[Tech - Audio]Popping Fuses and removing Alt whine

["Brad Sterling" <bgsterling@earthlink.net>]

Hi all,

        Well, I finally got around to installing a pair of amps and a
subwoofer to my 16v.  However, I need help from the electrical/stereo
know-it-alls out there.  One, I keep blowing the five amp quick blow fuse on
the back of the stereo (the stock Heidelberg IV) after about 30-40 minutes
of playing the stereo.  Two, I'm getting some annoying alternator whine.
Here are some details on what I hooked up and how I did it:
* Stock head unit (Heidelberg IV) with stock wiring
* Aftermarket RF CD changer
* Profile two channel, 40-watt amp for the front 4x6s using high level
(speaker) input
* Profile four channel, 60 watt amp for the rear 4x6s and subwoofer using
high level (speaker) input
* 12" Kicker Freeair sub in the spare wheel well running off a two bridged
channels
* Power and ground from the battery posts to a wire block in the hatch via
6ga wire.  40a fuse in line about 12" from the battery (at the shock tower).
12ga wire from the wire block to the amps.
* Wire block has switched power via a relay activated by the Fuba power line
* Everything works fine for 30-40 minutes, then the 5a quick blow fuse on
the head unit pops.  The two times it has happened, it was just prior to a
decent bass beat with decent volume (I had to speak loudly to my passenger,
but not scream).  For the record, the gain on the subwoofer channel is
turned to add enough bass for some bottom end but to avoid thump.
* While I was installing everything, I added a 12ga ground wire from the alt
(90a) to the battery negative post.  Better grounding according to the
voltmeter in the dash, but I thought this was causing my alternator whine
across the speakers.  I moved the ground (temporarily) to the shock tower.
Still the improved ground according to the voltmeter, but the whine was
still present.

Am I overloading the head unit?  I would think upping the amperage on the
fuse would just increase the risk of blowing up the head unit, yes (he
smiles wryly as he displays his electrical ineptitude)?  I'm big into
subtlety and stealth, so I would prefer not to change the head unit.
Perhaps I need to ground the head unit better to avoid the whine?  Any help
would be appreciated.

- Brad
'86.5 Volkswagen Scirocco 16v
'76 International Scout II


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