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Correct. You have to lift the rear carpet and you can then access the rear electronics that includes the amp. Take care removing the carpet as it goes under the wheel well covers and is easy to tear. If you're thinking of replacing the amp, don't. It is needed for more than just providing power to the speakers.
This depends in part on what you're looking to do. If you're just adding a sub you probably don't need a fix82. If you're looking for a more complete upgrade read on. I suggest looking at a PAC or Nav-tv interface instead of the FIX82. They allow you to pull pure signal from the HU. The FIX82 is a good product, but it is limited. The stock Bose system does all sorts of manipulation of the signal that is based on engine rpms, music volume, speed, ambient noise, etc. The FIX82 wasn't designed to overcome all that. The optimum setup would be the NavTV or a PAC, a DSP, and then amplification. Then there are the speakers. Bose uses cheap speakers. They then use a great deal of equalization to overcome their deficiencies. This allows them to control costs. You could still use the Bose speakers, but they are very low impedance and you would need to ensure the amplification you use can handle those low impedances. If you replace the Bose speakers there's no limit on sound and cost.
Regardless, the biggest issue with the C7 is tire noise. It is loud enough it will mask the OEM system or even a good sound system. Greater volume helps a little and goes a long way towards promoting tinnitus. A good sound deadening can improve the experience of the Bose or a aftermarket system. To be really effective this consists of the proper application of CLD and a noise barrier. This is a big project. I did my C7 and to do so I gutted the interior - seats, carpet, and interior plastic. How well did this work? There are pros and cons. The pros are it is much quieter. Before a conversation with the passenger @60mph require talking loudly. Stereo wasn't enjoyable to use at that speed and forget talking or stereo above 70. It is now quieter than my wife's RC350 Lexus. It is significanty quieter at 80mph than it was at 50. The con is it is so quiet. It is a little surreal in relation to how noisy it was. Along with reducing road noise it also reduced exhaust noise. So if I'm just cruising along I don't have much exhaust noise. There's still plenty of noise when I get on it. In the past I've always had exhaust in stealth. Now I'm up one setting.
According to JL, the FiX82 would balance and flatten the signal prior to going to the VX800/8i amp. When I spoke with AudioControl about the PAC they kinda laughed and said PAC meant well but didn't really cut it. I've replaced my door and rear sub speakers. The sound was drastically improved but it seems to lack a deep punch. I was originally looking at AudioControl but then moved to JL Audio.
The adjustments by the Bose system vary over volume, ambient noise, engine speed, etc. The Fix82 is better than nothing, but it cannot fix all of that. The only way to get a clean signal free of the Bose equalization is to use something like the Navtv M650-GM. Talk to any decent installer and they will tell you the same. It depends on what you're looking for. To get really top notch sound you will need something like the M650 and a DSP. Audiocontrol sells equipment they tout as a competitor to PAC/Nav-TV, so of course they will not say nice things about their competition. Ask then this - Do they sell a device that will counter the adjustments the Bose system does? Does that include the nonlinear things Bose does at different volumes? Does that include the "noise reduction" Bose does based on engine RPMs? etc, etc? If they do they're doing an outstanding job keeping that information away for the car audio community.
The only way to remove all that equalization is to access the signal before it is touched by Bose and the only way to do that is from the MOST bus. For that you need a device designed to do that. That means the M650-GM or the PAC. They're not cheap. Again, it depends on what level you're looking for. You don't have to go that way to improve the sound and the Fix86 may be good enough for you. You won't get to the sound quality you'd get with the MOST interface and a DSP that has been tuned properly, but you may not be looking to go that far.
MOST is the audio information in the C7's network. Most car manufacturers handle it this way (hardware & software). The M650GM + the VX800 would be a good combination. The VX800 has a built in DSP. After it is all connected up all you need to do is do the tune. You may need to get a mic for that. If you're not set on saving every penny you can, I suggest buying the amp from Crutchfield and use their support to assist in what you need. Tuning can take a while to get right. If you get frustrated most car audio shops will do it for you. If you go that way be sure to check their reputation out to ensure they know what they're doing and being able to listen to one of their installs would be a big plus. If you do they'll probably push you to replace the mids & tweeters. A tuned system will get the most out of the Bose components but it is a little like the difference between a 327 and a LT4. They'll both move you down the road but the experience isn't the same.
I've already replaced all the speakers except dash and sides, which someone told me doesn't contribute to the sound platform at all. When I was looking at AudioControl they had an optional mic and tuning software. I don't see any mic option with JL Audio. The Tun software just shows using the computer. So, if I went with the M650GM, I wouldn't need the Fix86? Thanks for your help.
Also, Crutchfield is no help at all. They said they've never gotten their hands on a Corvette and can't help with audio at all. Kinda sucks.
Last edited by Matthewstorm; 03-29-2019 at 11:20 AM.
Whomever told you the sides/dash don't contribute to the sound should not be someone you ask any audio questions. A large portion of what you hear comes from those speakers. They are very important. If you get the M650GM and the VX800 don't buy a FiX86. The M650GM eliminates the need to fix the Bose equalization and the VX800 has a built in DSP. There's nothing left for the FiX86 to do.
The interior of a car is a complicated environment for sound. There are many surfaces that sound can bounce off and you're sitting very close to the speakers. Add to that the speakers are distributed throughout the car and getting it to sound right is a challenge. A DSP is the tool that can adjust the frequency level and timing so music sounds right. It levels out the response from speakers and the interior surfaces. To do that you need to have a mic. Typically a tune consists of placing a mic in the driver's position, making physical measurements and entering them into the software, and then having the software run frequency sweeps to correct response problems. This is often done for the passenger position also and a final merged tune is then used. Now some DSPs make this easier than others, and more is/can be done than I mentioned. Crossover frequencies and various speaker characteristics are an important part of this. Pick a wrong crossover frequency and the DSP won't be able to do a good tune. It is a complicated process and that is why I mentioned you may get frustrated.
When talking to Crutchfield you'll have to control the conversation somewhat. Most serious audio system replacements for the C7 are done in dedicated shops. Crutchfield's experience is limited to larger vehicle bases. What you need to find out is what you will need in addition to the VX800 so you can make adjustments. That it goes in a C7 isn't the point. You can probably contact JL Audio and they'll give you want you need too.
All this said, you may not need to go with a full tune. Install the M650-GM and the VX800. Listen to it. Not 100% happy? Try doing a DIY tune. If you're happy, then you're done. If not,try a more involved tune. Still not happy? Try again or take it to a pro tuner or possibly look into replacing the upper door speakers (mid ranges) and maybe the tweeters in the dash too.
I've replaced all the door speakers. I guess I'll look into replacing the side speakers next. Looks like I'll go with the Nav-TV and VX800/8i.
What the hell is a Twiddler? On my speaker placement graphic it says a 5.25 Twiddler is installed center dash.
LOL. From what I can tell, twiddler is Bose-speak for a speaker that is supposed to do mids and tweeter but does neither well. They're actually 3.25". There are 3 of them, one in each door and in the center of the dash. In my install I dropped the center and in dash tweeters and will be using the Illusion C3CX for the doors.
The center speaker is the exact same as the ones in the doors so if the Infinity speakers fit the door they'll fit the center dash. My dash tweeters are still there, but the wires to them are cut. I replaced the center with a C3CX when I did the doors, but the current plan is to not use it. My C7 is in the shop right now getting amplifiers and DSP installed and tuned. Coincidentally, I used the same Morels for the rears. You'll need to make an adapter plate to mount them. They're a little overkill for rears as rears are really more for fill.
The only question I have is if the tweeters will fit. They're excellent speakers. I didn't take mine out so I don't know what room you have or even how to remove the grilles.
I have absolutely no idea if the Tweeters will fit. I only know they're 1". I've tried to find out but no luck. My installer thinks by taking out the A-frame pillar covers the speaker covers will pop out.
Do you have the template for the mounting plate, by chance? Or a photo?
What AMP and DSP did you go with?
Just curious, why did you disable your dash speakers?
Appreciate your input.
I've read removing the pillar covers is the way to get the tweeter covers out. Amps are Arc X2 and the DSP is Mosconi. I decided against the OEM tweeter locations for a couple reasons - imaging is easier and arguably better when you're not bouncing the highs off the windshield and the C3CX have tweeters built in (coaxials). The center may still be used. Normally for a center to work well it should be able to go lower than the C3CXs are comfortable with and centers don't make a huge difference. Oh, and a DSP with enough channels was going to bump the cost up a significant amount. Sorry, I don't have a drawing of the plate any more. It is pretty simple. Pic below. IIRC, it is 1/16" ABS. Pretty simple, just a flat piece with mounting holes and a hole for the speaker.
Thanks for this pic. I forwarded it to my installer. Why did you go with a separate DSP instead of with just an AMP like the JL Audio VX800/8i that has it built in? Just curious.
It is what my installer wanted to use. I think it gives more flexibility in tuning and the separate amps give us better power matching for the different speakers.
So, got the Morel's and Audiofrog tweeters installed. Wow, that made a HUGE difference. My installer had these preformed cups he used for the Morel's that pushed the sound into the cabin. Those OEM speakers are real crap. Doing the NAV-TV and JL Audio VX800/8i next week. Also, ordered the large Stealthbox for the rear. Got it from Crutchfield Outlet and got a huge discount.
03-27-2019, 07:25 PM
A good sound deadening can improve the experience of the Bose or a aftermarket system. To be really effective this consists of the proper application of CLD and a noise barrier. This is a big project. I did my C7 and to do so I gutted the interior - seats, carpet, and interior plastic. How well did this work? There are pros and cons. The pros are it is much quieter. Before a conversation with the passenger @60mph require talking loudly. Stereo wasn't enjoyable to use at that speed and forget talking or stereo above 70. It is now quieter than my wife's RC350 Lexus. It is significanty quieter at 80mph than it was at 50. The con is it is so quiet. It is a little surreal in relation to how noisy it was. Along with reducing road noise it also reduced exhaust noise. So if I'm just cruising along I don't have much exhaust noise. There's still plenty of noise when I get on it. In the past I've always had exhaust in stealth. Now I'm up one setting.
