with just your finger, it no longer can ring true. You don’t need to wrap your entire hand around a bell to keep it from ringing. Your finger is not absorbing sound, just preventing the bell from ringing.

Focus then moved to the body panels. Special sound deadening material (in this case, Silent Coat brand) was then applied to the insides of the doors and trunk to bring the sound level down. The key to effective application of such materials is not to waste money covering entire panels – the Reddit comments are particularly enlightening here. It only takes a small amount of material to stop a panel from vibrating, with most testing suggesting anymore than 30% coverage of a panel brings diminishing returns.

With your car’s sound environment tidily improved, you might be looking for ways to improve your sound system. There’s plenty of ways to go about it – you can even use guitar effects.

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.

Continue reading “A Retro Car Stereo With Arduino Inside”

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.