Please help with alternator whine in speakers and popping noise when powering on/off.

[aod]

Originally Posted by scottfab

Sure sounds like a fly-by-night operation. If the new setup does the same thing as the old and you still want to proceed, you're going to have to design the thing yourself. This means more than just isolating the differential drive circuit but possibly isolating some grounds too. The other alternative I've heard others do is dump the Bose and go with a whole new system. It's sure on my list of possible improvements. I just hate having to mess with stock dash looks.

Strange thing is that Metra isn't a fly-by-night outfit. They make a lot of different things and have been around for quite a while. Unfortunately, it just seems like Bose systems don't like to play nicely with anything else which isn't too surprising I guess. I would like to keep it as factory as possible other than updating the head unit so I'm going to do my best to make this path work. Especially since I've already spent $320 getting all the amps in the speaker pods repaired. And to be honest, the factory speakers do sound quite good.

[secondchance]

Scottfab,
I stand corrected. It has been a while since I graduated - yes, it is microfarad.
My first enclounter w/ alternator while was in 1980 when I installed Mitsubishi electronic head unit w/ 4 channel, 100 W Mitsubishi amp in my first Corvette - 1979 L48 car w/ mighty 185 horses.
I rewired hi-fi unit a dozen times over in 12 months period trying to rid the system w/ the whine. Eventually, one of the installers I was talking to suggested running a capacitor. This solved my issue.
I ran into a same problem w/ my 94 Z. All I know is it worked. $5 and 10 minutes is worth a try.
Ground loop isolators solved my popping issue as well.

[secondchance]

Originally Posted by scottfab

As for "ground loop isolators" otherwise known as signal transformers this may help but .... I'd be pissed at the harness manufacturer if this is so since they claim to be compatible with Bose. I do think this is the case here and is why I asked for a wiring diagram from the vendor to be posted. Generally I think this is a fly-by-night vendor just scooping up $ for a piece of crap. I'm waiting the hear what a new head unit and harness does. (as was posted)

My understanding of why the pop occurs at turn on or turn off is due to the amp reading voltage dirrence at ground point as various electrical equipment shuts off and confusing this with audio signal (I am no expert but this is my understanding from reading internet postings). Solution would be to shut off the amp before the head unit but w/ radio/amp being connectedour "courtesy" circuit made this solution tough. Again, GLI solved this annoying problem.

[aod]

Update: It needed ground loop isolators. Once those were placed inline, it took care of all the popping issues as well as alternator whine. It seems like a kludge to me, but the system sounds good now. Thanks for all the ideas and help!

[secondchance]

Originally Posted by aod

Update: It needed ground loop isolators. Once those were placed inline, it took care of all the popping issues as well as alternator whine. It seems like a kludge to me, but the system sounds good now. Thanks for all the ideas and help!

Glad it all worked out.

[scottfab]

Originally Posted by aod

Update: It needed ground loop isolators. Once those were placed inline, it took care of all the popping issues as well as alternator whine. It seems like a kludge to me, but the system sounds good now. Thanks for all the ideas and help!

Well that pretty much proves the harness you bought is a poor design and that the claim about comparability is false. A well designed adapter would have included isolation (either optical or transformer)
AND they would have actually plugged it into a Bose system and found the noise issues.
It comes as no surprise to me that just running a single ended source into a differential amp input would have issues. Apparently this is what the harness tries to do. Pretty fly-by-night if you ask me.

[aod]

And alternator whine is back. It came back last night while just driving around. It doesn't pop when turning on or off though. Can these ground loop isolators go bad? I'm worried the alternator is on its way out but hoping for just needing to replace those isolators.

[secondchance]

Originally Posted by aod

And alternator whine is back. It came back last night while just driving around. It doesn't pop when turning on or off though. Can these ground loop isolators go bad? I'm worried the alternator is on its way out but hoping for just needing to replace those isolators.

First, turn the volume down to zero. Do you still hear the whine with engine idling? If yes, get close to all 4 speakers and see if you hear the whine on all four or one or two speakers. If you hear the whine on one speaker, disassemble and scrape 6 pins on the amp where the harness plugs in. You might have poor connection.

Good luck!