So I spent many hours yesterday cutting wires, removing the Bose amplifier, installing the Alpine PXE-H660 signal processor and new amplifiers.

I eliminated the Bose amplifier altogether (for now). There are low-level signals for Front L/R and Rear L/R, but there is no low-level signal for the subwoofer, the Bose amp was mixing and producing that channel itself, now the Alpine box is doing that. I'm using the Alpine box to amplify the Tweeters/Front Doors separately, so I'm amplifying a total of 7 channels.

I ran through the Audyssey setup several times, everything was very quiet until I figured out the Alpine box has its own volume control. The Alpine does a great job of removing low frequencies from the doors - no more door rattle! And it really cleans up the stock subwoofer - bass drum beats now sound like a drum instead of a big muddy boom.

There are some drawbacks to the way I have things wired right now - I've lost almost all informational tones in the car. The parking sensor beeps are gone, the door-open-while-running ding is really really quiet, and the turn signals make no audible noise anymore lol :) Some people may find this really annoying. I haven't tested bluetooth/onstar/nav cues yet, but I'm guessing they're gone too. I really hated the parking sensor beeps and considered cutting the sensor wires, so having them gone is a major win for me personally. Not having the turn signal ding is a little weird, but it makes for a really quiet car :) I'm willing to sacrifice bluetooth phone calls for a better sounding system, many people probably wouldn't.

I could wire this differently and leave the Bose amp in and just use its speaker outputs for the input to the Alpine box (I didn't because in my experience that always introduces noise) and I may try that out too when I have more time.

Just wanted to give an update...

Hmmm
It doesnt make sense to me that the audio cues are no longer functional as if you look at the schematics I sent you, there is absolutely no serial data connection to the Bose amp. It merely amplifies what is sent to it on the 4 analog channels from the radio head unit (including cues). ARE you utilizinging all 4 analog inputs to the Alpine? or just 2 perhaps? (I believe the tones, chimes and signal lamp tone are on the LF channel)
OR
The only 2 circuits that you havnt dealt with are the "power up" and mute circuits. (connector X2 terminals 12 & 14 on the Bose amp) Both are merely simple switched outputs from the head unit to the Bose amp, but connect to pull-down resistors internal to the bose amp (see page 2 of the schematic).But the amp still "looks" for fault on these circuits so I suspect at this point you likely have radio DTCs set for these currently "open" circuits (B1287, B1265) which might cause various "defalt" actions. (and potentially contributing to your loss of the audio cues)

Perhaps measure the resistance from those terminal pins of the Bose amp to it's metal housing/case terminate the circuits to chassis ground with an near identical resistor or pot. (They are likely 22-100K ohms)

I realize you appear to be somewhat unconcerned by the loss of various audio cues, but IMHO to be successful these mods must not result in any loss of functionality yet hopefully improve SQ. (too many people here would be unwilling to upgrade the amp and speakers at the cost of these audio warnings and cues)

PS> Regarding your original benchmark FR measurements. What were you using as a measurement tool (hardware/software), which miicrophone was used, and what was your microphone mounting method and placement. I'm a vacuum tube amp/speaker designer and builder and have most of this gear but would want to compare apples-apples as in my experience automobiles are a very difficult environment to obtain very good numbers from. (as opposed to say a test studio or well designed listening room/home theater)

Thanks for breaking trail here!!
WopOnTour

Actually I was wrong, the parking sensors tones are still there, just really quiet. I consider this a first attempt, and I'll spend more time on it in the future. I agree that my current setup is far from perfect, I have to work on some other stuff today (side business) or I'd put more time into it. Maybe next weekend.

My original analysis was done with a DOD spectrum analyzer with the calibrated microphone it was sold with.

http://www.dod.com/processors/rta.htm

I also used a Radio Shack digital SPL meter with a CD I created with 1/3 octave test tones. The DOD can only show +6 or -6 dB differences, and the stock frequency response has peaks much worse than +6 dB. I had the mic placed between the front seats at ear level.

Automobiles do pose some serious challenges because of reflections and resonant frequencies, which is why I went with the Alpine/Audyssey unit. It uses a 512 band EQ and chooses appropriate crossover points automatically based on measured response.

Where is the subwoofer? I've given up trying to find it.

Where is the subwoofer? I've given up trying to find it.

http://www.flickr.com/photos/26241848@N04/6125680961/in/photostream/lightbox/

Its the black plastic box with the silver amplifier mounted on top of it in this pic. You lift up the floor panel in the back, remove the 4 nuts holding that big plastic tray down and remove it.

Where is the subwoofer? I've given up trying to find it. Spare tire well as this threads picture points out/describes. Other info:
http://gm-volt.com/forum/showthread.php?7027-Chev-Volt-Sound-30-smaller-40-lighter-and-uses-50-less-energy

Actually I was wrong, the parking sensors tones are still there, just really quiet.

Most of the tones are still there, I'm just on a learning curve with the Alpine box, I've been resetting it to re-run the calibration and every time I do that its resetting its internal volume level to about 30% and confusing me into thinking everything is really quiet.

http://www.flickr.com/photos/26241848@N04/6125680961/in/photostream/lightbox/

Its the black plastic box with the silver amplifier mounted on top of it in this pic. You lift up the floor panel in the back, remove the 4 nuts holding that big plastic tray down and remove it.

Thanks! I spent 15 minutes with several of the perky auto show people last April in NYC crawling around the interior looking for that. We figured there'd be an obvious grill someplace. I can now sleep serenely tonight with that mystery solved.

rubley - see my post on eliminating road noise in back. I'm sure you know about this stuff but maybe useful for your project
http://www.dynamat.com/download/PASMAG_Dynamat_Door_Install_Tech.pdf

Well, I learned the hard way that the speakers are definitely less than 4 Ohms (stupid Bose), 2 channels on one of the amps I bought are burned out. :( My own dumb fault. So if you're thinking about doing an upgrade you definitely need an amp capable of handling 2 Ohms, unfortunately amps always lose sound quality when running 2 Ohm loads.

@kickincanada: Yeah, I've used Dynamat before, I used it in a computer once, and I'll probably end up doing it in the Volt :)

I spent some more time on it this weekend. It looks like the burned out amp also screwed up the signal processor (left front and subwoofer output are dead). So now I need to send that back for repair. Uggh.

I learned some lessons on running wires. There is a plastic bulkhead below the floor just behind the seats, I decided to drill through it to run power/speaker cables. Unfortunately it wasn't until after I ran the wires that I realized that the spot I ran the cables through interferes with the spot where plastic clips hold the floor down. I could easily drill different holes a couple inches over, but for now I just removed the clips from the floor panel (there are still 2 clips holding it down to the plastic floor tray.

I ran a 4 gauge power and ground wire. The + wire is secured to the fuse panel on top of the battery, it has its own 60 amp inline fuse. The ground wire is attached at one of the bolts holding down the electronics box in the back. Because there are so many channels to amplify, I'm using 2 runs of 8 conductor 16 gauge wire (thick gray cables in the pics), and a converted Ethernet cable to handle the low level signals from the head unit, Ethernet cables have 8 wires so it worked perfectly.

So now I'm on hold waiting for the signal processor to get fixed. I switched to using some old school amplifiers I had laying around, but they're just taking up too much space, so I'm going to be switching to some new Class D (high efficiency) amps that take up much less space. JL Audio makes a 6 channel amp and 1 channel subwoofer amp that are both very small. I have the mono amp already (XD300/1), the 6 channel will be arriving soon (XD600/6). http://mobile.jlaudio.com/products_amps.php?amp_id=577

More pics posted with notes

http://www.flickr.com/photos/26241848@N04/

Sorry to hear about the setbacks.

As an upcoming owner with a base stereo, I am guessing it should be much easier to upgrade. Since there is no Bose amp, Bose speakers or Bose subwoofer, I wonder if the wiring is different.

Yeah, things could be totally different. I shouldn't have used amplifiers only rated for 4 ohms, I knew the Bose speakers might be non-standard, so that's my own fault. I'm fine with being a guinea pig for this stuff :)

Comming from my Mercedes Benz sound system, Harmon Kardon, i have to say I'm pretty disappointed on the sound quality, even with some equalizer tweaking. My HK sounded incredible, but other than that I do really like my Volt, but would love a much better sound system, without loss of functionality.

Maybe only a speaker upgrade would help???

other than that I do really like my Volt, but would love a much better sound system, without loss of functionality.

Are you a B Volt or a C Volt? If you're a C (2012) Volt, do you have the base radio or the Bose radio? I certainly respect your opinion, but it would help set the context to know what you're listening to.

Maybe only a speaker upgrade would help???

The drivers are actually pretty good, certainly you could do better with a nice aftermarket setup, but the real source of the problem is the lack of a crossover on the door speakers and the terrible resonance caused by the Bose "subwoofer" (I put it in quotes because its only approximating the sound a subwoofer should produce).

Comming from my Mercedes Benz sound system, Harmon Kardon, i have to say I'm pretty disappointed on the sound quality, even with some equalizer tweaking. My HK sounded incredible, but other than that I do really like my Volt, but would love a much better sound system, without loss of functionality.

Yeah, the eq settings won't help, you need to remove bass from the doors (no setting for that) and eq the subwoofer.

There are ways to integrate the signal processor without losing any of the tones (they're not actually gone, just really quiet). You'd have to send the head unit output to the signal processor, and send the output to the input of the Bose amplifier. In that case, you'd need to add some inline high pass filters for the door speaker outputs of the Bose amp to remove the bass. I think that would work. Its tricky because the Bose amp is mixing the left/right channels and producing the subwoofer output by itself, but its also sending that bass to the doors, which you would have to remove after amplification.

I can't stand the parking sensors, so I'm going to leave it the way I have it :)

I'm still waiting for the signal processor to get fixed and sent back to me... tip: don't buy stuff from a non-authorized dealer...

I bought a handheld realtime analyzer to make things easier, its much more portable than the rack mount one I was using, and it has a larger dB window, my old one only showed +/- 6 dB and the Bose system isn't good enough to stay in that window.

http://www.amazon.com/Phonic-Hand-Held-Spectrum-Analyzer-PAA3/dp/B0009RK7YS/ref=sr_1_1?ie=UTF8&qid=1319576022&sr=8-1

Too many haters, see you later
Are you the guy who started all this? BAN HIM !!!!!! ;-)

Too many haters, see you later

That is to bad, your project is interesting but the religious like fervor seems to have lead to your falling out. Perhaps more a project tack may raise interest again.

Personally I couldn't tell the difference in any case. To many years of firearms, stamping plants and rock and roll concerts have taken their toll.

rubley, hang in there. For most people the volt's sound system will sound a lot better than their previous car. For most people Lady Gaga is better than Mozart (at least in my daughter's world, LOL). Still, there will be some who actually do know the difference (musicians, owners of truly high end home sound systems, etc) who might be interested in upgrading the volt sound system, like me.

Yes, the volt is the first car I've owned where listening to classical music is actually fun instead of frustrating, and yes it sounds 1,000% better than my previous cars. And yes, being a musician, I also share the "the kick drum doesn't really sound right" feeling. So, if you or someone else gets it figured out where the sound could be upgraded without loosing any of the OEM features (turn signal sounds, backup beeps, etc) at some reasonable price I'd go for it.

Too many haters, see you later


Jeez....all i wanted to say was that 'I' that would be 'ME' Love the Bose sound system. Oh, and my hearing is better than all of yours, I have a phd in ears so surely I KNOW BEST! ;)
....BTW I have a black beauty too...but i originally wanted Cyber Gray...no go for 2012.
Are you the guy who started all this? BAN HIM !!!!!! ;-)

Actually you are misquoting sparks. He was referring to Britt1 and not you.

I generally love your enthusiasm and many post. Agree or disagree about the stereo I'm glad there are folks like you that are digging deeper into customization. So thanks for that.

I have a 2011, with Bose, nav, the hole nine yards. It's adequate for sound quality, but can't touch my Mercedes e500 by a long shot.

Hi Rubley, thanks for all your work on this. I'm wondering if I could use a single box to do some of what you are doing here. Would this work in the Volt?

http://www.jbl.com/estore/jbl/us/products/MS-8/MS-8_JBL_US

Could you put caps in with the door speakers to cut out the bass? I realize it's only 6db rolloff, but it can make a difference. When I did a lot of Car Audio in the 1980's we did this pretty regular. Back then there wasn't as many people using "real" EQ's and electronic crossovers. The Kenwood, Sony, and Alpine slider equalizers (half din) were popular, mounted with a stereo in GM dash kit (radio on top and EQ below or vise versa, usually depended on the car and depth available). The EQ's had a sub out that allowed you to add the sub. But the crossover wasn't good enought to protect 4x6 GM replacement plates in the dash (one 4" and a tweeter), so we added caps to get the bass out and protect the speakers.

It's a decent option in my opinion to remove some bass, if you order some quality caps.

Please don't stop posting. I enjoy peoples posts. I consider the Bose system fine for me now, but I enjoy seeing what can be done.