# Very Picky Amp? MRV-1005 RCA Input Issues



## kiwizz (Jul 18, 2010)

I have posted this in the caraudio.com forums too, but nobody responded (noone had an answer?). Hopefully someone here may have an idea. Heres how the story goes:

So, Here is what I am dealing with:

I bought myself a new car (Nissan X-Trail). The new car had a built in navigation system, so I had to pull the audio from the rear speakers and use a step down converter. After connecting everything up, I find that the subwoofer is not working. (Everything was fine in the 95' Jetta)

I have checked everything I can think of. The +12 is good, the remote is good, ground is supposedly good (not too sure how to check this one - connected with short cable straight to chassis) The RCA audio is good, all the cables are fine.

Funny thing is the amp worked a couple times after fiddling with the switches, maybe worked twice, and now wont. The lamp goes on, but no sound. I had a look at the insides and checked to see if anything had fried, but it all seems fine.

Can anyone think of a reason why the amp isn't working? Anywhere I should be looking specifically?

AMP: http://dl.dropbox.com/u/10434/AMP.jpg

UPDATE1:

I connected the amp to my previous head unit and it seems the amp and subwoofer are working fine. This brings me to the conclusion that the hi lo converter or the audio signal are at fault.

Does anyone know of a way to test a hi lo converter with a multimeter? If the hi lo converter is fine, is there any other reason that would prevent the amp from getting a signal?

Thanks again. 

UPDATE2:

I'm going CRAZY!

Looks like the amp wont output sound until it has been connected to the amp out rca jack on my old headunit. If i then remove the RCA cables and connect them to the hi low converter it works! I also connected the hi lo converter to my old head unit and tried it, still no luck. The amp wont start playing unless it gets a signal via the sub out first.

I took it to a car audio installer and he said the amp is probably broken. But it works fine when connected to the preout.... I also checked that the hi low converter was working with another amp, no issues there.

Any ideas on why this would be happening?

Update 3

Bought another high low converter and still no luck. Looks like I need to buy another amp. 


So does anyone know what would prevent the amp from accepting a signal from a high low converter?

Thanks!


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## Coolfreak (May 27, 2008)

Are you sure you have the positive and negative wires connected to the positive and negative of the speaker wires?


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## kiwizz (Jul 18, 2010)

Yes, and It works fine with my old head unit. So it must be something to do with the rca signal.


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## Coolfreak (May 27, 2008)

I am talking about the high low converter. There is no way both converters are bad. And you already know that the RCA cables work since you hooked them directly to your old headunit and they worked fine. So that means you are doing something wrong with connecting the high low converter.


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## jaggerwild (May 21, 2007)

Update one tells it all, your not getting a signal from the new head unit.
By chance, on the AMP internals. Your looking for swollen Capacitors burnt traces on the PCB board, and them black ceramic things will blow right up or just plain melt. Smell it for burnt electronics before you open it up, if it has a smell then you know right away.


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## lcurle (Oct 5, 2008)

You cannot use am amplified signal with a line level converter. Meaning, the stock system has a built in amplifier and is already producing a high level signal. If you are using a LOC it will not read the impedence from the stock speakers, you have to find the amplifier and tap into the high level inputs pre-amp.


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## kiwizz (Jul 18, 2010)

Thanks for all the replies! If I use a different amp (the shop guy let me test one) the audio is fine, meaning the head unit and high low converter are also good.

This means that there is something that is preventing my amp from being 'compatible' with the high low converter. Everything else works - it only stops working when connected to the high low converter.


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## lcurle (Oct 5, 2008)

I had an Alpine MRP-1000 do that to me as well, just had to swap it out and use the High LEvel Inputs on the amp instead of the RCA's


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## kiwizz (Jul 18, 2010)

The amp has no high level inputs, only rca input


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## lcurle (Oct 5, 2008)

what type of LOC are you using and can you adjust the impedence?


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## kiwizz (Jul 18, 2010)

I have tried the Boss B65N :http://www.onlinecarstereo.com/CarAudio/p_20050_Boss_Audio_B65N.aspx and the BOSCHMANN BA-20.

Both work fine with the other amp.


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## lcurle (Oct 5, 2008)

ok, what you need to do is find the speakers wires that are coming from the head unit, not at the speaker. I think that vehicle has a factory amplifier for the door speakers, so the LOC will not pick up the signal. You are trying to take a signal that has already been amplified and get the low end of it, but you cant.
Like you said in a previous post, everything works fine with the RCA out on your old head unit, so your equipment is fine, signal issue is what we need to fix.


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## kiwizz (Jul 18, 2010)

I apologize if I failed to explain clearly enough. The High/Low converter is connected to the wires coming out of the head unit (not from the speakers & there are no additional amps). Also my new head unit & high/low converter work fine with a different amp.


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## lcurle (Oct 5, 2008)

if you swapped the amp out with a different one using the same connections, then the only variable is the amplifier.


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