Sub amp trips up HU. :(

duanebro

I have an old JL audio amp, e2150, from way back. I hooked it up in my car and it still works. But the car doesn't like it. If i have the high level input plugged in when turning the car on it disables the speakers and tells to take the car in for service. Once it completes its check I can plug the input in and everything works fine. I have a 2022 outback with a base audio system.

I have posted this issue on several car audio forums where the overwhelming response is that I need load resistors. However my understanding is that load resistors are for when you remove the speakers to load the amp.

I am adding the amp's high-level inputs in parallel with the speakers. This is adding a 5k ohm load in parallel with the speakers. I don't see how load resistors can be added.

I think that the amp is causing some sort of distortion that the hu is detecting.

dynamo

I’d be curious if a standalone line out converter did the same thing. If no then you could just use that instead of the amp high level inputs; not sure if you have one laying around to try..

Wolf

The Axxess converter units have transformers in tow, and can be seen as isolated by the car and not trip the sensor.

DrewsBrews

How long for it to complete the check? wonder if something like this could work to delay connecting the input..
https://amazon.com/Delay-Timer-Relay-Self-Locking-Switch/dp/B07ST3W48G/ref=asc_df_B07ST3W48G?tag=bngsmtphsnus-20&linkCode=df0&hvadid=80608076993778&hvnetw=s&hvqmt=e&hvbmt=be&hvdev=c&hvlocint=&hvlocphy=&hvtargid=pla-4584207595449868&psc=1

Kindof a brute force method, but if all else fails..

jhollander

The JBL must show a lower impedance that 5K when testing. The Suby wire harness should have a line out connection for the subwoofer.

https://parts.subaru.com/a/Subaru__Outback/_52016_6022339/AUDIO-PARTS-SPEAKER-WOOFER/B14-862-03.html

duanebro

I am planning on replacing the amp. I would like to avoid using a LOC if possible. I just wanted to post this here to make sure I wasn't wrong. I am having a hard time figuring out which brands have clean high level inputs.

dynamo

If you are adding a sub you may want to consider a clean sweep or audio control type device to restore missing bass (maybe not if the harness has a sub output like John said) because it seems in my experience it’s not unusual for new oe audio systems (even base ones) to limit actual low bass and appear to likely employ psychoacoustics like missing fundamentals, etc, as well as rolling off the bass as volume goes up to protect the factory speakers.

Bryan@MAC

@duanebro i have a an AudioControl LC2i if you're interested. I could probably let it go for $40??

dcibel

FWIW a high level input is truly just a low level input with an additional voltage divider, possibly a couple protection diodes.

Here's a schematic for the input section of an old "SUB-250" plate amp, Rin+/- is the high level input, just a couple resistors and it's then connected directly to the low level input circuit.

duanebro

@dynamo said:
If you are adding a sub you may want to consider a clean sweep or audio control type device to restore missing bass (maybe not if the harness has a sub output like John said) because it seems in my experience it’s not unusual for new oe audio systems (even base ones) to limit actual low bass and appear to likely employ psychoacoustics like missing fundamentals, etc, as well as rolling off the bass as volume goes up to protect the factory speakers.

I checked the base roll off by sweeping at increasingly higher volumes after replacing the speakers. I saw no compression even at max volume. (Which is shocking)

duanebro

@Bryan@MAC said:
@duanebro i have a an AudioControl LC2i if you're interested. I could probably let it go for $40??

I picked up a JBL A600. I will try this one out to see if it does the same thing. (Free returns on amazon if needed).

duanebro

I hooked up the JBL A600. Works great. The car doesn't freak out like it did with the old amp.