Thread: Need help building VW Monsoon amp input

Here come the pictures:

First, the final product, The Monsoon Box:

This is the "output" side. The little DC jack takes 12V power (actually, it powers a 6V regulator, so probably anything above 8V would work), these RCA jacks have about +6V referenced to the ground supplied by the 12V plug. The other (input) side has just two RCA jacks, they don't see the +6V.

Now, the schematic:



Here's the basic idea:
Take a 5V or 6V voltage regulator, attach three diodes to the output. In the second picture I included the diode package so people can see the part number. Notice the polarity indicator on the diode. This way the 5V flows to the RCA jacks, but the signals on those jacks don't come back thru the diodes so they can't cross to the other signal lines.



Take a ground loop isolator and splice the outputs from the diodes into one side of the RCA outputs from the GLI. One diode goes to L+, one goes to R+, and one goes to both the L and R -. If I was doing it again, I would wire up 4 diodes to the voltage regulator output rather than joining the L- and R-. It doesn't actually matter since other parts combine the - lines into a common one.


No, I didn't just tape everything together. Those are but connectors that I covered with electrical tape.

So, does it work? I don't know. A test version of this circuit worked great. This box produces ~5.8V on the output side and nothing on the input side. Before I installed in the car, I was adding a relay to control the 12V input to this box. While testing the wiring for the relay, I smoked my m1-atx. So, I'm ****ed now and I have to deal with that.

NOT QUITE THERE YET! But an install pic:

That's the box on the left, and the relay at the top.

Allright, I burned my m1-atx, but I installed and tested the monsoon box with a portable radio. Sounds great, but the amp doesn't turn off when I pull the 12V input power. It may be because the 12V is the same that provides power to the amp or it may be that I'm completely wrong about needing 5-6V on all inputs (does the multimeter lie?) In any case, I'm going to convert this into a "6V on common -" only box and see if that work. In my tests it sound the same, if I do this, the diodes aren't needed.

Oh, one more thing. How would I verify that the - output lines from the head unit have signal?

Originally Posted by kbyrd

NOT QUITE THERE YET! But an install pic:

That's the box on the left, and the relay at the top.

Allright, I burned my m1-atx, but I installed and tested the monsoon box with a portable radio. Sounds great, but the amp doesn't turn off when I pull the 12V input power. It may be because the 12V is the same that provides power to the amp or it may be that I'm completely wrong about needing 5-6V on all inputs (does the multimeter lie?) In any case, I'm going to convert this into a "6V on common -" only box and see if that work. In my tests it sound the same, if I do this, the diodes aren't needed.

Great!

I built mine today but havent installed it or tested it yet, since i ended up getting a bad sore throat today maybe tomorrow ill install it since i think im staying home from work.

Did your amp turn off instantly when you pulled the power before?

Originally Posted by WebDog

Great!

I built mine today but havent installed it or tested it yet, since i ended up getting a bad sore throat today maybe tomorrow ill install it since i think im staying home from work.

I am as well, but it was planned time off, not sick. You asked for an IM handle in some thread a while back. I updated my profile. IM me if you want to talk about this.

Originally Posted by WebDog

Did your amp turn off instantly when you pulled the power before?

I think so, but I never actually checked. The way I checked this time is to turn off relay but turn the audio source (portable radio) back on. Didn't you post somewhere that if you didn't use a ground on the voltage regulator this happened to you? I'm keeping a close watch on my current draw so I have to be sure the amp turns off. My goal for tommorow is to fix this, or verify that the amp turns itself off after some time.

Finally, I can't find a fuse in the fuse panel for the monsoon amp. I pulled every large fuse (and all the 10amp small ones) on the panel one by one with a multimeter showing 12v the whole time across the wires that supply the amp. Any ideas?

Is the fuse in the amp itself?

Originally Posted by kbyrd

I am as well, but it was planned time off, not sick. You asked for an IM handle in some thread a while back. I updated my profile. IM me if you want to talk about this.


I think so, but I never actually checked. The way I checked this time is to turn off relay but turn the audio source (portable radio) back on. Didn't you post somewhere that if you didn't use a ground on the voltage regulator this happened to you? I'm keeping a close watch on my current draw so I have to be sure the amp turns off. My goal for tommorow is to fix this, or verify that the amp turns itself off after some time.

Finally, I can't find a fuse in the fuse panel for the monsoon amp. I pulled every large fuse (and all the 10amp small ones) on the panel one by one with a multimeter showing 12v the whole time across the wires that supply the amp. Any ideas?

I Know the fuse, its a 20 amp... Ill let you know what one it is later today...

Webdog and I talked and tested a bunch today. The 3-diode 5V on all channels solution is a bust.

Something about the diodes in the 5V path causes the amp to stay on. If you apply a + and a gnd to the voltage regulator and pull the +, the amp turns off. If you apply the same wires but pull the gnd, the amp stays on. It appears the diode is preventing some path to ground that the amp needs to turn off. If you could somehow apply ground after the diodes (but after cutting + to the regulator so you avoid a short circuit!), then this works. We could probably use 3 regulators, but I wonder if the AC signal would cross regulators. I don't strictly need a diode just a "one way gate".

In any case, I'm still using the project box, but I'm just back to a GLI instead of a capacitor and a voltage regulator applying 6V to only the common line of the audio signal. It's alimnh's/r32 juhl's original solution but with a GLI instead of a capacitor to protect the source.

Here is my solution:
I am running the 12v line directly from the power distribution block (under the steering column) to power the 5v regulator. So when the car turns off, the amp automatically turns off and the same line is used to signal the m1-atx to start the shutdown sequence. So this eliminates the pop. The 12v line has an inline fuse. The ground for the 5v regulator is the same groudn as the m1-atx.
Give that a shot.