Using CAR AUDIO components in your arcade/juke - lessons learned

[edub]

For the past two weeks, I've been googling and "foruming" and "PMing" to determine the right way to hook up car stereo components in my arcade machine. Many thanks to Gryhnd and others for steering me in the right direction.

I decided to share my final solution so that others could learn - i.e. feed back to the group what the final results were - FWIW.

If you ever think about using car stereo equipment for your arcade or jukebox, consider some of the points below. As you know, multiple solutions exist, but here's at least one that is simple and straightfwd (now that the lessons are over with). 

The tradeoffs of using car stereo equipment in your cab/juke are (some of these are subjective I realize):

+ installation (speakers, amps, etc)- hey, these things are made to be screwed in and installed flushmount with grills - nice fit for just under the marquee vs. a std PC 2.0 or 2.1 system)

+ sound quality is superb without the need of a subwoofer (although, many may want to add subs, this solution doesn't preclude it - in fact, it is encouraged with the car amp)

+ ruggedness: these components are built to withstand bumps, pounds, etc - like in a car. Plenty tough for a cab/juke.

- some thought needs to go into it (power matching mostly and correct wiring) - but hopefully this post will help

- may cost more (about $130-170) than other solutions - can be cost prohibitive for some

Here's what I ended up with and some lessons learned:

1. First - power matching is CRUCIAL. If your amp puts out too much power to the speakers or draws too much power from the power supply (PSU), then it will either break something or degrade it over time. So, make sure your speakers, amp and PSU are matched in terms of power (see my component list below). This was, by far, my biggest struggle. I purchased 2 ohm speakers first and the car amp and then thought "oh, gee, how am I going to POWER these things?" I had it backwards. Match them all up to start with before you hit the BUY button. I ended up with some really nice Infinity speakers I can't use. 

2. Consider using a capacitor (fairly large - 1-5 farads) between the PSU and car amp. This will clean up the audio and provide a charge to the amp when "extra power" is necessary. If you read car audio blogs/forums, you'll see this is common practice. Sure, this is mostly to attenuate noise from the alternator (which I don't think exists in my cabinet yet), but it won't hurt. Required? No. Overkill? Maybe. Safe and secure? Absolutely.

3. Before you buy the amp, look a the power ratings. With 2 ohm speakers, my amp would put out a max of 350W per channel - that's 700W max for two speakers. Yikes. The power supply I purchased only had the ability to power up to 350W. My mistake. So, check the power ratings of the amp at the ohm level of your speakers. Typically 4 ohm speakers and 180W per channel amp are the best match due to common power supplies out there (350W, 12V, 30A).

4. Don't buy a PC "brick" for an AC/DC power converter - even if it has the right specs. You want extra "protection" circuitry built into the better power supplies - like over temp. Yes, they cost more, but they are worth it.

5. I think the best "no-brainer" solution is the sweet spot offered currently by the components themselves: 350-360W power ratings ALL the way around and use 4ohm speakers. After digging and searching and getting things wrong several times, this was what I learned.

6. Remember that car audio is built to be installed in a car and powered by a car battery which is 12V (13.5V or so when running) and, put your seatbelt on, has the capability of delivering 150A or more to start the car. Ok, just the audio doesn't need that much current - 30A is plenty fine. My amp actually would be hooked to a 30A fuse on the car's fusebox, so 30A is about right.

7. Won't 30A blow your home breaker? Well, using Ohm's law, V=IR and P=VI. So, while the PSU is delivering a max of 30A at 12V to the audio equipment - that's 360W, the draw on the "home 120V circuit" is 360W/120V = 3A. So, if your circuit breaker is 10-15A, no worries. I struggled with this for awhile until others on this same forum helped set me straight.

So, here's what I ended up with (along with some links in case you're interested):

- Polk Audio DB651 - $60 - 4 ohm impedance - 180W x 2 = 360W max
http://www.amazon.com/Polk-Audio-6-5-Inch-Coaxial-Speakers/dp/B000P0PF9G/ref=sr_1_1?ie=UTF8&qid=1298415210&sr=8-1

- Crunch Pounder Amplifier (GPV700.2) - $60 - At 4 ohms, the amp will drive 175W per speaker - totaling 350W.
http://www.amazon.com/Crunch-Pounder-GPV700-2-Channel-Amplifier/dp/B001QX5Z0U/ref=sr_1_1?s=electronics&ie=UTF8&qid=1298415422&sr=1-1

- Power supply (PSU), $30 - 350W, 12V DC, 30A regulated switching power supply. Many are available on ebay.
http://cgi.ebay.com/New-12V-DC-29A-350W-Regulated-Switching-Power-Supply_W0QQitemZ120684303397QQcategoryZ58288QQcmdZViewItemQQ_trksidZp4340.m263QQ_trkparmsZalgo%3DSIC%26its%3DI%252BC%26itu%3DUCI%252BIA%252BUA%252BFICS%252BUFI%26otn%3D10%26pmod%3D110638260344%26ps%3D63%26clkid%3D7276010542514558677#ht_5279wt_966

- 5 Farad Capacitor - $35 - wired between the PSU and amp. The one I purchased self charges - so no tricky hookup problems. Again, you could get one cheaper, but the protections built into this one were worth the price:
http://cgi.ebay.com/5-Farad-Car-Audio-Capacitor-Car-Gas-Saver-/300371994742?pt=LH_DefaultDomain_0&hash=item45ef90e876#ht_515wt_1097


Again, the point here is: match the power ratings of all components: PSU is 350W, AMP is 350W at 4ohms (175W per channel), speakers are 360W total (180W per channel). And, the capacitor is there to aid in delivering extra power when needed and just sits there and charges up when not needed - it also helps guarantee a cleaner audio signal, getting rid of any noise that may exist from the power source or other components in the system/cab.

For more information and some good reading, you can go to Gryhnd's Rat Rod post here:
http://forum.arcadecontrols.com/index.php?topic=104021.0

For more info on the use of capacitors in car audio, try:
http://answers.yahoo.com/question/index?qid=20101226173754AAlHDGf


I hope my experience helps others who are going down this same road. In fact, if I had only read THIS POST long ago, I would have avoided the mistakes I made. Go figure. 

Obviously - comments are welcome. Others have better/different ideas - I'm sure.

Cheers,
edub

[Necroticart]

My question is, did you shield your speakers to avoid the electromagnetic field they generate which in turn will mess up your arcade monitor.

[edub]

Good question. Fortunately, LCDs and plasmas don't require shielding (from what I've learned). Only monitors with tubes (CRT) that operate based on a magnetic field. I have an LCD TV as my monitor, so I'm not worried about it.

However, if I (or others) DID use a tube-style monitor, what do you think is the best way to "shield" the speakers? What is the best material to use and how is it best installed into stock car audio speakers (or any speaker for that matter)?

It seems that one of the "down and dirty" ways to shield unshielded speakers is to purchase a steel pipe end cap that fits the magnet/driver. Help it stay in place with a small amount of electrical tape and, voila, most of the problem is solved. Depending on the strength of the magnet and proximity of the affected CRT, it might take two end caps (one inside the other) to reduce the interference enough.

But, I'm interested in your thoughts as well - what works for you?

Cheers,
edub

[gryhnd]

You can make you own shielding easy enough it seems (look here in the forums and/or google), and you can also use bucking magnets (magnets that counteract the field given off by unshielded speakers).

[Nacimroc]

Great post edub! Rare to find it explained easy enough for even me to understand 

[edub]

No worries. There is SO MUCH stuff out there - and ideas galore. I just wanted to put it all in one post once I figured it out with the help of many on this forum. Sometimes it seems that everyone else knows exactly what to do - except for ME! 

Well, I'm sure there are other ways to skin the cat regarding audio, but at least it's ONE solution of many - and in one place. Others have helped me avoid major newbie mistakes - time to return the favor. As I build my cab - one step at a time - I will document it in a similar fashion. To be honest, I wouldn't have a CLUE without the folks on this forum who give their time to assist others.

Cheers,
edub

[lilshawn]

Best way to shield speaker magnets is to simply place a metal cup over the magnet. easy peasy. I buy dollar store metal cups (they kinda look like chrome, just make sure it "sticks" to the magnet IE its magnetic) they come in a few different sizes. I just find one that fits over the magnet and then cut down the sides so its not too high.

A gob of hot glue to make sure it doesn't go anywhere.

This has worked for me in all but the largest speaker magnets. I haven't found a cup big enough yet... Maybe a mixing bowl...

*runs off to dollar store*

[rmusick]

Edub, Thank you SOOOOOO much for posting this.      I bought the EXACT same speakers the other day at Frys,  I put a el cheapo Sony amp in the cab i got at a thrift store.. not near enough power to run them.  I will def. look into your technique.  Do you have any pics of your set up you can post?