Headless (unit) Car Audio Project

Dans Car-Pi Diem Project (2010 Chevy Cobalt)
(Diagram and flowchart at the bottom.)

Currently a Pi-2 but thinking about using a Pi A+ and just rely on a single external usb SSD HD and a powered usb hub, as really, there’s no network while your driving!

Givin’s:

DAC - http://iqaudio.com/?page_id=454 (but will probably buy that for my home use due to the built in Headphone amp, and use my existing HiFiBerry DAC+ for the car.)

Screen – A debate. Will need to determine if a 5” or 7” touchscreen will be used first. Hardware options will make this choice for me eventually. Several amazon wish-list items have been flagged already for either use case. Using HDMI was a pre-req as the DAC will be using the GPIO pins that other non-HDMI options would rely on.

Physical EQ selected instead of an audio processor. First being it has a physical volume control knob, as I don’t want to have to rely on the touchscreen to change the volume in traffic. Not to mention the EQ has the possibility for flashy led’s and who doesn’t like those!!! But also, it’s a simple 4 speaker setup that uses 4 of the same drivers, so custom rolloff points and different crossovers for front/rear aren’t really needed.

Optional / Questionable:

Vacuum Tube Preamp to add that warmth right out of the dac? Would road travel (granted mostly stop-n-go) be too hard on a tube?

RCA Distribution Amp? Would it be required over just using some split / piggyback RCA cables? (Do they even make one that uses 12v DC?) Also I worry about added noise being they’re powered. SOLVED! The EQ output’s 7v across all three pairs, that should do me fine!

Any idea’s on how to add an “aux” input for my phone? - SOLVED! I listen to a lot of audiobooks during my commute, and this is kind of a deal breaker to not have. I’d rather not have an RCA switch box if it can be avoided. They’re all horribly ugly, and as often as it would be used it would need to be easily accessible so would probably be on display in the dash which I don’t really want.

Eventual Upgrades:

Focal 6 1/2” 2 ways front and rear.

T-Line Sub Enclosure / Amp Rack (replacing an existing sealed box setup currently in use.)

So I figured out my audio input and switching question using the idea from this post:
http://www.instructables.com/id/Curiously-Small-Audio-Switch/
It will bypass volumio and basically just go straight from my phone to the eq/amp’s so that in itself should be interesting!

Without a box of course, and I used an on/off/on DPDT switch so that I can “mute” the system quickly if I hear sirens or get a call etc.
I plan on fabricating an in dash replacement panel for where my stock head unit stays now, and will have the locations for the switch and audio input jack either laser cut or I might give it a shot before any fiberglass work that might be needed.

I’ve also found my older pioneer 4 channel amp, and dug out a PPI (way overkill) for the sub, so the amplification part is already 3/4 of the way done!

I need to go out and purchase a few high level to line level converters, and a hook up for the stock stereo molex plug to simplify the wiring a bit, and then figure out how and where I’m going to shove all this hardware and map out my power routing.

I’m also actually now thinking of adding a standalone wireless router to this build, so I can connect my phone to the access point and manage it that way, until I decide on the screen. (looking like a 5" is going to be used, as the 7" fits, but won’t allow room for the equalizer without figuring out some hinge mechanics for lifting the screen to access it which I just don’t want to bother with at this point. Or maybe I just run multiple pi’s on the same network!

Now I just need to figure out a nice way to allow the pi to be turned on and off cleanly with the remote line when I start the car!

As always, any input and ideas are welcome!

Another update, that audio switch should use a 3PDT switch to truly isolate the grounds from each source. But that has just become a moot point, as I found that the EQ I was looking at:
http://smile.amazon.com/dp/B000EZV3T8
It just happens to have an aux rca input as well, so 1 custom cable coming up and my problem’s solved all in a 1/2 din slot! Man that would have saved some work, as I actually just finished soldering up the switch for no reason. :confused: Oh well, it’s still a viable option for those looking to add this feature to your own car-pi build’s!

Cable’s done :slight_smile:

I’ll only be using the one wrapped in black anti-abrasion tape, just had to share that yes, I did braid the wires because if I don’t someone, somewhere will throw a fit :laughing: !

Parts have started to arrive! It looks like I might have enough to get this started this weekend! Exciting!

Nice project, keep the info coming :slight_smile:

I am thinking about doing something a bit similar without all the amps aso, just so i can play wireless from my phone to the car stereo.

Streaming to the pi would be a nice feature, let me know how you get along on that! I can’t recommend the drok buck converter enough for powering my router and pi both.

IT’S ALIVE!!!
I’ve also created a static site to document this a bit more in depth without making this thread unbearable with a bunch of images. It can be found here: http://car-pi-diem.s3-website-us-west-1.amazonaws.com/ if your interested.

Basically I couldn’t be happier! It sound’s amazing, and the choice for a sealed 10" sub with about 500 watts was the perfect amount.

Here’s how it sit’s currently:

I plan on adding a panel mount USB adapter so I can access the music on the pi without having to take my dash apart once the front panel is made, but other than the front panel (and trim) in place it’s working, and better yet SOUNDING great!

Very good work indeed !
To stream to the pi, you can actually use any upnp app (it’s super convenient and sounds reasonably well). I personally use
play.google.com/store/apps/deta … upnp&hl=it

It just works like a charm!

Hi @danstinebaugh

I’ve been studying your car audio project with great interest, as I’m planning my own, slightly more simple verison.

My car has a 3.5mm aux input socket so I was thinking I could put a HiFiBerry DAC+ on the pi and connect directly into my exisiting car stereo system.

My only issue is safely powering the pi. I notice that you didn’t end up using the Mausberry switch.

Can you explain how you connected your pi and how you are able to safely switch it off when the car is switched off??

Many thanks

Matt

Well I have an old dedicated phone just for volumio in my car (which is still working great!) and I just shutdown from the settings menu in volumio’s web interface, although I do have a small push button connected to a gpio pin that’s looking in a loop for a high single and when found it shutds down the pi as well, I just have to remember to do this before turning off the ignition. Suffered through a few re-formats of the sd card because of that. But for the most part it’s not a problem.

Based my solution on something like this: http://www.instructables.com/id/Raspberry-Pi-Shutdown-Button/step4/Raspberry-Pi-Shutdown-script/

Just a thought and I don’t know if you want to dig this much after it’s done, but you could probably replace that button with a relay to turn off the unit when the car turns off. If you can get a wire with constant power to the unit, then run the on while the car is running wire to the relay, it should “press then button” for you when you turn off the ignition.