# Noiose floor "hiss" sound from LOC.



## Aarmin (Mar 22, 2009)

*Noise floor "hiss" sound from LOC.*

I have a premium (not those cheap versions) Line Output Converter. It allows me to use my OEM head unit to convert to RCA cables.

From volume 0 (no music sound) to as high as I wish to go I get a constant "hissing" noise. This is a big let down, because this is why I installed the LOC in the first place, to use RCA cables.

Is this normal for LOCs? JL Audio CleanSweep, AudioControl, Phoenix Gold... ?

I unplugged my RCA cables, and the noise goes away.
I re-grounded my LOC to the headunit ground. No better.

Sadly, the hiss sounds the same, or even worse, than when high had my speaker level inputs connected directly to the amplifier. 

And on a final thought, the LOC I am using is: Maxxsonic MX-1; could it be that the MX-1 just is not that good (I can't find any reviews)?


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## Aarmin (Mar 22, 2009)

*Re: Noise floor "hiss" sound from LOC.*

What is a good input level control for a OEM head unit (speaker level inputs)? I measured 7volts, so I adjusted my LOC to 7v input, and 4v output (within my amps range).

Shouldn't a quality LOC minimize white noise (hiss)? Anybody here use a LOC?


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## diamondjoequimby (Jun 30, 2009)

what kind of car is it in?


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## Aarmin (Mar 22, 2009)

2005 Honda Accord; none premium audio (no factory amplifiers).


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## Aarmin (Mar 22, 2009)

This means a LOT to me, so please help me out here 

White noise sounds like this: SimplyNoise.com - The best free white noise generator on the Internet.

Just curious, how do you guys set your gain (as in to avoid this noise) from OEM to a LOC? I measured 7volts on my speaker-level-inputs.

Apparently, another user from another forum, said if the JL Audio Clean Sweep is installed and configured correctly, this would minimize or illuminate the white noise. Now I'm thinking about dishing out some more $$ for a Clean Sweep.


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## BassAddictJ (Oct 1, 2009)

is the hiss from the alternator? does it change pitch as you rev the engine?

ive had cases where no matter what i do i just cannot get a background noise to stop even though all connections throughout the system were solid. try an rca in line noise filter from walmart for 8 bucks, if that doesnt work take it back and get a inline noise filter for the power/ground of the LOC and see if that helps. these filter can be had off the internet for 20 shipped.


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## PaulD (Nov 16, 2006)

I downloaded the pic and enlarged it. Looks like it's also a crossover as well. Try turning down the knob on the bottom left that says F & R input, then turn down the knob on the amp that says gain or sensitivity on it. Turn both all the way counterclockwise, then try both at maybe 1/4 to 1/3 of clockwise.


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## diamondjoequimby (Jun 30, 2009)

I am sure there is a gain setting tutorial somewhere on here.

If I am doing it by ear (which I try do do as little as possible for gains) turn LOC and amp gain all the way down, then the H/U to ~75% volume, and start to bring the amp gain up. If you can't get enough out of the amp slowly bring up the gain on the LOC until you do. If this brings noise into the system, drop the gain on the amp until the nosie is gone, then bring the LOC up until it sounds correct or until you get a hint of noise, then back off the LOC a bit.

Usually I use the r-shack amplified speaker method w/ a test tone...that way you can maximize the unclipped output of each component.


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## MiniVanMan (Jun 28, 2005)

It's a gain matching problem, and depending on the transformers used to do the ground isolation in your unit, you could very well have even less gain potential than you think. Start around .5 volts output and work up from there. Once you have a good output setting then match your amps.

Could take a bit to find your sweet spot, but it should eliminate most of the noise you're hearing.


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## Aarmin (Mar 22, 2009)

Took the advice to turn my input level on the LOC all the way down, along with my amps gain all the way down, and now I have no hissing noise!

Will fine tune it later from their, but its raining and sadly my new speakers just do not sound right.

Thanks gents.


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## sienna1 (Sep 4, 2009)

Aarmin said:


> Took the advice to turn my input level on the LOC all the way down, along with my amps gain all the way down, and now I have no hissing noise!
> 
> Will fine tune it later from their, but its raining and sadly my new speakers just do not sound right.
> 
> Thanks gents.


I ran into this same problem using LOCs with my OEM head-unit. I'm currently using an AudioControl LC6i that replaced a reQ-5 (hoping that this would solve the problem). The problem is with the head-unit not the LOC or amplifier. You'll find that once you replace the OEM speakers, etc..... that the already present high noise floor becomes more noticeable. You can minimize the hiss but reducing the input gains on the LOC and amp as was previously mentioned. Every piece of electronics in the chain will add some noise. I kept the LC6i because it was much more musical (detail, separation, depth....etc) than the reQ-5.


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## Aarmin (Mar 22, 2009)

That is what I am afraid of. 

Would more amplification increase the noise? I just bridged my amplifier, and although it added more depth to my speakers (especially midbass), it sounds as if I have more hiss noise. 

I do not hear the noise when playing music, except if I have the volume turned down. That is one thing, I actually sometimes listen to music at low volume.


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## Aarmin (Mar 22, 2009)

I feel like a noob :worried:

I played around some more this morning. I hooked my Alpine amp directly via speaker-level-inputs with the gain all the way down, and now I do not hear any hissing noise (at least in 4-channel mode) from the drivers seat. Only when I put my ear a couple inches from the tweeter, but that is normal?

I had a fealing the MX-1 LOC maybe created the noticeable noise; maybe the AudioControl and Clean Sweep are of good quality. I was also getting a turn-off pop sound, but no longer; another culprit of the MX-1.

I will try it in bridged mode (50watts is to shy for the Morels) whenever I find a turn on source to tape into, because my MX-1 LOC is currently used to turn on my amp.

I think I will stand by Alpine amps for high-level inputs! My Sony amp (installed before through speaker-level-inputs) added to much noise.


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