LOC = bass. No LOC = poo. Help? *cry* p.s. - long story

[Roasted 10+ year member]

There are 4 wires on a line output converter. Two positive, two negative. One pair per speaker. Then, I plug the RCA's into the converter, and the other side goes to the amp.

So it kind of goes like this.

Head unit - speakers - line output converter - rcas - amp.

 

[Raven 10+ year member]

Have you mentioned what kind of LOC you used?

Simply put, HUs put out a LOT more power to speakers than to RCA leads. According to PPI, going direct from HU speaker leads to an amp's low input means about four times the amount of power, or roughly 12 dB. If you got a cheap LOC, it could be doing exactly that, explaining the huge burst of output. You could have also damaged the input making it less sensitive.

My guess is this is a fault in understanding how that specific amp's input works. I would also guess that you've got no idea how to properly set a gain (No offense).

 

[Bake 10+ year member]

What is the rated power on your decks outputs? If it is a high power head unit there will be a huge difference between the signals you are sending to your amp. Even after using the loc your amps would get a much stronger signal than what it gets from your preouts. I doubt anything has damaged the input circuits on your amp that made it less sensitive. Solid state electronic circuits usually do not work at all if a component has failed.

 

[Raven 10+ year member]

What is the rated power on your decks outputs? If it is a high power head unit there will be a huge difference between the signals you are sending to your amp. Even after using the loc your amps would get a much stronger signal than what it gets from your preouts. I doubt anything has damaged the input circuits on your amp that made it less sensitive. Solid state electronic circuits usually do not work at all if a component has failed.

When a sub is dying, it's VCs will usually end up having a higher impedance because of heat damage. In the same way, I bet if you heated a resistor, it's resistance would change before it completely failed. All it would take is one damaged resistor to make an amp half as sensitive as it used to be. Sending a direct signal from a HU and cranking the gains and volume could easily do it, IMO.

[/offtopic]

 

[Bake 10+ year member]

I really don't think you could heat a resistor enough to change its physical properties without causing it to fail. I could be wrong. But, I haven't ever seen a resistor change it's resistance enough to effect the circuit that it is in. If heat effected solid state devices as you suggest then amplifiers would get weaker over time with normal use. There are plenty of fifteen year old amps out there that are just as strong as the day they were built.

 

[theCybe 5,000+ posts]

The RCAs you're using from the LOC aren't the same set that are coming from the headunit obviously - RIGHT?

So I say try a new set of RCA from the headunit first.

[shrug]

Why skip a simple step?

 

[Raven 10+ year member]

I really don't think you could heat a resistor enough to change its physical properties without causing it to fail. I could be wrong. But, I haven't ever seen a resistor change it's resistance enough to effect the circuit that it is in. If heat effected solid state devices as you suggest then amplifiers would get weaker over time with normal use. There are plenty of fifteen year old amps out there that are just as strong as the day they were built.

The effects of heat on metals and other materials used in amplifiers is well documented. Yes, you are right that if you take care of an amplifier they can last until the most biodegradable media in them fails. However, part of taking care of them involves avoiding excessive amounts of heat. //content.invisioncic.com/y282845/emoticons/cop.gif.57eb2cc10a7efd04d31083ca3c30d53c.gif I bet most of them don't see LOCs either. =p

 

[Roasted 10+ year member]

The RCAs you're using from the LOC aren't the same set that are coming from the headunit obviously - RIGHT?
So I say try a new set of RCA from the headunit first.

[shrug]

Why skip a simple step?

Okay. I really REALLY don't want to sound like a jerk, but I've said this at least a dozen times already.

Step 1: RCA's are going from my amp to my head unit. Like I said, I'm not getting the output I should.

Step 2: Pop the deck out, unplug RCAs, and take the RCA ends that WERE in the deck and go back to the trunk with them, and plug them into the LOC.

Step 3: Turn on head unit, magically I get great sub output.

Conclusion: I have one pair of RCAs. They are used in both scenarios. This concludes the RCAs are NOT damaged or bad in any way shape or form.

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Going back to a different route, I kind of thought about something. I asked my buddy here at work who used to work for an installation company so he dealt with problems like these. He said he's completely stumped, but the fact that 3 decks have now acted the same way he said sounds like there's something miswired within the actual vehicles harness.

To test his thoughts on this, I figured this is what I could do.

My original head unit, aka head unit number 1 (I've tried 3 now) is now in my girlfriend's car. What I'm going to do is turn my car on so the alternator is running and the remote wire kicks the amp on. Then I'm going to put the RCA wires from HER head unit to MY amp. That way, her head unit is the "brain" that will be sending the signal to the amp... while my head unit turns the amp on being that the remote wire will be activated.

Conclusion: If my old head unit in her car works, which in my car the preouts didn't, then something is beyond f*cked in my car.

 

[Roasted 10+ year member]

Have you mentioned what kind of LOC you used?
Simply put, HUs put out a LOT more power to speakers than to RCA leads. According to PPI, going direct from HU speaker leads to an amp's low input means about four times the amount of power, or roughly 12 dB. If you got a cheap LOC, it could be doing exactly that, explaining the huge burst of output. You could have also damaged the input making it less sensitive.

My guess is this is a fault in understanding how that specific amp's input works. I would also guess that you've got no idea how to properly set a gain (No offense).

No offense taken, but have you know I do know how to properly set a gain, and it has been properly set. In fact I actually had my gain set lower in the first place because I'm at the point right now where I don't want my ears ringing all day and I actually want to hear some music, so I turn the sub gain down a bit to level out the music vs bass portion.

I have no clue what kind of LOC it is. It's an American... something...

It has 6 wires (two pos two neg two ground) and it's black... I got it from Circuit City for 10 bucks. In fact I don't even think they sell them over the counter there, because my girlfriend's cousin just charged me 10 bucks when I was there and got one from the installation room. He said if people specifically ask they sell them, but they don't put them on the floor.

 

[Slody4Futbol 10+ year member]

yeah it's an american international **AI**... did you use a DMM and check the rca's? when plugged into the head unit? and plugged into the LOC ?? i bet the voltage level is higher when plugged into the LOC...

 

[theCybe 5,000+ posts]

Maybe I missed the part where you said you only had one set of RCAs.

 

[Roasted 10+ year member]

yeah it's an american international **AI**... did you use a DMM and check the rca's? when plugged into the head unit? and plugged into the LOC ?? i bet the voltage level is higher when plugged into the LOC...

I don't have a DMM... and wasn't planning on getting one unless this "test" with my girlfriend's headunit in her car failed.

 

[Raven 10+ year member]

No offense taken, but have you know I do know how to properly set a gain, and it has been properly set.

97 times out of 100, improper gains is the problem. Gotta get the most likely out of the way, especially considering you have no DMM.

I'm stumped, can you please just pick up a cheap *** $10 DMM and do some voltage measurements on your RCA outs, Speaker lead outs, and amp? //content.invisioncic.com/y282845/emoticons/tongue.gif.6130eb82179565f6db8d26d6001dcd24.gif

 

[Bake 10+ year member]

You never did say what the rated power of you deck is. If it is high power it will make a difference. And checking the input to the amp with a meter will most likely answer your questions.

 

[Roasted 10+ year member]

97 times out of 100, improper gains is the problem. Gotta get the most likely out of the way, especially considering you have no DMM.
I'm stumped, can you please just pick up a cheap *** $10 DMM and do some voltage measurements on your RCA outs, Speaker lead outs, and amp? //content.invisioncic.com/y282845/emoticons/tongue.gif.6130eb82179565f6db8d26d6001dcd24.gif

I know what you're saying, but I can guaran-fking-tee you that this is NOT the case here.

Reason: When the amp is plugged into the head unit, I can turn the amp's gain up 100% of the way just for testing purposes and I'm LUCKY if I get about 2-3mm of movement in the subwoofer.

Tell me that isn't fked up... It's not right... I just, don't know what else to say. The gain is not the problem here.