I had an 4 channel amp and components put into the front doors of my 2010 Jetta.

The 4 channel amp is set up for each channel to power each door (rear doors have stock components).


My issue isn't with the stock speakers, but rather with the after market ones. I had the gains set to about 75% on the amp and noticed that when I used the cars electrical system I would get static (feedback???) from the front speakers - most notably the tweeters-.

I went back to the installer and they simply recommended that I turn the gains on the front door down to where there was no longer any feedback. This has been fine.. however the issue is that with the gains so low on the AMP to get music "loud" when I want it loud I have the head unit cranked to 32 / 35 clicks.

Is this something that I am just being picky over?

Why would having the gains up (not all the way) have this feedback effect?

Specs on equipment used are:

JBL GTO608C components - RMS - 70 watts - 2 ohms

JBL GT5-A604 amp - RMS 4x 80 watts at 2 ohms / RMS 4 x 60 at 4 ohms



Any advice would be great!

Thanks guys you are the best!

 

first off if the HU has a range of say 0 to 80, there is nothing wrong with 80 being full power/ stupid loud and 0 being silent.

having the gain too high can bring out the alternator whine... are you sure it is completely gone at 0 volume? If there isn't any whine than I say you are in good shape and got your moneys worth as long as the system does what it is supposed to do (balance, L/ R control, volume, etc.)

 

Aslong as the deck itself isnt clipping which any good deck shouldnt but cant be said for all decks

 

When we tested my Pioneer deck with an Oscope and had all bass enhancements turned off, it would go to 40 (full blast) without any signs of clipping.

Then we turned on Loud - clipping @ vol level 38, Turned it off
Turned on BBE (bass management system) with zero gain - clipping @ vol. 39
Turned BBE to +1 - clipping @ vol 36
Turned BBE to +2 - clipping @ vol 31
Turned BBE to +3 - clipping @ vol 25!!!

So then I decided "bass isn't that loud with all this shut off", so I turned on loud and BBE but with no gain. It starts to clip a little around 36 but I only listen to it around 30-34 max.

Depending on your deck settings, the amp could easily be receiving a clipped signal. You have to start with HU, then match amp. Only real way is to get your hands on an Oscope for an hour or so and test, test, test.

 

Doing some investigating last night, it certainly sounds like it is only coming from the drivers side tweeter.
It only seems to happen when I apply some brake (and turn on the brake lights)

The HU is the Kenwood DNX 5140 so a middle ish range HU.. not sure if clipping would be an issue with it.

 

OK what you need to know (and you need to tell your installer) is you have a noise issue not a gain issue. With the symptoms you have described it sounds as if some low level noise is being induced into the system (this is different from typical alternator whine from a bad ground) from your instrument panel (which is also located on the drivers side of the vehicle). This "should" take all of 3 minutes to fix, but it could be more complicated, and they might not have done something... interesting.