R32 JUhl

A bridgeable amp is different from BTL. Bridgeable means you can take an amp that has 2x40 W outs and bridge them together for 1x80 output - like to drive a sub.

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kbyrd

I though they were the same thing. A 2 channel amp has four ouput terminals, L+, L-, R+, R-. A non-bridgeable amp has the signal on the L+ and R+, varying the voltage while both - terminals share a common ground, usually the same ground as the amp itself (0V). With a bridgeable amp, the L+ will contain signal while and the R- will contain an inverted right channel signal. To use an amp like this in bridged mode, you connect the L+ and R- only to a single speaker. If you fed the amp a mono signal (with a Y connection or whatever), you would end up with a the single channel's signal on L+ and an inverted (180 degree out of phase) on R-. I thought this was what BTL was.

The problem I can see is that the head unit doesn't vary voltage around a 0V reverence, it varies it around 6V reference. Also, based on that thread for vwvortex, the amp expects all the inputs to be BTL around 6V. It just happens to look for 6V on one of them for a turn-on signal.

Searching I found several circuit type parts that do BTL (I think around 6V), but nothing in a nice neat package. Am I being nuts. Does your solution or the one posted here accomplish the same thing. What are the output specs of the headphone or line out jack of the average PC soundcard?

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alimh

KByrd,

I was tyring to figure out the same thing about a couple of months ago. Here it goes:

The Monsoon HU puts on a differential output ot the Monsoon Amp. This is explained in the diagram below:

Now, all this means is that it is easier (less loss) to carry a signal over a long distance if it is differential. Although, it really doesn't have to be. Proven, because my setup works and does not have differential outputs. The problem is, it is a bit noisy. Maybe R32Juhl can still help us out with this. I figured out that the 5v signal (in my original diagram) is introducing noise... and specifically, it is engine noise AND harddrive noise. I can hear both the spark plugs firing and harddrive spinning. I put a capacitor to try to reduce this but haven't had time to really play aroudn wiht it. If I do figure out how to do it, I will definately post.

As far as BTL, I had never heard of that so I googled it and I found several definitions (all applying to audio applications) for what it means and refers to.

BTW: The monsoon baises the outputs to 5v since this is the required voltage to turn on the logic circuits in the monsoon amp.

kbyrd

I'm sure it turns on at 5V, but I think the actual head unit biases to 6V. It's got a 12V source, and it's supposed to be half battery voltage. There's probably some slop there.

Thanks for the explaination. I'm convinced I can't buy a device that will supply this, I need to build the circuit here or R32 Juhl's version. Problem is, I'm new at this.

So I don't hijack this thread, I started a new one in the car audio section. Thanks for any help. Please post replies there.

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