User:Freat
From DRC
'My mobile audio (car) BruteFIR Project '
Project goals:
- Install a linux based computer into the trunk/boot of my car
- Process all audio via BruteFIR
- Crossover
- Room Correction
- Integrate the computer with the BMW iBus for control via the steering wheel buttons
- Change / apply different filters
- Control EQ
- Display status information to the dashboard and/or headunit display
Current Status April 21, 2008
So I added the Sundown amp last week for the sub and what a difference. The RF 325.2 was not providing enough power to let this thing really shine. Then last night I moved to completely active XO for the tweets, mids, and sub. I also replaced the Vifa tweeters with the LPGs. These have better power handling. This big change made such a dramatic improvement in clarity I didn't realize how loud I was playing until my doors seemed to want to shake apart! :) I tried bringing the XO for the mid/sub down to 60Hz but there was too much of a hole in the overlap. Now setting my levels is going to take some tinkering. Right now I'm just doing it by ear, but when I have the time I'll play some logarithmic sin wave sweeps.
Current Status April 15, 2008
I had gotten the computer (linux) into my car and convolving the audio but was not happy with it. So I've started again, but this time I'm focusing on doing the crossovers first. Running a linear phase crossover between the sub and mains has made such a difference that I ordered another amp so I'll be able to run the tweeters and mids separately. I can't wait! Well, also the amp I ordered is for the sub, and higher powered. The current sub amp will go to the mids, mids to the tweets. So yeah, louder sub too.
Once I've got the crossovers ironed out, I can focus on the other cool stuff. In a car I think controlling each speaker individually can be even more critical. In my case, the tweeters are about 3 feet from the mids. This has got to be introducing some phase / issues.
Last year's Status
Well I got through the initial steps using a laptop with a crappy built in soundcard. It's one of the resampling ones to boot. Also a bit frustrating, I purchased a power inverter to power the laptop in my car and it introduces so much noise that it's essentially unusable. Hmm... I'm just now thinking maybe I'll try a UPS between the two to clean up the signal.
Either way the laptop was just to learn how to do this, and I have the drc-fir mailing list to thank for helping to answer my questions, and even plot out some graphs for me!
Next step is to build the system that I will install. I may use the memory stick option, but write it to a CF card instead. The old mobo I have most likely doesn't support booting from USB anyways and I've got an old 128MB CF card and a IDE / CF converter.
I plan on creating a convolver PC to go in my car and process the audio from my headunit.
Current Setup:
- 2003 BMW 330xi
- Factory Headunit
- Pentium III 866 running FC6 minimal install (that's right, linux in my trunk)
- 2 X Rockford Fosgate 325.2 Amps
- 1 X Sundown Audio SAX-100.2
- Fronts: 2 way Vifa speakers from Madisound with crossovers
- Rears: Who needs rears!
- Sub: I built a custom .48ft^3 sealed enclosure for an 8" Soundsplinter sub (Soundsplinter rli-8). The sub is made from 1/2" MDF and fits snugly up against the ski-pass hole in the back seat, so it fires directly into the cabin. --add pics
- Streetwires 1 Farad stiffening capacitor
- 4 Gauge power wire throughout
I'm currently researching using BruteFIR_on_a_USB_memory_stick for a solution.
Here are a few different graphs of the measured IR from my car. Here they are
