Quantcast

Mac mini meets Corvette: Installation

Corvette | by Andrew

Following are the images from installing all of the electrical components. Click on the thumbnail for a larger view.

Project Table of Contents
1) Pre-Installation planning
2) Electrical Installation
3) Final mounts & demo video

Audio Quality Issues
After the installation was complete I spent some time tuning the iTunes equalizer to optimize audio quality. During this time I noticed there was a fair amount of noise coming through the audio feed. It was a pulsating hum that fluctuated with the hard drive accessing in the Mac mini. This is typically caused by ground loop noise where electricity that should be grounded to the chassis of the car finds a faster path to ground by going through your audio cables. It’s common when your actual ground isn’t efficiently grounding your system and electricity is lazy like the rest of us and takes the easy way out. After driving around a bit and re-testing my grounds I determined that the grounding problem was not in my power cables but simply caused by the design of the Mac mini allowing an easier path for the electricity via the 3/8″ audio out cable instead of it’s power cable. There are a number of solutions out there to solve this, but the easiest and most effective in my case was to purchase a Ground Loop Isolator from Radio Shack. Sadly this problem also occurs in some other Macs, including my G5 at work. Installing the ground loop isolator removed about 90% of the hum which was enough to make it inaudible while driving.

Day to Day Use
After driving around for a day or so with the completed system in place a few things rose to the surface which needed tweaking.

First was an oddity, every time the Mac mini booted the system volume level was set to 50%. I wanted iTunes volume and the system volume set at 100% all the time in order to provide the right volume control on my head unit. With both of these volumes at 100%, the volume control on my head unit was a normal ratio of graphical bars to decibel output. With the Mac mini’s volume at 50% however, I had to crank the head unit volume to reach listening levels. This Apple knowledge base article confirms that it’s a real bug and there’s no permanent solution. Until Apple provides a fix, I have this AppleScript launch at startup which sets the Mac’s volume to 100%.

Next, I quickly found that the shutdown process was annoying and lengthy. As I mentioned earlier I’m choosing not to sleep the mini every time the car is turned off, so that means when the ignition is switched to off, the P1900 sends a sleep command to the Mac mini which the mini ignores as specified in the System Prefs “Allow power button to sleep the computer”. At this point the P1900 is going to kill power to the mini in 60 seconds, so I need to manually shut down the computer within this time. Going to the Apple Menu and the selecting the tiny “Shutdown” command wasn’t easy, so this simple AppleScript in the dock allows for a single tap on the LCD to turn off the computer before the P1900 stops providing power.

Continue to part 3: Final mounts and demo video>

Project Table of Contents
1) Pre-Installation planning
2) Electrical Installation
3) Final mounts & demo video

just 1 comment so far...

  1. Electrical Installation blogs on Feb 25th 2009 at 5:18 am

    thank you for information




Leave a Reply

Home |  About |  Advertising |  Add a Listing |  Blog |  RSS |

© 2007-2009 Copyright sho'fr - Terms & Privacy