Wrapper

[captainobvious]

Originally Posted by analogrocker

I installed my miniDSPs about a week ago. I am impressed by the sound quality, but I have run into a snag and that is I get a turn-off thump through my sub amp when turning my car off. I do have the miniDC Isolator installed, which I thought was supposed to eliminate thumps. Well, it doesn't in my case.

If I connect the rca interconnects directly from my HU to my amp, I get ZERO thump when turning off the system. Same thing without any interconnects connected to the amp - no thump. It's definitely not a grounding issue with the amps either. I even tried connecting my remote turn-on lead to different sources, isolating it from the miniDC altogether and that still didn't fix the problem. So I rule out the remote turn-on line as the culprit.

The only thing I can think of that's going on is that when I turn off the car, the amps are signaled to be turned off by the miniDC Isolator like they are supposed to, then the miniDSPs turn off (like they should), but what's most likely happening is that the amps are not fully turned off yet when the miniDSPs turn off. So when the miniDSPs turn off, the thump is getting amplified and played through the subs. In other words, it's most likely a timing issue with the miniDC Isolator or it's the fault of my amp(s) not turning off quick enough.

As for the output voltage... Well, it seems to be adequate. I could probably live without a line driver.

Do you get a turn-ON thump or noise when using rcas direct to the amps? If not, then turn-on and turn-off are not an issue for you and you should be able to bypass that feature by using splicing the remote lead from the head unit and running it direct to the amplifiers as well as the minidsp's. (Foregoing the remote output that you would have used coming off of the minidsp units). You should still have the power isolation, yet avoid using any of the delay circuitry designed for the remote lead then. The only hiccup I could see here is if you get a turn on noise once you set it up this way. In that case, you could simply use a relay on the remote lead before it hits the amplifiers. Commonly found on eBay for a few bucks.

EDIT:
As for the line driver, my minidsp units will be inches from the amps so there shouldnt be much distance loss in the cables. The deck doesnt have the strongest rca level outs though either (80PRS) so I picked up a Phoenix Gold line driver to ramp up the signal from the pair of source RCA's running to the minidsp's which should help to avoid any extra noise on the input side. $40 on ebay from a seller. You can find deals like this if you look around.