Amp shutting off with Alpine PXA-H100

[Exiled]

Hope some of the audio experts here can help me out. I recently installed an Alpine Media Receiver to replace my stock head unit and everything went fine. I was able to turn up the volume very high and the amp worked without any problems.

Today I installed an Alpine PXA-H100, which is basically a separate audio processor that tunes the sound to fit each car's acoustic environment.

To do the install I had to flip a switch on the head unit to tell it to use the external audio processor instead of the one on the headunit. The head unit connects to the H100 through an alpine cable and then the RCA cables from the amp plug directly into the H100. The H100 also has it's own separate power and ground wires, I connected these by tapping into the oem wire harness, the headunit also connects to this harness. There is also a switch on the PXA-H100 which can be set to 3-way cross over or front/rear/sub. I have it on the front/rear/sub setting as that was selected by default and gives full range to each channel. The H100 has three pairs of RCA's coming out from it, front, rear and sub. I only have the front rca's connected.

After installation i discovered that the volume was much lower than prior with just the head unit by itself. When I would turn the volume higher the amp protection light would come on at roughly 80% volume. The amp I have is an Audison LRX 250.

I have the amp HI/LO-Pass switch set at Amp:Hi-Pass, Preout:Lo-Pass.
Both the Lo-Pass and Hi-Pass are set on bypass.
Levels (input sensitivity) adjustment is set at 5 on a scale of 10.

The amp is powering a pair of components (Hertz HSK 165). I'm not sure if I have the cross over dial on the amp set correctly but it is dialed at the lowest setting on the amp (40Hz)

Right now I'm not sure what to do as i've tried playing around with the various settings but still get the warning light when the volume is too high. I'll probably take my car to an audio specialist if I can't figure this out with help online.

Thanks for taking the time to read and any advice is appreciated!

 

[RYU]

This will probably an iterative process to find the culprit but i'll give it a shot.

So it looks like your amp is going into protection mode. Have you tried disconnecting the speaker leads from the amp to speakers and putting the volume up high. If it does not go into protection mode then perhaps you shorted some speaker wires.

You can also try removing the H100 and putting it back to the way it was. If it's all fine then the H100 may be the culprit. Perhaps the line level voltage output of the H100 is too high (just a guess on my part).

Basically, the way I use to diagnose these problems is to work backwards and uninstall components until I find the culprit. I also bypass wiring by running new RCAs and speakers wires even if it's just for testing purposes. Sometimes if you're not careful it's easy to screw right into a wire and have that screw ground the wire into the body of the car.

Good luck!

 

[Hapa88]

If you want your speakers to play the full-range (which I am assuming you do), then the Amp filter should be set to Bypass on both Hi-Pass and Lo-Pass.

Based the manual you should be in "Configuration 4" on Page 15 of this manual:
http://www.audison.it/content/eng_lrx2manuale.pdf


The Pre-Out settings are irrelevent because you don't have another amp hooked to this one (so it could be either or Bypass).

Lastly, I assume you have the KTX-H100 IMPRINT Tuning Kit, which includes the microphone, IMPRINT Sound Manager set-up software and a USB PC cable and have gone through the process of doing the tune in the car? I would think the tune would have an effect on the overall output of the PXA-H100 system.

 

[Exiled]

Hey Ryu & Hapa88, Thanks for taking the time to offer your advice!

After reading your replies I spent the better part of the afternoon going through the system and was able to fix the problem. I don't quite understand how it works but basically I had replaced a wire harness adapter that was used with the oem head unit to adapt to aftermarket amp/speaker. I had removed this piece since I had switched to an aftermarket HU to aftermarket amp/speaker adapter instead. This piece allowed the other speaker connections on the Aftermarket HU to connect with the stock wire harness.

For some reason, when the rear/sub speaker channels are connected through the wire harness the H100 would be lower in volume initially and would set off the safety led on the amp at high volumes. But I thought it wouldn't be an issue since there are no speakers connected to those wires.

After putting back the oem-aftermarket adapter it solved the issue by not allowing those connections. Not sure why those connections would cause the amp to shut off but seems like the HU was sending signal to the speakers at the same time the H100->Amp was. So right now im using both an aftermarket/oem adapter and the aftermarket/aftermarket adapter. Oh yah and for the speaker signal from the amp basically I just tapped into the existing wires through the original wire harness. I think that has something to do with it but either way its fixed YAY! and on a side note the H100 made a huge difference in the sound stage! :smile:

 

[syndicate]

Ex,
Are the speakers OEM? If they are, the Alpine Amp is not designed to run at 2 Ohms. The factory Bose speakers are usually 2 Ohms. This causes too much current to flow through the amp and causes the protection circuit to kick in. If the speakers are aftermarket, make sure that the speaker wires are not touching. Another thing to try is to unplug the factory sub harness. The rear speaker is connected through this and there seems to be a common ground in the harness so essentially, you would be grounding out the speakers by leaving this hooked up. If you can snap a pic of the wiring behind the radio, that would help. Good luck.
Jay

 

[syndicate]

Hey Ryu & Hapa88, Thanks for taking the time to offer your advice!

After reading your replies I spent the better part of the afternoon going through the system and was able to fix the problem. I don't quite understand how it works but basically I had replaced a wire harness adapter that was used with the oem head unit to adapt to aftermarket amp/speaker. I had removed this piece since I had switched to an aftermarket HU to aftermarket amp/speaker adapter instead. This piece allowed the other speaker connections on the Aftermarket HU to connect with the stock wire harness.

For some reason, when the rear/sub speaker channels are connected through the wire harness the H100 would be lower in volume initially and would set off the safety led on the amp at high volumes. But I thought it wouldn't be an issue since there are no speakers connected to those wires.

After putting back the oem-aftermarket adapter it solved the issue by not allowing those connections. Not sure why those connections would cause the amp to shut off but seems like the HU was sending signal to the speakers at the same time the H100->Amp was. So right now im using both an aftermarket/oem adapter and the aftermarket/aftermarket adapter. Oh yah and for the speaker signal from the amp basically I just tapped into the existing wires through the original wire harness. I think that has something to do with it but either way its fixed YAY! and on a side note the H100 made a huge difference in the sound stage! :smile:

Oops, just saw this. :redface: