HI Folks:

I purchased an Axxess AX-DSP-MOST1 interface to add new amp and speaker to my 2018 C7. The company website states the interface should be compatible with my car. The unit does communicate with my car but I don't think it can decode the audio signal from the head unit. I have applied the latest firmware from Metra but no luck.Has anyone used this interface on their 2018 C7 with any success? I have the 9 speaker Bose stereo.

Thanks

 

What isn’t working? Did you run the setup app? I don’t have this unit but am looking to purchase one.

 

I applied latest firmware with the update tool, and I also have the latest phone setup app.

Here is the email I sent Metra customer support:

I can get the AX-DSP-MOST1 to communicate with the car, the led lights on both the AX-DSP and MOST1 interface boxes is on and steady. I can also get the AX-DSP-MOST1 to connect through a BT connection. I am selecting the 2018 Corvette option on the installation app. I can get the chimes to sound through the speakers when commanded, but other than that I cannot get any sound through the interface. I believe that the AX-DSP-MOST1 can not detect an audio signal from the factory head unit. I believe this is the case because I can see the AX-DSP-MOST1 turn on the amp for the chimes to sound however, it does not detect a signal from the head unit so it does not trigger the Signal Sense function. On the other hand, the amp comes on when I select the “Always On” function.

So far I have not received confirmation the interface has been tested with the 2018 C7

 

Do you get sound from the radio when "always on" is selected?

 

No sound, a little static noise but so sound regardless of audio settings at any volume. Only the test chime (triggered by the phone app) works.

After hours of troubleshooting and searching for answers I think the best option is to send this unit back and get the PAC version.

Frankly, I doubt Metra tests the cars they list in their application guide. A small change in the signal that feeds the factory amp.could have rendered the interface useless.

Btw, I found a spreadsheet that lists "AX-DSP certified vehicles". C7 Corvettes are not on the list:

https://www.google.com/url?sa=t&rct=...3nB3uk5hQips4e

 

OP, go with the NAV-TV GM650 unit. I got mine for $375 from a dealer. Used it to interface an entire new system.

 

I'm going to do a little research on the NAV TV. Could you pass the name of the dealer you got it from? That is, unless that violates forum rules. I found the PAC AP4-GM61 for $299, but I would pay the extra 75 bucks for the NAV-TV, since it seems that several folks here like the unit.

Were you able to install yours near the factory amp location, or did you have to place it near the head unit? Also, did you have to cut into the any of the factory harnesses?

 

Interesting... did Metras tech support get back to you? They clearly list the 2014+ Corvette on their website as being compatible.

The C7 stereo is a parts bin unit shared with several other GM vehicles so in theory it shouldn't matter that its installed in a Corvette. However I guess it is possible GM changed something in the signal (noise cancelling? factory subwoofer?) that requires additional processing the Axxess doesn't like.

My main interest in the Axxess unit was they claim you can completely remove the factory amp and do all wiring at that one location. Contrast this with the PAC and NAV units that both require the factory amp to remain in place and connected with connections done to the radio interface module in the passenger footwell. I found this requirement to be odd but maybe it explains why the Axxess isn't playing nice with the factory setup. The NAV unit is more expensive then other solutions but its proven to work. The PAC unit has some nice features like adjustable EQ and center channel volume but requires a PC to do the setup vs a Bluetooth app for Axxess. I found in the past that USB via a PC with these kinds of devices can be hit or miss. How with the NAV the only setting changes are via DIP switches so no programming required thus one less thing to go wrong.

 

Hi JMII

No word from Metra tech support yet.

The Metra unit was appealing due to the easy of installation and the 31 channel eq. I have no idea how the NAV and PAC units would be connected to both the amp and the head unit, unless they came with very long harness or if the harness was extended by the user.

Keeping the factory system is starting to sound better every day. I miss how easy the audio swap was on my C6...I guess it's the price of progress!

 

Unfortunately, my dealer is located in Durham, NC. Not sure you'd get the same deal. I think there's a dealer on the Forum saying he can get it for a good price.

You can run a digital cable from the NAV-TV unit that's installed under the passenger foot rest to the amp in back.

 

Both use a T-harness that connects at the factory radio module location in the passenger foot well. Then the NAV or PAC unit stays up there with a long set of standard RCA analog runs or fiber optic digital signal runs to wherever you hide your aftermarket amp. The T-harness connects to the factory wire loom running back to the factory amp so you don't have to extend or modify anything. This harness is plug-n-play making it easy to return everything to stock when desired.

Attached are the manuals which show how they connect up. Now if you were adventuresome and handy with wiring you could insert the NAV or PAC unit at the factory amp location by modifying the supplied T-harness but then your cutting factory wiring.