I had Circuit City replace 4 speakers and add an amp to my C6. The 2 front speakers are now 3.5" Infinity 3012cf (75w) and the back speakers are 5.5" Infinty 5012i (135w). The amp is an Infinity 7541a (656w).

There are a few noticeable problems with the sound and I'm wondering if the installer did something wrong or if any of the equipment/wiring is faulty.

a) The sound has very little bass and way to much treble (even when I turn the bass to 10 and the treble to 0)
b) When the radio is off, there is a high pitched, but not loud, sound that increases in pitch as I accelerate
c) When the car is off and Accessory Mode is on, the music only comes from the dash and sounds totally muffled
d) The dinging sound when I open the door is much louder

Any ideas about what went wrong and how to fix it?

 

Unfortunately, circuit city (along with most electronics stores) simply don't specialize in car audio. The more advanced audio technicians are hired by specialty stores like car toys, or mobile one.


Thoughts

a) The sound has very little bass and way to much treble (even when I turn the bass to 10 and the treble to 0

- the setup you have is going to have this effect. the 3.5" speakers in the front just aren't designed to play much lower than 1000Hz with any accuracy. If you want a more powerful bass sound, replace the 3.5" in the front with 6.5". (custom speaker plate will be required)

b) When the radio is off, there is a high pitched, but not loud, sound that increases in pitch as I accelerate

- I believe this sound is caused by a ground loop. It's a problem commonly associated with poorly grounded amps. I'd check the grounding point of your amp's ground wire and make sure it's a clean connection.

c) When the car is off and Accessory Mode is on, the music only comes from the dash and sounds totally muffled

- This sounds like a bad amp hookup, but might be caused by the stock speakers that weren't replaced and still running off the head unit. (I'm not that familiar with the C6 audio setup so I could be wrong here)

d) The dinging sound when I open the door is much louder

- I have no clue on this one.

 

I had Circuit City replace 4 speakers and add an amp to my C6. The 2 front speakers are now 3.5" Infinity 3012cf (75w) and the back speakers are 5.5" Infinty 5012i (135w). The amp is an Infinity 7541a (656w).

There are a few noticeable problems with the sound and I'm wondering if the installer did something wrong or if any of the equipment/wiring is faulty.

a) The sound has very little bass and way to much treble (even when I turn the bass to 10 and the treble to 0)
They did not hook up the factory subwoofer system.
b) When the radio is off, there is a high pitched, but not loud, sound that increases in pitch as I accelerate (the amp is hooked up to an accessory switch, not remote turn on with the radio, thus causing the amp to be ON even with the radio off (the high pitch sound is the ground loop mentioned by radioflyer before)
c) When the car is off and Accessory Mode is on, the music only comes from the dash and sounds totally muffled (the amp is not hooked up to the same factory Accessory Mode) the factory system plays through the dash - thus proving point (a) - the factory subwoofer system in the doors is not hooked up.
d) The dinging sound when I open the door is much louder (Is the radio ON? I think this is a known issue with going with aftermarket amps, the factory signal also gets amplified...

Any ideas about what went wrong and how to fix it?
(Yes - get a real professional to fix the mess) Sorry, too many issues to get into detailed step by step. I am thinking they did not use the correct wiring adapter for the C6 when adding aftermarket amplifiers and speakers.


Answers in blue

 

They messed it up bigtime. You need to find somebody that knows the Vette's stereo and not idiot kids that make assumption and don't bother to research how screwed up the Bose system is.

 

If the stock source is still in, you are experiencing the volume- dependent eqailization. Due to the fact that the speakers are covered under warranty and GM has no interest in replacing blown speakers there are certain protections built in. The one you're encountering is as you raise the volume, the bass attenuates.

The probably uses LOC's on the outputs of the stock amp which means you also are dealing with the DSP designed to make the $1 cost Bose speakers sound decent. You have changed the speakers and now you have a mis-match.

You really should not be doing business with them anyway, they just fired 3500 of your fellow Americans who they felt should not be getting a living wage.

 

Thanks everyone. Your help is greatly appreciated.

I just realized that they put the amp behind the front seat, so now there is even less leg room on the passenger side than there was before. Is there a better place for the amp in a C6?

 

Better make sure they didn't screw that amp into the wall... isn't the fuel tank in the same place on the C6's as the C5's?

Prey they used a board under the carpet...

Mark

 

a) The sound has very little bass and way to much treble (even when I turn the bass to 10 and the treble to 0)

Your car came with 10 inch speakers and 3.5 " speakers in the doors. They have disconnected the 10" speakers which played the low frequencies in your factory install. If they are still in the doors it might be trivial to reconnect them. If your factory amp is still installed, you can fix this in 30 minutes. Find a post about removing the door panels, and see if you can reconnect them in the door.

b) When the radio is off, there is a high pitched, but not loud, sound that increases in pitch as I accelerate

The whine is your alternator working, but the amp is grounded poorly, so some of the output of the alt is leaking into the sound circuit and it becomes audible. Again an easy fix since your amp is close to a good ground. There is a good ground location under the trim panel on the door frame, just in front of the rear wheels. Loosen the bolt, run a fat wire to the ground (-) of the amp, tighten the bolt. If that doesnt fix it, you will need to find the point where the factory system grounds and try to ground it all at the same point (star ground).

c) When the car is off and Accessory Mode is on, the music only comes from the dash and sounds totally muffled

The music is coming from the factory center channel speaker on top of the dash. Easy fix, ....well it requires console removal so its a simple fix but not as easy as the others. You need to find a 12 volt source that that is running when the accesory mode is on. I believe the best one is the factory wire running to the factory head unit. Its white I think and it will stay powered after shutdown until you open the door. My testing showed that this one stays on to run the fan in the NAV unit so it remained on for roughly 2 minutes and then powered down

Wire the "Remote on" - on the amp to this wire. Installers will typically use a small gauge (blue colored) wire for this job as it is merely a trigger voltage and not a power supply.

The cool part of this problem is that it means you most likely still have a factory amp thats running and can easily re-connect your factory 10"s to get some bass back.

d) The dinging sound when I open the door is much louder

C6 Corvettes use the left channel audio for the audible feedback such as chimes. This is also known as DIC chimes. You might be able to adjust yours to a level you like by searching the C6 forums for DIC chimes. The adjustment is something like holding the "6" button down until the level is right.

If this isnt possible, you want to turn the "gain" down on the amp and use more volume from the factory stereo to provide more signal voltage relative to the DIC chime. This may affect the relative sound levels between the factory powered spekers (10's and center) and your new speakers.

If it were me, I would fturn the gain all the way down so no sound was coming from my new amp. Find some music that is typical for what you listen to, then turn the factory stereo up to find the level that I listen o most often using the 10's and center as a gauge. Then slowly start stepping the gain up so that the new speakers match the sound levels of the existing speakers. Once that is close, then make fine adjustments using the bass and treble controls on your factory system.

 

The folks on this forum are the most helpful I've ever encountered on the internet. Thank you for your help.