James C. Liu's Weblog

Tuesday February 10, 2009

DIY MP3 car stereo for just $49

With the 2008 election over, my venerable car cassette deck in my old beater Toyota P/U was relegated back to playing music instead of listening to talk-radio. The only problem being that in the past couple of years, the old LED display has pretty much died so I can't tell actually what radio station I'm tuned to. And to make matters worse, recently, I wanted to clean the engine and maintain my battery (like how retro is that? maintaining a battery? - you know the truck is old). So I disconnected the battery terminals and took it out, then hosed down my engine compartment.

Cleaning My Engine compartment

For those of you who bother to clean the dirt, dust and grime off your engines, you probably do what I do. That's to spray a light coat of mild degreaser around on a warm engine (not hot engine - so you don't crack any thing that might crack due to sudden temperature differentials). Wait a few minutes and then spray water gently over the engine to remove the dirt. Some folks will then spray a thin coat of water displacement compound or anti-corrosion spray like Corrosion-X or something and then wipe off the excess. I like doing this with a warm engine because the mild heat aids evapouration. The result is usually a clean engine to work with that looks new and well maintained. If you're wondering if I do both the top and bottom, the answer is yes. But underneath the car usually requires full strength degreaser and removal of some plastic splash guards.

Cleaning My Car Battery

As for the battery, I take a cloth, spray a bit of lubricant on the cloth, and wipe the battery surface down, clean the terminals, and replace worn felt washers at the base of the terminals with some vinyl rubber gasket material. I buy bulk soft garden hose washers and stretch them to fit over the battery terminals and find they work great and last a long time. My factory battery has a small coloured bubble. Red is bad, Blue/Green is good, and clear means needs to be charged. It's quite old. But still starts the car and holds a decent charge and the bubble is still blue/green. But I think it's around 7 years old now and I don't know why I replaced it with a factory battery, when I could have gotten a one for 1/2 the price from Costco. The battery is maintenance free, but I do get some corrosion and white deposits on it over time, and leaves and other bugs end up in the tray below, as well as water when I drive in rainy weather. So getting it all clean feels good for the car, even if it's all cosmetic and has no functional value.

Car Stereo Memory and Power

The problem I forgot by doing all this service on the engine and battery was that the car radio loses its memory. Typically, most car stereos require at least 2 power leads. One comes from the line that has an ignition key activation and is the main power. There's usually a 12 - 15 amp fuse in-line on that wire. There's also a direct line to the battery that has a 3 amp fuse for am/fm station memory and possibly a power eject for the cassette deck. Many new car radios add a 3rd power line that gets power from head-light activation/dash dimmer. This powers the face-plate lights and LEDs when the headlights or parking lights are on and allows the dimmer dial/knob on the dash to adjust the face plate brightness. Needless to say, without power, my truck stereo lost memory and without LEDs functioning on the front, I had no clue how to set time or station pre-sets, not that I would be able to tell unless I actually listened to the broadcast long enough to confirm the station call name.

Cheap MP3 Audio support for the Car

So imagine the surprise it was when one day, while having a lunch run to Fry's Electronics, I saw a Clarion DB-185MP car audio deck for just $49 on sale (one-day-only!). It's not a pricey deck, regularly $80 - $100 in many places, but here's a car deck that plays CD, MP3, WMA, has 4 x 50Watts per channel, and includes an AUX port and has very good radio sensitivity. Compare that to my colleague's 2001 Lexus 300is. No AUX port. No MP3 support. And his is one of those built-in deals that takes a double-DIN and has a custom dash bezel. Needless to say, it's a proprietary deck that costs an arm and leg to service/support. He plays MP3s through an elaborate cassette adapter, but it hisses a bit every 3 seconds due to some motor running around in the deck thinking the cassette adapter is really a cassette, and once the MP3 player is off, the deck ejects the adapter thinking it got no signal and the tape has wound to the end. What he'd die for to get an aux port or USB port. Clarion makes the DB-285MP that is the same as above only it includes a USB port.

For me, the idea of having a CD/MP3 player for my venerable truck was a great idea long overdue. I'd only been procrastinating because I had installed my stereo 16 years ago and recall it wasn't pleasant because I didn't have repair manuals then and took a long time for me just to figure out how to pull the dash off to install. But time heals many fears and for some reason, I had this idea that I did it once, so I'd be able to do it again, even if my memory was kinda fuzzy. So it was an impulse buy. And out the door I went, thinking I had a great deal. It was only after that I got on-line and did some research on whether this deck fit or not. Crutchfield.com is a great resource. They have lots of information on whether a stereo fits your car or not. And if you buy from them, they include wiring harness, mounting brackets, and instructions. I paid a higher price 16 years ago and bought from them, but this time, my impulsiveness got the better of me. Checking online said the stereo did NOT fit my dash.

But not to be discouraged, I tried that evening after work to install my stereo. I measured the opening and found it should be wide enough and deep enough. Not sure why Crutchfield said it didn't fit. Perhaps that was their assessment with the provide bezel/frame which doesn't fit my dash, but I didn't think I needed it, since it was only cosmetic, and the dash provides a surrounding trim/frame. The built in screw holes on the deck do mount in the car's original bracket, only the screws I had were too long and penetrated the metal housing on the deck. Thankfully, instructions listed metric M8 screws x 6mm deep as recommended screws and luckily, my local Home Depot had them in stock. After a quick run before they closed, I had the deck mounted in the dash and called it a night.

I resumed early the next morning and only in daylight realized how much a mess it was in my truck with the dash still off. And in my haste the night before to install the deck to check for fit, I ripped off the wiring harness and pulled the wires I had inserted into the connector block. Leave it to Toyota to have a propriety connector for just their stereos and I'm certain that I would have thrown away the installation manual years ago. So I sat there with the ground connector on the new deck fixed to the car body, and a stripped end of the wire inserted into various holes in the connector block. After a few minutes, I found the battery terminal line that is always on. This powers the eject and the radio station preset memory. Then repeating with the car ignition turned to ACC, I found the main power line. I couldn't find the LED lighted panel light so I decided to twist this all together with the main power line activated by the ignition switch.

One Thing Leads to Another

I put old JVC 4 inch mount 120Watt/40Watt RMS speakers into the dash mounts a long time ago, and after plugging in the speaker wires, and cranking up the volume, the right side vibrated a lot. I thought maybe I had inverted the polarity. So flipped the wires. Then the speaker really made a lot lower volume with more hissing. So I removed that speaker, and found two small tears in the surround. So I got online and went to Parts-Express.com and bought a sale pair of 4 inch speakers with 150Watt max/40 Watt RMS and installed those a few days later. These new speakers sounded great - but so good in fact, that I realized I really wanted to upgrade and pump out more bass. Not enough to make the neighbours down the street hate me, but enough so music would sound more real.

With four channels x 50Watts each, I decided first to order a cheap Walmart Roadmaster Bass Blaster. Youtube has a bunch of videos of kids taking this cheap $20 subwoofer and hooking up to an 800Watt amp and blasting the speaker to oblivion, even catching fire. For any real audio lovers, a 6.5 inch bass tube isn't going to really pump or thump like a 4 x 33 inch MTX Jackhammers sucking 8000 Watts. But I still want my hearing, so hooking this up to the right rear channel on my stock clarion head unit worked just fine. After reading the manual for the deck, I found out more about tuning the custom bass/treble and Q factors and Frequency response than most people should know. But the result was decent sound and richer bass without feeling like I was driving in a machine gun designed to fire slugs of potato.

But there was no place to put that bass tube in my little 2 seater truck. It's resting on the floor where the passenger sits and for the time being, I'm happy with it but passengers aren't. It's gotta go eventually, so I ordered some low-profile small subwoofers, a pair of low-pass inline crossovers, and bought a big slab of MDF panel. The plan is to make a couple of subwoofers for under or behind my seats that are only 4 inches thick and can do the job of filling in the base from 80 - 500 Hz or so. Those woofers were on sale for just $10/each, and the cross overs were just $8 each and buyers gave them great reviews. Can't wait until I get those hooked up and tested.

It's kind of a fun DIY project that hasn't cost that much and now makes me love my truck more than ever. In fact, I love my truck so much that I last weekend, I purchased the premium serpentine belts to service my truck - yeah the one's with 3 yr warranty. I was thinking of going cheap since I was going to EOL my truck and sell it on account we just got another minivan (used Sienna - a great buy in these tough economic times) so I can haul all the kids. I've been fixing that van up too to my quality specs and learned some things about dealer service that were unexpected. But that's for my next blog. February 10, 2009 04:42 PM PST Permalink

Hacking nevada audiohd parser for S10 update 6

I received a phone call from a partner asking about running a demo on a new workstation/desktop platform at a tradeshow soon. He needed to get audio working on a number of systems to play simple clips, maybe some online YouTube stuff. He knew the Solaris audiohd driver was working great in latest Nevada SXCE but he hasn't been able to get the same support for audiohd drive on Solaris 10 update releases.

Just last week, a colleague mentioned the same problem on a new hardware platform also going through bring up with Solaris 10 update. So I got around to finally trying to back-port the latest audiohd codec parser to S10 from the Nevada source. Luckily the work was trivial. I just needed to remove a single function symbol in a struct and comment out a couple other lines for audiohd_quiesce() and rebuild on S10. The code needs to compile using Sun studio compilers 11 or later or a full complement of GCC compiler tools with C99 support. On solaris 10, just 15 minutes and I have audiohd working with a number of new platforms. The codec capabilities parser is sure great.

I don't know if there are plans in place to back-port the parser formally to S10 update. Audio is still considered a secondary function, and likely, that's the priority where it'll remain. But I know for users like myself, audio is clearly a top priority to get working on any solaris system. Plus, I've been getting re-acquainted with all that 80's synth band music which I hadn't heard in a while, like Depeche Mode, Electronic, and New Order. I just bought the best-of collections for all 3 bands and listen to them on my test S10 lab boxes. Kinda cool and nostalgic at the same time.

I've put together a src tar-ball and uploaded it to http://blogs.sun.com/PotstickerGuru/resource/audiohd-solx86-4.tar.gz. Hopefully, some folks can get some use out of it if they plan to stick with S10 update only. February 10, 2009 02:11 PM PST Permalink