ground noise in dvd playback, please help

I started getting ground noise yet again even with a ground loop isolator. Ive tried everything I can possibly think of to eleminate the problem and nothing is working. The ground noise is much worse with actual DVD's rather than VCD's or CR-R/RW. Its hardly noticeable when playing a VCD. So far ive tried new rca's, new fm modulator, new dvd player, 3 different grounds.(seat bolt, frame, and my distribution block which is bolted to the frame as well) My ground right now is back on the seat bolt which has been cleared of all paint and is bare metal. I chose the seat bolt because it keeps the ground around 5" rather than running to the other side of the car to the distribution block and having a 2' or longer ground. I have no idea... any suggestions would be much appreciated. Thanks

Did you isolate the power & the RCA wires from each other? Also, are you using an amplifier in this system?

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Jeff
Velocity Custom Home Theater
Mobile Audio/Video Specialist
Morden, Manitoba CANADA

I have the power and RCA run on different sides of the car so I wont have this issue. The only place there are power and RCA together is behind the deck where the FM Modulator is attached to the factory headunit (maybe 6" long). Im using an audiobahn 1200W 2CH amp for my 3 JL 10W6 subs. Today I tired a RCA style ground loop isolator and it didnt do much. I also tried a power style ground loop isolator from radioshack(it hooks into the power/ground) and it cut down the noise almost to nothing. Im pretty happy with it now but it would still be nice to figure out whats causing this.

Try looking for a better 12 volt source.  Some have engine transient bleed over.  I use an o-scope to find the best source.  They are fairly expensive, try using a friends or ask an install shop.  If all else fails, use an UPS.