Hope someone out there can help. I have a stock BMW HU but have added Mac Amp for front and rear Focal Speakers and a JL Audio amp for the JL Audio sub. The sound was weak so I recently added an Audio Control DQX EQ. The sound is pretty good, haven't finished tuning it, but now I have a problem. At initial start up the system is scratching and pops but goes away. Also having engine whine. Took it back to the shop today and they fooled with things but have not figured it out. Audio Control wasn't open for them to get some advice. Anyone out there have any ideas? Thanks for your reply.
Sounds like either the audiocontrol unit is defective and introducing noice (try bypassing it with a pair of RCA barrell connectors) or you have a bad set or RCA lines somewhere, or most probably, you have a bad ground somewhere causing a ground loop.
Well if I could get the manual to download I would tell you how to fix it. The DQX has a setting that adjust the signal that goes over the sheilding of the rca. The reason they did this is that some amps and head units use this to produce a ground loop. (It was a while ago that I read this so my memory is a little scratchy) I am guessing that the DQX is set wrong for your amp or headunit and you need to change this setting to the other config. Look thru your manual, and you will find what I am talking about.
Thanks GlassWolf and Jeremy! I know the shop traded out the DQX thinking one may be defective but the noise continued, so I don't think that the unit is the problem. How would I have the shop track down a ground loop? THey say they looked at that and still can't figure it out. The shop has the manual but I will try to download it to read and see if I can figure it out.
I don't know of how you check it. I would just swap the setting and see if it fixes it. I will try to download the manual again tonight. That is the same processor I am putting in my car, so I want to know myself.
Something else to check is that the line output converts are adjusted corectly. In the manual it tells how to adjust the input sencitivity of the unit to match the output of your headunit. They may have the lineout converters set to high causing some of the problem.