Contour Enthusiasts Group Archives Forums Modifications Audio Wiring question. Help!

Ok, here's my situation. I have a pretty decent system in my car. One four channel for the doors, and the other 2 channel for sub. This 2 channel amp is a PPI amp. Now, my problem is - is that I have a MTX-6000 dual voic coil sub. How I originally wired it was each voice coil to each channel. All of the sudden the PPI amp shorts an the red light (protect) system kicks in. However, when I unhook one of the voice coils the amp works fine. Even in bridged mode. What I dont get is Why doesnt it work with both channels hooked up - one to each voice coil? Please help!!

oh oh. Could be a the voice coil is shot. Did u try doing this to each voice coil or just the one? By the way is PPI anyways? They are that brand made by Viper isn't it? We got some books into the store they look really good but expensive hehe.

First, is your amp mounted upside down or somewhere it can't radiate heat? Make sure it can radiate the heat it generates.

Second, what is the impedence of your sub? (dual 2,4, or 8ohm coils). Make sure your amp is stable at the load you're running.

Third, check your ground (sand off the paint, make sure it's a good spot, etc).

I don't want to hijack this post, but I have a question too. My amp just quit on me the other day. It's a JBL P80.4. The manual says "the total impedance of the speaker system connected to the amplifier in bridged mode must be at least 4 ohms in bridged mode".

In each door I had a 4 ohm mid and an 8 ohm tweet connected in parallel and bridged to the amp. They add like resistors don't they so 1/4 + 1/8 = 1/R. R would equall 2.666. When I measured the resistance through the setup with the multimeter I got something like 4.6.

Did I fry my amp, or was the amp bad or am is my understanding of this flawed, and is there no way to run my amp bridged with these speakers?

The amp was working for about 2 weeks with the prior wiring scheme. All grounds/power connections are correct and in working order. I tried hooking each voice coil up individually and it worked. The amp ONLY shorted out when Both voice coils were hooked up to each channel.. The amp is mounted flat on the rear fold down seat. Heat would not be an issue becuase it wont even opperate right after turning it on.
Impedence of the sub is 4 ohm. In other words 4 ohm each voice coil. The amp is a 2 channel amp made for 4 ohm operation, but is 2 ohm stable. So after answering your questions I am still left baffled.
Any other ideas? I hooked each voice coil sperately to each channel, one at a time. It all worked. The only thing is - is that it wont work when both voice coils are hooked up..
Thanks for the help as of yet, but still need more!! Thanks fellas

Hrmm... wierd..i can ask our tech today if i remember but if it was me i would take the sub and amp back to wherever you bought it and get them to test it out.

Actually, I don't think that is quite right. You mids and tweets weren't wired in parallel, the crossover you installed would take away the parallel effects. What you ended up with was a 4 ohm load under 2000hz and an 8 ohm load above it.

You should have been ok with the setup. If I understand your setup correctly, you bridged the amp to two channel mode, correct? This should be sending 160w to each of the component sets. 160w under 2000hz, 80w over 2000hz.

It looks like you've got everything hooked up correctly. I really can't see any other issues besides a possible defect in the amp.

I'd try one more thing. Hook up the voice coils in series, which will end up as an 8ohm load. Then, bridge the circuit to the rear channels. This will result in the same output as 4ohm stereo (what you're trying to do).

Thanks for the reply Dave, you are absolutely correct as to how I wired everything. I guess I forgot about the crossover. I am just trying to make sure I didn't break that amp myself. It was running fine for several short drives, then I go out and start my car and the amp wouldn't put out anything eventhough it was getting power.

It's getting fixed by JBL right now. I just don't want to have it go bad again. I suppose it was just a bad apple.

JE

Thanks for the reply Dave, you are absolutely correct as to how I wired everything. I guess I forgot about the crossover. I am just trying to make sure I didn't break that amp myself. It was running fine for several short drives, then I go out and start my car and the amp wouldn't put out anything eventhough it was getting power.

It's getting fixed by JBL right now. I just don't want to have it go bad again. I suppose it was just a bad apple.

JE