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Discussion Starter #1 (Edited)
Equipment:
(2x) 1995 Subaru Impreza WRX's
(2x) Oxygen O'car HU
(2x) Alpine KTP445 amps

Alpine KTP445 is a class D amp placed between the HU and the car's factory radio wiring harness.

I cut and soldered the KTP445 in place between the deck and factory harness on both amps identically since they are the same HU and same vehicle. So now I have 2 identical amps wired up to identical wiring harnesses to identical decks in two of the same make, model, year cars.

Installed HU#1 and AMP#1 into car #1 (Black WRX wagon), sounds fantastic.
Installed HU#2 and AMP#1 into Car #2 (White STi sedan), no sound from speakers. but deck powers up

Installed HU#2 and AMP#2 into Car #1, Sounds fantastic.
Installed HU#1 and AMP#2 into Car #1 sounds fantastic.
Installed HU#2 and AMP#1 into Car #1 sounds fantastic.
Already know HU#1 and AMP#1 work great.

Installed HU#1 and AMP#1 into Car #2, NO SOUND. but deck powers up
Installed HU#1 and AMP#2 into Car #2 NO SOUND. but deck powers up
Installed HU#2 and AMP#1 into Car #2 NO SOUND. but deck powers up
Already know HU#2 and AMP#2 = NO WORKY but deck powers up

SO all combos work in Car#1 and NO combos work in car #2, I think it must be the car that is causing the problem. I look for blown fuses. Find nothing wrong, switch fuses around. No difference.

I test speakers at different location in the stream to find the source:
@ door = NO SOUND
after AMP but before factory harness = NO SOUND
After HU but before AMP = SOUND PLAYS ... WTF?

I get out my multimeter and start testing wires:
After HU but before AMP = constant yellow works, 12V ign work, blue/white remote turn-on works (reads 12v), all speak wire (read 6.5 V for each +/-)

After AMP but before factory harness results = constant yellow (12v), Red ign (12v), blue/white (12v), all speaker wire + read 2.5v and all - read 0.03v.

If I plug that same Harness/AMP/HU combo back into Car #1 it works fine.


WTF, WTF, WTF? I've been working on this for 2 days and I have been pulling my hair out. I'm out of ideas and am going to beat something with a hammer.

HELP PLEASE.




EDIT: video detailing the problem ...

http://www.youtube.com/watch?v=gq9VequIDOc
 

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Napoleon of DIYMA
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stupid question, does the factory deck was working before in car #2?
 

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I test speakers at different location in the stream to find the source:
@ door = NO SOUND
after AMP but before factory harness = NO SOUND
After HU but before AMP = SOUND PLAYS ... WTF?

I get out my multimeter and start testing wires:
After HU but before AMP = constant yellow works, 12V ign work, blue/white remote turn-on works (reads 12v), all speak wire (read 6.5 V for each +/-)

After AMP but before factory harness results = constant yellow (12v), Red ign (12v), blue/white (12v), all speaker wire + read 2.5v and all - read 0.03v.

If I plug that same Harness/AMP/HU combo back into Car #1 it works fine.
If you are getting no output from the amp, but it does power up, then it has to be a signal issue between the deck & the amp. Either that, or there is another harness unplugged someplace in car #2.


Does car #2 have an OEM amp? If so, you may have to bypass it and wire the speakers directly to the outputs of the Alpine amp.
 

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Discussion Starter #4
stupid question, does the factory deck was working before in car #2?

There was no factory deck. It is an STi RA, it came with a piece of plastic where the deck should be.


If you are getting no output from the amp, but it does power up, then it has to be a signal issue between the deck & the amp. Either that, or there is another harness unplugged someplace in car #2.


Does car #2 have an OEM amp? If so, you may have to bypass it and wire the speakers directly to the outputs of the Alpine amp.
No OEM amp. The outputs of the KTP 445 are the ones that don't work.
If I put the speakers on the wire before the amp they play. If I touch them after the amp they do not play. The amp is the point where the signal is lost.
 

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Napoleon of DIYMA
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Have you try different RCA in car #2?
 

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bad speaker wire going to the speakers causing a short. check for any shorts after the amp using the multimeter for continuity and resistance.
 

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There was no factory deck. It is an STi RA, it came with a piece of plastic where the deck should be.
I don't know why, but being an RA, you may have to wire each speaker individually (KICK ASS CAR BTW, closest I am to RA is gears in my RS trans:laugh:)

Try a speaker on a small length of wire to see..

Being the light model without any stereo, they may have done something funky... I don't know, but I would love to poke around for a few days on it.. :D
 

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No OEM amp. The outputs of the KTP 445 are the ones that don't work.
If I put the speakers on the wire before the amp they play. If I touch them after the amp they do not play. The amp is the point where the signal is lost.
I'm gonna agree with Aaron'z - try running a piece of wire from the output of the amp directly to the speaker(s), bypassing the harness in car #2 entirely.

There has gotta be something simple (possibly unique to car #2) being overlooked.
 

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Discussion Starter #9
Have you try different RCA in car #2?

There are no RCA's as this is not a typical amp install.

bad speaker wire going to the speakers causing a short. check for any shorts after the amp using the multimeter for continuity and resistance.
How can this be if I am testing the speaker on the wire directly between the amp and the factory wiring harness.

I don't know why, but being an RA, you may have to wire each speaker individually (KICK ASS CAR BTW, closest I am to RA is gears in my RS trans:laugh:)

Try a speaker on a small length of wire to see..

Being the light model without any stereo, they may have done something funky... I don't know, but I would love to poke around for a few days on it.. :D
Tried that. I'm in New Brunswick Canada if you want to drive to poke around it.




I'm gonna agree with Aaron'z - try running a piece of wire from the output of the amp directly to the speaker(s), bypassing the harness in car #2 entirely.

There has gotta be something simple (possibly unique to car #2) being overlooked.
I have tried testing speaker on wire directly before and directly after the amp. It works before the amp but not after (but only does this in one car, in the other car it works at both places).





* I AM UPLOADING A VIDEO TO YOUTUBE THAT MAY HELP GIVE A CLEAR PICTURE*. It will be loaded in an hour.
 

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How can this be if I am testing the speaker on the wire directly between the amp and the factory wiring harness.
The factory never screwed up wiring in a car? they had no way to test it. You probably got a wire crossed when you soldered it up. your harness or the factory wiring is to blame. and if you're testing with the factory wiring still hooked up, then you're not really testing.

I have tried testing speaker on wire directly before and directly after the amp. It works before the amp but not after (but only does this in one car, in the other car it works at both places).
disconnect from factory wiring then test again.
 

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445's can be a pain. I've put in probably 15 of them and had lots of issues. The primary issue they have is that they are VERY sensitive to power supply and ground. I've gotten to the point where I will always run a 10awg power to the battery and a good ground (not the factory ground). In every occasion that I have had issues this has cleared it up.

I am assuming of course that you have checked speaker impedance and more importantly ground shunts on your speaker wires. 445's will shut down outputs if there is a ground shunt. They also don't like 2 ohm impedances (ala JBL/Infinity) without new power and ground.

Hope this helps. Let me know.
 

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Factory wires might be grounded or shorted, causing the alpine to protect/turn off. If any one of them is, it could protect the entire amp. Would try like they say with only your speakers direct to the amp don't hook up any of the factory wires. If so trace down what is up with those, test factory wires for grounds (should not be any), crossed/connected wires, etc. If used car who knows what someone else did I've run into that also.
 

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Discussion Starter #17
445's can be a pain. I've put in probably 15 of them and had lots of issues. The primary issue they have is that they are VERY sensitive to power supply and ground. I've gotten to the point where I will always run a 10awg power to the battery and a good ground (not the factory ground). In every occasion that I have had issues this has cleared it up.

I am assuming of course that you have checked speaker impedance and more importantly ground shunts on your speaker wires. 445's will shut down outputs if there is a ground shunt. They also don't like 2 ohm impedances (ala JBL/Infinity) without new power and ground.

Hope this helps. Let me know.
The speaker is a 4 Ohms alpine so I'm guessing that is about as compatible as possible.

I do NOT know what a 'ground shunt' on a speaker wire is.
 

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Discussion Starter #18
Factory wires might be grounded or shorted, causing the alpine to protect/turn off. If any one of them is, it could protect the entire amp. Would try like they say with only your speakers direct to the amp don't hook up any of the factory wires. If so trace down what is up with those, test factory wires for grounds (should not be any), crossed/connected wires, etc. If used car who knows what someone else did I've run into that also.
How can I test without ANYTHING attached to the factory harness? The HU would not turn on? I don't have the capabilities to bench test it (no inverter).
 

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No worries on the test bench. Your process of elimination was perfect and fortunate that you have 2 identicle vehicles and 2 identicle setups. You have already eliminated the head units and amplifiers by your prior testing.

You now know that the issue is on the car side of the equation. If you have the ability to "temp up" a better power supply and ground, I encourage you to do that.

Make sure you check for ground shunts on all eight conductors of the four speakers.

Step 1) Unplug the factory harness from the deck/amp combo.

Step 2) Set your multimeter for the continuity setting.

Step 3) Ground the black test probe.

Step 4) Test each of the eight speaker wires with the red probe. If you get beeping from the meter on any of the speaker wires you have a ground shunt. You will need to pull that speaker out and make sure the wires are not touching metal.

Step 5) Plug the amp deck back in and test.
 
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